MXene Film as an Interlayer for Thin-Film Composite Membranes with High-Performance Nanofiltration

Nanofiltration is seen as a potential technique for desalination and purification of drinking water. Improving water permeability without compromising on the high rejection rate in nanofiltration membranes is a major challenge. This article describes interfacial polymerization (IP) mediated by tannic acid (TA)–MXene interlayer to prepare an ultrathin film composite membrane (TFC_i) possessing negative surface charge and optimized water transport channel. Nanofiltration process and the formation of the polyamide surface layer are both dependent on the TA–MXene intermediate layer. It is capable of storing amine monomer, decelerating interfacial polymerization, and producing a 30-nm-thick polyamide selective layer devoid of defects. With a rejection rate of 96.0% for divalent ions and a permeation flux of 22.3 L m^–2 h^–1 bar^–1, the nanofiltration membrane that was acquired exhibits exceptional performance and stability in the operation of long-term nanofiltration. In contrast to traditional TFC membranes, the TFC_i membrane successfully overcomes the long-standing contradiction between permeability and selectivity. This study offers a straightforward method for fabricating TFC membranes that exhibit outstanding performance.