Bifunctional Janus\nMembranes for Multicomponent Contaminated\nSeawater Separation and Recovery

Solar-driven interface desalination has emerged as a\npromising\nstrategy to address the global freshwater shortage crisis. However,\nthe separation and recovery of multicomponent oil-contaminated seawater\nremain a key challenge. This study reports a novel high-strength Janus\nphotothermal membrane with a unique reverse wettability design. On\none side, the membrane has hydrophilic and oleophobic properties,\nwhile on the other, it has hydrophobic and oleophilic characteristics.\nThe Janus membrane demonstrates dual functionality: solar desalination\nand oil–water separation. This dual functionality enables efficient\nseparation and recovery of four components from contaminated seawater:\npurified water, salt crystals, light oil, and heavy oil. As a result,\nthe Janus membrane achieves an evaporation rate of 2.06 kg m<sup>–2</sup> h<sup>–1</sup> under 1.0 sun. The ion (Na<sup>+</sup>, K<sup>+</sup>, Ca<sup>2+</sup>, and Mg<sup>2+</sup>) removal rate approaches\n100% with nearly complete recovery of salt crystals. Furthermore,\nvarious types of oils can be accurately separated, with separation\nefficiency approaching 100%. An integrated separation device successfully\nseparates and recovers the four components. This research presents\nsignificant potential for efficient separation and recovery of complex\ncomponents in oil-contaminated seawater.