MXene-based materials for oil-water separation: mechanisms, performance, environmental implications, and future...

Oil-water contamination from industrial effluents and accidental spills presents a persistent environmental challenge, necessitating efficient and sustainable separation technologies. Two-dimensional MXenes, a class of transition-metal carbides and nitrides, have emerged as highly promising materials for oil-water separation due to their atomically thin layered structures, high electrical conductivity, and abundant surface terminations (-O, -OH, and -F). These intrinsic characteristics impart superhydrophilicity and underwater superoleophobicity, enabling selective water permeation while effectively repelling oil phases. To further enhance separation performance, a wide range of MXene-based architectures have been developed, including polymer-MXene composite membranes, three-dimensional porous hybrids with carbon nanomaterials, and multifunctional composites incorporating metal oxides, biopolymers, or clays to improve mechanical robustness, fouling resistance, and chemical stability. Oil-water separation using MXenes proceeds through synergistic mechanisms such as interlayer nanochannel size-sieving, wettability-controlled selective transport, capillary-driven sorption in aerogels and sponges, photothermal-assisted demulsification of viscous oils, and externally stimulated (magnetic or electro-assisted) oil recovery. This review emphasizes recent advances in MXene-based material design, separation mechanisms, and composite engineering for oil-water remediation, with particular focus on establishing a mechanistic framework that links material properties to separation behavior across different system configurations. By identifying current limitations and future research directions, this review aims to provide a comprehensive framework for the rational development and practical deployment of MXene-enabled oil-water separation technologies.