Design of a novel TA-MoS2 nanosheets interlayer-based loose nanofiltration membrane for enhanced dye/salt separation

From the view of sustainable development, the loose nanofiltration (LNF) membrane with high permeability and excellent separation of dye/salt mixture becomes more attractive for dye-containing wastewater. However, the previous LNF membranes inevitably suffered from the permeability-selectivity trade-off due to the inherent nature of polymer-based selective layer. This study reported a tannic acid (TA)-MoS2 nanosheets (NSs) interlayered nanocomposite polyester (PE) LNF membrane (iLNF-3) that exhibited a remarkably enhanced water permeance of 55.8 LMH·bar−1 compared to the control LNF membrane of 27.3 LMH·bar−1, and a higher separation selectivity of dye/salt (rejection rate: 99.6 % for congo red, 98.0 % for methyl blue, 5.6 % for Na2SO4, respectively). Furthermore, the iLNF-3 showed high ionic interference resistance, long-term stability, and superior antifouling performance. The enhanced permeance and dye/salt separation were mainly attributed to the introduction of a high-permeability TA-MoS2 NSs interlayer. In particular, the permeability was improved due to the "gutter" effect and nanochannels and the formed thinner PE selective layer caused by TA-MoS2 NSs interlayer. Notably, the selectivity was enhanced owing to the looser porous structure of PE layer resulting from the slow diffusion rate of aqueous monomer. This study can provide a foundational framework for the development of iLNF membranes for treating dye containing wastewater.