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Nanofiltration separation process is a selective , simple operation and low energy consumption technology , has been widely used in various industrial fields . The nanofiltration process many advantages , it has great potential value in non- aqueous systems in the fields of petrochemical , pharmaceutical , and food . Traditional nanofiltration membrane usually is difficult to expand to a non - aqueous system , for further research and development solvent nanofiltration membrane , to broaden the scope of application of the nanofiltration process is extremely important . The article was prepared by two-step process of a polyimide solvent resistant nanofiltration membranes , polyimide solids content , the scraped film thickness , phase inversion process of time, the temperature of the thermal imidization and thermal imidization on the membrane performance the impact . Holding eventually by solid content of 13% , the film thickness of 150μm, the water phase conversion 1h, the thermal imidization procedures for 200 ° C for 2.5h, 250 ° C 2h 300 ° C for 2h, fabricated performance more excellent polyimide resistant The solvent nanofiltration membrane . In this study, to characterize the performance of optimized polyimide solvent nanofiltration membrane , total reflection Fourier transform infrared spectroscopy (ATR-FTIR) test showed that the optimized PI nanofiltration membrane imidization completely while using further said re - assay the degree of imidization of 92.23% ; scanning electron microscope (SEM) tests show that the performance of the nanofiltration membrane out of the typical asymmetric structure ; rate of 72.3% while the porosity of the test result table mask . This experiment the PI solvent nanofiltration membrane comprehensive performance testing , including the solvent resistance of the membrane ; pure solvent through performance ; different molecular weights , different charge , the different valences salt solution interception performance ; film at high temperatures interception performance . The results showed that the solvent nanofiltration membrane in the cyclohexane ring has ketone , methanol, tetrahydrofuran, ethyl acetate , NMP have better stability , can be used normally . Test several pure solvent , membrane flux remained fairly even higher with the commercialization of nanofiltration membrane . The membrane , the majority of positive charge and negative charge dyes have a higher retention rate, in addition to methyl orange , other dye retention rate higher than 90% . The high temperature testing showed that this PI solvent nanofiltration membrane at 80 ℃ normal use, and at the same time maintaining a higher retention rate flux enhance about 2 times, exhibits excellent high-temperature separation performance .
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