Study On Improving Hydrophilicity Of Polysulfone Separation Membranes By Blending With Amphiphilic Isomerized Polyimide

Polysulfone(PSf)is one of the most commonly utilized as a material in ultrafiltration membranes fabrication originated from its excellent mechanical and thermal stability properties.It has been widely used in water treatment,hemodialysis and other fields,but polysulfone membrane materials can easily lead to membrane fouling problem during the membrane operation due to its intrinsic hydrophobicity characteristic,which can drastically decrease membrane permeability and increase the membrane operating cost.In this study,a sulfobetaine isomerized polyimide(iso-PI)zwitterionic additive with intermediate hydrophobicity and hydrophilicity at ends was designed and synthesized,which would be well dispersed and high solubility in organic solvent.The three different molecular weight sulfobetaine isomerized polyimide were synthesized by controlling the different ratio of the monomers.The structure of the synthetic additives was characterized by both ~1H-NMR and FT-IR.The synthetic additive were blended with polysulfone,a conventional phase inversion method was utilized to fabricate polysulfone ultrafiltration membrane.Study the effect of three different molecular weight sulfobetaine isomerized polyimides on polysulfone membranes properties by investigating microstructure,hydrophilicity,osmotic separation and antifouling properties of the prepared modified membranes.The results show that polysulfone membrane permeability,hydrophilicity and antifouling properties can be improved by blending with sulfobetaine isomerized polyimide without PEG Porogen addition.the best blending membrane water flux can increase to 218 L/(m~2 h)with good hydrophilicity.The dynamic recovery rate experiment also showed that the introduction of the amphoteric particle additive can greatly reduce the flux loss of the membrane fouling by the BSA solution,and the amphiphilic particle additive maintains a high recovery rate through three pollutant circulation experiments.The mermbrane thermal stability is also improved by the introduction of the sulfobetaine isomerized polyimide.the blending modification additive can still stably exist in the membrane after the high temperature water bath,which indicates that the introduction of.sulfobetaine isomerized polyimide can both improve the polysulfone membrane hydrophilicity and membrane stability.For studying the polysulfone membrane properties effect of PEG and the amphiphilic nanoparticle additive into the casting solution,a PEG/amphiphile nanoparticle additive polysulfone ultrafiltration membrane was prepared.The results show that the introduction of sulfobetaine isomerized polyimide into the polysulfone membrane with exist of PEG can further enhance membrane permeability and not impair the membrane pollutants interception performance.In addition,the prepared hydrophilic modification membrane has also improve membrane hydrophilicity,antifouling performance and thermal stability to some extent.