Preparation Of Antifouling Polyethersulfone Ultrafiltration Membrane And Its Application In Effective Separation Of Oil-in-water Emulsion

With the rapid development of the current industry,water environmental issues have attracted more and more people's attention.Especially the treatment of industrial organic wastewater and oily sewage is becoming one of the focus points.Various water treatment methods and processes have been widely used in the process of water quality conditioning,and membrane separation technology is considered to be one of the important measures in solving this problem.Polyethersulfone(PES)is the ideal membrane material,with the advantage of high temperature resistance,high strength,stable physical and chemical properties,but in practice the PES membrane is easy to be polluted seriously,because of its hydrophobic nature,which will cause the decrease of separation efficiency and the increase of operating cost.In this paper,hydrophobic PES membranes were modified by two-step hydrophobization with physical blending and chemical grafting to improve its anti-fouling properties and enhance its practical application.Firstly,the hydration modification of PES membranes by physical blending was carried out.The hydrophilic block polymer PAA-F127-PAA was polymerized by the surface-initiated Reversible Addition Fracture Chain Transfer Polymerization(RAFT)using Pluronic F-127(F127)and Acrylic Acid(AA),and then as an additive blended with PES in different proportions to prepare the PES/PAA-F127-PAA membranes by the non-solvent phase separation(NIPS)method.The results showed that,in the process of minimizing the interface free energy,the hydrophilic PAA-F127-PAA would spontaneously migrate to the membrane surface,and the pure water flux,the hydrophilicity,and the anti-fouling ability of the membranes were significantly improved.However,with the increase of additives' content,the pure water flux increased first and then decreased.When the amount of additive added to 5wt%,the performance of the membrane was the best.Compared with the pure PES membrane,the pure water flux increased from 122.11L/(m2·h)to 333.72 L/(m2·h),the contact angle decreased from 82.6° to 64.3°,and the flux recovery rate increased from 45.75%to 81.34%.In addition,in order to improve the performance of the modified film,the membrane was further chemically grafted.By controlling the polymerization time of activators regenerated by electron transfer atom transfer radical polymerization(ARGET ATRP),the strong hydrophilic polymers NH2-PDMAPS with different length were synthesized with tert-butyl(2-(2-bromo-2-methylpropanamido)ethyl)carbamate(Boc-Br)and dimethylaminoethyl methacrylate(DMAEMA).Based on the blending membranes with the best performance,PES/PAA-F127-PAA/NH2-PDMAPS membranes were prepared by the amidation reaction between NH2-PDMAPS and PAA segments on the membranes.Experiments showed that,with the growth of the grafted chains on the membranes,the pure water flux of membranes increased first and then decreased.When the polymerization time was 8h,the performance of the modified membrane was the best,the pure water flux was 280.78L/(m2 h),the contact angle was 45.3°,and the flux recovery rate was as high as 93.45%.Compared with the properties of the pure PES membranes,its pure water flux increased by 129.9%,its contact angle decreased by 47.1%,and its flux recovery rate increased by 106.6%.The antifouling ability of the membranes was significantly improved,and the separation effect of oil-in-water emulsion was significantly enhanced.