Modeling of gas permeation through mixed matrix membranes using a comprehensive computational method

Majid Pakizeh,Salman Ofoghi,Seyed Heydar Rajaee Shooshtari 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.11

Three different morphologies can occur at the interface of inorganic and polymeric phases in mixed matrix membranes (MMMs). These morphologies are characterized by their different parameters such as partial pore blockage factor (α), polymer chain rigidification factor (β), and thickness of rigidified layer or void region. In this study, the morphology of three MMMs has been evaluated using a comprehensive computational method. The average absolute relative error (%AARE) is used as a criterion for optimizing three various MMM morphological parameters. According to the obtained optimum parameters, it was confirmed that two MMMs of C60/Matrimid and PVAc-Zeolite 4A have pore blockage and polymer chain rigidified defects. The results show that the morphology of ZIF-8/6FDA-DAM can be considered as an ideal morphology. After obtaining the morphological parameters, the permeability of the studied MMMs was predicted based on the modified Maxwell model and good agreement was observed between the calculated value and the experimental data.

Hydrogen recovery from Tehran refinery off-gas using pressure swing adsorption, gas absorption and membrane separation technologies: Simulation and economic evaluation

Majid Pakizeh,Ali Mivechian 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.4

Hydrogen recovery from Tehran refinery off-gas was studied using simulation of PSA (pressure swing adsorption), gas absorption processes and modeling as well as simulation of polymeric membrane process. Simulation of PSA process resulted in a product with purity of 0.994 and recovery of 0.789. In this process, mole fraction profiles of all components along the adsorption bed were investigated. Furthermore, the effect of adsorption pressure on hydrogen recovery and purity was examined. By simulation of one-stage membrane process using co-current model,a hydrogen purity of 0.983 and recovery of 0.95 were obtained for stage cut of 0.7. Also, flow rates and mole fractions were investigated both in permeate and retentate. Then, effects of pressure ratio and membrane area on product purity and recovery were studied. In the simulation of the gas absorption process, gasoline was used as a solvent and product with hydrogen purity of 0.95 and recovery of 0.942 was obtained. Also, the effects of solvent flow rate, absorption temperature, and pressure on product purity and recovery were studied. Finally, these three processes were compared economically. The results showed that the PSA process with total cost of US$ 1.29 per 1 kg recovered H2 is more economical than the other two processes (feed flow rate of 115.99 kmol/h with H2 purity of 72.4 mol%).

Preparation and characterization of dimethyldichlorosilane modified SiO2/PSf nanocomposite membrane

Majid Pakizeh,Amir Neghad Moghadam,Mohammad Reza Omidkhah,Mahdieh Namvar-Mahboub 한국화학공학회 2013 Korean Journal of Chemical Engineering Vol.30 No.3

Investigations on nanocomposite membranes imply that these hybrid materials recommend promising newgeneration membranes for gas separation in future. In this study, to investigate the effects of preparation parameters on the morphology and gas transport, various parameters including nanofiller content, surface modification and polymer concentration were considered. Two types of fumed silica nanoparticles (nonmodified and modified) were used to study the surface modification effect on agglomeration, void formation and gas separation properties of prepared membranes. Prepared nanocomposite membranes were characterized by scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR) and tensile strength techniques. The gas permeabilities of hydrogen, methane, and carbon dioxide through pure PSf and nanocomposites were measured as a function of silica volume fraction, and permeability coefficients were determined using a variable pressure/constant volume experimental setup. Results showed that gas permeabilities increase with silica content, and proper H2/CH4 and H2/CO2selectivities can be achieved with modified type of silica nanoparticles due to inhibition of particle agglomeration and bonding with polymer network. Hydrogen selectivity was improved by using 15 wt% polymer content instead of 9 wt%in preparation of nanocomposite membrane with same silica content. Gas permeation results indicated that increasing of feed pressure from 3 bar to 6 bar has a positive effect on selectivity of H2/CH4 but negligible effect on that of H2/CO2for modified silica/PSf membrane.

Optimization of lead removal from aqueous solution by micellar-enhanced ultrafiltration process using Box-Behnken design

Bashir Rahmanian,Majid Pakizeh,Abdolmajid Maskooki 한국화학공학회 2012 Korean Journal of Chemical Engineering Vol.29 No.6

The main objective of this research was to use Box-Behnken experimental design (BBD) and response surface methodology (RSM) for optimization of micellar-enhanced ultrafiltration (MEUF) to remove lead ions from synthetic wastewater using spiral-wound ultrafiltration membrane. The critical factors selected for the examination were surfactant concentration, molar ratio of surfactant to metal (S/M) and solution pH. A total of 17 experiments were accomplished towards the construction of a quadratic model for both target variables. The experimental results were fitted with a second-order polynomial equation by a multiple regression analysis, and more than 95%, 93% of the variation could be predicted by the models for lead rejection and permeation flux, respectively. The optimum condition was found by using the obtained mathematical models. Optimization indicated that in CSDS=2mM, pH=6.57 and S/M=9.82 maximum flux and rejection efficiency can be achieved, simultaneously.

The effect of chemical modification of SiO2 nanoparticles on the nanofiltration characteristics of polyamide membrane

Nasim Rakhshan,Majid Pakizeh 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.12

This study presents the synthesis and characterization of oleic acid (OA)-modified silica/polyamide (PA) nanocomposite membranes. The thin film composite (TFC) polyamide was prepared with M-phenylendiamine (MPD) and trimesoyl chloride (TMC) via interfacial polymerization over porous polysulfone. Five different thin film nanocomposite (TFN) membranes were fabricated by dispersing OA-modified silica nanoparticles in TMC solution. Chemical and thermal properties, surface morphology, roughness, film thickness and hydrophilicity of synthesized membranes were characterized by ATR-IR, TGA, FESEM, AFM, TEM and contact angle analysis. The results showed that incorporating OA-modified silica into thin film layer improved chemical and physical properties of nanocomposite membranes. The effects of modification of nano silica on pure water flux and MgSO4 rejection were investigated. OAmodified silica/PA membranes showed higher pure water flux in comparison with neat polyamide TFC membrane but lower than unmodified silica/PA membrane; while significant increase in salt rejection was exhibited for OA-modified silica/PA membranes. The maximum rejection for OA-modified and unmodified nanocomposite membrane was obtained about 98.7% and 95.2%, respectively.

The role of tetragonal-metal-organic framework-5 loadings with extra ZnO molecule on the gas separation performance of mixed matrix membrane

Mehrzad Arjmandi,Majid Pakizeh,Omid Pirouzram 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6

The effect of more ZnO molecule in tetragonal structure of MOF-5 than cubic structure on the gas permeation properties of T-MOF-5/polyetherimide mixed matrix membranes was investigated. T-MOF-5 was first successfully synthesized and carefully characterized by XRD, FTIR, SEM and N2 adsorption technique at 77 K. Novel T-MOF- 5/PEI MMMs were prepared using solution casting method and characterized by FTIR and SEM. The SEM pictures of the MMMs showed that T-MOF-5 nanocrystals changed the morphology of PEI and exhibited acceptable contacts between the filler particles and the polymer chains. Gas permeation properties of these membranes with different TMOF- 5 contents were studied for pure H2, CO2, CH4 and N2 gases. Permeation measurement showed that the all gases’ permeability, diffusivity and solubility were increased with T-MOF-5 loading. H2 permeability and the ideal selectivity of H2/CO2 and H2/CH4 in MMM with 25 wt% loading of T-MOF-5 nanocrystals were increased. This behavior was attributed to more ZnO molecule in T-MOF-5 structure. The experimental gas permeations through T-MOF-5/PEI nanocomposite with different filler loadings were fitted on Higuchi model. Good agreement between the experimental data and the predicted gas permeability was obtained.

The effect of functionalized SiO2 nanoparticles on the morphology and triazines separation properties of cellulose acetate membranes

Nasim Rakhshan,Majid Pakizeh 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.34 No.-

This study investigates the removal of triazines from an aqueous solution using a novel SiO2/CAnanocomposite membrane. The membranes were fabricated with phase inversion by dispersing SiO2nanoparticles in the CA casting solutions in the range of 0.01–0.1 wt.%. ATR-IR, FESEM, AFM, and contactangle analyses were employed to characterize the prepared membranes. The effect of silicananoparticles on the performance of membranes was studied through the pure water flux and MgSO4rejection obtained at an applied pressure of 10 bars. Nanocomposite CA membranes generally showedhigher salt rejection and experienced less flux than neat CA membranes, due to morphology changes. Inaddition, the observed salt rejection tended to enhance as silica loading increased up to a criticalconcentration. Three triazines (atrazine, propazine, and prometryn) were removed from water by theprepared membranes, and their rejections were compared. The results showed that the triazinesrejection was increased by pressure and feed concentration. The effects of the molecules’ properties,including molecular size, hydrophobicity and dipole moment, were studied. The results revealed that therejection of prometryn with a larger molecular size was always higher than the other two triazines. Itwas observed that there was a direct relation between dipole moment and triazine rejection, while thisrelation was not observed in the case of hydrophobicity.

Mixed matrix membranes incorporated with cubic-MOF-5 for improved polyetherimide gas separation membranes: Theory and experiment

Mehrzad Arjmandi,Majid Pakizeh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.5

Cubic metal-organic framework 5 (C-MOF-5) nanocrystals with a high surface area (2387 m2/g) were successfully synthesized. The structure of C-MOF-5 nanocrystals was characterized by XRD, FTIR, particle size analysis, and N2 adsorption techniques. Novel mixed matrix membranes (MMMs) containing C-MOF-5 inside an polyetherimide (PEI) matrix were prepared using solution casting method and characterized by SEM, FTIR, and single gas permeation analyses. The SEM images of the MMM cross-sections revealed that C-MOF-5 particles have changed the morphology of polymer matrix. In addition, it has attained the proper distribution of filler as well as good compatibility between the filler and the polymer. The results showed that the C-MOF-5 nanocrystals facilitated the gas transport along the membranes and for all gases (H2, CO2, CH4, and N2), permeabilities, diffusivities, and solubilities of the MMMs were increased with increasing the loading of C-MOF-5 nanocrystals at ambient temperature and pressure of 6 bar. Incorporation of 5 wt.% of C-MOF-5 into pure PEI resulted in 40% increase in H2 permeability and the separation factor ðaPi ; jÞ of H2/CO2, H2/CH4, CO2/CH4, and CH4/N2 was changed from 5.99, 111.89, 18.67, 0.9 to 6.13, 117.42, 19.17, and 0.92, respectively. For high loadings of C-MOF-5s (15 and 25 wt.%), the mentioned separation factors ðaPi ; jÞ were increased except for H2/CO2. CO2 and CH4 permeability was strongly affected by the solubility coefficient and less affected by the diffusion coefficient. On the other hand, N2 permeability was strongly affected by the diffusion coefficient and less affected by the solubility coefficient. The experimental gas permeations through C-MOF-5/PEI nanocomposite with different filler loadings were fitted well on Higuchi model.

Optimization of preparation conditions of polyamide thin film composite membrane for organic solvent nanofiltration

Mahdieh Namvar-Mahboub,Majid Pakizeh 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.2

Separation performance of polyamide composite membranes is affected by several parameters during formationof thin upper layer via interfacial polymerization. We investigated the effect of various polyamide synthesisconditions on the performance of organic solvent resistant polyamide composite membranes through the model equationsdesigned by 2-level fractional factorial design. The dewaxing solvent recovery was selected as separation process. Fivefactors were changed in two level includin; TMC concentration (0.05-0.1%), MPD concentration (1-2%), support immersiontime in organic solution (2-4 min), support immersion time in aqueous solution (1-2 min), and curing temperature(70-80 oC). The resultant equations showed 93.48% and 94.82% of the variability (R2adj) in data used to fit oilrejection and permeate flux models, respectively. The analysis of variance revealed that both models were high significant. It was also observed that TMC concentration, MPD concentration and immersion time in TMC have morepronounced effect on the oil rejection and permeate flux than other factors and interactions. Optimal polyamide preparationconditions were obtained using multiple response method for 94% oil rejection as target value. According tothe results, the best value of permeate flux (8.86 l/(m2·h)) was found at TMC concentration of 0.1%, MPD concentrationof 1.94%, immersion time in TMC of 3.88 min, immersion time in MPD of 1.95 min and curing temperature of71.96 oC with desirability factor of 1.

Experimental study on mercury ions removal from aqueous solution by MnO2/CNTs nanocomposite adsorbent

Hamideh Khademzadeh Moghaddam,Majid Pakizeh 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

MnO2-coated carbon nanotubes (MnO2/CNT) were prepared, characterized and used to remove Hg(II)from aqueous solution. Characterization of the prepared hybrid adsorbent was carried out usingtransmission electron microscopy (TEM), N2 adsorption–desorption, X-ray diffraction (XRD) and thermalgravimetric analysis (TGA). The synthesized MnO2/CNT sorbent possessed specific area of 110.38(m2 g 1), mesopore size (2.70 nm) and total pore volume of 0.522 (cm3 g 1). XRD diffraction analysisrevealed the birnessite-type MnO2 is produced through the hydrothermal synthesis and was coated onCNTs surface. A series of batch adsorption experiments were conducted to study the effect oftemperature, pH, initial concentration, the presence of other heavy metals and contact time on Hg(II)uptake by the adsorbent. Optimum conditions obtained were 50 8C, pH 5–7 and contact time of 80 min. Hg adsorption on MnO2/CNT was a fast process and the kinetics followed a pseudo-second-order rateequation. The adsorption isotherms were analyzed using Langmuir and Freundlich models, and theFreundlich equation best describes the interaction between mercury species and MnO2/CNT. Thermodynamic parameters of DH8, DS8 and DG8 were calculated and it was found that the Hg(II)species adsorption on the MnO2/CNT is endothermic and spontaneous. From the D–R isotherm, the meanfree energy was calculated as 7.07 kJ mol 1 indicating that the sorption of Hg(II) was taken place byphysico-chemical mechanism.