Tailored design of polyamide nanofiltration membrane with small-sized MXene quantum dots for promoting water transport

The traditional 2D nanosheets, given its relatively large size, has obstacles in water transmission and may also cause non-selective defects in polyamide membranes. To account for size effects, we successfully synthesized MXene quantum dots (MQDs) with ultra-small size through simple hydrothermal reaction, which were then utilized to construct MQDs polyamide nanofiltration membranes. Compared to the blank membrane, the MQDs membranes prepared obtained remarkable improvements in permeance and salt rejection, achieving a water permeance of 16.3 Lm−2h−1bar−1 and Na2SO4 rejection of 98.2%. Furthermore, MQDs membranes demonstrate exceptional antifouling properties and long-term performance stability. Molecular simulation reveals that the incorporation of MQDs effectively restricts the diffusion of piperazine (PIP) into the organic phase, thereby forming a loose membrane structure. Simulation of the transport process confirms that the loose membrane structure is more conducive to water transport, and exhibits reduced contact force between bovine serum albumin (BSA) pollutants and the surface of MQDs membranes. This work sheds light on high-performance nanofiltration via MQDs-regulated interfacial polymerization strategy.