| Polyetherimide (PEI) hollow fiber membranes were prepared by phase inversion method based on the phase separation behavior of PEI dope. Moreover, in order to improve the hydrophilicity of the membrane, PEI was sulfonated and the sulfonated polyetherimide (SPEI) was blended with PEI to prepare membranes.The phase separation behavior of PEI dope was studied according to the linerized cloud point (LCP) correlation. It was found that the phase separation behavior of the three systems, i.e., PEI/DMAc/H2O, PEI/DMAc/ethanol and PEI/DMAc/acetic acid (AA), all agree with the LCP correlation. The binodal lines of the three systems were calculated according to the LCP correlation. The binodal lines of the PEI/DMAc /(H2O+DMAc), PEI/DMAc/(ethanol+DMAc) and PEI/DMAc/(AA+DMAc) systems were also calculated according to the LCP correlation. It was found that the binodal lines of the systems are shifted away the PEI/DMAc axis with the addition of DMAc into the nonsolvent/DMAc mixture. Moreover, the shift of the binodal line is more remarkable when the coagulation ability of the nonsolvent is weaker. Furthermore, because of the additive property for cloud point component, the phase separation of PEI/DMAc/(H2O+AA) system also agrees with the LCP correlation,PEI ultrafiltration (UF) hollow fiber membranes were prepared by phase inversion method and some spinning parameters were investigated. With the addition of DMAc into the internal coagulant solution, micropores are found in the inner surface of the hollow fiber, and formation of the finger-like macrovoid is suppressed in the cross section of the hollow fiber by SEM examination. With higher dope concentration, the pore structure is tighter, and a membrane with higher retention and lower pure water flux is obtained.A A was used as an additive to improve the PEI UF membrane performance. With the addition of AA into the dope solution, spinodal phase separation is induced and the finger-like macrovoid formation is suppressed. In addition, the water flux of themembrane was improved.PEI was sulfonated by chlorosulfonic acid (CSA) in order to impart hydrophilicity to the polymer. With the increase of the CSA/PEI repeat unit ratio and/or reaction time, ion exchange capacity (IEC) of the sulfonated polyetherimide (SPEI) increases accordingly. Water absorption test and contact angle measurement showed that the hydrophilicity of the SPEI increases with the increasing of IEC. Membranes were fabricated from SPEI/PEI blend with different ratios. The morphologies of the blend membranes were observed by SEM. It was found that the membrane pore size became larger when SPEI with higher IEC was used. With the increasing of SPEI ratio in the blend membranes, the membrane pore size increased, too. The contact angle data of the membranes showed that the hydrophilicity of the blend membrane was elevated because of the sulfonate group on the SPEI molecular chain. At last, a blend membrane with contact angle of 73?was obtained, in contrast to 91?for the PEI membrane.SPEI was blend with PEI to prepare hollow fiber UF membranes and several spinning parameters were investigated. With the addition of SPEI, spinodal phase separation was observed. Increasing the air gap distance, micropores were found in the outer fiber surface and the pore size was larger with longer air gap distance. The tendency to induce spinodal phase separation was suppressed at longer air gap distance. The water flux of the membrane showed a maximum with different air gap distance and the retention decreased with increasing of air gap distance. A SPEI/PEI hollow fiber membrane with water flux of 54.2 1/m2 h (0.1 MPa) and 78% retention of dextran (Mw=40 000) solution was obtained.The filtration of Bovine serum albumin (BSA) solution was carried out in order to examine the fouling tendency of the SPEI/PEI blend membranes. With increasing the SPEI ratio in the blend membrane, the membrane flux lost due to the reversible adsorption of BSA increases, and the BSA adhered to the membrane surface is more easily washed...
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