Preparation of Cross-Linked Polysulfone Anion Exchange Membrane and Its Application in Electro–Electrodialysis Purification of Wet Process Phosphoric Acid

Anion exchange membranes (AEMs), as critical components of electro–electrodialysis (EED), must simultaneously achieve mechanical robustness and low membrane area resistance. In this work, a novel AEM was developed by integrating microphase separation architecture with a cross-linking strategy, achieving superior mechanical properties and conductivity. Chloromethylation polysulfone (CMPSU) was synthesized through the reaction between polysulfone and nontoxic chlorotrimethylsilane. The olefin cross-linked polysulfone AEMs (CQAPSU) were prepared via high temperature thermal cross-linking of the N,N-dimethylvinylbenzylamine with flexible unsaturated side chains during the membrane formation process. The optimized CQAPSU-0.75 membrane exhibited exceptional performance, with low membrane area resistance (4.3 Ω·cm2) and high tensile strength (28.96 MPa). In EED purification of wet process phosphoric acid, CQAPSU-0.75 demonstrated >80% metal ion removal efficiency while effectively suppressing proton leakage. This work resolves the longstanding trade-off between dimensional stability and conductivity in AEMs through innovative microphase separation/cross-linked integration, showing significant potential for industrial EED applications.