Light-boosted simultaneous acid and salinity gradient energy recovery from wastewater via a nanochannel membrane with multi-objective ion separation ability

The discharge of industrial wastewater has surged to unprecedented levels due to rapid industrialization. Developing effective strategies for the concurrent recovery of resources and energy from wastewater presents a promising pathway toward sustainable development. In this study, a composite nanochannel membrane with light-boosted ion separation capabilities was designed for the concurrent recovery of acid and salinity gradient energy from metallurgical industrial wastewater. The membrane demonstrated remarkable photothermal conversion efficiency, utilizing the synergy between localized surface plasmon resonance of Ti₃C₂T_x component and molecular vibration of Cu-TCPP component to achieve rapid temperature rise from room temperature to 139.5 °C within 60 s under illumination. This photothermal effect created an effective temperature gradient within nanochannels, enhancing the separation efficiency for both H⁺/Cl⁻ and H⁺/Fe²⁺ pairs by amplifying the differences in diffusion energy barriers. When applied to acidic wastewater, the membrane achieved an outstanding salinity gradient energy conversion power density of 7.31 W/m² over an expanded testing area, along with a H⁺/Fe²⁺ selectivity of 64.18 for acid recovery. Both energy harvesting and acid recovery performance surpass those of state-of-the-art membranes under identical testing conditions. This work presents a critical strategy for energy conversion and resource recovery from wastewater, contributing to sustainable solutions for energy, environmental, and resource challenges.