Seyed Mohammad Reza Razavi | Isfahan University of Technology (original) (raw)

Uploads

Papers by Seyed Mohammad Reza Razavi

Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR) techniqu... more Nowadays, due to the remarkable oil reduction in oil fields, enhanced oil recovery (EOR) techniques have been considered by a large number of scientists and company. Situ oil extraction is normally done by these techniques with high efficiency. In this particular study, five different surface active agents (surfactant), two kinds of oil with various API, two kinds of sulfonated polyacry-lamide, two different electrolyte solutions with various TDS and two distinctive alcohols were tested and evaluated. An optimal formulation in terms of the properties and quantity of materials has to be used in order to enhance oil recovery, achieved by investigation of surface tension and the phase behavior of mentioned substances. Rheological behavior of polymer flooding and surfactant was studied. Employing this formulation, the maximum micro emulsion of oil in water occurred. Due to the synergy between surfactant and alcohol (as a co-surfactant), relatively lower amounts of sur-factants were used which led to the dip in the cost of operation, and ultimately the efficiency of operation improved.

In this study, medium density polyethylene (MDPE) incorporated with Triclosan antibacterial subst... more In this study, medium density polyethylene (MDPE) incorporated with Triclosan antibacterial substance has been prepared and Triclosan release rate was investigated. The crystallinity level and matrix polarity, as two significant parameters in antibacterial release control, were studied. Triclosan, a well-established widespread antibacterial agent, was incorporated into medium density polyethylene (MDPE) and Maleic anhydride grafted polyethylene (PEg -MA) was used to change the polarity of the MDPE matrix. A mas-terbatch of 10 wt% Triclosan incorporated with the MDPE and various PEg -MA concentrations were prepared using an internal mixer. Then the masterbatch was diluted in the MDPE matrix to produce compounds with 0.1, 0.5, and1 wt% Triclosan via twin screw extruder. The compounds were molded by compression molding method and then were cooled in three different cooling rate methods: isothermal cooling (I), quenching (Q),and moderate 5–10 • C/min cooling rate (M). Cooling rate effects on crystallinity level were investigated applying sample density measurement. UV–vis absorption spectroscopy was used to probe the release of Triclosan. Antibacterial properties of the compounds against Escherichia coli, Klebsiella pneumoniae, and Staphylococcus aureus were measured. The results showed that by addition of PEg -MA, Triclosan release rate was increased. It was confirmed that the sample crystallinity was decreased by the cooling rate enhancement. The results also showed that quenched samples indicated higher release of Triclosan. Cooling rate reduction and raising the polarity increased the release of Tri-closan and improved the antibacterial properties of the compounds.

In this work, treatment of real hypersaline refinery wastewater by hollow fiber membrane bioreac... more In this work, treatment of real hypersaline refinery wastewater by hollow fiber membrane bioreactor coupled with reverse osmosis unit was studied. The ability of HF-MBR and RO developed in this work, was evaluated through examination of the effluent properties under various operating conditions
including hydraulic retention time and flux. Arak refinery wastewater was employed as influent of the bioreactor which consists of an immersed ultrafiltation membrane. The HF-MBR/RO was run for 6 months. Average elimination performance of chemical oxygen demand, biological oxygen demand, total suspended solids, volatile suspended solids, total dissolved soild and turbidity were obtained 82%, 89%, 98%, 99%,
99% and 98% respectively. Highly removal performance of oily contaminant, TDS and the complete retention of suspends solids implies good potential of the HF-MBR/RO system for wastewater refinement.

In the present study, separation and mass transfer of acetone using a polymeric hollow ﬁber membr... more In the present study, separation and mass transfer of acetone using a polymeric hollow ﬁber membrane by a supercritical ﬂuid as a dense solvent was simulated. The propane is used as supercritical ﬂuid for extraction of acetone. The simulated hollow-ﬁber membrane contactor has three compartments: tube, porous membrane and shell. The aqueous solution and solvent pass in the lumen and shell sides, respec- tively. The model equations have been solved by CFD technique using a ﬁnite element as numerical method. The simulation results were compared with experimental data obtained from literature and showed great agreement with the measured values. The simulation results of acetone extraction also showed that reducing the feed rate and increasing the solvent velocity will enhance the separation of acetone.

In this paper, the capability of hollow-ﬁber membrane bioreactor (HF-MBR) for real pe... more In this paper, the capability of hollow-ﬁber membrane bioreactor (HF-MBR) for real petroleum reﬁn-
ery wastewater treatment was studied. A pilot immersed HF-MBR was designed, and the treatment
investigated under various hydraulic retention time (HRT), ﬂux, temperature, and different operational
conditions. The bioreactor included an ultraﬁltration membrane (UF) and Arak reﬁnery wastewater used
as the inﬂuent stream. The HF-MBR was running throughout 160 days. The result indicated that aver-
age elimination efﬁciencies of chemical oxygen demand (COD), biological oxygen demand (BOD5), total
suspended solids (TSS), volatile suspended solids (VSS) and turbidity were attained 82%, 89%, 98%, 99%,
and 98%, respectively. Furthermore, the mixed liquor-suspended solid (MLSS) and mixed liquor volatile-
suspended solids (MLVSS) concentration raised from minimal concentration to about 6.6 and 6.1 g/L,
respectively.

The aim of this work was to evaluate the anti-bacterial and mechanical properties of chitosan bas... more The aim of this work was to evaluate the anti-bacterial and mechanical properties of chitosan based solvent-cast blends with synthetic poly(ethylene terephthalate) (PET). The amount of chitosan loading was varied from 1% to 9% (w/w). Chitosan and PET were homogeneously dissolved in a ternary solvent system with different mass ratios in a trifluoroacetic acid, chloroform, and acetic acid solution and processed into uniform films. Molecular interactions between chitosan and PET were investigated using Attenuated Total Reflectance-Fourier Transform Infrared (ATR-FTIR) spectroscopy. Morphology and tensile properties of these blend films were investigated. The antibacterial activity of the samples was evaluated utilizing the colony forming unit method against three typical human pathogenic microorganisms, Escherichia coli, Klebsiella pneumonia, and Staphylococcus aureus. The results indicated that the PET/chitosan films showed a significantly higher growth inhibition rate compared with the PET film. Chitosan release from a wide range of blends was studied using the ninhydrin method. The release tests revealed that dissolution of the biocide glucosamine groups, i.e. the chitosan water soluble fractions, also increased with the increase in the amount of chitosan content. Results obtained from ATR-FTIR spectra suggested that there exist pronounced interactions that probably resulted from hydrogen bond formation between different components. SEM micrographs showed that the compatibility of the two polymers was reduced when the fraction of chitosan was increased. Tensile strength and elongation at break of the blends reduced with the increase in chitosan content. These results indicated that the blends became brittle upon increasing the chitosan content.

In this study, a mathematical model is proposed for prediction of CO2 absorption from N2/CO2 mixt... more In this study, a mathematical model is proposed for prediction of CO2 absorption from N2/CO2 mixture by potassium threonate in a hollow-fiber membrane contactor (HFMC). CFD technique using numerical method of finite element was applied to solve the governing equations of model. Effect of different factors on CO2 absorption was analyzed and for investigation of absorbent type effect, functioning of potassium threonate was compared with diethanolamine (DEA). Axial and radial diffusion can be described with the two dimensional model established in this work. The obtained simulation results were compared with reported experimental data to ensure accuracy of the model predictions. Comparison of model results with experimental data revealed that the developed model can well predict CO2 capture by potassium threonate in HFMCs. Increment of absorbent flow rate and concentration eventuate in enhancement of CO2 absorption. On the other hand, capture of CO2 will be reduced with increment of gas flow rate. According to the model results, potassium threonate can be considered as a more efficient absorbent as compared with DEA.

In this study chemical absorption of CO2 from N2/CO2 gas mixture in tetramethylammonium glycinate... more In this study chemical absorption of CO2 from N2/CO2 gas mixture in tetramethylammonium glycinate ([N1111] [Gly]) solution using hollow-fiber membrane contactors by employing CFD method was investigated. A two dimensional mathematical model was developed to describe diffusion in axial and radial directions of the HFMC . Also, the model gives an account of convection in the tube and the shell sides with chemical reaction between CO2 and absorbent. Results of simulation showed good agreement with experimental data that reveals the validity of the model. CO2 absorption from gas mixture increases as the flow rate and the concentration of the absorbent goes up. On the other hand, increment of gas flow rate decreases removal of CO2. The proposed model can predict CO2 capture from gas mixtures in HFMCs.

Separation of CO2 from air was simulated in this work. The considered process for removal of CO2 ... more Separation of CO2 from air was simulated in this work. The considered process for removal of CO2 was a hollow-fiber membrane contactor and an aqueous solution of 2-amino-2-metyl-1-propanol (AMP) as absorbent. The model was developed based on mass transfer as well as chemical reaction for CO2 and solvent in the contactor. The equations of model were solved using finite element method. Simulation results were compared with experimental data, and good agreement was observed. The results revealed that increasing solvent velocity enhances removal of CO2 in the hollow-fiber membrane contactor. Moreover, it was found that counter-current process mode is more favorable to achieve the highest separation efficiency.

Abstract Simulation of transport phenomena in capture of CO2 from air was carried out in this wor... more Abstract Simulation of transport phenomena in capture of CO2 from air was carried out
in this work. Separation of CO2 as an air pollutant from nitrogen using porous membranes
is simulated to optimize the process. Computational ﬂuid dynamics approach is utilized for
numerical simulation of process aiming to predict the concentration of CO2 in the membrane
module. 2-Amino-2-methyl-1-propanol as chemical absorbent was considered in the sim-
ulations. Hydrodynamics and mass transfer of system were investigated by the developed
numerical procedure. The simulation results were validated through comparing with exper-
imental data, and good agreement was achieved. The simulation results revealed that CO2
removal rate increases with an enhancement of absorbent ﬂow rate, and decreases with the
increasing gas ﬂow rate. This simulation procedure can predict CO2 capture from air using
porous membranes.

A two-dimensional model for the mass transport of carbon dioxide from the gas mixture in nanoporo... more A two-dimensional model for the mass transport of carbon dioxide from the gas mixture in nanoporous membrane contactors was developed in this work. A solution of 2-amino-2-methyl-1-propanol and piperazine (activator of absorption) is used as a chemical solvent for capture of CO 2 . The diffusion in the radial and axial direction of the fibers, through the membrane and the shell of membrane contactor was investigated. The convection inside the tube and shell was also investigated along with chemical analysis. Computational fluid dynamics technique was used to solve the model equations including continuity and momentum equations. The predictions of the model were compared with the experimental data and good agreements were observed which confirmed the validity of developed mass transfer model. According to the presented results, an increase in the gas and liquid flow rate results in an increase in the rate of CO 2 absorption (at N Re < 20). Also, an increase in the concentration of piperazine results in an increase in the CO 2 absorption of the gas mixture. This study indicates that the proposed model is capable of predicting the rate of CO 2 capture in membrane contactors with good precision.

Please cite this article in press as: S.A. Miramini, et al., CFD simulation of acetone separation... more Please cite this article in press as: S.A. Miramini, et al., CFD simulation of acetone separation from an aqueous solution using supercritical fluid in a hollow-fiber membrane contactor, Chem. Eng. Process. (2013), http://dx.