Preparation And Properties Of Polyethersulfone Composite Ultrafiltration Membrane Based On Tea Polyphenols And Polyvinyl Alcohol

Polyethersulfone ultrafiltration membrane has been widely used in sewage treatment and drinking water purification,but there are some problems,such as low permeation flux,membrane easy to be polluted,and the trade-off effect between membrane flux and rejection.In this paper,Tea polyphenols(TP)-Polyethersulfone(PES),Tea polyphenols(TP)-Polyvinyl alcohol(PVA)-Polyethersulfone(PES)composite ultrafiltration membranes were prepared by phase transformation method with Tea polyphenols and Polyvinyl alcohol as modifiers,and the morphology and properties of the composite membranes were studied.The purpose is to adjust the pore structure and chemical properties of Polyethersulfone ultrafiltration membrane and improve its ultrafiltration performance.Firstly,TP-PES flat composite ultrafiltration membrane with different TP addition was prepared by PES and TP,and its structure and ultrafiltration performance were studied.The experiment shows that TP is hydrophilic,which can not only acts as a porogen,but also forms hydrophilic sites on the membrane surface.With the increase of TP addition,the water contact angle of the membrane decreased first and then increased,the flux increased first and then decreased,and the Bovine serum albumin(BSA)rejection rate did not change significantly.When the addition of TP was 0.2 wt.%,the pure water flux of the membrane was largest,reaching 236.39 L/(m~2·h),and the BSA rejection rate reached 98.05%.Then,in order to improve the stability of TP on the membrane surface and in the membrane pores,on the basis of the above casting solution,change the solvent and add 0.4wt.%Polyvinyl alcohol.TP-PVA-PES flat composite ultrafiltration membrane with different TP addition was prepared,and its structure and ultrafiltration performance were studied.The experiment showed that PVA can be connected with TP by hydrogen bond and adhere to the membrane matrix to produce a hydrophilic layer.With the increase of TP,the water contact angle of TP-PVA-PES composite ultrafiltration membrane decreased,and the flux first increased and then decreased.The BSA rejection rate of all membranes was more than90.00%.When the addition of TP was 0.2 wt.%,the pure water flux of the membrane was the largest,reaching 219.68 L/(m~2·h),and the BSA rejection rate reached 96.50%.Finally,TP-PES and TP-PVA-PES hollow fiber membranes were prepared by dry wet spinning.The effect of core liquid flow on the morphology and performance of hollow fiber ultrafiltration membrane was studied.The experimental results show that the core liquid flow rate has a great influence on the internal morphology,structure and performance of hollow fiber membrane.With the increase of core liquid flow,the porosity of membrane and the ultrafiltration performance increases.The pure water fluxes of PES,TP-PES and TP-PVA-PES hollow fiber membranes with core liquid flow of 26 m L/min were 36.69 L/(m~2·h),68.31L/(m~2·h)and 126.65 L/(m~2·h)respectively,and the BSA rejection rate was more than 93.00%.