Sulfonated Ti3C2Tx lamellar membrane for efficient monovalent anion selectivity

Abstract

Monovalent selective ion-exchange membranes with characteristics of interception of multivalent ions and passage of monovalent ions, have aroused widespread research interest. However, most of monovalent selective ion-exchange membranes are dense polymer membranes, which suffer from low ion flux. Herein, a highly aligned two-dimensional (2D) thin anion lamellar composite membrane was developed successfully to address this weakness by assembling sulfonated Ti3C2Tx(STi3C2Tx) nanosheets on quaternized-chitosan (QCS) modified commercial Nylon-66 microfiltration membrane (N66). The QCS modified N66 that provides continuous sites and the STi3C2Tx lamellar ion channel that endows electrostatic repulsion and ion steric effect synergistically enhance the flux and selectivity of the composite membrane. Concretely, the resultant 2D thin anion lamellar composite membrane (N66-QCS/STi3C2Tx) achieves a high Cl−/SO42− selectivity and Cl− flux of 14.67 and 20.35 × 10−8 mol s−1 cm−2, which are 1.94 and 3.08 times higher than the commercial Neosepta ACS (7.56 and 6.60 × 10−8 mol cm−2 s−1). Furthermore, the negatively charged N66-QCS/STi3C2Tx shows favorable hydrophilicity and sufficient antifouling potential. The strategy of fabricating sulfonated Ti3C2Tx anion-exchange membrane provides fundamental information for the rational design of separation membranes that target to acquire high comprehensive performance.