Study On The Fabrication And Performance Of Novel Organic Solvent Resistant Separation Membrane

1.Using the domestic polyacrylonitrile（PAN）as raw material,asymmetric nanofiltration membranes were successfully prepared by non-solvent induced phase separation method（NIPS）.Nanofiltration membranes with different separation performance were obtained by adjusting the heat treatment temperature of the casted dope layer before phase separation and controlling the volatilization rate of tetrahydrofuran（THF）.Moreover,the study attempts to use Co⁶⁰ray irradiation modification to improve the performance of the PAN membranes.The morphology,hydrophilicity and surface zeta potential of the membranes were systematically characterized.The water flux,retention of salt ions and small molecular dyes were measured.The results showed that with the increase of heat treatment temperature of the liquid film layer,the permeation flux of the obtained membranes to the Na₂SO₄ 、 NaCl 、 MgSO₄ and MgCl₂ aqueous solution decreases gradually,and the rejection ratio of the corresponding salt ions increases gradually,and the maximum rejection ratio to the Na₂SO₄ can reach 85.6%.Optimized membrane for filtration of the four kinds of studied dye aqueous solutions obtained water flux in the range of 2.14-111.5 L·m^-2·h^-1.Meanwhile the larger dyes retention rate could reach more than 99.8%,which could meet the requirements for de-colorization of dyes in aqueous solutions.The results show that the domestic PAN is a low-cost nanofiltration membrane material for dye wastewater treatment.2.Thin film composite（TFC）polyamide reverse osmosis membranes were prepared by interfacial polymerization of 1,3,5-cyclohexanoyl chloride（CHTC）,2,2’,4,4’-benzotriformyl chloride（BTEC）and Benzoyl chloride（TMC）with m-phenylenediamine（MPD）respectively,on poly（ether ether ketone）-polyphenylene sulfone copolymer（PEEK-Co-PPSU）porous membrane,which had fine organic solvent resistance.The membranes preparation conditions were thoroughly optimized,and the properties and separation performance of the obtained membranes were studied systematically.The resulted membrane based on the three kinds of acyl chloride monomers exhibited a flux in the range of 9.53-71.89 L·m^-2·h^-1 for saline and organic-water mixtures.The PA-TMC film exhibited the best separation performance with Na Cl rejection of 98.53% and water flux of 29.52 L·m^-2·h^-1,which has reached the applicable level.Furthermore,the PA-TMC membrane modified by aziridine could reach a retention ratio as high as more than 90% for 5wt% and 10wt% DMF aqueous solution,and this membrane is expected to be used in treatment of organic solvent contained wastewater.3.Finally,the optimum conditions for preparation of PEEK composite membrane were investigated further.The results showed that the PEEK composite membrane has excellent resistance to organic solvents,and is stable in various common organic solvents.The rejection of toluene in 5wt% toluene-95wt% methanol mixture could reach 100%.The rejection of toluene in 10wt% toluene-90wt% methanol mixture could reach 96.85%,and the corresponding selectivity is 35.73.At the same time,the rejection to small molecular dye mesorosaniline（MW = 318 Da）dissolved in methanol could reach 91.6%,with methanol flux of15.81 L·m^-2·h^-1.In conclusion,the membrane has potential for separation of organic solvents mixtures with different polarity and for use as the routinely organic solvent nanofiltration membranes.