Molecular Design And Ultrafiltration Performance Of Hydrophilic Side Chain Poly (Aryl Ether Sulfone)

Compared to the traditional separation process,the separation membrane technology is simple and low cost,and it takes advantages of high efficiency and low energy consumption.Today,it has been widely applied in the fields of food,medical care and water resources,especially in potable water resources.Water treatment separation membranes,UF membranes can be used as a pretreatment in combination with other separation processes or can be used separately.It plays an important role in reverse osmosis pretreatment,drinking water treatment,industrial wastewater treatment,pharmaceuticals,pigment extraction and many other fields.The pore size of the ultrafiltration membrane is smaller than that of the microfiltration membrane and the treatment process is more refined.It can remove pollutants from the water,and it can also selectively enrich and recover useful substances in the wastewater,which can save resources.PAES is widely used as an ideal membrane material,but membrane fouling during the use of the membrane has always limited the life and the performance of the membrane,and increased the cost and energy consumption.How to increase the membrane fouling resistance and improve the membrane performance has become a topic in membrane technology research.Therefore,in this paper,PAES materials were designed at the molecular level.First,we synthesized PAES with phenolic groups side-chain,then grafted of sulfonic acid groups containing alkyl chains by ring-opening reaction of 1,3-propane sultone,PAES with hydrophobic backbone and hydrophilic side chains synthesized.In the phase reverse process,the hydrophilic side chains move toward the surface of the membrane and the inner surface of the pore,thereby enriching the membrane surface to form a hydration layer.Increased hydrophilicity reduces water penetration resistance while the presence of hydration layers provides higher fouling resistance.The experimental results show that the water flux and the antifouling performance of the modified membrane are better than PPSU membrane,three-pass cycle experiments show that the flux recovery of the membrane reaches over 90%.At the same time,the introduction of hydrophilic side chains will also increase the pore formation on the membrane surface.However,the introduction of hydrophilic side chains has only single increase in membrane flux.Second,we designed and prepared a block polymer based on polysulfone structure,PSf-b-EP was prepared using phenol-based polysulfone and epoxy resin.Then grafting polyacrylic acid side chains by free radical-initiated reactions using active sites of epoxy resin segments,PSf-b-EP-PAA with functional carboxylic acid chain were prepared.Compared to PPSU membrane,PSf-b-EP-PAA membrane has superior performance,the highest flux reached 700L/m~2h and the flux recovery rate reached more than 95%,and extremely excellent resistance to contamination is obtained in long-term use.At the same time,the character of the PAA chain confer pH-response to the membrane,which allows the membrane to exhibit different fluxes and other properties at different pH values,makeing it selective for separation.Compared with the first part,PSf-b-EP-PAA has excellent performance.In summary,two different types of hydrophilic side-chain polymers were synthesized,and UF membranes were successfully prepared.After structure and performance characterization,the effects of different molecular structures on the morphology and properties of UF membrane were analyzed.