Alternating electric field-based ionic control and layer-by-layer assembly of anion exchange membranes for enhancing target anion selectivity

Abstract

Separation and recovery of target anions from wastewater is a sustainable method for chemical production industry. In this study, the novel anion exchange membranes with high antifouling and target ion selectivity performance were designed by the layer-by-layer (LbL) assembly of dopamine, positive and negative polyelectrolytes under the alternating current electric field and ionic control (AC[ion]) process. The resulting membranes were fabricated with different LbL assembled multilayers to evaluate the target ion selectivity. Besides, the different LbL assembled methods, including the electrostatic deposition self-assembly (EDS), AC[Cl−] assembly and AC[NO3−] assembly methods were carried out to evaluate the ion effect in membrane assembly process on final target ion permeation rate, respectively. With the initial concentration of 50 mM of NaCl, NaNO3 and Na2SO4 in mixed solution and the constant current density of 5.00 mA cm−2 of electrodialysis, the permselectivity of resulting membrane could be enhanced by the increased multilayers. Besides, the ion control in the alternating current electric field assembly process could enhance the relevant target ion permeation rate. The increased values of membrane surface electrical resistance fouled by organic pollutants were used to evaluate the antifouling property of membranes in electrodialysis, and the resulting membranes showed a high antifouling performance. This work provided a promising membrane separation technology in target anion recovery from wastewater for sustainable development.