Preparation And Performance Characterization Of Azide Cross-linked Monovalent Selective Anion Exchange Membrane

Ion exchange membrane is the core component of electrodialysis(ED),along with the expand application realm of ED,the demand for high performance mono/multi-valent anion selective membranes is more and more huge.While the preparation of the mono/multi-valent anion selective membranes still faces many challenges,the preparation of high permeability,low resistance and stable mono/multi-valent anion selective membranes is the key point of the present research.In this article,the mono/multi-valent anion selective membranes were prepared by surface modification of anion exchange membranes(AEMs),and in order to improve the service life of the modified membranes,azide groups were introduced to cross-linking.Two modified methods were researched to prepare stable mono/multi-valent anion selective membranes,one is modification by layer by layer electro-deposition and cross-linking,another is modification by surface layer infiltration and cross-linking,and the performance of the modified membranes were characterizedFor the modification of layer-by-layer electro-deposition and cross-linking,PSS/HACC multilayers was coated on commercial AEMs by alternating electro-deposition,to improve the monovalent anion membrane selectivity of the AEMs.Subsequently,photosensitive molecules DAS were infiltrated into the multilayers and cross-linked with the polyelectrolyte multilayers and membrane surface under UV irradiation in order to improve the durability and stability of the modified layers.The modified membranes were found to have an excellent mono/multi-valent anion selectivity and stability.For the modification of surface layer infiltration and cross-linking,a photosensitive molecule DAS was infiltrated into the membrane surface and immobilized in the structure by cross-linking under UV irradiation.This method immobilized negative charge in the surface layer of the AEMs without increasing membrane thickness,improving the mono /multi-valent anion selectivity of modified membranes and reducing the increase of the resistance of modified membranes.The optimized membrane(D-5)shows the highest perm-selectivity of 11.21 and it can maintain constant selectivity during the 80 h ED experiment,while the increasing rate of the membrane area resistances is 27.48%.