Dissertation no. 1
| Dissertation title |
Lactose recovery from cheese whey using membrane filtration in dairy industry |
| Student name |
Fatemeh Esfandian |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2016 |
| Supervisor |
Prof. Ali Asghar Ghoreyshi & Dr. Majid Peyravi |
|
Advisor |
Prof. M. Jahanshahi |
| Abstract |
Lactose recovery from cheese whey produced in the cheese whey was investigated by ultrafiltration and nanofiltration membrane processes to reuse from its valuable and nutrient compounds and decrease the environmental pollution of cheese whey. Accordingly, the cheese whey prepared from Kalleh dairy factory passed through fabricated ultrafiltration membrane to separate the protein and remove the impurities of whey. In the first part of this project, the ultrafiltration membranes were fabricated and evaluated for cheese whey ultrafiltration. In order to improve the structural parameters and performance of membranes, ultrafiltration membranes were fabricated with different concentration of LiCl (0, 0.1, 0.5, 1 wt %) and finaly 0.5 wt % LiCl was obtained as an optimum concentration. Then, the polysulfone/ sulfonated polyethersulfone blending ultrafiltration membranes were synthesized with blending ratios of 100/0, 50/50, 25/75 and 0/100 at the optimum concentration of LiCl. The results of the performance and fouling behavior in cheese whey filtration indicated that the ultrafiltration membranes comprise both two polymers (polysulfone and sulfonated polyethersulfone) had higher flux and desirable protein rejection. However, the ultrafiltration membrane with polysulfone/ sulfonated polyethersulfone ratio 0/100 showed lowest total resistance (0.61) and the highest rejection (93%). Then, permeate of synthesized ultrafiltration membrane was collected and passed through thin film composite nanofiltration membranes to recover the lactose which the 98% lactose recovery was obtained. Thin film composite membrane was synthesized by interfacial polymerization on sulfonated polyethersulfone sublayer. In order to modify the performance of membrane and change in the structure of top thin layer of composite membrane, 1.5 wt % of two ketone co-solvent (propanone and butanone) was added to organic phase. It was found that adding co-solvent to organic phase caused to change in membrane structure, reduce the roughness and increase the flux. Also, the rejection of these composite membranes didn''t significantly decrease. The highest value of flux related to thin film composite membrane with pororanone and was 10 Kg/m2.h. |
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Dissertation no. 2
| Dissertation title |
Ligand Immobilization on High Density Nano Porous Kappa Carrageenan Zinc Adsorbents and its Evaluation for Protein Nano Particles Separation |
| Student name |
Nastaran Tavakoli |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering-Biotechnology |
|
Publish year |
2016 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
Prof. Ali Asghar Ghoreishi |
| Abstract |
Kappa carrageenan-Zinc (Kc-Zn) chemical structure, with 75-250 μm particle size and 1.7g/ml density as a new expanded bed’s adsorbents matrix, evaluated for macromolecules and biologic nanoparticle adsorption in batch and expanded beds and compared with Streamline industrial adsorbents. Therefore, Tannic acid affinity ligand (TA) used for affinity matrix preparation for both Kc-Zn and Streamline structures. Egg Albumin or OvAlbumin protein and its nanoparticles were used as a target protein model. Effective various parameters such as pH and ionic strength that influence on protein adsorption function were investigated and results were used in experiments. Effects of time and initial concentration were studied in batch system and the highest capacity, 16.32 mg/ml was measured. Also, the pseudo-first-order and second-order kinetic models were used to describe the experimental kinetic results and the highest adsorption percent occurred in the initial 15 minutes. Experimental data was analyzed with Langmuir, Freundlich and Sips isotherm models and well matched with Langmuir model. Expanded bed adsorption breakthrough curves was studied for nanoparticle’s adsorption and effect of some parameters for instance, particle’s siz and feed velocity were assessed. While the velocity was increased, adsorbents showed a decrease in Dynamic binding capacity (DBC) and bigger particle size of adsorbent illustrated similar result too. Also this adsorbents showed better nanoparticles adsorption result in compared to protein’s macromolecules. |
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Dissertation no. 3
| Dissertation title |
Synthesis and evaluation of nano porous molecularly imprinted polymer “Dicamba herbicide” particles and its application in separation processes |
| Student name |
Tooraj Beyki |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering-Biotechnology |
|
Publish year |
2016 |
| Supervisor |
Dr. Mohamad Javad Asadollahzadeh |
|
Advisor |
Prof. Mohsen Jahanshahi |
| Abstract |
For the first time, uniform molecularly imprinted polymer (MIP) nanoparticles were successfully synthesized by precipitation polymerization in acetonitrile using dicamba as template, methacrylic acid (MAA) as functional monomer and trimethylolpropane trimethacrylate (TRIM) as cross-linker. The synthesized polymers were characterized by Fourier Transform Infrared (FTIR) spectroscopy and Differential Scanning Calorimetric (DSC). Furthermore, Scanning Electron Microscopy (SEM), Brunauer–Emmett–Teller (BET) analysis were utilized to investigate the morphological characterization. The MIP nanospheres were obtained with the average diameter of 234 nm and the specific surface area of 165.4 m2.g−1. Batch-wise guest binding experiments were carried out to determine the rebinding capacity of the produced MIP nanoparticles towards the template molecule. The binding characteristics were then assessed using Scatchard analysis and some well-known models. A quantitative description of the experimentally measured kinetics isotherms was also obtained using Pseudo 1st-order and Pseudo 2nd-order kinetic models. Finally, competitive binding experiments were carried out to evaluate the selectivity of the imprinted polymer nanoparticles. Compared with the corresponding non-imprinted polymer (NIP), the MIP exhibited higher adsorption capacity and outstanding selectivity towards dicamba in an aqueous solution. Langmuir–Freundlich isotherm best fitted the adsorption equilibrium data of MIP and the kinetics followed a pseudo 1st-order model. |
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Dissertation no. 4
| Dissertation title |
Membrane bioreactor using membrane-activated carbon hybrid for the treatment of industrial wastewater |
| Student name |
Fatemeh Aghili |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Prof. Ali Asghar Ghoreyshi |
|
Advisor |
Dr. Ahmad Rahimpour & Dr. Mostafa Rahimnejad |
| Abstract |
Advanced treatment of cheese whey wastewater (CWW) was investigated by hybrid batch mode membrane bioreactor (MBR) and adsorption process. In the first part of this study, the adsorption, activated sludge (AS) and combined activated sludge-adsorption (AS-PAC) processes were evaluated for reducing chemical oxygen demand (COD). The equilibrium and kinetic data for adsorption of organic matters in CWW onto three types of powdered activated carbons (PACs) were described by hybrid Langmuir–Freundlich and pseudo-second order models, respectively. The results indicated that AS-PAC process outperformed individual AS process in different COD concentrations. The most significant result was observed at the 7500 mg/L COD with 4 g/L of the broom sorghum PAC (BSPAC) which could improve COD removal efficiency from 52.3% for AS to 63.8% for AS-PAC process. Also, in this part the bioregeneration of PAC in AS-PAC process was demonstrated by modeling of the dynamic behavior of the AS, adsorption and AS-PAC processes in terms a set of coupled differential equations. In the second part, the BSPAC mixed matrix nano porous polysulfone membranes (MM-BSPAC/PS) were synthesized and characterized by field emission scanning electron microscope, atomic force microscopy and surface area analyzer. Also, the results of the performance and fouling behavior in CWW treatment indicated that the pure water flux and organic matters removal were about 200 L/m2h and 44% for the 0.5% MM-BSPAC/PS, respectively. As a consequence, the irreversible fouling rate (Rir) of the 0.5% MM-BSPAC/PS was about 17%, and it was more than that of other membranes while for this membrane the initial CWW flux was about 95 L/m2h. Also, PAC pre-coat technology was used for enhancing the treatment efficiency. The 30 g/m2 BSPAC coated 0.5% MM-BSPAC/PS could reduce the Rir to 2%. This technology also enhanced the COD removal and CWW flux up to about 95% and 130 L/m2h, respectively. Finally, hybrid batch mode MBR and adsorption process was run for advanced treatment of CWW with 10000 mg/L COD. After coagulation process as the pretreatment, CWW feed to the AS-PAC process and the COD was reduced to 2300 mg/L. Then, for advanced treatment of CWW the 30 g/m2 BSPAC coated MM-BSPAC/PS membrane configuration was used, and at the end of hybrid process, the COD reached to about 130 mg/L. |
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Dissertation no. 5
| Dissertation title |
Preparation and modification of nanoporous ultrafiltration membranes using funcshionalized chitosan for protein separation |
| Student name |
Samaneh Mokhtari |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Dr. Ahmad Rahimpour |
|
Advisor |
Dr. Setareh Habibzadeh |
| Abstract |
Due to their excellent chemical resistance, good thermal and mechanical properties, Polysulfone and Polyeyhersulfone membranes are widely used in ultrafiltration. However, in the application involving protein solution, because of the inherent hydrophobic characteristic of the protein, adsorption on the membrane surface and in the pores often cause serious membrane fouling and a rapid decline of permeation flux. The main purpose of this project is surface and morphology modification of polysulfone and polyethersulfone membranes. Thus three kinds of modified membranes were fabricated. In the first, chitosan and polyvinyl alcohol, two highly hydrophilic polymers, were used to modify the hydrophobic polysulfone membranes surface by a dip-coating method. The results of field emission scanning electron microscopy and Fourier transform infrared spectroscopy study of modified membranes indicated that chitosan and polyvinyl alcohol were well coated on polysulfone membrane surface. The results of water contact angle measurement and atomic force microscopy showed that the hydrophilicity and smoothness of polysulfone membranes were significantly improved. Results showed that increasing coating time and concentration cause higher rejection and lower water flux. In addition ultrafiltration performance of unmodified polysulfone membrane improved. UF-P0.2 membrane (modified by 0.2 %wt polyvinyl alcohol and coating time of 2 min) with 205.4 L.m-2.h-1 flux, 96.6% rejection, 81% FRR and 19% Rir and UF-C0.075 membrane (modified by 0.075 %wt chitosan and coating time of 20 sec) with 150.75 L.m-2.h-1 flux, 98.7% rejection, 84% FRR and 16% Rir showed best performance among the fabricated membranes. In second kind, the influences of Salicylate alumoxane nanostructures incorporation to the casting solution were investigated in terms of hydrophilicity, permeation performance, morphology and antifouling properties. Results indicated that by use of 0.1 wt% nanostructures, the pure water flux of the membranes reached to the maximum about 300 L.m-2.h-1. The nanocomposite membrane containing 1 wt.% of Salicylate alumoxane, because of its optimum performance in 143.2 L.m-2.h-1 flux, 99.3% rejection, highest FRR value of 87% and the lowest irreversible fouling resistance value of 13%, was chosen as the best choice. In the third kind, different content of epoxy-functionalized chitosan (ECS) incorporated to the polyethersulfone casting solution. The results of water contact angle measurement showed that the hydrophilicity of polyethersulfone membranes was significantly improved. By addition of 1%wt ECS, BSA flux and rejection were increased from 105.6 to 139.5 L.m-2.h-1 and from 96.2% to 98.8%, respectively. Comparison of modified membranes with unmodified membranes indicated that flux recovery increased to 42% and Rir decreased to 33%, representative good antifouling properties of modified membranes. |
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Dissertation no. 6
| Dissertation title |
Modification of cellulose triacetate membrane using carbon nanofibers for forward osmosis application |
| Student name |
Zoheir Dabaghian |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Dr. A. Rahimpour |
|
Advisor |
Prof. M. Jahanshahi |
| Abstract |
In this work, forward osmosis (FO) cellulose triacetate (CTA) membranes were fabricated via phase inversion method and then were modified using carbon nanofibers (CNFs) for FO application. At the first, CNFs were functionalized with various hydrophilic functional groups such as carboxyl and amine groups in order to make a hydrophilic property. Fourier transform infrared spectroscopy (FTIR) evidenced the formation of functional groups on the CNFs. In the first part of this work, the low different contents of carboxylated CNFs (0.25, 0.5 and 1 wt%) were added in the casting solution as additive to improve the FO performance of membrane. The synthesized FO membranes were characterized in terms of surface properties, structure of membranes, intrinsic separation properties and as well as FO performance and subsequently compared with commercial membrane. The membrane surface hydrophilicity was enhanced with increasing carboxylated CNFs content in the casting solution. The FO experiments were performed by 10 mM NaCl solution as a feed solution and 1 M NaCl solution as a draw solution in both orientation of membrane. The modified membrane exhibited the most promising results by showing superior performance in term of higher water flux and low solute diffusion in comparison with the commercial and neat membranes. The water flux of the prepared membrane reached to a maximum of 15.6 L/m2 h which is nearly 2 times as high as that of neat membrane in 0.5 wt% carboxylated CNFs as optimal content. Also the reverse salt flux of this membrane is less than 0.5 g/m2 h. In the second part of this work, forward osmosis CTA membranes were synthesized by introducing 0.5 wt% of pristine carbon nanofibers (optical content), carboxylic and amine functionalized CNFs into casting solution. The osmotic water flux of the modified membrane using amine functionalized CNFs reached to a maximum of 18 L/m2 h when 10 mM NaCl solution as feed and 1 M NaCl solution as draw solution which is above 2 times as high as that of the neat CTA. Also mid-term FO test was perfumed by seawater as feed solution in order to investigate the effect of ICP phenomena which, membrane modified with functionalized CNFs show a much smaller reduction in water flux during experiment. The low structural parameter (s = 0.52–0.58 mm) and membrane behavior in mid-term test indicated hydrophilic functional groups on CNFs with increment of porosity significantly improved membrane performance as well as increased membrane resistance against ICP. This work indicates that the CTA membranes modified with hydrophilic porous CNFs are promising for practical FO applications.¬¬¬¬ |
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Dissertation no. 7
| Dissertation title |
Fabrication and modification of flat and hollowfiber membrane using CNF |
| Student name |
Azimberdi Sayyadli |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Dr. A. Rahimpour |
|
Advisor |
Prof. M. Jahanshahi |
| Abstract |
In this study, polysulfone (PSf) ultrafiltration membranes were fabricated via phase inversion method and then modified by carbon nanofibers (CNFs) in casting solution. Due to the intrinsic hydrophobicity of carbon nanofibers and insolubility in polar solvents, various methods for proper dispersion of the CNF were considered. Because of the relative compatibility of Normal methyl pyrrolidone (NMP) to the CNF compared to other solvents, this solvent was used for the nanofibers distribution. For appropriate dispersion of carbon nanofibers in the polysulfone membrane’s casting solution, 2 methods of nanofibers functionalization and the use of surfactants were investigated. The results indicate that the addition of 1wt% surfactant Triton X-100 to the casting solution causes better distribution of CNFs and improves the performance of ultrafiltration membranes in bovine serum albumin aqueous solution separation. The flat-sheet membranes containing different content of pristine and functionalized CNFs were fabricated and tested in cross-flow ultrafiltration process. The membrane contain 0.2wt% CNF showed the highest amount of distilled water flux of about 138.8 LMH. By increasing the percentage of nanofibers from 0.02 to 0.1, protein resistance improved and flux recovery increased from 77.4 to the desired level of 100%. The optimized composition of flat-sheet membranes was used in fabrication of hollow fiber membranes by dry-wet method and then evaluated in cross-flow filtration. FTIR analysis confirmed the presence of carboxyl and hydroxyl functional groups on the surface of functionalized CNFs. In addition, the presence of these hydrophilic groups led to hydrophilicity increment of nanocomposite membranes and due to this fact the surface contact angle of the nanocomposite membrane decreased. But due to the hydrophobic nature of CNFs, no distinct change was observed in hydrophilicity of the CNF nanocomposite membrane compared to pure polysulfone membrane. The FESEM analysis of the CNF containing membranes compared to the net ones revealed considerable increase in the surface porosity of the both the flat-sheet and hollow fibers module. |
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Dissertation no. 8
| Dissertation title |
Synthesis and application of nano pore molecularly imprinted polymer (MIP) membranes for selective recognition and separation of pesticides from water or wastewater |
| Student name |
Tannaz Kashani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
For the first time, In the present Study nano pore molecularly imprinted polymer membranes for selective separation of 2,4-dichlorophenoxyacetic acid were prepared and evaluated. 2,4-dichlorophenoxyacetic acid (2,4-D) is a herbicide widely used for broad-leaved weeds and is classified as a possible carcinogen and mutagen by the International Agency for Research on Cancer. Regarding what is said, in this study 2,4-D was chosen as the target molecule to produce nano pore molecularly imprinted polymer membranes .At first, nano pore molecularly imprinted polymers prepared by precipitation polymerization and using 2,4-D as a template molecule, methacrylic acid (MAA) as functional monomer and trimethylolpropane trimethacrylate as cross linker (TRIM). Produced MIPs were dispersed in Polysulfone in different mass ratio and then molecularly imprinted membranes were prepared in flat sheet form using phase inversion method. Recognition properties of MIPs and MIMs were evaluated by performing binding experiments with the template and its structural analogue phenoxyacetic acid (POAc). Flux, Permeability and permselectivity of membranes were studied. Also, their properties were characterized by scanning electron microscopy (SEM), atomic force microscopicy (AFM) fourier transform infrared (FT-IR) and Brunauer–Emmett–Teller (BET) analysis. Synthetic molecularly imprinted polymers have an spherical structure with a mean diameter of 550 nm and average pore diameter of 14 nm. Results from binding experiments at 2,4-D aqueous solution with 500 mg/l concentration, demonstrated that MIP and MIM-2 with the best performance among other membranes have equilibrium binding capacity 34.6 mg/g and 34.57 mg/g, respectively. Further, This membrane exhibited a selectivity factor of 12.96 towards 2,4-D at 500mg/l concentration. Results from permeability experiments on aqueous solutions of 2,4-D indicated that MIM can recognize 2,4-D molecule and can be used in selective separation of 2,4-D from aqueous samples. |
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Dissertation no. 9
| Dissertation title |
Modification of thin film nanocomposite forward osmosis membrane support layer structure for controlling internal concentration polarization |
| Student name |
Fatemeh Pourhosein Alamdari |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
Forward osmosis (FO) process has attracted increasing interest because of its potential applications for low energy desalination. However, the internal concentration polarization (ICP) has been considered as one of the key issues that can significantly reduce the water flux across the FO membrane. In this study thin film composite membrane were synthesized by interfacial polymerization on polysulfone supporting membrane for forward osmosis application. Different preparation conditions on forward osmosis membrane including polymers and silica nanoparticle concentrations were discussed. The prepared membranes were characterized by ATR-FTIR, SEM, AFM and hydrophilicity measurement. The FO performance was evaluated using 10mM NaCl solution as feed solution and 2M NaCl solution as draw solution in both orientations. The result showed where increasing Polysulfone and polyvinylpyrrolidone concentration resulted in higher salt rejection and FO water flux. The desired FO membrane prepared under the optimum condition (16 w/w% PSF, 2 w/w% PVP) exhibited a NaCl rejection of 82% and FO water flux 9.45L/m2h. The nanocomposite substrates (PSFN) were prepared by incorporating different amounts of sio2 nanoparticles (ranging from zero to 1-3 wt.%) into PSf matrix. The nanocomposite substrates so prepared were then characterized with respect to hydrophilicity, overall porosity, surface roughness and cross-sectional morphology. It was found that both hydrophilicity and porosity of the substrate were increased upon addition of sio2. In addition, long finger-like structures were developed by increasing the sio2. The thin polyamide active layer was fabricated by interfacial polymerization on the nanocomposite substrate, and the resulting PSFN-TFC membrane showed significantly enhanced water permeability compared to the TFC membrane prepared on a conventional polysulfone substrate. The water flux of the (PSFN-TFC) membrane reached to a maximum of 17/57 ± 1 L/m2h which is nearly 2 times as high as that of the TFC membrane. The increase in water permeability can be attributed to decrease in structural parameter which resulted in decreased internal concentration polarization (ICP). Based on the results obtained in this work, it can be concluded that adding an appropriate amount of sio2 nanoparticles into PSf substrate could potentially improve the performance of thin film composite(TFC) membrane during FO applications. |
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Dissertation no. 10
| Dissertation title |
Preparation, evaluation and application of Nanobiostructures of Clove oil for food application and prolongation of food product storage |
| Student name |
Mohammad Hassan Shahavi |
|
Degree |
Ph.D |
| Field of study |
Chemical Engineering-Biotechnology |
|
Publish year |
2015 |
| Supervisor |
Dr. Morteza Hosseini & Prof. Mohsen Jahanshahi |
|
Advisor |
Prof. Ghasem D. Najafpour |
| Abstract |
Clove oil is rich in organic phenolic compounds, known as Eugenol having many potential applications in food, agricultural, pharmaceutical and cosmetic. In order to build an environmental friendly nanopesticide that can easily be used in spraying, clove oil nanoemulsions prepared and evaluated with the use of surfactants Tween® 80 and Span® 80 via ultrasound emulsification methods. The effect of important parameters in the preparation of nanoemulsions, including the cycle duty of ultrasound, ultrasound intensity, ultrasonication time and clove oil content were evaluated. The nanopesticides made by ultrasound at various clove oil concentrations were defined at ultrasonication time of 300 seconds, duty cycle 0.75% and ultrasonic intensity 208 W/cm2. The stability of droplets size of nanoemulsions for long duration (6 months) was evaluated. The results of optimum conditions (10% oil) after 180 days showed that clove oil nanoemulsion had high physical stability (average droplet size of 43 nm to 100 nm). Inasmuch as, the results of the optimization factors in clove oil nanoemulsion prepared with maximum stability (-40.7 mV), minimizing the polydispersity index (0.49) and average droplet size of 50 nm with Taguchi design method to measure the antibacterial activity of clove oil nanoemulsion on the pathogens to determine MIC and MBC on Escherichia coli; those were 16, 16 and Bacillus cereus, 32 and 64 μg/mL, respectively. These results represented the highest antibacterial activity of clove oil nanoemulsion optimized by Taguchi design method against the mentioned bacteria. Enhanced applications and protected clove oil from volatilization and oxidation, encapsulation in nano scale by biocompatible polymers via ultrasonication emulsification were studied by 28 various formulas of combination of three mixture and one process factor via D-optimal design. The effective parameters such as clove oil content (2 to 10 wt%), active emulsifier level (0-4% wt%), Arabic gum (0-20 wt%) and whey protein concentrate (0-20% wt%) were investigated. The experimental data obtained were analyzed by analysis of variance (ANOVA). Optimum formulated products with minimum size of the average particle diameter, clove oil nanocapsules were evaluated. Under optimum conditions, particle size of encapsulated clove oil was 128.2 ± 4.3 nm. In the final stage, molecular imprinted polymer with high performance was identified and the encapsulation of eugenol in nanometer scale was used. In preparation of molecular imprinted polymer polymerization with methacrylic acid as functional monomer and trimethylolpropane trimethacrylate as the cross-linking agents were employed. The results showed that the molecular imprinted polymers had maximum adsorption capacity of eugenol (41.6 mg/g) than non-molecular imprinted polymers. Furthermore, the results showed that the molecular imprinted polymer is an excellent choice with active sites to interact with eugenol from clove oil (with adsorption efficiency 85.74%). |
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Dissertation no. 11
| Dissertation title |
Fabrication and Modification of composite and mixed matrix membrane with nanoparticles for CO2 from CH4 gas separation |
| Student name |
Asieh Dehghani Kiadehi |
|
Degree |
Ph.D |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Prof. Mohsen Jahanshahi & Dr. Ahmad Rahimpour |
|
Advisor |
Prof. Ali Asghar Ghoreishi |
| Abstract |
Selectivity and permeability are the major parameters in gas separation process. Hence, nowadays in order to improve aforementioned parameters, modification and enhancement issues for such membrane have been highly noticed. In this study, in order to increase performance of the polymeric membrane, Carbon nanofiber (100 nm diameter and 20-200 µm Length) and TiO2 nanoparticles (Medium-sized particles 25nm) were added to the mixed matrix membranes. These nanoparticles with various concentrations are added to the polysulfone solution. Then, their performance and structure from selectivity and permeability point of view are analyzed. The carbon nanofibers were used due to high porosity characteristic and gas selective absorption in the structure of the polysulfone membrane. The results show that with increasing CNF concentration 0.01 to 1wt. %, CNFs/PSF membrane selectivity from 4.73 to 12.08 enhanced. The fabrication of MMMs usually involves difficulties such as weak contact of the fillers in the polymer matrix and poor distribution of the fillers in the polymer matrix phase; as the result, gas selectivity decreases. To solve such problem, ethylenediamine (EDA) were implacemented as surface functional groups on the nano materials. The results showed that with increasing the functional carbon nanofibers in the mixed matrix membranes from 0.5 to 1.5 wt.%, the permeability was increased from 0.48 to 4.5 GPU respectively. Then, different concentration of functionalized and non functionalized TiO2 (2 to 10 wt.%) were added to polymeric solution for synthesizing mixed matrix membranes. Membrane structure and performance indicated that functional amine groups improved membranes properties. So the permeability and selectivity of both CO2 and CH4 gases in perecens of functionalized nanoparticles was increased 2 times compared to non functionalized nanoparticles. The last step of this study a thin polymeric layer with polydimetilsiloxane was used on the top of based polymeric membranes to synthesize of composite membranes. Also different concentration of functionalized carbon nanofibers from 0.5 to 1.5wt.% were added to the polydimethy siloxan solution. The results of performance of these membranes indicate that a presence of functional carbon nanofiber were enhanced selectivity of composite membranes from 3.47 to 5. |
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Dissertation no. 12
| Dissertation title |
Influence of draw solution in forward osmosis process |
| Student name |
Zahra Shabani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Dr. A. Rahimpour |
|
Advisor |
Prof. M. Mohsen Jahanshahi |
| Abstract |
Forward osmosis (FO) is an emerging membrane separation process for desalination. However, employing suitable draw solute is a big challenge. In this work, we synthesized hydrophilic magnetite nanoparticles through the co-precipitation approach and their performance of FO as draw solution were evaluated. Ascorbic acid, chitosan, starch and polyvinyl alcohol were used as functionalizing agents to enhance the dispersibility and stability of magnetic nanoparticles. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) showed that the morphology of the magnetic nanoparticles were spherical. X-ray diffraction (XRD) patterns indicated that the synthesized magnetite nanoparticles were pure. Vibrating sample magnetometer (VSM) showed the saturation magnetization value of magnetite nanoparticles amounted to 83.8 emu/g. Fourier transform infrared spectroscopy (FTIR) analysis was used to confirm the interactions between the Fe3O4 particles and coating agent. The application of these water-soluble magnetic nanoparticles as draw solutes in forward osmosis (FO) was investigated. Cellulose triacetate membrane were synthesized by immersion precipitation process for forward osmosis application.The FO performance was evaluated using deionized water and 10mM NaCl solution as feed solution and the synthesized magnetite core-shell nano composites as draw solute. The results demonstrated that magnetic nanoparticles coated with dehydroascorbic acid can generate the highest driving force and consequently highest water flux among others. By increasing the concentration of magnetic nanoparticles coated with dehydroascorbic acid from 0.01 to 0.06 g/L, flux increased from 4.33 to 7.1 L/m2.h. These nanoparticles can be easily separated from the diluted draw solution by an external magnetic field. |
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Dissertation no. 13
| Dissertation title |
Preparation and Evaluation of Nanostructured membrane with self-cleaning properties for landfill leachate treatment |
| Student name |
Nader Shafaei |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Prof. Mohsen Jahanshahi & Dr. Majid Peyravi |
|
Advisor |
Prof. Ghasem D. Najafpour |
| Abstract |
To create self-cleaning and improve antifouling property, Polysulfone (PSf) membranes were modified with WO3 and Polyaniline (PANI) nanoparticles (0-2 wt. %) via phase inversion method for ultrafiltration of landfill leachate. To evaluate the role of UV light on self-cleaning property, all synthesized membranes were tested with and without UV. For this purpose, first the effect of using WO3 nanoparticles in the membrane structure was investigated and then adding both WO3 and PANI nanoparticles into the casting solution was evaluated. In the first case, Contact angle measurements showed that the angle of membrane with 1wt. % WO3 as a modified membrane decreased from 71.6° to 39.7°. Results show that the addition of WO3 affects the pore size, porosity and hydrophilicity of the WO3/PSf membrane; as, the porosity for 2wt. % WO3 achieved to 84.86%. The flux of the membrane with WO3 nanoparticles after being radiated by UV light was increased in comparison to the same membrane without UV light and the flux decline rates were also decreased by UV light for modified membranes.The flux of the membrane with 2 wt. % WO3 was also better than the other modified and neat membranes. This fact indicates that the self-cleaning property have been created by WO3 nanoparticles on the surface of membrane in the presence of UV light. The Chemical Oxygen Demand (COD) removal of leachate for modified membranes were also improved with increasing the WO3 nanoparticles and the highest COD removal of the modified membrane was 54.91% which was belong to the membrane with 2 wt.% WO3. This was increased to 77.45% after UV radiation. In the second case, the WO3 mass ratio in nanoparticles concentrations was varied: 0, 40 and 60 wt. %. Contact angle measurements showed that the angle of measurement decreased with increasing the nanoparticles concentration. The membrane hydrophilicity indicates that the modified membranes displayed higher porosity, more finger like pores than the PSf neat membrane; as the porosity for modified membrane with 2 wt. % PANI achieved to 86.8%. UV light has been effected on membranes including WO3 nanoparticles and improved the flux permeation. The flux before UV radiation has improved by enhancing the ratio of PANI/ WO3 in loading nanoparticles. For each loading of nanoparticles without UV radiation, the Flux Recovery ratio (FR) was also increased by enhancing the ratio of PANI/WO3 nanoparticles, while the capability of membranes having WO3 nanoparticles indicated better antifouling abilities after UV radiation and it has reached to 98.87% by increasing WO3. This fact demonstrates that WO3 nanoparticles have created the feature of self-cleaning on the surface of the membrane in the presence of the UV light. The Chemical Oxygen Demand (COD) removal of leachate for modified membranes were also improved. The membrane containing 2 wt. % loading nanoparticles has highest COD removal before (76.65 %) and after (78.42%) UV radiation. |
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Dissertation no. 14
| Dissertation title |
Synthesis and improvement of Metal Organic Frameworks (MOF) structure for hydrogen storage |
| Student name |
Saeed Khoshhal Salestan |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2015 |
| Supervisor |
Prof. S.A. ghoreishi |
|
Advisor |
Prof. M. Jahanshahi |
| Abstract |
In this study a special kind of metal organic frameworks (MOFs), named as Cu-BTC, was synthesized and its hydrogen storage capability was investigated. This adsorbent was synthesized at atmospheric pressure using ultrasonic and reflux condition technique. In order to identify the effects of solvent content, reaction temperature and effect of a pattern in synthesis process on the structure and hydrogen adsorption capacity of this nanostructure, three different solvent content, three different temperatures and SiO2 nanoparticles were tested. The MOF structure were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), Energy dispersive X-ray (EDX), Thermogravimetric analysis (TGA), Differential scanning calorimetry (DSC) and N2 adsorption/desorption at 77 K. Hydrogen adsorption experiments were carried out at ambient temperature using the volumetric technique in a dual cells apparatus. The optimized operation conditions were selected in sample preparing. It was found that increasing solvent content during synthesize of Cu-BTC is effective in enhancement of hydrogen uptake to a certain amount. The sample synthesized at 80 °C shows 0.1 wt% hydrogen adsorption capacity more than the sample synthesized at 140 °C and this enhancement is attributed to the increase of crystallinity and micropore volume. Also by using of SiO2 nanoparticles, smaller and regular crystals were achieved. The isosteric heat of adsorption was calculated by substitution of Freundlich equation with temperature dependent parameters in Clausius-Clapeyron equation. The results demonstrated that isosteric heat of hydrogen adsorption was monotonically decreased with surface loading. Also, the n-the order kinetic model was successfully applied to describe experimental kinetic data considering the order of adsorption reaction as an adjustable parameter. The value of 1.59 obtained for the order of kinetic model indicated that the adsorption process mechanism follows a combination of physisorption and chemisorption. |
| |
Dissertation no. 15
| Dissertation title |
E-spun Cellulose Acetate Nanofiber Containing a Herbal-Froriepia subpinnate-Extract/ White-cheek Shark (Carcharhinus dussumieri) Fish Skin Gelatin Nanocomposite Edible Films: Fabrication, Structure, and Characteristics |
| Student name |
Hoda Shahiri Tabarestani |
|
Degree |
Ph.D |
| Field of study |
Food Science and Technology |
|
Publish year |
2015 |
| Supervisor |
Dr. Naser Sedaghat, Prof. Mohsen Jahanshahi |
|
Advisor |
Dr. Ali Motamedzadegan, Dr. Mohebbat Mohebbi |
| Abstract |
The purpose of this study was to investigate the potential of Froriepia subpinnate herbal extracts, Electrospun Cellulose Acetate Nanofibers (ECAN), and Froriepia subpinnate herbal extracts (1%, 3%, and 5%)-loaded Electrospun Cellulose Acetate Nanofibers (F1ECAN, F3ECAN and F5ECAN) to improve the mechanical properties, barrier, physical, appearance, microstructure, thermal stability, and antioxidant activity of edible film based on white-cheek shark (Carcharhinus dussumieri) fish skin gelatin (WSG). In this regard, after fish gelatin extraction in the optimal pretreatment conditions and determination of the biophysical properties of the gelatin (WSG) biopolymer, the optimum point for the WSG film formula were found to be 3.3% WSG, and 19.3% glycerol. Then, with the aim of improving the physico-chemical and antioxidant properties, active biodegradable films based on WSG were developed by the incorporation of Froriepia subpinnate herbal extract (1%, 3%, and 5%) to the film forming solution. The incorporation of the Froriepia subpinnate herbal extract into the films gave rise to a pronounced increase of opacity and tensile strength (TS) with minor modifications of the elongation at break (E@b), decrease of the film water vapor permeability (WVP) and solubility. According to the results of FTIR, adding the herbal extract led to the considerable changes on the helix conformation and the secondary structure of WSG film. Moreover, according to the SEM micrographs, for the active WSG films denser, more compact internal structure, and uneven surface were observed, with the complete significant agreement of roughness increase compared to the WSG film without extract. The antioxidant properties of active WSG films especially radical scavenging capacity by the DPPH assay and reducing ability by the FRAP assay showed the value of 8.34-11.4 and 3.15-11.17-fold higher than WSG film without extract, respectively. Considering the results of TGA, DSC and DMTA it is noted that active WSG films, particularly at a concentration of 3% herbal extract showed firmer network with more ordered structural fraction compared to the control film, and thus required higher enthalpy for the destruction of intermolecular interaction. In the other part of this research, electrospun cellulose acetate nanofiber was prepared using 2-step optimization statistical method including Plackett-Burman design (PBD) for the screening of significant process variables of electrospinning condition and solution parameters and Response surface methodology (RSM) to obtain a quantitative relationship between selected electrospinning parameters and average fiber diameter. According to the results, using the solution flow rate of 0.75 mL/h, voltage of 17 kV, and cellulose acetate concentration of 13.89% led to the formation of bead-less fiber with the average size of 240 nm. At the same time, electrospinning technique was successfully done as a single-stage for nanoencapsulation of herbal extracts and practical potential of neat and functional cellulose acetate nanofibers as the nanofillers of the WSG nanocomposites and nanoactivecomposite were evaluated. Regardless of the type of CA nanofibers (neat or functional) with increasing its concentration in the WSG matrix, significant changes in the thermal stability, higher Tg, the higher degree of crystallinity, improved TS, and reduced WVP was obtained. According to XRD, WSG-ECAN nanocomposites showed higher degree of intercalation compared to those of the WSG-FECAN nanoactivecomposites. |
| |
Dissertation no. 16
| Dissertation title |
Fabrication and Evaluation of High Density Nano Porous Adsorbent Suitable for High Flow Rates in Expanded Bed Process |
| Student name |
Sadaf Mohsenkhani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering-Biotechnology |
|
Publish year |
2015 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
Expanded bed adsorption as an innovative technology in bioproduct separation has significant advantage in compare with the other separation methods. This technique integrates purification steps in a single unit operation. Aiming at reduced operational time, less requirements for capital investment and consumables and increased overall yield. To form a stable expanded bed, Proper adsorbent design is necessary. Essential adsorbent properties such as physical and chemical stability, porosity, hydrophilicity and adsorption capacity depend on polymeric layer in adsorbent matrix. In this study by investigating on different types of biopolymers a novel composite matrix with kappa carrageenan as polymeric layer and zinc powder as densifier were prepared by water-in-oil emulsification method and named as Kc-Zn. In order to characterize the morphology and structure, prepared composite matrix were observed by optical microscope and scanning electron microscope. Composite beads showed good spherical shape with nano-scale pores and suitable size distribution in range of 50-320 µm. mean particle diameters was in the range of 158.8-215.9 µm and pore size was estimated in range of 60-180 nm. The other important properties of prepared composite particles were also determined. The results showed that prepared composite matrix had a suitable wet density in the range of 1.39-2.27 g/ml, water content of 72.67-36.41% and porosity of 98.07-80.24%. Performance of prepared composite matrix in an expanded bed were investigated by RTD experiments. The results indicated that in a constant liquid velocity by increasing the density of matrix, expansion factor of bed was decreased and axial mixing coefficient was increased. The obtained results determined that kappa carrageenan-Zinc matrix showed suitable expansion properties and formed stable and uniform expanded bed. Thus, prepared matrix showed good potential for possible use in high flow rate expanded bed operation. Also, physical and hydrodynamic properties of prepared Kc-Zn matrix were compared with commercial Streamline DEAE. Results indicated that prepared matrix could form more stable expanded bed and are suitable for expanded bed processes. |
| |
Dissertation no. 17
| Dissertation title |
Preparation and characterization of hollow fiber thin-film composite nanofiltration membranes for water treatment |
| Student name |
Zohreh Abolfazli |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Ahmad Rahimpour |
|
Advisor |
Dr. Mohsen Jahanshahi |
| Abstract |
In this study, initially, polysulfone hollow fiber ultrafiltration membranes were fabricated using wet-drying spinning method and used as a substrate.Then, hollow fiber thin film composite membranes were synthesized by interfacial polymerization reaction between Piperazine (3% w/v) as an amine monomer and Trimesoyl chloride (0.5% w/v) as an organic monomer on the substrate and modified with three methods. In the first method, fabrication and modification of composite nanofiltration hollow fiber membranes were investigated by adding Piperazine in the casting solution and after that, interfacial polymerization method was studied. After fabrication of polysulfone substrate containing Piperazine, composite membranes were fabricated by the interfacial polymerization process and the effect of Piperazine on the membranes performance was investigated, eventually. As the second method, synthesizing and modification of composite nanofiltration membranes using tri-ethylene tetra amine (0.5, 1, 2, 4, and 10% w/v) as the hydrophilic agent in aqueous phase were studied and the effect of additive concentration on membrane performance was investigated. In the third method, the silica nanoparticles (0.005, 0.05, 0.1 and 0.5 w/v) were used as additive to the aqueous phase for fabrication and modification of nanocomposite membranes and the effect of nanoparticles concentration on the membrane performance was studied. Membranes were characterized by infrared spectrometry, scanning electron microscopy (SEM), atomic force microscope (AFM), and surface hydrophilicity measurements (contact angle). The results showed that in a new method of fabrication and modification of the composite hollow fiber membranes in the presence of Piperazine, solvent flux (23.25 l/m2hr) and salt rejection (27.42 %) were improved. Also, the results of the experiments for triethylene tetra amine modified composite hollow fiber membranes showed that by increasing of concentrations of triethylene tetra amine, flux rates were improved. Also, the results of addition of silica nanoparticles showed that the rejection rate increased by increasing of nanoparticles concentration. Finally, the results of the experiments for both of triethylene tetra amine (4%) and Silica (0.1%) modified composite hollow fiber membranes showed that flux (30.66 l/m2hr) and salt rejection (26.05 %) were improved. |
| |
Dissertation no. 18
| Dissertation title |
The Use of Nanotechnology in Order to Improve the Performance of Membrane Electrode Assembly (MEA) of Hydrogen Fuel Cells through the Electrocatalyst and New Catalyst Layers |
| Student name |
Maryam Yaldagard |
|
Degree |
Ph.D |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Naser Seghatoleslami |
|
Advisor |
Prof. Mohsen Jahanshahi |
| Abstract |
In this thesis in the first part nanocomposite films of Pt-Co nanoparticles deposited on graphene nanoplate based gas diffusion layer electrode are fabricated via an electrochemical route involving a series of electrochemical process. Pt-Co nanoparticles of 11.37 nm in average size are prepared by galvanostatic codeposition on the surface of in situ reduced graphene nanoplates on carbon paper. The topographical features, structure, morphology and composition of the prepared film samples are characterized by Atomic Force microscopy, Raman Spectroscopy, FTIR analysis, X-ray Diffraction, FESEM and EDS. At the same time, the catalytic activities of prepared electrodes for the oxygen reduction reaction are evaluated through cyclic voltammetry, linear sweep voltammetry and chronoamperometry and electrochemical impedance spectroscopy measurements. Raman spectroscopy measurements confirmed the graphitic structure of the produced graphene nanoplates. The nanoparticles in the film were observed to be uniform spherical objects and well distributed. Catalytic properties of Pt-Co/GNP/GDL electrode were compared with Pt/C/GDL using half cell polarization measurements based on both mass activity and specific activity. The as prepared Pt-Co/GNP/GDL electrode exhibits high catalytic activity for the ORR, which may be attributed to structural changes caused by alloying and the high specific surface area of graphene nanoplates catalyst support. In the second part a Pt/PANI/WC/C electrocatalyst was developed to increase the methanol electro-oxidation and oxygen electro-reduction activity and stability of commercial Pt/C electrocatalyst. WC/C was coated with protonated polyaniline (PANI) in situ during the polymerization of aniline. Fourier transform infrared (FTIR) results illustrate the presence of PANI in the composite. The conductivity of PANI coated - WC/C has been compared with the conductivity of the corresponding mixtures of WC/C and Vulcan XC-72. X-ray diffraction results showed that Pt particles were dispersed on the support with mean particle size of about 10.56 . Transition electron microscopy images showed that the nanosized WC/C were successfully coated by PANI. Based on the electrochemical properties characterized by cyclic voltammetry, CO stripping and rotating disk electrode measurements it was found that the as prepared Pt/PANI/WC/C electrocatalyst exhibited a comparable activity for methanol oxidation reaction and oxygen reduction reaction with respect to the commercial one. A significant reduction in the potential of CO electro-oxidation peak from 0.75V for Pt/C to 0.52 V for Pt/PANI/WC/C electrocatalyst indicates that an increase in the activity for CO electro-oxidation is achieved by replacing the carbon support by PANI coated WC/C .Chronoamerometry results also showed, in the presence of methanol the Pt/PANI/WC/C electrocatalyst still maintains a higher current density than Pt /WC/C and Pt/C. In third part novel successive two–step methods have been developed to efficiently prepare Cu/Pt-Pd core-shell structured catalyst on uncatalyzed Nafion–bonded carbon paper electrode for polymer electrolyte membrane fuel cell. Copper nanoparticles with diameter size distribution of 84-160nm are obtained by modulation potential electrodeposition.In copper electrodeposition the charge-transfer step is fast and the rate of growth is controlled by the rate of mass transfer of copper ions to the growing centers. After the copper electrodeposition the replacement of Cu by PtPd occur spontaneously by an irreversible redox process. The nature and composition of PtPd/Cu on pretreated carbon paper are characterized by field emission–scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX) spectroscopy respectively. The as prepared PtPd/Cu electrode is found in the form of core-shell structured with uniform dispersion on the surface with average nanoparticles of 41.5 nm in diameter. Electrochemical activity of PtPd/Cu and convectional Pt/C on pretreated carbon paper electrodes toward oxygen reduction reaction are studied by linear sweep voltammetry experiments. Low values of Tafel slope and free activation energy indicate that Cu/PtPd with core-shell structure possess a greater electrochemical activity than convectional Pt/C catalyst. ECSAs results also show that Cu/PtPd with core-shell structure has a higher stability than Pt/C electrode. In section fourth the PANI conductive polymer in order to promote the composition of macro- porous layeron gas diffusion layer was introduced toVulcan and the performance of membrane electrode assembly were evaluated in single cell. Results indicate the significant improvements in MEA with modified macro-porous layer compared with unmodified macro-porous layer. |
| |
Dissertation no. 19
| Dissertation title |
Preparation and surface modification of reverse osmosis membranes with high permeability for sea water filtration |
| Student name |
Asieh Peyki |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Ahmad Rahimpour |
|
Advisor |
Dr. Mohsen Jahanshahi |
| Abstract |
In this project, the preparation of thin film composite reverse osmosis membrane through the interfacial polymerization between an amine and a poly acyl chloride was studied. This membrane consists of three layers, that each of which are produced by a separate mechanism. A very thin polyamide layer that plays a major role in the separation performance, a porous polysulfone layer with the sponge structure which is required to operate at high pressure, and a polyester layer. In the first stage of this project, some effective parameters such as amine concentration, reaction temperature and immersion time in amine solution on the interfacial polymerization reaction, were investigated. Each of these parameters affect on the flux and the rejection of membranes, separately. The lower amin concentration, the higher temperature and immersion time at the amine solution leads to formation of more dense polyamide layer. So the rejection of prepared membranes at these conditions increases and the flux has a reasonable amount. The obtained results indicated that the concentration of 0.5 wt%, temperature of 45 ° C and immersion time of 3 min choose as the optimal values of preparation conditions. In the next step reverse osmosis membrane was modified by addition of silica nanoparticles with a particle size of 15-20 nm in the amine solution. Different concentrations of nanoparticles( 0.005 to 0.5 wt% ) were added to the amine solution. FTIR and contact angle analysis results indicated that the nanoparticles were successfully placed on the membrane surface and hidrophlicity and fouling resistance of the membranes was increased significantly. SEM and AFM images indicated the presence of particles on the membrane surface and increased the surface roughness.In the final step, the membranes were placed in a crossflow cell to evaluate those performance with different feeds in short and long-term tests. Results indicated that the flux and rejection of modified membranes was changed from 29.92 (l/m2.h) and 90.48% to 43.65 (l/m2.h) and 90.314% respectively. |
| |
Dissertation no. 20
| Dissertation title |
Landfill Leachate treatment by hybrid nanofiltration method |
| Student name |
Mahsa Alimoradi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering-Biotechnology |
|
Publish year |
2014 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
Dr. Majid Peyravi |
| Abstract |
Since treatment of landfill leachate is quite complicated, there is a need to develop a system that is capable of providing high treatment efficiencies. In this study, a laboratory-scale integrated landfill Leachate treatment process based on a membrane bioreactor (MBR) and nanofiltration (NF) technology has been planed and established. In this regards, an aerobic bioreactor with a nano pores membrane which was manipulated in the form of plate and frame by phase inversion method with an area of 0.04 m2 was carried out. The synthesized PSf membrane was immersed into the bioreactor as an internal MBR. The biologically treated effluent procured from the Membrane Bioreactor is pumped out with a peristaltic suction pump and then, was further treated using a Nanofiltration process. Nanofiltration process was suggested as a post-treatment, in order that upgrade MBR effluent. NF membrane was prepared by interfacial polymerization of m- phenylenediamine (2 % w/v) and trimesoyl chloride (0.1% w/v) on the polysulfone support membrane. Maximum COD removal of about 75% was attained in MBR at food-to microorganism (F/M) ratio (BOD basis) of 0.2 gBOD/MLSS.d under a optimum HRT of 24 h. The addition of NF process increased the efficiency up to 97%. Also the effect of powdered activated carbon (PAC) assessed as a combination of biological method to improve the efficiency of COD removal at concentrations of 0, 0.5,1,2,3,4 and 5 g/l .The obtained results indicate increasing of COD removal. The addition of consecutive membrane operations to biological treatment resulted in high removal efficiency by removing bio-refractory compounds. Further, NH3 –N, TKN and Heavy metals removal efficiency, amounted to 97 ± 2%,96 ± 2% , 99 ± 2% ,respectively. |
| |
Dissertation no. 21
| Dissertation title |
Synthesis and evalouation of nano particle molecularly imprinted polymer (MIP) for ellagic acid and its application in biosensor |
| Student name |
Milad Elyasi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
In this work, the molecularly imprinted polymer nanoparticles for Ellagic acid were prepared by precipitation polymerization. Then, a high sensitive and simple method was applied for design and preparation of the selective electrochemical sensor for Ellagic acid determination. By attachment produced MIP to the carbon paste electrode. We prepared a cyclic voltammetric sensor, sensitive to Ellagic acid. In this sensor, the MIP functioned as both: a preconcentrator and a high selective recognition element in the carbon paste structure. Also, the effect of time and the amount of MIP used in the design of the carbon paste electrode was investigated. Totally, the proposed sensor was used successfully for ellagic acid determination at a concentration of 10-4 M. |
| |
Dissertation no. 22
| Dissertation title |
Fabrication and immobilization of nano porouse composites for expanded beds adsorption of nanobioparticles |
| Student name |
Setareh Asgari Mehrabadi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
Expanded bed adsorption (EBA) is an integrated technology for capturing target bioproduct directly from unclarified feed stock. This process combines centrifugation, evaporation, filtration, and initial capturing of the proteins in a single step. The specially designed adsorbent is essential for the formation of a stable expanded bed. To this approach novel nanoporous adsorbents, for nanobioproduct/bioproduct adsorption have been fabricated by coating 4% agar gel onto Ni powder based on a water-in-oil emulsification method. The optical microscope and scanning electronic microscope were utilized in order to characterize the morphology of the prepared matrices. The results indicated that the matrices prepared had a regular spherical appearance, appropriate wet density of 1.64-2.78 g/ml, water content of 34-62.74%, average diameter of 344.77-383.41 µm, prosity of 90-98% and pore size of about 30-140 nm. moreover, the adsorbent density influence on expanded bed performance were estimated with respect to hydrodynamic characteristics. It was found that the axial dispersion coefficient increased with the increasing of matrix density and the expansion factors were decreased with increasing matrix density under the same velocity. The results indicated that Agar-Ni matrix shown good stability in expanded bed, and they are suitable for expanded bed processes. Subsequently affinity dye-ligand, Reactive Blue 4 (RB4), was covalently coupled with the Agar-Ni and Streamline adsorbents to prepare affinity adsorbents. Bovine serume albumin (BSA) was selected as model protein to test the adsorption behavior for the Agar-Ni gels modified by Reactive Blue 4 in batch and expanded bed adsorption. Effects of some parameters such PH and ionic strength on protein adsorption was investigated. The experimental data showed that adsorption equilibrium isotherms appeared to follow a typical Langmuir isotherm. Adsorption studies showed higher maximum adsorption capacity (64.01 mg/ml adsorbent) compered to the commercial adsorbent (54 mg/ml adsorbent). Also, the pseudo-first-order and pseudo-second-order kinetic models were employed to describe the kinetic adsorption processes. The kinetics followed the pseudo-first-order model. The effects of various operating parameters on breakthrough curves were also studied in a column of 1 cm internal diameter. Steep breakthrough curves were observed at high flow rates and high initial concentrations. The optained results indicated that reduction in dynamic binding capacity (DBC) with increasing the flow rate and decreasing the initial concentration. In comparison with RB4-Streamline, RB4-Agar-Ni composite showed a good potential adsorption behavior in batch and expanded bed adsorption. BSA nanoparticle adsorption by RB4-Agar-Ni was evaluated in the same operation conditions. |
| |
Dissertation no. 23
| Dissertation title |
Synthesis and Application of Nano Pore Molecularly Imprinted Polymer (MIP) Membranes for Separation of Organic Pollutants in Environment |
| Student name |
Sahar Ashrafian |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. S. Ahmad Ataee, Dr. Mohsen Jahanshahi |
|
Advisor |
|
| Abstract |
In this research, the adsorption and selective separation behavior of nano pore molecularly imprinted membranes (MIMs) for environmental organic pollutants were investigated. As respects phenol and its derivatives are important pollutants in water sources, in order to evaluate the performance of the MIM as a novel technology, focused on mentioned pollutants. The molecularly imprinted polymer (MIP) micro/nanoparticles were prepared by precipitation polymerization using phenol as the template molecule, followed by dispersing at different mass ratios into polysulfone (PSF) to form the hybrid molecularly imprinted polymer (HMIP) membranes in the shape of flat sheet via phase inversion induced by immersion precipitation method. The synthesized MIPs and MIMs were evaluated by batch binding, recognition and selectivity experiments and the Scatchard equation was used to analyze the chemical binding properties of them. Furthermore, their morphology were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and Brunauer-Emmett-Teller analysis. The molecularly imprinted porous polymer micro/nanospheres with mean particle size of 200 nm, mean pore diameter of 8 nm and specific surface area of 51 m2/g were obtained. In addition, synthesized polymer and membranes were characterized by Fourier transform infrared spectroscopy (FTIR). The equilibrium adsorption capacity of the optimized MIP and MIM in concentration of 2000 mg/L of aqueous phenol solution reached at 75.9 and 66.01 mg/g, respectively, and the selectivity factor of the optimized MIP was 3.57. Separation of aqueous phenol solution and also similar concentration of its structural analogue (catechol) in the H-cell setup, indicated that the maximal separation factor of the MIM was 2.19. Finally, the flux and permeation performance of different membranes were tested by dead-end filtration system. |
| |
Dissertation no. 24
| Dissertation title |
Evaluation Of Operating Parameters On Treatment Of Landfill Leachate By Anaerobic method |
| Student name |
Amin Arvin |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering-Biotechnology |
|
Publish year |
2014 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
Dr. Majid Peyravi |
| Abstract |
During the past several decades, industrial and commercial growth, technological advances, lifestyle developments, the ubiquitous tendency towards prodigality in today''s society and changes in the productivity and consumption habits cause to increase municipal and industrial solid wastes. Among different methods for waste treatment, Landfilling have been more attention due to the economical advantageous. However, landfills due to the generation of leachate have been identified as potential sources of ground and surface waters contamination. Further, landfill leachate may percolate through soils and cause extensive pollution of streams, creeks and water wells. Anaerobic treatment methods are more suitable for the treatment of concentrated leachate streams because of lower operating costs and the production of usable biogas products. In this study anaerobic baffled reactor (ABR) was manipulated for treatment landfill leachate. For this purpose, experiences were accomplished in different organic loading rates by changing in hydraulic retention time (HRT) and landfill leachate concentration. ABR reactor was fabricated from perspex with the volume of 6 litters. The reactor was containing seven chambers with equal size, shape and volume. Parameters that were evaluated in this research are included: chemical oxygen demand (COD), alkalinity, nitrate, conductivity, Total Kjeldahl nitrogen(TKN), Total dissolved solids(TDS), suspended solids (SS) and PH. The results showed that COD removal in HRT of 12, 24, 48 and 72 hours was raised more than 50 percent in landfill leachate contain 2700 mg/l COD. The highest COD removal rate of the hydraulic retention time was 86%. |
| |
Dissertation no. 25
| Dissertation title |
Synthesis and evaluation of nano pore molecularly imprinted polymer (MIP) for thymol and its application in solid Phase Extraction |
| Student name |
Motahareh Masumi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Prof. Mohsen Jahanshahi |
|
Advisor |
|
| Abstract |
For the first time in this study, Nano pore molecularly imprinted polymers were prepared using thymol as a template. A molecularly imprinting polymer with high performance for recognizing thymol was prepared by the novel surface molecular imprinting technique. At first, Silica nanoparticles were modified with γ-methacyloxypropyl trimethoxysilane (KH-570) as a support material. Then, optimized surface molecularly imprinted polymers (SMIP) were obtained through polymerization with methacrylic acid as the functional monomer and trimethylolpropane trimethacrylate (TRIM) as the cross-linking agent. The produced polymers were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM); Brunauer–Emmett–Teller analysis (BET) and Fourier transform infrared spectroscopy (FT-IR). The SMIP were obtained with the average core shell thickness of 17 nm, an average pore diameter of 3.9 nm, and the high specific surface area of 282.3 m2 g-1. The adsorption properties were revealed by batch binding experiments. The results indicated that the SMIP had higher binding capacity for thymol than its non-imprinted polymers. The selectivity of the SMIP obtained was clarified by using thymol and structurally related compound. The selectivity coefficient of SMIP for thymol in respect to competition species (Eugenol) obtained was 2.93, which revealed SMIP had good selectivity and site accessibility for thymol. Kinetic binding study showed that adsorption capacity of SMIP increased continuously with time and reached saturation adsorption at 90 min. |
Dissertation no. 26
| Dissertation title |
Investigation on the new making methods for electrochemical biosensor toward hydrogen peroxide using modification of electrode by nanoparticles |
| Student name |
Soheila Narimani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ali Shokouhi rad |
| Abstract |
A new amperometric biosensor for hydrogen peroxide was developed based on adsorption of horseradish peroxidase (HRP) at the AgNPs/ MWCNT/ polyaniline/ Au modified electrode. For modification of biosensor, MWCNT having carboxylic groups MWCNT-COOH was prepared by appropriate pre-known method using H2SO4 and HNO3 afterward MWCNT-COOH and aniline were electrodeposited onto Au electrode by applying certain polymerization cycles and definite scan rate. Then AgNPs were electrodeposited on modified electrode by constant applied potential for certain seconds. The resulting AgNPs/ MWCNT/ polyaniline/ Au modified electrode was prepared by electrodeposition of AgNPs onto the MWCNT/polyaniline/Au modified electrode. For Preparation of enzyme electrode (HRP/ AgNPs/ MWCNT/ polyaniline/ Au modified electrode), HRP was immobilized onto the surface of obtained electrode through covalent coupling by appropriate immersing time of enzyme, number scan, scan rate, concentration of aniline and carbon nanotube. The fabricated electrode was characterized by AFM and SEM as layer by layer. Under optimized conditions, the detection limit was 0.39. The resulting biosensor offered an excellent detection for hydrogen peroxide with expanded linear response range, and excellent selectivity. |
| |
Dissertation no. 27
| Dissertation title |
Fabrication and modification of composite nanofiltration membranes with polyethyleneimine(PEI) thin layer |
| Student name |
MohammadReza Shirzad Kebria |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
A thin film composite nanofiltration (NF) membrane was fabricated by interfacial polymerization of polyethyleneimine (PEI) and terephthaloyldechloride (TPC). The product of reaction between PEI and TPC was formation of polyamide layer on top surface of the membrane. SiO2 nanoparticles with molecular size of about 15-20 nm were added to the aqueous solution as modification agent. Polysulfone flat membrane was employed as the substrate for interfacial polymerization. Solvent-resistant ability of the NF membrane was investigated by using 2-propanol as a solvent. Crystal violet dissolved in water and 2-propanol separately. Also, performance of fabricated membranes was investigated in case of NaCl removal from aqueous solution. Characterization of membrane by FTIR analysis showed new functional groups on the surface of membrane due to the presence of SiO2 nanoparticles. Also contact angle measurement confirmed improvement in the hydrophilic properties. The top surface morphology and cross-section of the membranes were analyzed by Scanning Electron Microscope (SEM) images. SEM pictures showed that the SiO2 nanoparticles well dispersed on the surface of the membrane. Also, the roughness parameters of membrane surface were measured by Atomic Force Microscope (AFM) analysis. Roughness parameters obtained from AFM analysis, indicated that the surface of fabricated membranes became rougher after adding SiO2 nanoparticles. By adding SiO2 nanoparticles, membrane performance showed growing trend in case of solvent flux. Based on TPC concentration, membrane rejection performance showed declining trend or remained constant, at first. Finally in optimal percentage of SiO2 nanoparticles, membrane showed a good result for both flux of solvent and rejection of solutes. Membrane performances exhibited high rejection to crystal violet for aqueous and organic solutions. For aqueous solution, rejection of 100% and for organic solution, rejection of 99% was obtained. Also for salty water, fabricated membranes showed superior rejection of 76.6 % against NaCl molecules. Keywords: Nanofiltration, Interfacial polymerization, Polyethyleneimine, SiO2 nanoparticles, Solvent-resistant, Crystal violet. |
| |
Dissertation no. 28
| Dissertation title |
Separation and purification biodiesel by membrane reactor |
| Student name |
Mina Ghandehari Yousefi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2014 |
| Supervisor |
Dr. Ahmad Rahimpour |
|
Advisor |
Dr. Mohsen Jahanshahi |
| Abstract |
Biodiesel production process as a clean-burning involves two to three reaction steps each followed by separation and purification.Wet washing technologies for purification and separation of biodiesel have problems such as high energy and water consumption and considerable wastewater generation. Recently, the application of the Membrane technology appears to be a perfect candidate for biodiesel refining. In this study membrane process was used for biodiesel purification. Biodiesel was prepared by transesterification reaction of canola oil and methanol at the presence of sodium hydroxide as alkaline catalyst. This investigation is also aimed at studying the effect of different membranes on the purification and separation of biodiesel from canola oil. So four types of membranes were prepared. The sulfonated poly ether sulfone and nafion solution were used to bulk modification in the membrane casting solution. The blend PSf/nafion membranes were prepared by adding nafion solution in the casting solution. Results indicated that the modified membranes containing 1 wt.% nafion solution had the best yield compared with other concentrations. The blend PES/SPES membranes were prepared by adding SPES (0,3,5,10 wt%) in the casting solution. Results indicated that the yield of biodiesel was increased with increasing in SPES concentration while biodiesel flux was not changed. For the blend membranes fabricated from poly ether sulfone and functionalized carbon nanotube, the flux of biodiesel was increased by adding CNT (0, 0.05, 0.5, 1, 2 wt%) while yield of biodiesel was not changed. In the commerical PVDF membrane, nafion solution were utilized to modify the surface of membrane in order to enhance the hydrophobicity of membrane.PVDF membranes were dipped in nafion solution for different coating time (0,3,5,7,10 min).The yield of biodiesel production was increased with increasing in coating time while biodiesel flux was decreased. |
| |
Dissertation no. 29
| Dissertation title |
fabrication and evaluation solvent resistant nanofiltration membrane and its application in downstream process of biodiesel purification |
| Student name |
Majid Peyravi |
|
Degree |
PHD Student |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Ahmad Rahimpour |
|
Advisor |
|
| Abstract |
Biodiesel is an alternative fuel for diesel engines and also can be used in combination with some industrial lubricants. Commercial biodiesels have been usually produced with identical process in all industrial units. However, there is a major challenge in downstream processing stage in biodiesel purification. In this study, biodiesel was prepared by transesterification reaction of canola oil with 100% extra methanol in the presence of 1 wt.% alkaline catalyst. In order to purify the crude biodiesel, solvent resistant nanofiltration (SRNF) membrane at the dead-end filtration was used. SRNF membranes have been fabricated based on both “dense asymmetric skin layer” and “thin film composite” membrane structures. In the thin film composite SRNF membrane, sulfonated poly (ether sulfide sulfone) as a new sulfone family and functionalized TiO2 nanoparticles were utilized to modify support and thin layer respectively. It was found that employing SPESS significantly improved swelling degree and increased TFC-SRNF membrane rejection up to 90%. Intercalation and distribution of the nanoparticles in the thin film nanocomposite membranes, not only improved the chemical and thermal stability of the membrane but also increased the flux permeation rather than the composite membrane. In the asymmetric SRNF membrane, the new sulfonated copolymer and functionalized carbon nanotube were used to bulk modification of the membrane casting solution. The glycerol removal was increased up to 65% by increasing in SPESS up to 5 wt.% at the blended membrane while biodiesel flux was decreased. The nanocomposite PI membrane contain 1 wt.% carbon nanotube had the best performance in biodiesel purification process where 100% glycerol removal was obtained. In addition, these additives improved the anti-fouling property of the solvent resistant membrane. |
| |
Dissertation no. 30
| Dissertation title |
Nano porous ultrafiltration membranes preparation and modification using hydrophilic polymers |
| Student name |
Alisa Mehrparvar |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Ahmad Rahimpour |
|
Advisor |
|
| Abstract |
Separation has received special attentions in recent decades due to being necessary in many industries. Among the available separation processes, ultrafiltration membrane processes, due to their proper separation behavior, has gained especial attention for separating macromolecules, colloids and viruses. One of the major problems that limits membrane processes including ultrafiltration is fouling that forces some limitations in applying the process in industries in large scales. As a result, it seems curtail to study to fouling phenomena and also its reducing methods. To obtain this, facial and structural modifications have been noticed for achieving optimum performance in membrane separation process with antifouling property. In this project, the main purpose is to make polymeric membranes with improved surface properties. To obtain this three series of membranes were synthesized. In first series, the effect of diaminobenzoic acid and gallic acid were studied on the structure of poly ether sulfone ultrafiltration membranes. In second series, the poly ether sulfone membranes were modified with sulfonated poly ether sulfide sulfone. In third series, novel ultrafiltration membranes were made with synthesiced poly ether sulfone amide. Then, the effect of surface modification with monomers such as diaminobenzoic acid and gallic acid were studied. All the membranes were characterized with scanning electron microscopy, atomic force microscopy, furrier transition infrared spectroscopy and contact angle. Performances of the fabricated membranes were measured in terms of flux and rejection of model macromolecules. Quantitative antifouling properties of fabricated membranes were studied with observing flux decline during membranes performance. Results of studies showed that in first series, the membranes with 8 wt. % diaminobenzoic acid (55 lit.m2.h-1 flux, 39 % Rt , 79 % FRR) and 6 wt. % gallic acid (33 lit.m2.h-1 flux, 19 % Rt, 88 % FRR) had best performance among other fabricated membranes. Between modified membranes in second series, membrane with 3 wt. % sulfonated poly ether sulfide sulfone was chosen as best choice for its optimum performance in flux with 60 lit.m2.h-1 and 85 % rejection, also acceptable resistance to the fouling. Among the third series poly ether sulfone amide membranes with (162 lit.m2.h-1 flux, 83 % rejection) had better flux and rejection than poly ether sulfone membranes. Among poly ether sulfone amide membranes with surface modification, membrane with galic acid on surface had better flux (122 lit.m2.h-1) and rejection (92 %). |
Dissertation no. 31
| Dissertation title |
CO2 Capture via functionalized nano carbon materials |
| Student name |
Mona Keramati |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.seyed Ali Asghar Ghoreishi |
|
Advisor |
Dr.Mohsen Jahanshahi |
| Abstract |
The adsorption of CO2 gas on raw, oxidized and amine functionalized active charcoal and Multiwalled carbon nanotubes adsorbents were experimentally investigated at the temperature range of 293-313 K and pressure range of 0 to 40 bar. In these experiments, measurements were conducted based on volumetric technique in dual sorption vessel. The systems temperature was controlled using a water bath and the pressure drop in the sorption vessel resulted by adsorption of gasses on adsorbent was recorded until it was reached to equilibrium constant pressure. Then, the amount of adsorption was calculated from the pressure drop using SRK equation of state. The adsorption of CO2 decreased with the growth of temperature and increased with increment of the pressure. Results indicated that oxidation and amine functionalization of adsorbents increased the adsorption of CO2. Also CO2 adsorption of amine functionalized charcoal with Triethylenetetramine (TETA) was more than of amine functionalized charcoal with Chitosan. The maximum amount of CO2 uptake achieved by AC-TETA was 16.16 mmol/g and by AC-Chitosan was 13.65 mmol/g at 298K and 40 bars. This increasing in AC-TETA was 1.9 and in AC-Chitosan was 1.6 by raw AC. Also the maximum amount of CO2 uptake achieved by CNT-TETA was 21.15 mmol/g, 1.95 raw adsorbent. In comparative among AC and MWCNT in raw state, oxidation and amine functionalization with TETA, MWCNT has better uptake than AC in the same state. The experimental data of CO2 adsorption were analyzed using different model isotherms such as the Freundlich and Langmuir. It was found that both model give very good fit to the experimental adsorption data. However Freundlich isotherm was fitted better. Small values of isosteric heat of adsorption evaluated from a set of isotherms based on the Clasius-Clapeyron equation indicate physical nature of adsorption mechanism in three states and for two adsorbants. Gas adsorption kinetic study on carbon nanotubes revealed that experimental data were fitted with Pseudo-first order and Pseudo-second order kinetic models. In raw adsorbants, Pesoudo-first order kinetic has fitted better and in oxidataion and amine functionalization adsorbant Pseudo-second order was fitted better than first order kinetic. |
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Dissertation no. 32
| Dissertation title |
Fabrication and characterization of nano structured polymeric hollow fiber membranes |
| Student name |
Seyed Mohammad Safa Mohammadi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Ahmad Rahimpour |
| Abstract |
Economic concept of membrane separation technology has led to developing hollow fiber membranes due to their high surface to volume ratio. Hollow fiber membranes are self-supporting and fiber wall acts as the selective layer. At the present work, the hollow fiber membranes have been fabricated by spinneret with ID of 0.64 mm and OD of 1.2 mm via wet and wet/dry spinning methods. Initially, Polysulfone hollow fiber membranes were fabricated under different air gaps (0 to 20 cm) and their effects on the structure and function of membranes were studied. Results showed that air gap length has reverse relation with value of ID and OD of hollow fiber membranes. Also by increasing air gap length, external middle layer has been reduced and it disappeared in air gap length of 20 cm. Increasing air gap length leads to reducing external surfaces roughness and increasing mean pore size of membrane external surface from 37.5 nm in air gap length of 0 cm to 242 nm in air gap length of 20 cm. filtration experiments showed growing trend For flux and Declining trend For rejection of hollow fiber membranes by increasing air gap length. In this section, the membranes spun from air gap length of 2 cm, exhibited the best performance in proportion to other membranes by flux of 8.96 L.m-2.hr-1 and rejection of 95%. In the next section, polysulfone hollow fiber membranes with different percentages of Ortho-phosphoric acid monomer have been modified; the membranes were fabricated in the same conditions and air gap length of 2 cm. between modified membranes, the membranes containing 5% Ortho-phosphoric acid in casting solution is suggested due to its optimal performance in terms of flux, 21.03 L.m-2.hr-1, rejection of 98%, reducing fouling Resistance and flux recovery of 86%. |
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Dissertation no. 33
| Dissertation title |
Synthesis and evaluation of Forward Osmosis membranes |
| Student name |
Maryam Amini |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Ahmad Rahimpour |
|
Advisor |
|
| Abstract |
Novel thin-film nanocomposite (TFN) membranes were synthesized by interfacial polymerization for forward osmosis (FO) application. Amine functionalized multi-walled carbon nanotubes (F-MWCNTs) were used as additive in the aqueous solution of 1,3- Phenylendiamine (MPD) to enhance the FO membranes performance. Different concentrations of F-MWCNTs (0.01, 0.05, 0.1 wt%) were added to the aqueous solution. The fabricated TFN membranes were characterized in terms of membranes structure and surface properties, separation properties, FO performance and compared with traditional thin-film composite (TFC) membranes. The surface hydrophilicity of TFN membranes was improved with increasing F-MWCNTs concentration in the aqueous solution. The morphological studies showed that the incorporation of F-MWCNTs significantly changed the surface properties of modified membranes. The FO performance was evaluated using 10 mM NaCl solution as feed solution and 2 M NaCl solution as draw solution in both orientations. The TFN membranes exhibited high water permeability and acceptable salt rejection in the range of 0.01-0.1 wt% F-MWCNTs loading in comparison with TFC membrane. The most permeable TFN had a water flux (95.7 L/m2.h) nearly 160 % higher than TFC membrane, which represent an excellent improve in FO membranes. |
| |
Dissertation no. 34
| Dissertation title |
Preparation and modification of piperazine-based nanofiltration (NF) membranes for pesticides removal from ground water |
| Student name |
Hayde Karimi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr. Ahmad Rahimpour |
|
Advisor |
Dr. Mohsen Jahanshahi |
| Abstract |
This study explored the removal of two pesticides (atrazine and diazinon) from aqueous solution by synthesized thin-film composite (TFC) piperazine-based nanofiltration (NF) membrane in the form of flat sheet. The interfacial polymerization technique was employed by using piperazine (PIP) and trimesoyl chloride (TMC) as reagents for fabrication of poly (piperazineamide) on a porous polysulfone (PSf) UF support. The prepared thin layers were characterized by FTIR-ATR, SEM, AFM, and hydrophilicity measurement as well as a dead-end filtration set-up. In this work, the effects of addition of triethylamine (TEA) and triethylentetramine (TETA) in aqueous phase on the performance and morphology of TFC membranes were examined. The different concentration of PIP (0.5, 1, 1.5, and 2% wt), TEA (0.5, 1, 1.5, and 2% wt) and TETA (0.5, 1, 1.5, and 2% wt) were used to modification process of NF membranes.The morphological studies representedthat a rough and dense film was fabricated on the PSf support membrane. The NF membranes performance was evaluated with atrazine (0.03g/l), diazinon (0.03g/l) and NaCl (1 g/l) in distillated water solution as feed solution, separately. In all experiments, diazinon was better rejected than atrazine.It was observed that the water permeability and diazinon rejection increased from 22 lm-2h-1 and 95.2% in the unmodified membrane (2% wt PIP) to about 41.56 lm-2h-1 and 98.8% in the modified membrane by TEA (2% wt PIP and 2% wt TEA) and to about 13.5 lm-2h-1 and 99% in the modified membrane by TETA (2% wt PIP and 2% wt TETA).It was also surveyed that the water permeability and NaCl rejection increased from 32 lm-2h-1 and 31.02% in the unmodified membrane (2% wt PIP) to about 27 lm-2h-1 and 50.36% in the modified membrane by TEA (2% wt PIP and 2% wt TEA) and to about 16.53 lm-2h-1 and 62.32% in the modified membrane by TETA (2% wt PIP and 2% wt TETA).This indicated a significant improvement in poly (piperazineamide) TFC NF membranes for NaCl and pesticides removal. |
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Dissertation no. 35
| Dissertation title |
Ligand Immobilization on Nano Porous Adsorbents and its Evaluation for Biological Nano Particles Separation |
| Student name |
Azita Rezvani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ghasem Najafpour |
| Abstract |
The performance of agarose-nickel (Ag-Ni) matrix, as a new class of expanded bed adsorbent support matrix, was evaluated in protein and protein nanoparticle adsorption and compared with Streamline commercial matrix. To this approach, Reactive Green 19 (RG19) affinity ligand was immobilized onto Ag-Ni and Streamline matrices to prepare affinity adsorbents (RG19-Ag-Ni adsorbents). RG19-immobilized matrices were examined in batch and expanded bed adsorption (EBA) of Bovine serum albumin (BSA) and lysozyme as model proteins. Effects of some parameters such pH and ionic strength on protein adsorption was investigated and the results were used in further adsorption experiments. Batch adsorption studies showed higher maximum adsorption capacity (31.4 mg/ml adsorbent) compared to the commercial adsorbent (24.40 mg/ml adsorbent) while investigating the contact time effect exhibited high adsorption rate (70% adsorption within 30 min) for RG19-Ag-Ni matrices as well as the commercial ones. Experimental equilibrium data were analyzed using Langmuir and Freundlich isotherm models and well agreed with Langmuir model. Also, the pseudo-first-order and second-order kinetic models were used to describe the experimental kinetic results. Effects of liquid flow rate and initial concentration in expanded bed adsorption were assessed using breakthrough curves studies. The results indicated a reduction in dynamic binding capacity (DBC) with increasing the flow rate and decreasing the initial concentration. In comparison with RG19-streamline, RG19-Ag-Ni adsorbents showed a reasonable breakthrough behavior and a higher DBC value (9.98 mg/ml adsorbent) in the same flow rate of 170 cm/h, which reached to 90% of the saturated adsorption capacity. In addition, with the flow velocity increase up to 2 times (to 350 cm/h) the ratio of DBC to saturated adsorption capacity was reported about 66%, which is a favorable result for expanded bed adsorption processes. BSA nanoparticle adsorption by RG19-Ag-Ni was evaluated in the same operation conditions. The results exhibited lower adsorption rate and binding capacity compared to that obtained for BSA adsorption. RG19-Ag-Ni was also investigated in protein and protein nanoparticle recovery in expanded bed which showed a favorable performance. Moreover, the adsorbent particle size influences on expanded bed performance were assessed with respect to hydrodynamic characteristics in viscous fluids and protein adsorption properties using lysozyme as model protein. The results indicated the small adsorbents had more hydrodynamic stability as well as higher adsorption efficiency even in high flow rate EBA processes. |
Dissertation no. 36
| Dissertation title |
Fabrication of hybrids of polymer and carbon nanofibers and its application in MEA of fuel cell |
| Student name |
Masoumeh Hezarjaribi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Ahmad Rahimpour |
| Abstract |
Gas diffusion layers(GDL) and catalyst supports are two important parts of the membrane electrode assembly(MEA) of polymer electrolyte membrane fuel cells(PEMFC) which can have significant impact on its performance. The design and modification of their properties by nanotechnology, lead to increase efficiency and improve performance of these components. In this study, a new design by the hybrid polymer and carbon nanofibers synthesized by electrospinning system for fuel cell electrode was modified.In fact, the hybrid system of carbon nanofibers and conductive polymer nanofibers as electrode of PEM were studied. Operating parameters on electrospun fiber diameters are determined by varying the parameter values. Electrospinning was carried out with applied voltage of 16kv,flow rate of 1ml/hr and tip to collector distance of 13cm. It was observed that smooth fibers with out beads were formed. Morphologies of the electrospun nanofibers prepared under different ES conditions were observed by scanning electron microscopy(SEM). Average diameter of the hybride nanofibers was about 95 nm. 20 wt.% Pt/C electrocatalysts were prepared by polyol process and XRD patterns indicated that the prepared catalyst was a face-centered cubic latic structure and also average platinium particle size was determined about 1.1nm. The Cyclic Voltammetry(CV) studies were also carried out to determine the electrochemical surface area(ESA) of modified electrode and to elucidate the adsorption properties of Pt surface. For comparison, the commercial Pt/C electrode with loading mass of Pt of 0.4 mg cm -2 was also tested. Modified electrode had higher current density compare to commercial electrode and ESA of modified electrode was calculated 160 m2 gr-1 and exhibited high catalytic activities towards commercial Pt/C 20%. |
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Dissertation no. 37
| Dissertation title |
Synthesis and investigation of mechanical, thermal and morphological properties of capsules and self-healing nanocomposites and appointment of mechanical properties of nanocomposite by quantum mechanic |
| Student name |
Morteza Ghorbanzadeh Ahangari |
|
Degree |
PHD Student |
| Field of study |
Mechanical engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Abdolhosein Fereidoon - Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Masoud Darvish Ganji |
| Abstract |
The preparation of microcapsules with adequate performance is required for the fabrication of self-healing composites. Self-healing microcapsules with improved morphology as well as thermal and water resistance were prepared by introducing either single-walled carbon nanotubes (SWCNTs) or aluminum oxide nanoparticles (nano-alumina) into a urea–formaldehyde resin (which acts as the wall material). The prepared microcapsules were studied using various characterization techniques, including Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), optical microscopy (OM), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and contact angle measurements. Based on comparisons with traditional poly(urea–formaldehyde) microcapsules, the modified microcapsules exhibited a smoother surface. Our results indicate that the presence of the nanoparticles did not affect the core content of the microcapsules, which was approximately 78 wt.%. The average size of the traditional microcapsules was reduced from 168 μm to 115 and 95 μm for the SWCNT and nano-alumina-modified microcapsules, respectively. In addition, the thermal resistance of the microcapsules was improved after modifying the capsule walls. After the microcapsules had been modified with SWCNTs, the water resistance of the capsules improved, and the contact angle increased from 44° to 50°. The elastic modulus and hardness of the microcapsules with and without a nanocomposite shell wall reinforced with carbon nanotubes and nanoalumina were examined using the nanoindentation method. The surface morphology, topography and roughness were investigated with atomic force microscopy (AFM). The results showed a significant increase in the elastic modulus and hardness due to the presence of reinforcement nanoparticles. In addition, it has been founded that the microcapsules with nanoalumina in the shell wall were stiffer and harder than the other microcapsules. The surface roughness parameters obtained from AFM images showed that the nanoalumina nanoparticles resulted in a smoother surface of the microcapsules. In addition, the absence of nanoparticles in the shell wall resulted in the formation of microcapsules with rougher surfaces. Finally, the calculated plasticity index for the microcapsules increased with the addition of the nanoparticles. The results indicate that the PUF shell behaves as a viscoelastic-plastic material. Carbon nanotubes exhibit extremely high stiffness and strength, and are regarded as perfect reinforcing fibers for developing a new class of nanocomposites. The use of quantum mechanical calculations is more accurate than other atomistic methods for studying the interface and mechanical properties on the nanoscale for such materials. Ab initio calculations based on density functional theory (DFT) are employed to investigate the interaction properties of epoxy on typical zigzag and armchair single walled carbon nanotubes (SWCNTs). The interaction energies for epoxy monomers with different orientations on SWCNTs are investigated. The results indicate that epoxy is weakly bound to the outer surface of the considered nanotubes and that the obtained interaction energy values are typical for physisorption. In addition, the influence of different defects (Stone–Wale, one- and two-atom vacancies) and functional groups (–NH2 and –OH) on the interaction properties between the epoxy and the respective SWCNTs has been investigated. Our results indicate that the interaction energy between the SWCNT and the epoxy decreased as the number of defects increased. In addition, the strongest interaction was observed for the SWCNT functionalized with the –OH group. Therefore, DFT calculations were performed to investigate the effect of the –OH functional group on the mechanical properties of SWCNTs interacting with epoxy. Also, we performed first principles calculations based on density functional theory (DFT) to investigate the effect of epoxy monomer content on the electronic and mechanical properties of single-walled carbon nanotubes (SWCNTs). Our calculation results reveal that interfacial interaction increases with increasing numbers of epoxy monomers on the surface of SWCNTs. Furthermore, density of states (DOS) results showed no orbital hybridization between the epoxy monomers and nanotubes. Mulliken charge analysis shows that the epoxy polymer carries a positive charge that is directly proportional to the number of monomers. The Young’s modulus of the nanotubes was also studied as a function of monomer content. It was found that, with increasing number of monomers on the nanotubes, the Young’s modulus first decreases and then approaches a constant value. The results of a SWCNT pullout simulation suggest that the interfacial shear stress of the epoxy/SWCNT complex is approximately 68 MPa. These results agreed well with experimental results, thus proving that the simulation methods used in this study are viable. |
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Dissertation no. 38
| Dissertation title |
Modification and evaluation of thin film composite and nanocomposite forward osmosis membrane |
| Student name |
Navid Niksefar |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ahmad Rahimpour |
| Abstract |
Forward osmosis technology has become increasingly attractive in past decades. FO is a membrane separation technology where the water flux is driven by an osmotic pressure difference a semi-permeable membrane unlike reverse osmosis membrane process.Therefore, FO becomes a system that increases interest because of the many avdantages namely low operation cost and low fouling propensity. In this study thin film nanocomposite membrane were synthesized by interfacial polymerization on polysulfone supporting membrane for forward osmosis application. Different preparation conditions on forward osmosis membrane performances were discussed, including monomer concentrations, reaction time,curing time,curing temperature, and silica concentrations. The prepared membranes were characterized by ATR-FTIR, SEM, AFM and hydrophilicity measurement. The FO performance was evaluated using 10mM NaCl Solution as feed solution and 2M NaCl solution as draw solution in both orientations. The result showed that a strong trade-off between the water permeability and salt rejection was observed, where increasing TMC and MPD concentration, time reaction and curing temperature resulted in higher membrane salt rejection but lower water permeability. The desired FO membrane prepared under the optimum condition (0.1w/v% TMC, 2w/v% MPD,reaction time=30s and curing temperature=80˚c) exhibited a NaCl rejection of 72% and FO water flux 10.3 Lit.m−2.h−1.after addition different concentration of silica nanoparticle(0.01,0.05,0.1 wt%) in the aqueous phase the surface hydrophilicity of TFN membrane was improved with increasing silica nanoparticle concentration inaqueous solution.The morphological study showed that the incorporation of SiO2 nanoparticles changed the surface properties of modified membrane and it can be observed that the silica nanoparticle well dispersed in the membrane.The TFN membrane showed higher water permeability and better salt rejection in range of 0.01-0.1 wt% SiO2 loading in comparsion with TFC membrane.The most permeable TFN had a water flux(36.35 Lit.m−2.h−1).The water flux increased nearly 2 times than TFC membrane. |
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Dissertation no. 39
| Dissertation title |
Preparation of Beta-carotene nano emulsion, for application in food industry |
| Student name |
Fatemeh Pilbala |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr. Seyed Morteza Hosseini |
|
Advisor |
Dr.Mohsen Jahanshahi |
| Abstract |
Functional ingredients such as carotenoids, fatty acids, natural antioxidants and various other compounds, are being widely used as active ingredients on a wide range of food products. Oil-in-water emulsions are important delivery systems for hydrophobic bioactive compounds, and allow the preparation of lipophilic nutrients such as carotenoids in liquid form, which may improve their bioavailability and solve oxidation problem of bioactive compounds. Functional ingredients can be added with poor impact to solution transparency. Carotenoids are one of the most important groups of natural pigments and can be found in fruits, vegetables, leaves and sea products. Recently, researchers have shown that carotenoids can prevent against a number of disease such as cancer, cardiovascular disease and cataracts. β-Carotene is an important member of the carotenoids family. β-carotene provides an important proportion of vitamin A in the human diet. For these reasons, there is a great interest in using β-carotene and other carotenoids. There are a number of approaches for the production of emulsions. The conventional method employed in the food industry uses valve homogenization. This process is energy intensive as only a small percentage of the applied energy is effective. Since the mid 1990''s a high energy emulsification device, a microfluidizer, has gained spread. Studies to date comparing ultrasonic emulsification with rotor–stator dispersing have found ultrasound to be competitive or even better in terms of droplet size and energy efficiency. Microfluidization has been found to be more efficient than ultrasound, but less possible with respect to production cost, equipment contamination and aseptic processing. At one research, comparing mechanical agitation to ultrasound at low frequency was found that for a given desired diameter, the amount of used surfactant was reduced, and the emulsions were less polydisperse and more stable. At this work, nanoemulsions of β_carotene were prepared with ultrasound. Nanoemulsions were prepared with Tween 20 surfactant and Amino whey whey protein and also a blend of surfactant and protein. Physical and chemical stability of prepared nanoemulsions were investigated. Results showed that it is possible to achieve emulsions at a nanoscale range and also stabilized nanoemulsions had high physical stability during 6 weeks of storage. Chemical stability of stabilized nanoemulsions with protein and a blend of surfactant and protein was high during 6 weeks of storage. |
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Dissertation no. 40
| Dissertation title |
Fabrication of hybrid nano adsorbent based on carbon- nanostructured due to removal of H2S from gas flow |
| Student name |
Razieh Jabari |
|
Degree |
PHD Student |
| Field of study |
Chemical Engineering |
|
Publish year |
2013 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr. Alimorad Rashidi |
|
Advisor |
Dr.Seyed Ali Asghar Ghoreishi |
| Abstract |
This dissertation focused on H2S removal from gas stream by using a metal oxide based on carbon nano-structures. It attempts to find the best nano adsorbent with high capacity for adsorption and storage of H2S which be able to highly convert the stored H2S to elemental sulfur and play a catalyst role. A setup including a fixed bed reactor with a continuous flow was designed to examine performance of the nano-adsorbents in H2S removal. To minimize the limitations of mass and heat transfer, the reactor should be designed such that a plug flow is created. The reactor feed was the output gas from an amine sweetening unit of Gachsaran gas complex with 250000 ppm concentration. The single walled and multi walled CNTs were synthesized via CVD method. The graphene oxide was produced by modified Hummer''s method. In order to synthesize a graphene with few layers and high quality chemical, thermal and a new spray pyrolysis methods were utilized. The effective factors were analyzed during each method. The results indicated that a high quality bi-layer graphene was synthesized by spray pyrolysis in 700º C. Then iron oxide nano-adsorbent based on four nanostructures was synthesized. The performances of four nano-adsorbents were analyzed to determine the best adsorbent in H2S removal. The results revealed that the graphene base demonstrates the best performance. In next step, four metal elements of nickel, cobalt, molybdenum and iron were employed to produce nano-adsorbents based on graphene and their performance in H2S removal were tested to identify the proper metal for this purpose. The results revealed that the cobalt has the highest adsorbent capacity and conversion ratio. To find the optimum conditions in the catalytic reaction, the effect of temperature, metal loading and GHSV variables were analyzed by DOE. Thereby, the optimum conditions were found at temperature of 150°C, metal loading of 10 wt.% and GHSV of 2000 hr-1. The nano-catalyst of cobalt oxide based on graphene has conversion ratio as 99/99% and H2S removal capacity as 4/74 gH2S/g in the optimum condition. To investigate the reactions between adsorbed and adsorbent, Langmuir, Freundlich and Temkin isotherms were investigated. The results show that the chemical adsorption takes place spontaneously and independently from the concentration. At the end, the nano-catalyst was reduced and its performance in H2S adsorption and conversion of it to sulfur was examined. Based on the good performance results of the synthesized nano-catalyst, a pilot set up with the capacity of 100liter catalyst was developed. To investigate nano adsorbents before and after reduction process SEM, TEM, FTIR, Raman, EDX, TPR and BET analysis were employed. |
Dissertation no. 41
| Dissertation title |
Fabrication and Evaluation of Nano Porous adsorbent and the investigation of its hydrodynamic properties in an expanded bed |
| Student name |
Fatemeh Asghari |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2012 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Seyed Ali Asghar Ghoreishi |
| Abstract |
Expanded bed adsorption (EBA) is a direct approach for primary recovery of nanobioproduct/bioproduct in downstream processing. The specially designed adsorbent is essential for the formation of a stable expanded bed. Based on water-in-oil emulsification method, two novel types of nanoporous matrices for expanded bed application were prepared (Ag-Ni and Ag-Zn). The optical microscope and scanning electronic microscope were utilized in order to characterize the morphology of the prepared matrices. The physical properties of the prepared matrices as a function of solid content (Nickel/Zinc powder) were measured. The results indicated that Ag-Ni matrices had a spherical appearance, average diameter of 133.68-148.4 μm, appropriate wet density of 1.73-2.56 g/mL, water content of 32.2-58.5%, porosity of 79.4-96.37% and pore size of about 100-150 nm. Furthermore, the Ag-Zn matrices had regular spherical shape, mean diameter of 140.54-191.11 µm, wet density of 1.33-2.01 g/ml, water content of 45-75%, porosity of 86-97% and pore size of about 40-90 nm. For better understanding the effect of solid phase (Nickel/Zinc) properties on the performance of the expanded bed, the expansion and hydrodynamic properties of Ag-Ni and Ag-Zn matrices with a series of densities were investigated in an expanded bed. It was observed that the expansion factors were decreased with increasing matrix density under the same velocity. Using measurements of residence time distributions, hydrodynamic properties in the expanded bed were investigated. It was found that the axial dispersion coefficient increased with the increasing of matrix density. In addition, the effect of the flow velocity and bed expansion degree on hydrodynamic properties in the expanded bed was investigated. It was found that flow rate was the most essential factor to affect on the hydrodynamic characteristics in the bed. All the results indicate that Agarose-Nickel and Agarose-Zinc matrices shown good expansion and stability in expanded bed; and they are suitable for expanded bed processes. The influence of Ag-Zn matrix size distribution on the performance of expanded bed has been studied. It was found that matrices with large particle size were suitable for high operation flow rate. In addition, the results indicated that matrix with a wide particle size distribution leaded to a reduced axial dispersion compared to matrix with a narrow size distribution. In this study, the effect of agitating speed on particle size of Agarose-Nickel matrix was also analyzed. It was observed that particle size of matrix was decreased with the increase of agitating speed. The influences of agitating speed on the expansion and hydrodynamic properties of Agarose-Nickel matrix were also investigated. The physical and hydrodynamic properties of Agarose-Nickel matrix were studied and compared with those of the commercial Streamline DEAE matrix. The obtained results indicated that Agarose-Nickel matrix shown better feature of expansion, lower axial mixing than the commercial Streamline DEAE matrix. |
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Dissertation no. 42
| Dissertation title |
separation of CH4 from syngas by adsorption on MWCNT |
| Student name |
Sanaz Monemtabari |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2012 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Mojtaba Shariati Niasar |
|
Advisor |
Dr.Seyed Ali Asghar Ghoreishi |
| Abstract |
In this research, the amount of H2 and CH4 adsorption and separation on activated carbon (AC) and Multiwalled carbon Nanotubes (MWCNTs) adsorbents were investigated at three temperatures of 283.15, 298.15 and 313.15 K and pressure ranging 0-40 bar. In this expriment, the measurements were done based on volumetric method in dual sorption vessels. Then, the amounts of adsorbed gases were estimated from SRK equation of state. The obtained results showed that these values were different for adsorbed H2 and CH4 and the amount of adsorbed methane was much more than hydrogen in both adsorbents. The experimental data of H2 and CH4 adsorption were analyzed by using two distinctive model isotherms of Freundlich and Langmuir. It was observed that both models give very good fit to the experimental adsorption data. The small amounts of isostric heat of adsorption, which were evaluated from a set of isotherms based on the Clasius-Clapyron equation, indicated physical nature of adsorption mechanism. To study gas adsorption, kinetic psudo-first order and psudo-second order kinetic models were used. At the end, the effect of NaBH4 on methane adsorption on Multiwalled carbon nanotube was studied. Results revealed that this kind of material leads to increase of methane adsorption on MWCNTs. |
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Dissertation no. 43
| Dissertation title |
CFD modeling of electrode-membrane assembly modified with nano-technology in polymer electrode membrane |
| Student name |
Maryam Ramzani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2012 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Faramarz Hormozi |
|
Advisor |
|
| Abstract |
In this thesis, modeling fluid flow and chemical reactions in a polymer fuel cell using computational fluid dynamics has been considered. The model as a two-dimensional, non-isothermal, steady state has been done in the FLUENT software. Chemical reactions at the anode and the cathode are considered as a single phase and multi component.Model examines the behavior of fuel cell in two different modes mean in the presence and absence of ZrO2 nanoparticles in the membrane layer. Influence of parameters such as temperature, pressure, mass flow rate at the cathode and the performance of the system in the presence of air in the comparison with pure oxygen at the cathode has been investigated on the polarization curve.Results offer understanding of the performance of fuel cell and finding optimizing parameters that can be cited as the results are used for optimization.The result of modeling has been revealed that the performance of fuel cell improved by increasing the temperature up to 70 ° C and after that the efficiency of system refused as the temperature increased. So here the temperature of 70 ° C is considered as an optimal temperature in the fuel cell without using nanoparticles. But in the presence of ZrO2 nanoparticles this temperature upgrade to 90 ° C and at 90 ° C with presence of nanoparticles have a similar performance of 70 ° C without presence of ZrO2 nanoparticles. in the investigation of the effect of pressure on the performance of fuel cell it’s effect from 1 to 2 atm was dramatic. Increasing mass flow rate on the cathode side of the fuel cell, improves performance and the other hand, the use of pure oxygen leads to better performance is quite noticeable.Good compatibility of results obtained with laboratory results confirms the correctness of this modeling. |
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Dissertation no. 44
| Dissertation title |
Design and construction of electrochemical biosensor based on modified electrode using Ag nanoparticles in various matrixes |
| Student name |
Ali Shokuhi Rad |
|
Degree |
PHD Student |
| Field of study |
Chemical Engineering |
|
Publish year |
2012 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Mahdi Ardjmand |
|
Advisor |
Dr.Aliakbar Safekordi |
| Abstract |
Rapid, accurate, reliable and reagentless determination of hydrogen peroxide is very important in fields of food, industry, environmental protection, clinical control and so on. Similar to techniques employed for hydrogen peroxide analysis, such as titrimetry, photometry, chemiluminescence and electrochemistry, electrochemical biosensor based on enzymes have received considerable interest because of its high sensitivity and selectivity.To fabricate mediated-free biosensors of hydrogen peroxide, the achievement of direct electron transfer between enzyme and electrode is one of the most important aspects. Horseradish peroxides (HRP) is one of the most well done enzymes toward hydrogen peroxide determination.In other hand silver nanoparticles, which are easy to synthesize, have been widely used to incorporate proteins because of their quantum characteristics of small granule diameter and large specific surface area as well as their ability to quickly transfer photoinduced electrons at the surfaces of Ag nano particles. Because of their good biocompatibility and catalytic activity, colloidal silver nanoparticles can provide an environment similar to the native environment of redox proteins and be used to immobilize proteins for their direct electrochemistry.In this paper, we used various modification based on AgNPs on GC electrode. Some hydrogen peroxide biosensors were fabricated based on the direct electrochemistry of HRP in different matrixes having AgNPs on GC electrode. The sensitivity and stability of each obtained biosensor were compared than each other. |
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Dissertation no. 45
| Dissertation title |
Synthesis & evaluation of three components Chitosan-Gelatin/Calcium phosphate nanocomposite for biomedical engineering application |
| Student name |
Zahra Babaei |
|
Degree |
PHD Student |
| Field of study |
Chemical Engineering |
|
Publish year |
2012 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Seyed Mahmood Rabiee |
| Abstract |
Calcium phosphate bone composites are self-setting biocompatible materials which have been developed for medical applications to restore damaged human calcified tissue. Our purpose in this study is the preparation and characterization of three-component calcium phosphate (CaP) nanocomposite structures by using two polymers for bone tissue engineering. Two types of polymer e.g. gelatin (Gel) and chitosan (CS) used to fabrication of calcium phosphate nano and micro composites by in situ precipitation method. The Gel/CaP and CS/CaP composites were prepared and compared to Gel-Cs/CaP composites with variety of polymeric/ inorganic phase ratio to investigate the effects of polymers on the composites properties. The fabricated biocomposites were characterized by FTIR, X-ray diffraction (XRD), transmission electron microscopy (TEM) as well as scanning electron microscope with X-ray elemental analysis (SEM- EDX).The FTIR characterization results confirmed that the crystalline Calcium Phosphate particles were mineralized in gelatin and chitosan matrix and the interaction between Ca2+ in calcium phosphate and functional groups in gelatin and chitosan molecular chains was formed. XRD result showed that hydroxyapatite (HA) and brushit (BR) was formed in to the polymeric matrix. More particles formed into the gelatin were hydroxyapatit while in chitosan matrix and chitosan-gelatin matrix were brushit. And also, the amount of formed BR increases in comparison with HA by increasing organic phase which it can be due to lack of complete penetration of the basic solution into the polymeric matrix. SEM results suggested that particles formed in three component composites were in rod like shape with the 100-200 nm in diameter and 500nm in length, while plate like particles in gelatin and rod like particles in chitosan were formed in micro scale. Moreover, SEM image indicated that polymeric matrix has the controlling role in particle size of calcium phosphate.TEM observation supported SEM results and showed that three component composites have calcium phosphate nanoparticles in comparison of two component composites. The elastic modulus and compressive strength of the composites was also improved by the employment of gelatin and chitosan together, which can make them more beneficial for surgical applications. |
Dissertation no. 46
| Dissertation title |
fabrication of antibacterial membranes using nanoparticles |
| Student name |
Arash Molla Hosseini |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2012 |
| Supervisor |
Dr.Ahmad Rahimpour |
|
Advisor |
Dr.Mohsen Jahanshahi |
| Abstract |
Fabrication of the antibacterial ultrafiltration membranes and antibiofouling nanofiltration membranes are performed in this project. In the first section, for fabrication of ultrafiltration membranes, two different silver nanoparticles were used with the size of 70 and 30 nanometer. Polysulfone was used as main polymer and polyvinilidine pyrolidune was used as hydrophilic agent.nanoparticles was added to the casting solution. Fabricated membranes containing silver nanoparticles had more hydrophilic surfaces. Fabricated membranes containing 30 nm silver nanoparticles had amorphous structure rather than other membranes. Presences of smaller silver nanoparticles lead to reduction in the surface pore diameters and pores in the structure of the membranes. Surface roughness of membranes was reduced with increasing silver content. Disstiled water flux and rejection of sample macromolecule were increased with increment in silver nanoparticles concentration. Antibacterial performances of ultrafiltration membranes with 30 nm silver nanopartilces were better than other membranes. Finally, ultrafiltration membrane with 4 wt% 30 nm silver nanoparticles was chosen as best fabricated membrane.Typical way to synthesis thin film composite membranes is interfacial polymerization between m- aqueous monomer meta phenylene diamine and organic monomer of trimesoyl chloride. In a new approach silver nanoparticles were coated on UF sublayer before interfacial polymerization of two monomers. New fabricated membranes were compared with typical membranes (adding silver nanoparticles to monomer solution). In comparison with typical silver containing NF membranes, new NF membranes had smoother surfaces. Performance of newly fabricated membranes was better than typical membranes. In antibiofouling experiment, both type of membranes showed good results. Trend studies of silver release pattern showed that new membranes kept silvers for longer time. According to the obtained results, new NF membranes had better performance in comparison with typical NF membranes.The new approach in fabrication of thin film membranes was repeated by using TiO2 nanoparticles. These membranes had defectless hydrophilic surfaces. The antifiouling and antibiofouling properties of these membranes were improved as a result of TiO2 presence. |
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Dissertation no. 47
| Dissertation title |
fabrication & modification of the performance of MEA in fuel cells in nano technology |
| Student name |
Ghader Mohammadi |
|
Degree |
master of science |
| Field of study |
Chemical Engineering |
|
Publish year |
2011 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Ahmad Rahimpour |
| Abstract |
Fossil fuel energy source are declining human development community to come in the not too distant, are experiencing fuel cell shortage .with rapid population growth and its reach to 10 billion people, another 50 years will increase the need for endless source of fuel. On the other hand, the extent of pollution from fossil fuels has created problems in sphere of the earth .thus the need for alternative, cheap and clean for fossil fuels is obvious. Such as energy, electrical energy is generated by fuel cells, because of the high efficiency and no environment pollution and consumption of hydrogen and other renewable resource as fuel, now the solutions to bypass the bottlelike of energy and environment pollution. (Nonrenewable and renewable energy sources, hydrogen gas can be obtained, Today, the most economical method of producing hydrogen from natural gas).One of the fundamental problems that prevent commercialization of fuel cells is that the cost is relatively high. Therefore, for cost reduction, improved functionality and optimum conditions by a special membrane electrode assembly (MEA) is essential, for this purpose, extensive research on fuel cells and components of the functional parameters have been.In this project, with made of MEA with various surface methods 25cm2, Comparison with commercial samples available in the market and provide the laboratory , Tests were made on samples And to examine various parameters to improve its performance was.In the present work, after reviewing the whole history of fuel cells and fuel cell types in the first chapter, Chapter Two examines the thermodynamics of fuel cells has been and electro-chemical fuel cell power has been studied. The third chapter introduces the components a polymer electrolyte fuel cell and MEA has been. The fourth chapter examines the types of construction methods and the results of some methods studied. The fifth season of the best ways to build and how to build a set of MEA According to the research and techniques are discussed in the previous chapter And the nanoparticles to improve the efficiency of the MEA is used. Finally, the results of different methods of construction have been studied. The polarizations are given on the chart and are compared with each other. |
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Dissertation no. 48
| Dissertation title |
loading of antibiotic drug on calcium phosphat nanostructures |
| Student name |
Reza Najafi |
|
Degree |
Master Of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2011 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Seyed Mahmood Rabiee |
|
Advisor |
|
| Abstract |
With great advances in surgical techniques and implants, implants infections are a serious problem for surgeons still. Bacterial infections are serious complications from behind. The treatment is usually based on a combination of surgical removal of dead bone tissue and Treatment with antibiotics. Physical antibiotics can not reach high concentrations, to solve this problem , local antibiotics can achieve higher concentrations.This study, Preparation of nano-hydroxyapatite (bone filler) and varying amounts of gentamicin (with in situ hybridization) is the main goal . Drug release was investigated in simulated body. Samples synthesized by Scanning Electron Microscope (SEM), Atomic force microscope (AFM), X-ray diffraction spectroscopy (XRD) and Infrared spectroscopy (FTIR).SEM and AFM images showed particles are spherical and from 50 to 100 nm and XRD and FTIR images showed This antibiotic has no effect on nano-hydroxyapatite, even improved properties , Moreover, with increasing drug nano-particle size is reduced. it Can lead to improved mechanical properties. Transfer and drug delivery is accepted as desirable and appropriate, So that the DDS (drug delivery system) has been realized. |
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Dissertation no. 49
| Dissertation title |
Synthesis,characterization and comparision survey for bone regenerate ability between pure hydroxyapatite and hydroxyapatite/chitosan nanocomposites powder in rat |
| Student name |
Mohammad Reza Nikpour |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2011 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Seyed Mahmood Rabiee |
| Abstract |
The bone matrix has two major phases at the nanoscale level containing of organic (collagen) and inorganic (Hydroxyapatite (HA)). Incorporation of Hydroxyapatite with organic polymer in favor of composites would be used in biomaterial engineering. In this research, nano-HA and HA/CTS nanocomposites content of 2, 4 and 6 gr chitosan were prepared via in situ Hybridization route and then studied for bone regeneration in 5 groups consist of pure HA, HA/CT2, HA/CT4, HA/CT6 nanocomposites and control group in the rat calvaria after 7, 30 and 60 days. Crystal nanostructure and phase present of products were investigated by X-ray diffraction (XRD) and FTIR spectrum, respectively. Morphology of the samples was observed by scanning electron microscopy (SEM) and atomic force microscopic (AFM). The results confirmed homogeneity interaction between HA and CTS matrix. It can be seen by increasing chitosan, improve the expected compatibility among HA and matrix. XRD results indicated that the approximate crystallite sizes of pure HA are found to be about 16nm. Investigation of in vivo in rat calvaria showed regeneration of new bone in the mean area: 57.267% for pure HA, 50.840%, 48.020% and 46.530% for nanocomposites, and 5.64% for the control after 60 days. Result obtained from in vivo tests confirmed feasibility of the synthesized powders as a bone substitute. |
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Dissertation no. 50
| Dissertation title |
Synthesis and application of metallic nano-foam for improvement of electrodes efficiency in fuel cells |
| Student name |
Kosar Raoof |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2011 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Jahanbakhsh Raoof |
| Abstract |
part1-A porous nano-structured Cu-foam with dendritic wall structures was synthesized by the simple electrochemical deposition of copper in the presence of hydrogen bubbles evolving during the reaction in 0.8M CuSO4 + 3M H2SO4 solution at the surface of carbon paper electrode.Bubble coalescence makes the porous structure that is suitable for mass and charge transport.at the next stage,Cu particles replaced with Pt which is more active than Cuwith simply immersion of the surface in a K2PtCl4 aqueous solution.scanning electron microscopy and energy dispersive X-ray spectrometry were used to characterize the structure of Cu-foam and Cu/Pt bimetallic foam. The catalytic ability of Cu/Pt bimetallic foam on the methanol electro-oxidation reaction was investigated by cyclic voltammetry method in the presence of 10M methanol in the 0.5 M H2SO4 solution. Preparation and characterization of bimetallic nano-structured electrode base on new approach,for application in direct methanol fuel cells are strongly discussed. Part2 In this study a novel prepration technique for membrane-electrode assemblies(MEAs) used in vanadium/air redox flow battery(VARFB) is presented. MEA have been prepared by depositing catalyst layer op platinum and iridium on the surface of solid polymer electrolytes(SPE). Electrochemical deposition was used to achieve good adhesion between platinum and iridium particle on the SPE and for reducing the contact resistance. platinum and iridium structure and composition were investigated by means of scanning electron microscopy(SEM) and energy disperse X-ray spectrometry(EDX). cyclic voltammetry(CV) can be used to determine the electrochemical characteristics of the Pt/Ir-SPE electrodes wich can be applied in VARFBs. |
Dissertation no. 51
| Dissertation title |
Separation of H2 from its mixture with CO2 through adsorption on multiwall carbon nanotubes |
| Student name |
Soodabeh Khalili |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2011 |
| Supervisor |
Dr.Seyed Ali Asghar Ghoreishi |
|
Advisor |
Dr.Mohsen Jahanshahi |
| Abstract |
The equilibrium uptake of H2, CO2 and their mixture on activated charcoal and two types of multiwalled carbon nanotubes (MWCNTs) adsorbents were experimentally investigated at the temperature range of 288–318 K and pressures up to 40 bar. The measurements were conducted based on volumetric technique in dual sorption vessels. The system temperature was controlled using a water bath. The pressure drop in the sorption vessels due to adsorption of gases on adsorbent was recorded till reached to equilibrium at constant pressure. Then, the amount of adsorbed gases was calculated from the pressure drop using SRK equation of state. The results showed that temperature had much less effect on adsorption of H2 on both activated charcoal and MWCNTs than adsorption of CO2 and mixture. The experimental data of H2 and CO2 adsorption were analyzed using different model isotherms such as the Freundlich and Langmuir. It was found that both models give very good fit to the experimental adsorption data. The results showed that the surface area and pore diameter of adsorbent were important in adsorption and separation processes. The calculations showed that presence of one gas has influenced on adsorption and reduce the adsorption of other gas. Small values of isosteric heat of adsorption evaluated from a set of isotherms based on the Clausius–Clapeyron equation indicated physical nature of adsorption mechanism. Gas adsorption kinetic study on carbon nanotubes revealed that experimental data were well fitted with Pseudo-first-order kinetic model and intra-particle diffusion models.In order to study functionalization of carbon nanotube on adsorption process, one of MWCNTs was functionalized by phenylenediamine and the uptake of CO2 was measured with MWCNT-NH2. Results indicated that this type of amine has increased the absorption of CO2. |
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Dissertation no. 52
| Dissertation title |
Synthesis and modification of performance of nanofiltration membranes using nanoparticles in industrial wastewater treatment processes |
| Student name |
Sara Pourjafar |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2011 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Ahmad Rahimpour |
| Abstract |
Nanofiltration is a brand new method and it's predicted that it can be an alternative method for conventional ones. Nanofilters attracted so much attention in wastewater treatment field due to their high ability of separation and purification. One of the industrial units is yeast manufacturing industry that has a high turbidity and COD in a reason of presence of melanoidins. Using conventional methods, such as physical, chemical and biological treatments could not reduce the COD level more than 80-85%. In this thesis, PVA/PES thin film nanofiltration membranes were synthesized with glutaraldehyde cross-linker and modified with TiO2 nanoparticles. the phase separation induced by immersion precipitation was employed for preparation of PES ultrafiltration membrane , and then nanofiltration membrane has been fabricated by dip-coating of PES supports in PVA solution and GA crosslinking agent. Finally, the PVA/PES nanofiltration membranes were modified with coating TiO2 nanoparticles on the surface. The effect of PVA, GA, TiO2 concentrations on the performance and morphology of the membranes was investigated with taguchi analyzing method in a synchronous manner. According to this, the l16 orthogonal array with four level of concentration was employed. COD and flux of the permeate phase a sample of yeast industry wastewater were considered in two series of experiments.The prepared membranes were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) and contact angle measuring tool. Also, cross flow filtration system was utilized for measuring the flux and COD level of the permeate phase. Water/isopropanol solution was employed for measuring the degree of membrane swelling. According to the results of taguchi analysis, optimum membranes from COD and flux point of view had over than 95% yield and their morphologies were investigated. The membrane with 2% PVA, 5%GA and 0.5% TiO2 concentrations has high rejection of COD and the membrane with 0.5% PVA, 1%GA and 0.05% TiO2 concentration has the best output in respect of permeate phase flux. |
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Dissertation no. 53
| Dissertation title |
Fabrication of CO gas nanosensor based on functionalized carbon nano tubes |
| Student name |
Meysam Seyfi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2010 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Alimorad Rashidi |
| Abstract |
Sensors are instruments that react in predictable way in special conditions; nowadays sensors have high sensitivity that even sense the little amount of gas, heat or radiation.In this project Fabrication of CO gas Nanosensor based on functionalized carbon nano tubes have been investigated.Recently sensors act in absorption, specification and desorption on sensitive material, and it’s apparent that the sensitive material with higher specific surface area have higher sensitivity due to the increase in surface area between gas molecules and the sensor leading to much increase in sensitivity.Recently lots of progress occurred in developing sensors applications such as low cost, low needed energy and easier portability. the most important point in sensors are sensitivity, selectivity and stability, that carbon nanotubes are the most applicable sensitive material in chemical sensors in a wide range of gases because of their special properties such as small size, high surface density, straight wall surface with high selectivity, high specific surface area, great conductivity and high tensile strength.In this research multi-wall carbon nanotubes have been used in gas sensor fabrication. Since functionalizing improve extraordinary the properties of carbon nanotubes. Therefore in this study the multiwall carbon nanotubes, simple, carboxylic acids, amides and SnO2 were used as sensitive material in sensor fabrication. Sensors were designed versus resistance variation. The aim gas was CO in this thesis. Different variables can be investigated in sensitivity of CO gas sensors such as sensor type, temperature, concentration, time duration and CO gas flow rate.In this thesis, the effects of CO gas temperature and type variation of sensors have been studied on sensor action and strength of its responsibility, while keeping other parameters constant.Results showed that in low temperature, SnO2 had the highest responsibility percentage among the sensors and in high temperature, all nanotubes demonstrated proper sensitivity except simple carbon nanotubes, also simple carbon nanotube didn’t have high sensitivity to CO gas. |
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Dissertation no. 54
| Dissertation title |
synthesis of Nano-bioactive glass and investigation of its characterisation in biological environment |
| Student name |
Nima Nabian |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2010 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
Dr.Mahmood Rabiee |
| Abstract |
Bioactive glass is used as both bone filler and as a coating on implants, and has been proved to be able to chemically bond to living bone due to the formation of an apatite-like layer on its surface. The aim of this research was preparation and characterization of nano bioactive glass by sol-gel process. The research reports changing cooling treatment of synthesizing method in order to investigate its effect on the physical properties of sol-gel derived nano bioactive glass. In order to test this hypothesis, two different methods of cooling treatment were applied after calcinations in synthesizing method. Nano bioglass material was crushed into powder and its bioactivity was examined in vitro with respect to the ability of hydroxyapatite layer to form on the surface as a result of contact with bovine serum albumin (BSA). The obtained nano bioactive glass was analyzed before and after contact with BSA solution. For the examination of nano product morphology, crystalinity as well as composition surface electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) analysis have been carried out. The SEM images showed that the morphology of nano bioactive glasses (NBGs) was completely changed. The TEM images showed that the NBG particles size were 20–40 nm. The bioactivity of bioglass nanopowder was confirmed by SEM and XRD due to the presence of a rich bone-like apatite layer. Therefore, this nano BSA-Bioglass composite material is promising for medical applications such as bone substitutes. |
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Dissertation no. 55
| Dissertation title |
Fabrication of gas nanosensor (natural gas) based on functionalized carbon nanotubes |
| Student name |
Fatemeh Mohammadzadeh |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2010 |
| Supervisor |
Dr.Jahanshahi |
|
Advisor |
Dr.Alimorad Rashidi |
| Abstract |
Gas sensors or chemical sensors are attracting a tremendous interest because of their widespread application in industry, environment monitoring, space exploration, biomedicine, and pharmaceutics. Gas sensors with high sensitivity and selectivity are required for leakage detection of explosive gases such as hydrogen and for real time detections of toxic or pathogenic gases in industries. Since the most common gas sensing principle is the adsorption and desorption of gas molecule on sensing materials, it is quite understandable that by increasing the contact interfaces between the analysts and sensing materials, the sensitivity can be significantly enhance. Recent development of nano technology has created huge potential to build highly sensitive, low cost, portable sensors with low power consumption. Among different nano materials, carbon nanotubes show the highest and the best responsing against the exposing gases. Here in this research, multi wall carbon nanotubes are used in gas sensor fabrication. Since functionalizing improve extraordinary the properties of carbon nanotubes, three types of functionalized carbon nanotube through oxidation and amid formation are used as sensitive layers in our sensors. They are: MWCNT-COOH, MWCNT- C12H27N (Dodecylamine) and MWCNT-C18H39N (Octadecylamine). Sensors are designed on CNTs based on two terminal resistors. The target gas is natural gas with 160ppm H2S. Often different parameters are considered in measuring the sensitivity. Here the temperature variation has been chose. The sensing behavior of sensors is interpreted during exposing to H2S for 20 minute and in 25, 40, 50, 60, 800C. Amine functionalized carbon nanotubes demonstrated the highest sensitivity in 25,400C, but in higher temperature carbon nanotubes responded better. MWCNT and MWCNT-COOH have metal and p-type semiconducting behavior respectively. MWCNT-Amines are classified as n-type semiconductors. Although their electrical resistance behavior with respect to temperature changes. |
Dissertation no. 56
| Dissertation title |
Effect of Electrical & Thermal Conductivities on Carbon Nanotubes Synthesis Using Arc Discharge in Liquid |
| Student name |
Asieh Dehghani Kiadehi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2010 |
| Supervisor |
Dr. Mohsen Jahanshahi- Dr. Mohammadreza Mozdianfard |
|
Advisor |
Dr. Gholamreza Vakilinezhad |
| Abstract |
Recently, arc discharge in liquid method has been developed to synthesize several types of nano-carbon structures such as: carbon onions, carbon nanohorns and carbon nanotubes. This is a low cost technique as it does not require expensive apparatus. In this study, production of carbon nanotubes by arc discharge in liquid was investigated using an automated set up equipped with a heat exchanging system. This automatic setup enabled efficient controlling of the gap between two electrodes and maintaining temperature of the solution constant during arc discharge operation. A modified acid treatment was applied for refinement of the nanotubes. Properties and yield of carbon nanotubes obtained by arc discharge in this study was affected by parameters such as: electrical conductivity, concentration, type and temperature of plasma solution, as well as thermal conductivity of the double walled steel beaker. Investigating the crystal structure and morphology of the carbon nanotubes produced using Raman spectroscopy, scanning electron microscopy and transmission electron microscopy showed that the best structure was obtained at the following conditions: voltage 25 volts, a combination of Ni: Mo as a catalyst with a ratio of 1:2 and in a solution with 22/7 mS electrical conductivity, at the temperature of 25ºC. The maximum yield of carbon nanotubes produced at this condition was 6.6 mg, which took place in 0.25 mol solution of LiCl. |
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Dissertation no. 57
| Dissertation title |
Synthesis and optimization of alpha-lactalbumin and human serum albumin (HSA) nanoparticles for drug delivery and food science |
| Student name |
Rabeah Mehravar |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2009 |
| Supervisor |
Dr. Saghatoleslami- Dr. Jahanshahi |
|
Advisor |
- |
| Abstract |
In recent years, application of protein nanoparticles have became of more and more interest to the food and pharmaceutical industry. Albumin is one of the protein materials that can be used for drug delivering to target site. In this study, alpha-lactalbumin was used to synthesis of nanoparticles by a two-step desolvation process for application in food science. It has significant nutritional properties and is associated with some positive health effect upon consumption. Acetone was added drop-wise for forming alpha-lactalbumin nanoparticles. At the end of process, glutaraldehyde 25% solution was used for preparing nanoparticles as a crosslinking agent. The alpha-lactalbumin nanoparticles were purified by three fold centrifugation (15000g, 20 min). The effect of three parameters was investigated on the nanoparticle size such as pH, temperature and different desolvating agent. The size of obtained nanoparticles was between 35 to 450 nm. In addition, Human Serum Albumin (HSA) was used to synthesis of nanoparticles by desolvation method for application in drug delivery system because of biodegradability, owning high capacity of drug loading and nontoxiticity. Ethanol and glutaraldehyde 8% solution were used as a desolvating agent and crosslinking agent respectively. The HSA nanoparticles were purified by five fold centrifugation (25000g, 10 min). Moreover the effects of different parameters i.e. pH, HSA concentration, agitation speed, glutaraldehyde concentration, organic solvent adding rate, the ratio of organic solvent/ HSA solution were examined in this research. Among these factors, pH, HSA concentration, organic solvent adding rate and the ratio of organic solvent/ HSA solution had the dominate effect on particle size. Taguchi method with L16 orthogonal array was implemented to optimize experimental conditions of the purpose. The best parameters for nanobioparticles production were obtained at pH=9, HSA concentration: 75 mg. ml-1, ethanol adding rate: 1.5 ml. min-1 and the ratio of organic solvent/ HSA solution: 4. Under these conditions the software predicted the 46.625 nm for HSA nanoparticle size, which in experiment 53 nm was achieved for the nanoparticles. Nanoparticles were analyzed by photon correlation spectroscopy (PCS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The image of SEM & AFM demonstrated that the shape of the nanoparticles was spherical. To the best of our knowledge, no reference found in the literature about synthesis of alpha-lactalbumin nanoparticle and using Taguchi method for optimization of HSA nanoparticles up to now and with respect to our study this work is carried out for the first time. |
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Dissertation no. 58
| Dissertation title |
Formulation Of Anticancer Drugs Loaded Protein Nanoparticles |
| Student name |
Parvin Golbayani |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2009 |
| Supervisor |
Dr. Jahanshahi |
|
Advisor |
Dr. Honari |
| Abstract |
Nanoparticles are colloidal particles, which are less than 0.1 µm in diameter. They have the unique property to accumulate at the site of solid tumors and therefore are very suitable for targeted drug delivery. A number of studies have shown that albumin accumulates in solid tumors making it a potential macromolecular carrier for the site-directed delivery of antitumor drugs.The purpose of the present study was to develop Doxorubicin (Dox) loaded albumin nanoparticles for regional drug release in solid tumors. These Bovine serum albumin nanoparticles were prepared by coacervation method. To characterize the nanoparticles, particles diameter, zeta potential, polydispersity, were determined by Zetasizer 3600 ZEN Malvern UK. The entrapment of Dox in albumin nanoparticles was also determined and in vitro release of drug was studied. Drug release from nanoparticles was observed in PBS. Differential scanning calorimetry method used to understand the thermotropic properties and phase transition behavior. The size of albumin nanoparticles increased after drug loading from Z average of 67 nm to 98 nm for magnetic stirring method and 106 nm for shaking method. The SEM results confirm the uniform shape of these particles. This work has also demonstrated that when Doxorubicin loaded Albumin nanoparticles were prepared, smaller and more uniform nanoparticles were produced at lower temperature. The second conclusion was that the size of drug nanoparticles which prepared by stirring method were smaller than the drug nanoparticles which produced via shaking method. The entrapment of Dox in albumin nanoparticles was also determined 39.45% for magnetic stirring method and 18.58% for shaking method. In vitro release study also shows that Doxorubicin loaded albumin nanoparticles are capable of releasing the drug in a slow sustained manner (almost 30-40% release at the end of 72 hrs). |
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Dissertation no. 59
| Dissertation title |
Protein Recovery & Purification in fluidized bed Adsorption |
| Student name |
Mohammad Hassan Shahavi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2008 |
| Supervisor |
Professor Ghasem D. Najafpour_Dr. Mohsen Jahanshahi |
|
Advisor |
_ |
| Abstract |
Expanded-bed adsorption (EBA) is a direct approach for primary recovery of proteins starting from unclarified fermentation broths. This process combines centrifugation, evaporation, filtration, and initial capturing of the proteins in a single step. The conventional chemical-engineering view of a fluidized bed is one in which there is a significant degree of mixing, both solid and the fluid phases, e,g, in gas-fluidized systems. In many applications, mixing of the solid phases is desirable for example, in order to obtain high rates of heat transfer and a uniform temperature within the beds used for combustion. But in Expanded Bed Adsorption mixing is an undesirable factor which disturbs the process efficiency. The purpose of this research was to investigate the effect of structural parameters such as column diameter, settled bed and expanded bad height of adsorbent, on mixing in the bed residence time distribution (RTD) studies using acetone tracers. Experimental data were obtained in this work to show an apparent increase of axial dispersion with an increase in column diameter. It has also been shown that expansion effect up to 1.3 times the settled bed height, was insignificant, but expansion higher then 1.3 time the settled bed will disturb the mixing and consequently the adsorption efficiency. Finally the effect of mixing on protein adsorption has been considered using the tow model proteins, egg albumin (EA) and bovine serum albumin (BSA). The experimental data showed that proteins adsorption model using an apparent decrease of adsorption efficiency with an increase in mixing. |
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Dissertation no. 60
| Dissertation title |
Synthesis and optimization of carbon nanotubes |
| Student name |
Razieh Jabari |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2008 |
| Supervisor |
Dr.mohsen Jahanshahi |
|
Advisor |
Professor Jahan-bakhsh raoof |
| Abstract |
Carbon nanotube, a new structure of carbon element, is composed of graphene sheets rolled into closed concentric cylinders with diameter of the order of nanometers and length of micrometers. Carbon nanotubes have many potential applications including material as a good conductor, quantum wires, nano-devices and field-effect transistors, storage of gas and AFM tip. These wide applications of CNTs are due to their unique structural and excellently physical and electronic properties. Three methods, laser ablation, arc discharge, and catalytic chemical vapor deposition are generally used to synthesize CNTs. Recently; Arc in liquid method has been developed to synthesize many kinds of nano-carbon structures such as carbon onions, carbon nanohorns and carbon nanotubes. This technique is considered as a low cost method because it does not require any expensive equipment. In here, this method was used for fabrication of nanotubes, and then a modified acid treatment method applied for purification stage. In this study, an arc discharge full automatic set up was used for fabrication of carbon nanotubes which enables the controlling of gap between the two electrodes and the voltage as well. Then a modified acid treatment method applied for purification stage. Properties and yield of carbon nanotubes obtained by arc discharge method is affected by various parameters such as voltage, current, kind and ratio of catalysts and plasma. To optimize the presses, a design of experimental (DOE) (Taguchi method with four parameters and four levels determined 16 experiment and applied Qualitek-4 software) was implemented. As the result of taguchi analysis in this study, Voltage, and catalyst were the most influencing parameters on the yield product of carbon Nanotubes. The maximum yield products of CNTs were obtained at 25v voltage, LiCl as a salt in solution, Ni: Mo as a catalyst and the 1:2 as a catalyst ratio (4.121 mg min-1). The scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Raman spectroscopy were employed to study the morphology of these carbon nanostructures that indicated both single and multi wall carbon nanotube synthesised have the best quality, elongated straight structures and high purity. |
Dissertation no. 61
| Dissertation title |
preparation and optimization of gelatin nanoparticles in drug delivery |
| Student name |
zahra babaei |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2008 |
| Supervisor |
Dr.Jahanshahi |
|
Advisor |
Dr.sanati |
| Abstract |
New drug delivery systems represent one of the frontier areas of science, which involves multidisciplinary scientific approach, contributing to human health care. Nano carriers have important potential applications for the administration of therapeutic molecules. These delivery systems offer numerous advantages compared to conventional dosage forms, which include improved efficacy, reduced toxicity, and improved patient compliance, convenience and drug targeting to active site. Polymeric nanoparticles (biodegradable and bioagreeable) use as drug delivery carriers in drug delivery systems. Gelatin is one of the Protein materials that can be used for drug delivering to target site. In this present study, nanoparticles of gelatin type A were prepared by a two-step desolvation method as a colloidal drug delivery system. Acetone was added drop-wise for forming nanoparticles. At the end of the process, glutaraldehyde solution was used for preparing nanoparticles as a cross-linking agent. The particles were purified by threefold centrifugation with 15000g and redispersion in 30% acetone in milliQ water. The particle size of the resulting nanoparticles was determined by photon correlation spectroscopy (PCS). Morphological features of gelatin nanoparticles were studied using SEM and AFM. The effects of different parameters were examined in this research: temperature, rate of agitation, concentration of gelatin, cross-linker, concentration of acetone and.... Among the all factors, temperature, rate of agitation, concentration of gelatin, concentration of acetone had the best effect on particle size. A colloidal drug delivery system, the essential parameters in fabrication was optimized by Taguchi design method. Introducing 4 factors in 4 levels to the software 16 experiments were carried out and the best parameters for nanobioparticiples production were obtained at temperature: 50 ºC, gelatin concentration: 45 mg/ml, rate of acetone adding: 80 ml and 600 rpm agitating. Under these conditions the program estimated the gelatin nanoparticle diameter 170 nm, which in the experiment 174 nm was achieved for the nanoparcile diameter. And also the shape of the nanoparticles demonstrated in SEM & AFM is spherical. |
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Dissertation no. 62
| Dissertation title |
activation of carbon nanotubesv for using in biosensors |
| Student name |
Foroogh Toubi |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2007 |
| Supervisor |
Dr.Jahanshahi |
|
Advisor |
Dr.Rostami |
| Abstract |
Carbon nanotubes for their high nanometer surface have dramatic effects on improving electrode surface in sensors. In this study different carbon nanotube, single wall, double wall and multi wall were produced by different methods such as arc discharge (ARC) and chemical vapor deposition, and then they were used for coating electrodes surface. Also for the first time, a carbon nanotube synthesis was made by arc discharge in liquid medium and different parameters such as voltage, current, kind and concentration of salt were investigated on produced nanotubes synthesis and then were used for coating electrodes surface. At first electrochemical oxidation of uric acid 5 mili molar in phosphate 7 by using bare electrode and coated electrode by carbon nanotubes were performed and then obtained picks were investigated. Different ranges of potential and scan rate were used for these experiments. After pretreatment of glassy carbon electrode, carbon nanotubes, which are prepared for coating the electrode surface, were located on the surface and finally cyclic voltametry experiments were carried out in different set ups. The results of these experiments suggest that multi wall carbon nanotubes which are prepared by arc discharge method can increase current more and shift potential peak more, in compare with multi carbon nanotubes which are made by chemical vapor deposition. Also multi wall carbon nanotubes have the most improvement in compare with double wall and single wall prepared by chemical vapor deposition. It is figured out from performed experiments that multi wall carbon nanotubes which are prepared by arc discharge are the best carbon nanotube for improving the surface of electrode for manufacture nano bio sensors. |
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Dissertation no. 63
| Dissertation title |
Fabrication and optimization of BSA nanoparticle as drug delivery vehicles |
| Student name |
mostafa rahimnejad |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2006 |
| Supervisor |
Dr.Mohsen Jahanshahi |
|
Advisor |
professor Ghasem D. Najafpour |
| Abstract |
Bovine serum albumin (BSA) was used for generation of nanoparticles in drug delivery system. The size of the fabricated nano-particles was measure by laser light scanning. Several process parameters were examined to achieve a suitable size of nanoparticle such as pH, temperature, BSA concentration, agitation speed, glutaraldehyde concentration, organic solvent adding rate and the ratio of BSA/ organic solvent. The smallest size of nanoparticles achieved, was 74 nm and the largest size was 503 nm .The impact of protein concentration and additional rate of organic solvent (i.e. ethanol) upon the particle size was investigated. The protein concentration of 5-40 mg.ml-1 was resulted; The mean nanoparticle size diameter has not been relatively changed by variation of solvent adding rate and cross linker concentration and in contrast mainly depended on the volumetric ratio of BSA/ Ethanol, BSA concentration and agitation speed. Taguchi method by definition 4 levels and 4 factors were used for optimization of fabrication nanoparticels. We achieved nanoparticles less than 100 nm after use taguchi methods. The minimum size of nanoparticles (74 nm) were obtained at 4 °C, pH 7.5,5 mg.ml-1 BSA concentration and agitation rate of 500 rpm The mechanistic fabrication of protein nanoparticles and their characterization is strongly discussed. The nanoparticle sample was purified with 48,800 g centrifuge then followed by dialysis, micro and ultra filtration and then analyzed by AFM, SEM, PCS, FTIR as well as SDS Gel electrophoresis. |
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Dissertation no. 64
| Dissertation title |
Adhesion of Biological Cells by Synthetic Pseudo Affinity Plates |
| Student name |
Homayoun Ahmadpanahi |
|
Degree |
PHD Student |
| Field of study |
Analytical Chemistry |
|
Publish year |
2005 |
| Supervisor |
Dr.Mohsen Jahanshahi - Dr.Vaqef hosein |
|
Advisor |
Dr.Parviz Aberomand |
| Abstract |
A series of sorbents containing various amounts of borate groups were prepared by chemical immobilization of p-aminoethylboric acid on a copolymer-treated organosilane spacer glass plates. It was found that baker’s yeast cells, some kind of cancer cells and some kind of bacteria selectively adhered to this supports. Yeast cells stained with procion red HE-3B formed denser and more stable layer on the copolymer-grafted supports modified with phenylboric acid via an organosilane spacer. Elution of plates was accomplished by using of fructose, a sugar with high affinity boronates. Adhesion of yeast cells toboronate-containing polymer fixed on solid support in different conditions was studied. Affinity adhesion of micron-size carbohydrate particles to boronate-containing polymer brushes fixed on solid supports was considered as a model system suggesting a new approach to isolation and separation of living cells. Regeneration of the grafted supports allowed several cycles of sequential adhesion and detachment of stained yeast cells. |
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Dissertation no. 65
| Dissertation title |
Comparative study of the hydrodynamic characterisation of adsobents in expanded bed adsotption for protein recovery and purifieation |
| Student name |
Maryam Khavarpour |
|
Degree |
Master of Science |
| Field of study |
Chemical Engineering |
|
Publish year |
2005 |
| Supervisor |
Dr. Mohsen Jahanshahi |
|
Advisor |
Dr. Ali-Asghar Ghoreishi |
| Abstract |
Expanded-bed adsorption (EBA) is a technique for primary recovery of proteins starting from unclarified broths. This process combines centrifugation, concentration, filteration, and initial capturing of the proteins in a single step. The conventional chemical- engineering view of a fluidized bed is one in which there is a significant degree of mixing, both of the solid and the fluid phases, e.g. in gas-fluidized systems. In many applications, mixing of the solid phase is desirable, for example, in order to obtain high rates of heat transfer and a uniform temperature within the beds used for combination. But in Expanded bed adsorption mixing is an undesirable factor which disturbs the process efficiency. Our purpose here is to investigate the effect of structural parameters such as column diameter, settled bed and expanded bed height of adsorbent, on mixing in the bed. Resistance time distribution (RTD) studies using acetone tracers. Experimental data obtained in this work show an apparent increase of axial dispersion with an increase in column diameter. It has also been shown that expansion effect up to 1/3 times the settled bed height, is insignificant, but expansion higher that this amount will disturb the mixing and consequently the adsorption efficiency. Finally the effect of mixing on protein adsorption has been considered using a model protein, Bovine Cell Albumin (BSA). The experiment data show an apparent decrease of adsorption efficiency with an increase in mixing. |
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