Sharif Digital Repository

Novel PVA/PEG cross-linked membranes were prepared with (0–20 wt. %) of silica nanoparticles. The presence of both the polymers and additive was confirmed by FTIR analysis. The thermal properties of the membranes were analyzed by TGA and DSC analysis. The morphological and mechanical properties of the membranes were studied by SEM analysis and tensile testing, respectively. The gas permeation performances of the membranes were examined using state-of-the-art gas permeability cell. It was found that permeability of all the gases increased with the increase of silica loading, whereas ideal selectivity of carbon dioxide with respect to nitrogen and methane increased up to 10 wt. % loading and... 

In this study, NH2-MIL-101(Al) metal-organic frameworks (MOFs) covered with 3-aminopropyltriethoxysilane (APTES) were incorporated into the polyethersulfone (PES) to produce mixed-matrix membranes (MMMs) for CO2 separation. The APTES functionalization was performed to improve the MOF dispersion in the PES matrix. Different analyses such as X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM) revealed that the MOFs surface successfully functionalized with APTES. An improvement in CO2/CH4 separation efficiency was observed in MMMs, and the performance... 

In this study, NH2-MIL-101(Al) metal-organic frameworks (MOFs) covered with 3-aminopropyltriethoxysilane (APTES) were incorporated into the polyethersulfone (PES) to produce mixed-matrix membranes (MMMs) for CO2 separation. The APTES functionalization was performed to improve the MOF dispersion in the PES matrix. Different analyses such as X-ray diffraction (XRD), Brunauer–Emmett–Teller (BET), Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM) revealed that the MOFs surface successfully functionalized with APTES. An improvement in CO2/CH4 separation efficiency was observed in MMMs, and the performance... 

Supersonic gas separator is proposed for methane purification. One-dimensional analysis is performed to examine the design aspects associated with the converging-diverging nozzle and the liquid separation chamber. The results indicate that at low swirl intensities, the separation chamber length is about 100 times of the nozzle throat. Increasing the swirl intensity would lower this length sharply and it will be less than 10 for swirl intensity of unity which is equivalent to a swirl angle of 45°. In addition, a sensitivity analysis of the separator performance to the inlet conditions like the temperature, pressure, and composition of the mixture is carried out. It is observed that increasing... 

In this study, the effects of the type and content of reactive diluents on the permeation/separation of carbon dioxide/nitrogen (CO2/N2) through acrylate-terminated polyurethane (APU)-acrylate/acrylic diluent (APUA) composite membranes was investigated. A series of APUs based on poly(ethylene glycol) (PEG)-1000 g mol−1, toluene diisocyanate, and 2-hydroxyethyl methacrylate was synthesized and then diluted with several reactive diluents. The results obtained from differential scanning calorimetry (DSC) and Fourier transform infrared analyses showed that the microphase interference of hard and soft segments increased with increasing reactive diluent content. Furthermore, with increasing alkene... 

Supersonic separators are used in gas separation processes such as dehumidification of humid air due to high performance and its good pressure recovery. In the present study, a comprehensive numerical and experimental investigation on the hydrodynamic behavior of air as working fluid and dehumidification performance of supersonic separator have been accomplished. The effect of the operational parameters on shockwave's position are examined. The outcomes show that by increasing the pressure level of supersonic separator, relative error between numerical and experimental results decreases from 20% to less than 10%. The effect of the operational parameters and humidity of inlet air on the... 

Supersonic separators (3Ss) are applied in gas separation processes. Two-dimensional simulation is employed to investigate the effect of operational and thermophysical parameters on the shockwave position. In addition, the impact of the cyclonic part and wet outlet geometry is evaluated by proposing four cases. Increasing the length of the cyclonic part exerts positive and negative influences on the performance of the 3S and the pressure recovery coefficient, respectively. The optimum length is determined between 10 and 15 cm. To demonstrate negative effects of wasted air from the wet outlet, its flow has been increased from 3.6 to 8.1 % of the inlet flow. Improved performance of the 3S is... 

The major obstacles in gas separation by mixed-matrix composite membranes (MMCMs) are poor dispersion and poor affinity between polymers and fillers. The present study demonstrates that these challenges can be overcome appropriately by utilizing a series of synthesized MMCMs. MMCMs were prepared with UV-curable polyurethane acrylate and UiO-66 as selective layer and polyester/polysulfone (PS/PSF) as support layer. The physical properties of prepared MMCMs were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and Fourier transform infrared spectroscopy (FTIR). Microscopic analysis by FESEM revealed that desirable nanoscale dispersion of UiO-66,... 

In industry, utilizing membrane separation technology to purify natural gas streams is of remarkable significance. Molecular Simulation was used in the current article to study the structural and gas separation properties of polydimethylsiloxane (PDMS)/zeolite 4A Mixed Matrix Membranes (MMMs). To explore the optimal performance of MMMs, several structural analyses, namely Fractional Free Volume (FFV), Radial Distribution Function (RDF), X-Ray Diffraction (XRD) and also Glass Transition Temperature (Tg) as one of the most important properties of membranes have been evaluated. Also, the solubilities and diffusivities of periodic cells were respectively measured using MSD and adsorption... 

We demonstrated a novel mixed-matrix composite membrane (MMCM) based on acrylated polyurethane (APU) and UiO-66 nanoparticles to separate CO 2 /N 2 mixture. UiO-66 and functionalized UiO-66 including NH 2 -UiO-66 and glycidyl methacrylate (GMA)-UiO-66 were loaded into APU/2-hydroxyethyl methacrylate (APUH) matrix at variable concentrations between 3 and 30 wt %. APUH/GMA-UiO-66 MMCMs exhibited strong adhesion with a support layer of polyester/polysulfone, which was not deteriorated after immersion in water for a long time (20 days). Incorporation of UiO-66 and its functionalized forms increased simultaneously permeability and CO 2 /N 2 selectivity, which were indeed superior in comparison... 

In this work, poly(vinyl) alcohol (PVA)/poly(ethylene) glycol (PEG) 600 g/mol cross-linked membranes with different alumina (Al2O3) content were synthesized. The membranes were then characterized by FTIR, TGA, DSC, SEM, mechanical strength and permeation properties for carbon dioxide and nitrogen gases at different operating temperatures. The FTIR results confirmed the acetal linkages of cross-linking at 1083 cm−1 and the presence of stretching and bending peaks of Al-O bond at 598 and 444 cm−1, respectively. TGA results showed that the thermal stabilities of the membranes improved with the addition of alumina particles. DSC analysis proved that the glass transition temperature of the... 

In the present experimental study, the effect of operating parameters such as inlet and outlet pressure as well as inlet temperature on the mass separation capability of vortex tubes (VTs) for a gas mixture is investigated. Specifically, concentrating heavier components of a gas mixture in the hot outlet stream is considered. Proposing a semi-empirical index from the experimental study, the simulation of different arrangements of VTs, and the effect of recycling a portion of the hot outlet stream on its mass separation performance are investigated. Moreover, the proposed separation method by VTs is economically compared with commonly used methods by distillation columns and two-phase... 

Mixed-matrix membranes (MMMs) are promising candidates for carbon dioxide separation. However, their application is limited due to improper dispersion of fillers within the polymer matrix, poor interaction of fillers with polymer chains, and formation of defects and micro-voids at the interface of both phases, which all result in the decline of the gas separation performance of MMMs. In this work, we present a new method to overcome these challenges. To this end, a series of MMMs based on polyethersulfone (PES) as the continuous polymer matrix and MIL-53-derived MOFs as the dispersed filler were prepared. FTIR-ATR, XRD, TGA, FESEM, and N2 adsorption/desorption analyses were employed to... 

The current investigation was to present composite membranes with strong interfacial adhesion between top polymeric selective layer and the bottom micro-porous support layer with appropriate gas permeation behavior and practically suitable processing characteristics. To this end, a series of acrylate-terminated polyurethanes (APUs) based on poly (ethylene glycol) (PEG) with different molecular weights (Mn) of 600, 1000, 1500, 2000 and 4000 g/mol, toluene diisocyanate (TDI), and 2-hydroxyethyl methacrylate (HEMA) were synthesized. Composite membranes were prepared with UV-curable acrylate-terminated polyurethane/acrylate diluent (APUAs) as selective layer and polyester/polysulfone (PS/PSF) as... 

Graphene oxide membranes were prepared by vacuum and pressurized ultrafiltration methods on the 12% modified Polyacrylonitrile (12mPAN) substrate to specify challenges, salient features, future directions, and potential of GO membrane for separation fields using characterization techniques and gas separation test (studied gases are CO2, He and N2), which is an efficient tool for better understanding of GO membrane behavior. GO membrane structure was examined over a wide range of parameters, such as pore size range of substrate and its surface properties, pH of GO dispersion, GO content, synthesis pressure, operating pressure and temperature. The results show that the GO content does not hold... 

In this research, Plackett–Burman experimental design was used as a screening method to investigate seven processing factors in the preparation of new polyethersulfone based porous nanocomposite membrane. Polymer concentration, nanoparticle type, nanoparticle concentration, solvent type, solution mixing time, evaporation time, and annealing temperature are variables that were evaluated to fabricate mixed matrix membranes using the evaporation phase inversion method for gas separation. According to obtained results, polymer concentration, nanoparticle concentration, solution mixing time, and evaporation time processing factors had significant effects on gas permeation. In addition, the... 

The solubility of carbon dioxide and hydrogen sulfide gases in the ionic liquid 1-ethyl-3-methylimidazolium trifluoromethanesulfonate ([C2mim][OTf]) was measured at temperatures from (303.15-353.15) K and pressures up to about 3.0 MPa. The Henry's law constants were determined from the new experimental data, which in turn were used to derive the change of some thermodynamic functions of dissolution of the gases in that particular ionic liquid. The new experimental data were correlated by a combination of the extended Henry's law and Pitzer's model for the excess Gibbs energy. The average relative percent deviation (ARD%) of correlated molality values from experimental data are within... 

Zeolite SAPO-34 was used for fabrication of mixed matrix membranes (MMMs) to improve the CO2/CH4/N2 gas separation performance of the neat Pebax1074 membrane. Permeability and selectivity of the MMMs were studied at different temperatures of 25-65°C and pressures of 4-24 bars. Also sorption of different gases in MMMs was measured at 35°C and different pressures, which showed enhanced solubility coefficients. Moreover, thermal, morphological and mechanical properties of MMMs were characterized by differential scanning calorimetry (DSC), scanning electron microscope (SEM) and tensile analysis. The results showed excellent improvement in... 

In this study, polyethersulfone (PES)-based nanocomposite membranes with the incorporation of inorganic filler of α-alumina were prepared via thermal phase inversion method. The fabricated flat sheet-mixed matrix membranes were characterized using X-ray diffraction, thermal gravimetric analysis, differential scanning calorimetry, scanning electron microscopy, and atomic force microscope analysis, and the permeation tests were performed for hydrogen, nitrogen and carbon dioxide. Also prepared α-alumina particles were identified by X-ray diffraction and the surface area, total pore volume and average pore diameter of particles were measured with a high-speed gas-sorption analyzer. The... 

New experimental results are presented for the solubility of carbon dioxide, hydrogen sulfide in the ionic liquid 1-octyl-3-methylimidazolium hexafluorophosphate ([C8mim][PF6]) at temperatures range from (303.15 to 353.15) K and pressures up to about 2 MPa. The solubility of the mixture of CO2/H2S in [C8mim][PF6] under various feed compositions were also measured at temperatures of (303.15, 323.15 and 343.15) K and the pressure up to 1 MPa. The solubility of carbon dioxide and hydrogen sulfide increased with increasing pressure and decreased with increasing temperature and the solubility of H2S is about three times that of CO2 in the particular ionic liquid studied. The measured data were...