Constructing carboxylated MXene interlayer in polyamide nanofiltration membrane for enhancing perm-selectivity and antifouling performance

Constructing nanomaterials interlayer for high-performance polyamide membranes is a popular technique in brackish water desalination, while selecting a suitable nanomaterial and convenient method for constructing interlayer remains a challenge. Herein, easily-modified MXene nanosheets were carboxylated to obtain excellent hydrophilicity, negative charge, and good compatibility with polymer, which were applied to construct carboxylated MXene (COOH-MXene) interlayered polyamide membranes by facile brushing process. COOH-MXene nanosheets have good compatibility with polyamide and supporting membranes, and make the membrane surface wrinkled, hydrophilic and negatively charged. The optimized membrane achieves a water flux of 12.9 Lm(-2)h(-1)bar(-1), 2.9 times of the blank membrane. The MgSO4 rejection is improved to 99.1%, and the NaCl rejection is only 11.4%, displaying excellent selectivity for monovalent and divalent ions. Moreover, the prepared membranes have good antifouling properties and long-lasting desalination performance. This study presents a new approach to brackish water desalination by constructing COOH-MXene interlayered membranes.