A multifunctional CNFs@MXene@ZnO hydrogel membrane for the efficient purification of wastewater

Developing efficient hydrogel filtration membranes and eco-friendly sustainable water purification methods remain a global challenge. In this study, one convenient hydrogel filter system based on CNFs@MXene@ZnO (CMZ) has been constructed by the one-step injection approach. Herein, MXene nanosheets and ZnO nanoparticles are loaded onto a 3D interwoven CNFs skeleton, constructing a multifunctional superhydrophilic interface. The results demonstrate that the CMZ achieves exceptional separation efficiency (>98 %) and water flux (>1600 L·m⁻²·h⁻¹·bar −1 ) for oil/water emulsions, with notable suspended solids retention (>97.5 %) for oil/water/solid emulsions. The system versatility is further proven by the clean water production performance from complex natural environmental waters, including river water, sea water, and snowmelt. Notably, after the separation process, the CMZ system exhibits the significant photocatalytic properties to degrade the pollutants upon the membrane surface under ultraviolet light conditions. Moreover, when the CMZ reaches its service life, secondary contamination could be avoided by the biodegradation process of the fully bio-based CNFs, enabling the membrane to naturally degrade within 30 days. This study presents not only an eco-friendly and efficient water purification material for complex separation systems, but also a novel, convenient and outdoor water treatment device, advancing the technology for complex separation systems.