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

Industrial development generates large quantities of oily wastewater, which poses a serious threat to the environment and human health. Heavy metal ions, dyes, and some water-soluble pollutants are also discharged with oily wastewater. Therefore, there is an urgent need for multifunctional separation technologies to deal with various pollutants. As an emerging two-dimensional material, titanium carbide (Ti3C2Tx) is of great importance in the field of oil–water separation because of the abundant hydrophilic groups on its surface. Herein, we developed a precise grafting strategy to modify MXene sheets with pyromellitic acid groups and prepared a multifunctional MXene-based membrane. Benefit from the abundant hydrophilic groups on the MXene sheets’ surface, the as-prepared membrane demonstrated outstanding superhydrophilic and anti-oil adhesion properties, and also showed remarkable separation performance (6731.8 L m−2 h−1 bar−1 and >99.97%) for high viscosity emulsions. Importantly, the presence of grafting groups improved the removal efficiency of several heavy metal ions (>99%) by the membrane. Additionally, it also demonstrated superior chemical stability, flexibility, and efficient separating harsh emulsions. This work provides a new insight into the development of the multifunctional MXene-based membrane materials.