Preparation And Properties Of Ultrafiltration Membrane Based On Poly(Aryl Ether Ketone) With Carboxyl Groups

Because of their excellent mechanical properties,film-forming properties and chemical stability,polymeric ultrafiltration membranes are widely used in many fields.However,polymeric ultrafiltration membrane materials have some problems,such as poor hydrophilicity,low permeability and serious membrane surface fouling,which seriously limit the development and application of ultrafiltration technology.In order to solve the above problems,researchers usually focus on the surface properties and membrane structure of membrane materials.In this paper,hydrophilic poly(aryl ether ketone)with carboxyl groups(PAEK-COOH)was blended with polyethersulfone(PES)and polyethyleneimine-graphene oxide(PEI-GO)to improve permeability,rejection rate and anti-fouling performance of the blended membranes,respectively.In this paper,hydrophilic PAEK-COOH was synthesized by nucleophilic polycondensation.A series of PAEK-COOH/PES blend ultrafiltration membranes were prepared by non-solvent induced phase separation(NIPS).The results showed that the hydrophilicity and porosity of PAEK-COOH/PES blend ultrafiltration membrane were improved due to the addition of hydrophilic PAEK-COOH polymer into the membrane substrate,and then the permeability and anti-fouling performance of the blend membrane were improved.When the mass ratio of PAEK-COOH/PES is 3:7,the corresponding blend film has good comprehensive properties.Compared with PES membrane,the water contact angle of blend membrane decreased from 85.8±1.5°to 66.9±2.0°,and the porosity increased from 57.82±3.2%to 76.42%±1.9%.The pure water flux of the blend membrane is 238.6±1.9L/(m~2h),which is 1.3 times of that of PES ultrafiltration membrane.The BSA rejection rate and flux recovery rate are 92.1±0.9%and 77.0±1.5%,respectively.The permeability of PAEK-COOH/PES blend ultrafiltration membrane was improved to some extent,but the rejection performance of the membrane was reduced.In order to break the“trade-off”effect between permeability and rejection rate,that is,to obtain ultrafiltration membrane materials with good permeability under the condition of ensuring high rejection rate.Polyethyleneimine modified graphene oxide(PEI-GO)hydrophilic additive was prepared by chemical modification.Hydrogen bonding exists between amino group in PEI-GO and carboxyl group in PAEK-COOH,which improves the stability of additive in membrane matrix.PAEK-COOH/PEI-GO mixed matrix membranes(MMMs)with different proportions were prepared by NIPS method by adding hydrophilic PEI-GO into PAEK-COOH.The water contact angle decreased from 73.03±1.5°to 58.13±1.5°,and the porosity increased from 81.8±8.6%to 87.2±4.4%.When the PEI-GO content was 1 wt%,the mixed matrix membrane exhibited the best ultrafiltration performance,the rejection rate increased to 99.9±0.02%,the pure water flux was 340.0±17.1 L/(m~2h),the flux recovery rate was 79.82%,and the molecular weight cut off(MWCO)decreased from 276.6 KDa(pure PAEK-COOH membrane)to 234.9 KDa.