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 Ti3C2Tx MXene-based membranes, enabling simultaneous PFAS concentration and electrochemical degradation and mineralization. Conductive thin-film composite membranes were fabricated by depositing Ti3C2Tx 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.