Highly permeable and stable hyperbranched polyethyleneimine crosslinked AgNP@Ti3C2Tx MXene membranes for nanofiltration

Abstract

Two-dimensional (2D) materials have proved their superiorities as building blocks for constructing high-performance nanofiltration (NF) membranes. Herein, we propose a novel MXene-based NF membrane with high water permeability and stability by intercalating Ag nanoparticles (AgNPs) into the laminar structure of Ti3C2Tx MXene with hyperbranched polyethyleneimine (HPEI) crosslinking. The pure Ti3C2Tx MXene membrane, the AgNP-intercalated Ti3C2Tx MXene (AgNP@Ti3C2Tx MXene) membrane and the AgNP@Ti3C2Tx MXene membrane with HPEI crosslinking (HPEI-AgNP@Ti3C2Tx MXene) were comparatively investigated regarding their physicochemical properties and NF performance. The prepared HPEI-AgNP@Ti3C2Tx MXene membrane exhibited competitive water permeabilities (24.64–30.73 L·m−2·h−1·bar−1) and nearly 100% rejections for Congo red, methyl orange, methyl blue and Rhodamine B solutions for long-term operation. Moreover, the HPEI-AgNP@Ti3C2Tx MXene membrane also showed excellent NF performance for MgSO4, MgCl2, Na2SO4 and NaCl solutions with the rejections of 84.15%, 77.01%, 74.67% and 56.58%, respectively. The NF separation mechanisms for the HPEI-AgNP@Ti3C2Tx MXene membrane were elucidated based on its unique physicochemical structure. These findings may offer novel insights into tuning the laminar structures of MXene-based NF membranes for enhanced water purification.