Polyamide-Based Electronanofiltration Membranes for Efficient Anion Separation
Zhang Zhao, Xingya Li, Hao Zhang, Fangmeng Sheng, Tingting Xu, Tingting Xu, Yanran Zhu, Huacheng Zhang, Liang Ge, Tongwen Xu, Tongwen Xu
Abstract
Monovalent anion (i.e., Cl–/SO42–) permselective membranes with high permselectivity, low cost, and excellent stability are urgently desired in the chlor-alkali industry. Herein, a facile interfacial polymerization strategy is employed to fabricate polyamide-based electronanofiltration (ENF) membranes for efficient anion separation. The densely cross-linked network structure and the strong electrostatic repulsion to anions of high valence by a high density of carboxylic residuals lead to the low permeation of SO42– and high permselectivity of Cl–. Specifically, the optimized ENF membranes show a Cl– flux of 2.31 mol h–1 m–2 and Cl–/SO42– selectivity of 98 at a current density of 10 mA cm–2. The Cl– selectivity of ENF membranes is 20 times higher than that of the commercial monovalent anion-selective membrane (ACS), while the Cl– flux is of a similar value. Moreover, the ENF membranes show excellent cycle stability as the permselectivity remains stable in a 10-consecutive electrodialysis process. Therefore, polyamide-based ENF membranes can be promising candidates for practical Cl–/SO42– separation in industry.