By John — Desalination News
Researchers at Pusan National University in South Korea, working with collaborators in Singapore, have developed a two-sided “Janus” membrane that removes oil from contaminated seawater and desalinates it in a single step — addressing a real-world problem that has limited solar desalination technology despite years of promising lab results.
Most experimental solar desalination systems are tested using clean saltwater under controlled laboratory conditions. But actual seawater near ports, shipping lanes and industrial coastlines is frequently contaminated with oil, which fouls the specialized membranes these systems rely on and can shut them down. The team, led by Professor Sanghyun Jeong of PNU’s Department of Civil and Environmental Engineering, set out to solve oil contamination and desalination together rather than as separate treatment stages — an approach distinct from other recent solar desalination work, such as the University of Rochester’s brine-free evaporator panels, which focus on eliminating waste brine rather than pre-treating contaminated intake water.
The new hydrogel membrane has two functionally distinct sides. One is hydrophilic — water-attracting — and made from a chitosan and polyvinyl alcohol hydrogel that allows water through while repelling oil droplets. The other is hydrophobic and contains copper oxide nanoparticles wrapped in a carbon shell, embedded within a nanofiber layer; this side absorbs sunlight, converts it to heat, and drives evaporation at the surface. Because oil rejection and solar heat generation happen on separate layers, the two functions don’t interfere with each other — a problem that has affected simpler, single-layer membrane designs.
In testing, the membrane removed more than 99.99% of oil from contaminated seawater and held that performance across different oil droplet sizes and repeated use cycles. During solar desalination, it achieved a water evaporation rate of 1.29 kilograms per square meter per hour — nearly three times that of a conventional single-layer membrane, according to the researchers.
Jeong framed the significance of the work beyond the specific oil-and-salt problem it solves, noting that combining multiple treatment functions into one membrane architecture points toward a broader design strategy for future water treatment systems — one that could extend to recovering useful resources from concentrated brine streams as well as treating contaminated coastal and industrial wastewater. The freshwater access implications are significant for regions such as Africa, the Middle East and Southeast Asia, where population growth and industrial expansion are intensifying water scarcity even as much of the available seawater sits near polluted ports and coastlines.
The study was made available online on June 1, 2026, and is scheduled for full publication in Volume 636 of the journal Desalination on October 15, 2026. As with other early-stage solar desalination research, the work has so far been demonstrated at laboratory scale, and questions about durability and cost under continuous field conditions remain to be tested before the technology could move toward commercial deployment.
(Source: Pusan National University / EurekAlert)