MXene Synthesis, Surface Functionalization, and Membrane Integration for Photocatalytic Removal of Heavy Metals from Wastewater: A Comprehensive Review

The accelerating global population growth and rising living standards have intensified pressure on freshwater resources, underscoring the urgent need for efficient wastewater treatment technologies. Conventional treatment methods are often inadequate for removing persistent and toxic heavy metal contaminants. MXenes, emerging two-dimensional transition metal carbides and nitrides, have garnered significant attention due to their remarkable hydrophilicity, chemical tunability, high surface area, and superior electrochemical properties. This review critically examines the development and application of MXene-based membrane nanomaterials for the photocatalytic removal of heavy metals from wastewater. Key aspects include novel synthesis routes, such as HF-free and eco-friendly methods, advanced structural modifications, and strategic surface functionalization to enhance photocatalytic and adsorptive performance. We further dissect the fundamental separation mechanisms, exploring electron transfer dynamics, interfacial interactions, and the synergistic roles of MXene composites. This comprehensive analysis aims to guide future research towards sustainable water purification technologies leveraging the unique capabilities of MXene-based systems.