Catalytic MnO₂/MXene/chitosan nanocomposite membrane in removing caffeine from wastewater

This study fabricated a novel catalytic MnO₂/MXene/chitosan nanocomposite nanofiltration membrane (MXMn), and its performance in removal caffeine from wastewater was compared with other three membranes of neat chitosan, MXene/chitosan and MnO₂/chitosan. Results indicated that the MXMn membrane achieved the highest caffeine removal efficiency of 99.9 %, attributed to the synergistic effects of MnO₂ and MXene, which enhanced ROS production and catalytic degradation. Electron paramagnetic resonance (EPR) analysis identified the radical species involved, confirming the ROS-driven degradation mechanism. Furthermore, fluorescence spectroscopy revealed a characteristic peak supporting ROS activity in the system. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the structural and morphological characteristics of the membranes, highlighting a uniform and stable integration of MnO₂ and MXene with the chitosan matrix. The incorporation of MnO₂ and MXene increased membrane porosity (23.76 %) and enhanced permeability (19.33 Lm⁻² h⁻¹ bar⁻¹) while sustaining effective contaminant removal. The MXMn membrane also demonstrated improved fouling resistance and a flux recovery rate of 98.6 %. This novel catalytic chitosan-based nanocomposite NF membrane offered a promising solution for efficient caffeine degradation, and antifouling performance to mitigate pharmaceutical contamination in wastewater.