A precise pyromellitic acid grafting prepared multifunctional MXene membranes for efficient oil-in-water emulsion separation and heavy metal ions removal

•A precise grafting strategy to prepare the multifunctional MXene-based membrane.•The membrane demonstrated excellent superhydrophilic, anti-oil adhesion, chemical stability, and flexibility properties.•The membrane showed outstanding separation performance (6731.8 L m−2 h−1 bar−1 and >99.97%) for high viscosity emulsions.•The successful modification of the pyromellitic acid groups ensured efficient heavy metal ions removal performance (>99%).