MXene-enhanced polymer nanocomposite membranes for next-generation wastewater treatment and desalination

Water scarcity and pollution around the world necessitate advanced separation technologies to overcome the drawbacks of traditional polymer membranes that in most cases are limited by low permeability-selectivity, hydrophobicity, and fouling. To address such shortcomings, nanofillers have been investigated, including graphene oxide (GO), carbon nanotubes (CNTs), and metalorganic frameworks (MOFs), but have not solved dispersion, stability, and functionality problems. More recently, MXenes, a sub-class of two-dimensional transition metal carbides, nitrides and carbonitrides, have become a promising future wastewater treatment and desalination membrane. Tunable surface terminations, metallic conductivity, and antimicrobial characteristics of MXenes make them suitable to enhance water flux, salt rejection, contaminant removal, and foulant resistance when used as polymer matrices (because of their inherent hydrophilicity). This is a review of MXene-based polymer nanocomposite membranes, including synthesis processes, fabrication, structure/property/performance correlation, and the performance in treating heavy metals, dyes, pharmaceuticals, and saline water. The main obstacles, which are MXene oxidation, large-scale production, and stability over time are presented as well as the functionalization and hybridization strategies to overcome these obstacles. This paper will summarise the potential of MXene-polymer nanocomposites as the next-generation membrane to purify water sustainably, by summarising existing developments, as well as outlining future research directions and opportunities. • MXenes have a high surface area with adjustable interlayer spacing. • Functional groups enable efficient adsorption of dyes, metals, and pharmaceuticals. • The performance of MXene-based membranes is better in terms of salt rejection and water permeability. • Hybridization techniques promote resistance to antifouling and durability of its operation. • Scalability and synthesis sustainability are still one of the challenges facing real-world deployment.