Metal-polyphenol cross-linked titanium carbide membranes with stable interlayer spacing for efficient wastewater treatment.

Membranes based on transition metal carbides/nitrides (MXenes) have significant water treatment potential because of their unique molecular sieving properties and excellent permeation performance. However, hydrophilic MXenes swell upon water immersion, and improving their stability remains challenging. In this study, a Fe-tannic acid (TA) complex was used as a cross-linker and surface modifier to prepare high-performance titanium carbide (TiCT) MXene laminar membranes. Fe-TA formation on the nanosheets increased the interlayer spacing and stabilized the laminar structure. The membrane with the highest performance among the as-prepared membranes exhibited a high water permeance of 90.5 L/m(-|-)h bar (which is twice that of the pristine TiCT membrane) and good separation efficiency (methyl blue rejection rate: ∼99.8 %; NaSO rejection rate: ∼5.0 %). Furthermore, the Fe-TA complex enhanced the membrane hydrophilicity, resulting in excellent antifouling properties. This study provides an environmentally friendly and facile method for fabricating two-dimensional loose nanofiltration membranes for textile wastewater treatment.