Highly permeable and durable mixed-matrix reverse osmosis membranes filled with cellulose nanofibers-hybridized Ti3C2Tx

Abstract

Exploration of optimized nanomaterial fillers has been highly realized as a key to improve the comprehensive performance of reverse osmosis (RO) membranes. In this study, a new kind of high-separating efficient mixed-matrix RO membrane is proposed by filling cellulose nanofibers (CNFs)-hybridized Ti3C2Tx with an enlarged layer distance and enhanced negative electronegativity due to a strong hydrogen-bond-interaction. Therefore, the two-phase monomer interfacial polymerization (IP) process of the polyamide (PA) membranes was mediated to change the RO membrane surface from a leaf-like to a nodular-like morphology with additional water molecular channels, increased hydrophilicity and enhanced roughness. With such a special microstructure, the maximum water flux of the Ti3C2Tx-CNFs/PA membrane was elevated up to 64 L m−2 h−1, 1.4 times that of the pristine PA membrane without reducing the salt rejection (98.8 %) at all. In addition, the incorporation of Ti3C2Tx-CNFs was also found to elevate the antifouling and chlorine resistance of the RO membrane effectively. Interestingly, the Ti3C2Tx-CNFs/PA membrane exhibited both organic protein and inorganic salt pollution resistance. At a chlorination intensity of 10,000 ppm·h, the salt rejection of the PA membrane at this time had dropped to 67.4 %, while that of the TC10/PA membrane still remained at 92.3 %, which could be ascribed to the chlorine adsorption/substitution reaction on the surface of Ti3C2Tx-CNFs and the protective effect on the membrane surface. This study thus has validated the beneficial effects of nanomaterial incorporation and pointed out a new perspective for promoting the real applications of high-performance and long-life RO membranes.