جستجوی مقالات مرتبط با کلیدواژه "membranes" در نشریات گروه "شیمی"

Poly(methyl methacrylate-co-nitrophenyl maleimide) (MMA-co-NMI) and poly(methyl methacrylate-co-hydroxyphenyl maleimide) (MMA-co-HMI) copolymers were synthesized using free radical polymerization of MMA with a new MI monomer containing phenyl and –NO2 groups. Proton exchange membrane fuel cell(PEMFC) were prepared using these copolymers as membrane matrix and phosphotungstic acid (PWA) as proton conductive additive. Dry-phase inversion method was employed to fabricate membranes with different concentrations of copolymers and PWA. Characteristics and proton conductivity of membranes were investigated using FTIR, SEM, TGA, DTG, DSC, ion exchange capacity, water uptake, and proton conductivity tests. Results revealed an increment in the thermal stability as well as ion exchange capacity of composite membranes prepared by addition of PWA. Moreover, applying MMA-co-HMI as copolymer and PWA as additive remarkably improved the proton conductivity of membrane (2.6×10−1 S.cm−1) due to the interaction between the functional groups of PWA (H3O+ ions, O atoms) and MMA-co-HMI copolymer (OH, C=O functional groups).

We developed some Ultrafiltration (UF)  membranes based on polysulfone (PSF) and poly acrylic acid (PAA) mixture. The Ultrafiltration membraneswere prepared by the phase inversion technique using Dimethylformamide (DMF) as a solvent. Immobilization of PAA in PSF matrix was confirmed by Fourier transform infrared spectroscopy (FTIR). The membranes have an asymmetric structure, as revealed by scanning electron microscopy (SEM). Natural water from Mahmoudia canal (a subdivision of the Nile River) is used as feed water. The permeate flux reached 120.0 l/m2.hr. The hydrophilicity measured by contact angle was enhanced by the addition of PAA to reach 66.00. The prepared membranes showed good tensile strength that reached 7.2 MPa. Turbidity rejection and dissolved organic carbon (DOC) rejection reached 98.4% and 65 %, respectively. These performances obtained at ambient operating conditions, make the fabricated membranes attractive for canal water treatment.

A mathematical model considering mass and momentum transfer was developed for simulation of ethanol dewatering via pervaporation process. The process involves removal of water from a water/ethanol liquid mixture using a dense polymeric membrane. The model domain was divided into two compartments including feed and membrane. For a description of water transport in the feed solution, Maxwell-Stefan approach was used, while for mass transfer inside the membrane the molecular diffusion mechanism was assumed. The governing equations were solved numerically using finite element method. The concentration profile inside the membrane showed a linear decrease and a parabolic fully developed velocity profile was obtained on the feed side. The results also confirmed that formation of concentration layer can be easily predicted using Maxwell-Stefan approach in dewatering of organic compounds using pervaporation process.

The current study presents synthesis and characterization of high impact polystyrene - TiO2 nanoparticles mixed matrix membranes for separation of carbon dioxide from nitrogen. The solution-casting method was used for preparation of membranes. The nano mixed matrix membranes were characterized using scanning electron microscopy to ensure the suitable dispersion of nano particles in high impact polystyrene matrix. The effect of TiO2 nanoparticles loading on membrane performance was investigated. The separation performance of synthesized membranes was investigated in separation of CO2 from CO2/N2 mixture. Effect of feed pressure and TiO2 content on separation of CO2 was studied. The results revealed that increase of feed pressure decreases flux of gases through the mixed matrix membrane. The results also confirmed that the best separation performance can be obtained at TiO2 nanoparticles loading of 7 wt.%.