Electroconductive MXene-Thin-Film-Composite Membranes for Coupled Osmotic Concentration and PFAS Mineralization

We introduce an integrated treatment system that couples osmotic dewatering with advanced oxidation (AO) using electrically conductive Ti₃C₂T_x MXene-based membranes, enabling simultaneous PFAS concentration and electrochemical degradation and mineralization. Conductive thin-film composite membranes were fabricated by depositing Ti₃C₂T_x either on the active layer or on the porous support, with the active layer retained on the opposite surface. These architectures enabled operation of advanced- oxidation forward-osmosis (AO-FO) and advanced- oxidation pressure-retarded-osmosis (AO-PRO) modes, respectively. The MXene-based membranes exhibited high electrical conductivity (5446 S·cm^-1) and achieved 99% rejection of perfluorooctanoic acid (PFOA). Electrochemical degradation experiments showed that increasing the applied current density from 200 to 500 A/m² enhanced PFOA degradation and mineralization. At 500 A/m^-2, total organic carbon removal reached 75% in the AO-FO mode and 93% in the AO-PRO mode. The superior performance of the AO-PRO configuration is attributed to the synergistic effects of stronger osmotic dewatering, which increases the local PFOA concentration, and the favorable structural and electrochemical properties of the MX-B membrane architecture, including lower charge-transfer resistance and enhanced physical stability, thereby accelerating PFOA degradation. Furthermore, the integrated process reduced energy consumption, highlighting the potential of MXene-enabled osmotic-electrochemical systems for energy-efficient PFAS destruction and safe effluent management.