Studv On The Antifouling Performance Of Anion Exchange Membrane By Compound Modification Of Dopamine/Poly(Sodium 4-styrene Sulfonate)

Fouling of ion exchange membranes,especially the organic fouling of anion exchange membrane(AEM),is a bottleneck that restricts the application of electrodialysis desalination technology,and surface modification is an effective method to solve this problem.However,the existing modification methods have their own advantages and disadvantages,so it is still necessary to combine the advantages of different modification methods to conduct composite modification of AEM.In this paper,dopamine(DA)and poly(sodium 4-styrene sulfonate)(PSS)were used to conduct composite modification of AEM.By comparing the surface properties and antifouling performance of modified AEM with different deposition components,it was found that the antifouling performance of the co-deposited modified AEM was better than that of the self-polymerized modified AEM.Subsequently,the process conditions of the co-deposited modified AEM were further optimized.The electrodeposition-self-polymerization step-by-step compound modification AEM was used to improve the antifouling performance and stability of the electrodeposition modification layer,and the effects of different modification methods on its antifouling performance were compared.The main research results were as follows:(1)The surface properties and antifouling performance of different modified AEM obtained by surface deposition of different modifiers were investigated.It was found that the surface of the codeposition modified AEM(PDA@PSS-M)was less hydrophilic than the polydopamine self-polymerized modified AEM,while the negative charge density was improved and the surface was smoother.The cross-linked structure of PDA during codeposition modification could assist PSS to form an effective modified layer,and the electrostatic interaction between PSS and PDA helped to form a more uniform and smooth modified layer,resulting in PDA@PSS-M having better antifouling performance for the model fouled sodium dodecylbenzene sulfonate(SDBS).In addition,the effect of the co-deposited modified layer on its desalination was negligible and relatively good stability.(2)By investigating the effect of co-deposition modification time and component ratio on the surface properties of modified AEM,it was found that the optimal modification time of DA and PSS co-deposition method was shorter than that of the PDA selfpolymerization method,i.e.,it had the potential to make the modification process more rapid.The mass ratio of DA:PSS was 1:2,which was more conducive to the improvement of the antifouling performance of AEM and the influence of the modified layer on the electrochemical performance of AEM was negligible.In addition,there was no reaction between PSS and DA during the codeposition process,and PSS could slow down the self-polymerization of dopamine,which was beneficial to improve the uniformity of the modified layer.(3)A new modified AEM(PSS&PDA-M)was prepared by adding a PDA self-polymerization modification layer outside the electrodeposited PSS modification layer.The study found that the addition of the self-polymerization modification layer would reduce the improvement of the hydrophilicity and negative charge density of the modified AEM surface,but its surface would become smoother and the stability of the modification layer was improved.In the electrodialysis desalination and antifouling tests,the composite modified layer had little effect on the transmembrane migration of ions and the antifouling performance of PSS&PDA-M was the best,indicating that the improvement of the stability of the modification layer had a significant effect on the antifouling performance of AEM.Compared with the codeposition modified AEM,the improvement of the surface hydrophilicity and negative charge density of PSS&PDA-M was low,and its antifouling performance was poor.