Over 99.99% of oil removed from seawater with higher evaporation rate using new membrane

Growing populations and expanding industries are intensifying freshwater shortages across parts of Africa, the Middle East, and Southeast Asia, increasing the need for sustainable water supplies. Solar desalination has emerged as a promising solution, using sunlight to convert seawater into freshwater with relatively low energy requirements. But real-world conditions pose a challenge. Seawater near ports, shipping routes, and industrial areas is often contaminated with oil, which can clog desalination membranes and reduce their performance. Although many experimental solar desalination systems have shown strong results in laboratory tests using clean saltwater, it remains uncertain how effectively they would operate in polluted seawater. New membrane design aims to make solar desalination more practical In an effort to overcome this limitation, researchers at Pusan National University developed a multifunctional hydrogel membrane that combines oil separation and solar-driven desalination in a single system. Led by Professor Sanghyun Jeong from the Department of Civil and Environmental Engineering, the team designed a membrane architecture that simultaneously removes oil contaminants while producing freshwater, eliminating the need for separate treatment stages. The study was published online on June 1, 2026, and will appear in the October 15, 2026, issue of Desalination. Inspired by the need for selective water treatment, the researchers developed a membrane with a “Janus” architecture, giving each side a distinct function. One surface is hydrophilic, made from a chitosan and polyvinyl alcohol hydrogel, allowing water to pass through while blocking oil droplets. The opposite surface is hydrophobic and incorporates copper oxide nanoparticles coated with a carbon shell, which are embedded within a nanofiber layer. This dual-sided design enables the membrane to handle different contaminants while supporting more efficient desalination and oil separation. Higher oil removal and faster solar water evaporation By separating the membrane’s functions across different layers, the researchers prevented oil separation and solar heat generation from interfering with each other, a common challenge in single-layer designs. The hydrophobic side absorbs sunlight, converts it into heat, and drives water evaporation at the membrane surface. Testing showed that the membrane removed more than 99.99% of oil from contaminated seawater while maintaining stable performance across different oil droplet sizes and repeated cycles. During solar desalination experiments, it achieved a water evaporation rate of about 0.05 gallons per square foot per hour, nearly three times higher than conventional single-layer membranes. According to Prof. Jeong, the new membrane technology could support more sustainable water treatment by harnessing renewable solar energy while combining contaminant removal and freshwater production in a single platform. The integrated approach has the potential to reduce energy consumption, simplify operations, and minimize secondary waste generation compared with conventional desalination methods. The researchers suggest that the membrane developed in this study represents a broader strategy for designing next-generation water treatment technologies. By integrating multiple treatment functions into a single membrane architecture, the approach could provide a framework for creating more efficient and adaptable systems beyond desalination applications. Recommended ArticlesGet the latest in engineering, tech, space & science - delivered daily to your inbox.Bojan Stojkovski is a freelance journalist based in Skopje, North Macedonia, covering foreign policy and technology for more than a decade. His work has appeared in Foreign Policy, ZDNet, and Nature.