Preparation Of Antibacterial And Antifouling Polyether Sulfone Composite Membrane

The shortage of water resources in modern social life is increasing,many water treatment technologies have been explored to solve the problem.And membrane technology has attracted much attention due to its advantages,i.e.simple operation,low investment,environmental protection and stable flux.However,membrane fouling often occurs in practical application,which limits the application of membrane technology.Membrane pollution mainly refers to the fact that organic compounds and colloid in the filtrate are easy to be adsorbed on the membrane surface and pore wall,leading to membrane fouling,thus decreasing the flux and selectivity of membrane,increasing energy consumption and operating costs.The key to inhibit organic pollution is to build a hydrophilic surface,forming a dense hydrate layer on the membrane surface,since strongly bound water molecules can prevent pollutants from adsorbing on the membrane surface,thus reducing membrane pollution,enhancing membrane separation performance and extending serving life.Many research been carried on various hydrophilic modification methods,including photoinduced graft polymerization,plasma treatment,coating,chemical treatment and other methods to improve the antifouling properties of separation membranes.In addition,the biological pollution caused by the attachment of microorganisms and their growth and reproduction on the membrane also causes physical obstacles in the flow process of the filtrate.The bacteriostasis of the separation membrane can be achieved via inorganic or metal nanoparticle modification,quaternary ammonium salt modification,photocatalytic modification and compound modification.PES has been the preferred membrane material for industrial and laboratory applications for many years,due to its excellent physical and chemical properties,mechanical properties and stable hydraulic properties.However the hydrophobic character of PES membrane leads to its easily being fouled.In this paper,a series of modified PES composite membrane with both antibacterial and antifouling properties were prepared by non-solvent-induced phase separation via blending hydrophilic terpolymer and bacteriostatic quaternary ammonium salt into the casting solution.The specific experimental contents are as follows:（1）hydrophilic terpolymer P（kh570-vp-dmaema）was prepared by solution free radical polymerization,where the monomer VP was the hydrophilic chain segment in the copolymer,and the tertiary ammonia on the monomer DMAEMA could be used for zwitterization.Ternary copolymers migrate to the surface of the membrane during the phase transformation process,effectively preventing the attachment of pollutants and improving the membrane hydrophilicity.A quaternary ammonium salt to improve the bacteriostatic property of polyether sulfone membrane through the condensation reaction between quaternary ammonium salt and terpolymer.The hydrophilic terpolymer and quaternary ammonium salt were blended into the casting solution,the effects of proportions of monomers in the ternary copolymer,the content of quaternary ammonium salt on the membrane were investigated,so as to improve the performance and microstructure of the membrane.The results showed that both quaternary ammonium compounds and terpolymer were grafted onto PES membrane successfully.The membrane hydrophilicity was significantly improved by using the modified ternary copolymer,and it was found that the quaternary ammonium salt and ternary copolymer showed good synergistic effect,that is,the membrane modified by using both quaternary ammonium salt and ternary copolymer had the highest hydrophilicity.The anti-fouling test and the membrane microstructure test also showed that the modified membrane with quaternary ammonium salt and ternary copolymer showed good anti-fouling performance and almost spongy microstructure.The bacteriostatic test showed that the modified membrane showed remarkable bacteriostatic effect.（2）The PES hollow fiber membrane was prepared through dry spray and wet spinning technology.Different spinning process conditions was explored to show the influence of coagulation bath composition,the temperature of liquid core and the air gap（dry spinning height）on the properties and structure of PES hollow fiber membrane.The test results showed that when DMAc content in the coagulation bath accounted for 30%,the pure water flux reached the maximum value of 307.9 L·m²·h^-1,the breaking strength and elongation at break also reached the maximum value,and the anti-fouling effect of the membrane also reached the best.When coagulation bath temperature was 30℃and 35℃,the performance and structure of the hollow fiber membrane were best.When the spinning height was 16cm,the mechanical properties of hollow fiber membrane reached the maximum value with a large pure water flux and rejection.