Design And Synthesis Of Poly(ionic Liquid)s And Their Application In Oil-water Separation

With the continuous development of industrialization in human society,the discharge of industrial oily wastewater and oil spills from offshore ships have caused serious water pollution problems.Therefore,in order to solve the problem of oil pollution in water and protect water resources,the secondary utilization of water resources has become an urgent problem to be solved.Inspired by the principle of bionics,people began to try to prepare special wetted surfaces to achieve oil-water separation.This method is efficient,convenient and green.This article utilizes biomimetic principles to design and synthesize polyionic liquid materials with hydrophilic and hydrophobic properties,as well as intelligent response to wet surfaces,and studies their applications in oil-water separation.（1）For the separation of immiscible oil-water mixtures,this article designs materials with special wetting properties.By adjusting the chemical composition of the material surface and introducing specific functional groups,and using Thomas Young,Wenzel,and Cassie Baxter as the theoretical basis for the three basic surface wetting theoretical models,biphenyl ring structured ionic liquids are used as polymer monomers to modulate different auxiliary crosslinking agents,Hypercrosslinked Poly（ionic liquid）s（HCPIL）material with a special wetting surface was constructed through Friedel Crafts alkylation reaction and used for separating oil-water mixtures in various specific environments.The experimental results show that when aniline is used as an auxiliary crosslinking agent,the static water contact angle and underwater oil contact angle of HCPIL-A2 material are close to 0°and 132°,exhibiting hydrophilicity/hydrophobicity,separation efficiency of over 98%,and water flux of about 5500 L·m^-2·h^-1.When benzyl alcohol is used instead of aniline,its static water contact angle and static oil contact angle are close to 126°and 0°,and HCPIL-B2 shows hydrophobicity/lipophilicity.The efficiency of separating chloroform and carbon tetrachloride is over 98%,and the oil flux is 7645 and 7241 L·m^-2·h^-1,respectively.In addition,the separation of oil-water mixtures can still be achieved through gravity after ten cycles.The HCPIL designed for separating oil-water mixtures can be selected based on the composition of the oil-water mixture.（2）For the separation of oil in water and water in oil emulsion,in this paper,ionic liquid[Bbmim]Cl is used as monomer,and anion in ionic liquid is exchanged,flexible crosslinking agent FDA is used as crosslinking group,aniline is used as auxiliary crosslinking agent,and polyionic liquid materials with rich micro mesoporous structure are obtained through Friedel Crafts alkylation process,and used for oil water separation research.Polyionic liquids containing special anions（PF₆^-,TF₂N^-）exhibit switchable wettability with solvent response due to their unique surface structure and chemical composition.The material surface is selectively captured into one phase（oil or water）,while the other phase is captured.According to the transformation of corresponding solvent,it can switch freely between hydrophilic and lipophilic,which is suitable for separating many oil-water mixtures,especially emulsion.The separation efficiency of various oil-water mixtures is over 99%,and the separation fluxes of oil-water mixtures or emulsions are 9450 L·m^-2·h^-1 and 800.32 L·m^-2·h^-1,respectively.In addition,they have strong durability and stability in environments such as high concentrations of salt and acid solutions.After dozens of cycles,it exhibits high underwater oil contact angle or oil-water contact angle,while maintaining efficient oil-water separation efficiency.In conclusion,this paper has developed a new type of polyionic liquid with different wettability and a"smart"polyionic liquid with switchable wettability and applied them to the research of oil-water separation.The new type of polyionic liquid with different wettability can efficiently separate the insoluble oil-water mixture system,while the"smart"polyionic liquid material can effectively separate the emulsion system.These studies provide new ideas and methods for achieving oil-water separation in oily wastewater.