Study On Preparation And Performance Of Polysulfone-based Poly(Ionic Liquid)s Membrane

Polysulfone membranes have been widely used in wastewater treatment,petrochemicals,biomedicine,gas separation,and other fields.However,the polyphenyl ring structure of the polysulfone molecule made the membrane hydrophobic.Polysulfone membranes were easy to adsorb colloids,microorganisms,and macromolecular organics in the water,causing problems such as membrane fouling,reducing membrane life,and increasing operating costs.As a new type of polyelectrolyte,poly（ionic liquid）s can significantly improve the antifouling performance of the membrane by its unique properties,such as chargeability and hydrophilicity.Therefore,to improve the comprehensive performance of the polysulfone membrane and overcome the shortcomings of the existing methods,this dissertation combines solution blending and post-polymerization modification,a polysulfone-based poly（ionic liquid）s membrane was prepared for the first time.The antifouling performance of the membrane was improved by hydrophilic modification and the construction of a catalytic membrane.The main research results of this dissertation are as follows:A polysulfone block copolymer PSF-b-P4VP with pyridine side groups was synthesized by reversible deactivation radical polymerization.The PSF-b-P4VP/PSF blend membrane was prepared by the non-solvent induced phase separation method.It was found that the hydrophilic segment P4VP can be spontaneously enriched on the surface of the blend membrane to improve the hydrophilicity and permeation flux of the blend membrane.For example,the static water contact angle decreased from 78.4±1.6°to 63.4±1.0°,and the pure water flux increased from19.7±0.2 L m^-2 h^-1 bar^-1 to 392.4±7.2 L m^-2 h^-1 bar^-1.At the same time,with the help of tertiary amine groups on the surface of the blend membrane to undergo quaternization with 3-bromo-1-propanol,a cationic poly（ionic liquid）s membrane can be prepared.The experimental results showed that the permeation flux and antifouling performance of the cationic poly（ionic liquid）s membrane improved further.For example,the pure water flux increased from 392.4±7.2 L m^-2h^-1 bar^-1 to 444.9±4.9 L m^-2 h^-1 bar^-1,and the flux recovery ratio increased from 73.5%to 78.0%.However,increasing the hydrophilicity of the membrane cannot wholly solve the problem of irreversible contamination deposited on the surface of the blend membrane.To solve the above problems,with the help of the robust scalability of poly（ionic liquid）s,the divalent iron was successfully coordinated through ion exchange to prepare iron-containing poly（ionic liquid）s membranes with separation and catalytic functions.The iron-containing poly（ionic liquid）s membrane has good heterogeneous Fenton catalytic activity and wide p H tolerance.Under the hydroxyl radicals action,the methylene blue dye could be removed entirely within a few minutes.In addition,the iron-containing poly（ionic liquid）s membrane showed obvious membrane filtration and heterogeneous Fenton synergy roles due to the confinement effect,further improving the permeability and rejection rate of the membrane.After five cycles of experiments,the iron-containing poly（ionic liquid）s membrane with good reusability could still maintain a permeation flux of 210.2±4.1 L m^-2 h^-1 bar^-1 and a rejection rate of 92.5%.In summary,this article developed a new strategy for preparing iron-containing poly（ionic liquid）s membranes from P4VP.The research results opened up new ideas for solving the problem of membrane fouling and provided theoretical support for the preparation of high-performance and multifunctional polysulfone-based poly（ionic liquid）s ultrafiltration membrane.