Bifunctional Janus Membranes for Multicomponent Contaminated Seawater Separation and Recovery

Abstract

Solar-driven interface desalination has emerged as a promising strategy to address the global freshwater shortage crisis. However, the separation and recovery of multicomponent oil-contaminated seawater remain a key challenge. This study reports a novel high-strength Janus photothermal membrane with a unique reverse wettability design. On one side, the membrane has hydrophilic and oleophobic properties, while on the other, it has hydrophobic and oleophilic characteristics. The Janus membrane demonstrates dual functionality: solar desalination and oil–water separation. This dual functionality enables efficient separation and recovery of four components from contaminated seawater: purified water, salt crystals, light oil, and heavy oil. As a result, the Janus membrane achieves an evaporation rate of 2.06 kg m^–2 h^–1 under 1.0 sun. The ion (Na⁺, K⁺, Ca²⁺, and Mg²⁺) removal rate approaches 100% with nearly complete recovery of salt crystals. Furthermore, various types of oils can be accurately separated, with separation efficiency approaching 100%. An integrated separation device successfully separates and recovers the four components. This research presents significant potential for efficient separation and recovery of complex components in oil-contaminated seawater.