Enhanced water flux and antifouling of a positively charged MoS2/PEI nanofiltration membrane through TA functionalization for effective dye desalination

The trade-off effect and fouling propensities of conventional polyamide nanofiltration membranes often compromise their efficiency in the treatment of textile wastewater. To address this limitation, an increased-flux and fouling-resistant polyamide selective layer was prepared using molybdenum disulfide (MoS 2 ) with positively charged polyethyleneimine. To optimize its nanofiltration performance, tannic acid-modified molybdenum disulfide (TA- MoS 2 ) nanosheets were incorporated into the polyamide selective layer. The abundant phenolic hydroxyl groups of TA improve the hydrophilicity while enabling non-covalent bonding with MoS 2 nanosheets. The MoS 2 provided abundant nanochannel, and the TA-induced hydration layer formation and reduced foulant adhesion. The synergistic effect enhanced the membrane hydrophilicity, optimized the pore size, and formed a loose polyamide structure. The pure water flux was increased by 45.2% compared with the unmodified MoS 2 -embedded membrane, while maintaining high MgCl 2 rejection (92.8%). The interception behavior of TA-MoS 2 nanofiltration membrane (TAM) toward dye molecules with five different charge capacities and molecular weights was investigated. The TAM demonstrated anti-fouling properties against dyes (FRR>93%). This work simultaneously achieved enhanced flux, antifouling properties, and dye/salt selectivity of nanofiltration membranes by synergistically integrating functional nanomaterials. • Positively charged membranes were fabricated by PEI/MoS 2 and PEI/TA-MoS 2 . • TSM and TAM remarkably enhanced the water permeance and fouling resistance. • The incorporation of TA-MoS 2 formed a loose polyamide structure. • TAM had excellent dye desalination performance and stability.