Access to clean drinking water remains a major global challenge.
According to the United Nations, about 2.2 billion people do not have safely managed drinking water.
Many regions, including parts of California and the Middle East, depend on desalination plants to turn seawater into fresh water.
However, current desalination technologies come with significant drawbacks. Most systems use large amounts of energy and often leave behind a highly concentrated salty waste known as brine.
When this brine is released back into the ocean, it can damage marine ecosystems by increasing salt levels and reducing oxygen in the water.
Now, researchers at the University of Rochester have developed a new solar-powered desalination technology that could provide a cleaner and more sustainable alternative. The system produces fresh water using sunlight, requires no chemical additives, and leaves behind no harmful brine waste.
The research team, led by Professor Chunlei Guo from the University of Rochester’s Institute of Optics, described the technology in the journal Light: Science & Applications.
The system relies on special solar panels made from black metal that has been etched using ultra-fast femtosecond lasers. This treatment creates a surface that absorbs nearly all incoming sunlight while also strongly attracting water.
When seawater comes into contact with the panel, a thin layer spreads across the surface. The absorbed solar energy heats and evaporates the water, leaving the salts and minerals behind. Unlike conventional systems, however, the salts do not accumulate where the evaporation occurs.
The researchers solved this problem by carefully designing microscopic grooves on the metal surface. These grooves guide the salts away from the active evaporation area to a separate region where they can collect without interfering with the desalination process.
The design takes advantage of a familiar phenomenon known as the “coffee ring effect.” When a drop of coffee dries on a table, the liquid evaporates while coffee particles gather around the edge, leaving a dark ring. The researchers use the same principle to move salts toward the outer parts of the panel.
To test the technology, the team used seawater collected from the Pacific, Atlantic, and Indian Oceans. The system successfully produced fresh water while continuously directing salts away from the working surface, effectively creating a self-cleaning desalination device.
One of the most important benefits is that the system captures nearly all of the dissolved salts as solid materials instead of producing liquid brine. These recovered materials could become valuable resources. Common salt can be collected, and more valuable minerals can also be extracted.
In a related study, the researchers showed that the same technology can recover lithium, a key ingredient in rechargeable batteries. By adding special nanoparticles to the panel surface, they were able to separate lithium from other salts. Tests using water from Utah’s Great Salt Lake recovered about half of the lithium present.
The researchers believe the technology can be scaled up for larger applications. If successful, it could help provide clean drinking water to millions of people while also recovering valuable minerals and reducing the environmental impact of desalination.
