MoS2 @PDA thin-film nanocomposite nanofiltration membrane for simultaneously improved permeability and selectivity

Abstract

Recent studies have documented that the incorporation of nanomaterials can effectively enhance the permselectivity of thin-film composite (TFC) membrane. The distribution and compatibility of molybdenum disulfide (MoS2) nanosheets lack of functional groups within polymer matrices are research hotspots. Here we present polydopamine (PDA) modified MoS2 (MoS2 @PDA) nanosheets as nanofillers to prepare thin-film nanocomposite (TFN) nanofiltration (NF) membrane. PDA not only enhanced the dispersion and compatibility of MoS2 in the polyamide matrices, but also resulted in defect-free TFN membranes due to its self-polymerization. The obtained TFN membrane loaded with 0.01 wt% MoS2 @PDA nanosheets (TFN-0.01) had water permeability of 6.7 L m−2 h−1 bar−1, 1.45 times of the TFC membrane. The Na2SO4 rejection increased from 97.1% to 98.2%, thus overcoming the long-standing permeability-selectivity trade-off of desalination membranes. Moreover, TFN-0.01 NF membrane had excellent long-term stability. Our results showed that PDA can effectively solve the dispersibility and compatibility problems of nanofillers in polymer matrices, especially for the nanofillers lack of functional groups.