Efficient Removal of Methyl Orange Using Poly Diallyldimethylammonium Chloride‐Grafted MoS₂ Nanofiltration Membrane

ABSTRACT Membrane separation technology has attracted widespread attention due to its high efficiency in separating specific dyes from wastewater. Molybdenum disulfide is a promising candidate for the preparation of high‐performance nanofiltration membranes. However, the effective exfoliation and functionalization of molybdenum disulfide nanosheets remain challenging. The study reports a novel method for preparing poly diallyldimethylammonium chloride grafted molybdenum disulfide nanosheets by simultaneously exfoliating and functionalizing molybdenum disulfide in poly diallyldimethylammonium chloride solution through ball milling. The filtration performance (including water permeability and rejection efficiency) of the poly diallyldimethylammonium chloride grafted molybdenum disulfide nanosheets‐functionalized polyethersulfone composite nanofiltration membrane is evaluated during the treatment of methyl orange wastewater, and the filtration mechanism is thoroughly investigated. The results show that poly diallyldimethylammonium chloride is successfully grafted onto the surface of exfoliated molybdenum disulfide nanosheets, effectively modulating the interlayer spacing and surface properties of molybdenum disulfide and making the composite membrane exhibit high water permeability (943.97 L m −2 h −1 bar −1 ) and high rejection efficiency (95.2%). Further investigation reveals that the composite membrane achieves efficient methyl orange rejection through electrostatic adsorption and size exclusion mechanisms.