Preparation And Performance Of PANI-MMT Modified PVDF Ultrafiltration Membrane

Polyvinylidene fluoride（PVDF）is a good seperation membrane material and it has become an optimal material due to its low cost,good chemical stability and heat stability.However,pure PVDF membrane has good hydrophobic property,so it can be fouled easily when it is used in practical,which limiting its wide application.Therefore,it is a matter to improve its anti-fouling property via hydrophilic modification so as to reduce dynamic energy consumption during membrane operation.PANI-MMT were synthesized by in situ chemical oxidative polymerization with ammonium persulfate（APS）as oxidant.Fourier transform infrared spectrum（FTIR）and X-ray diffraction（XRD）analysis showed that PANI had been intercalated into the layered structure of MMT.PANI-MMT was added into PVDF/PVP K30/NMP casting solution as addtive to prepare PVDF plate UF membrane.The effects of additive concentration on the structure and properties of the modified membrane were investigated by verifying PANI-MMT loadings..FTIR,water contact angle（CA）,Scanning Electron Microscope（SEM）,Atomic force microscope（AFM）,pure water flux,rejection rate and flux recovery rate（FRR）were employed to investigate the characteristics of all prepared membrane.The results indicated that the hydrophilicity of modified PVDF membrane was significantly enhanced and the retention rate of bovine serum protein（BSA）was all above 90%.The PWF reached to a maximum of 445.86 L.m^-2.h^-1when the addition of PANI-MMT was 0.5%wt.Compared with pure PVDF membrane,the FRR of modified membrane was obviously improved,which indicated that the antifouling property of the modified membrane had been enhanced.When the content of PANI-MMT is 0.5%wt,the comprehensive properties of modified PVDF ultrafiltration membrane（including hydrophilicity,pollution resistance and separation stability,etc.）are optimized.Chitosan（CS）and Sodium Montmorillonite（Na-MMT）were added to PVDF/PVP K30/NMP casting sulution as additives to prepare the other two modified PVDF membranes.The addition of CS and MMT were maintained at 0.5%wt.Under the same conditions,the properties of three kinds of modified PVDF UF membranes were compared and analyzed.