Scientists Turn Seawater Into Drinking Water Without Toxic Brine

A new solar desalination breakthrough turns seawater into drinking water while eliminating brine waste and recovering valuable minerals.

Billions of people around the world still do not have reliable access to safe drinking water. According to the United Nations, about 2.2 billion people lack safely managed drinking water services. To meet growing demand, many regions, including California and parts of the Middle East, depend on desalination plants that convert seawater into fresh water.

However, conventional desalination methods such as reverse osmosis and thermal distillation come with significant drawbacks. They consume large amounts of energy, often require chemical treatments before and after processing, and generate highly concentrated brine. When this salty byproduct is discharged back into the ocean, it can harm marine ecosystems by increasing salinity levels and reducing oxygen in the surrounding water.

Researchers at the University of Rochester have now developed a new approach that could address many of these challenges. Their solar-powered desalination system produces fresh water efficiently, avoids creating liquid brine waste, and does not require chemical additives to prepare the water beforehand.

The research team, led by Chunlei Guo, a professor of optics and physics and a senior scientist at the University of Rochester’s Laboratory for Laser Energetics, described the technology in the journal Light: Science & Applications.

Solar Desalination With Laser-Treated Metal

The system relies on special solar panels made from black metal that has been textured using ultrafast femtosecond lasers. This process gives the surface two important properties. It becomes highly effective at absorbing sunlight and extremely attractive to water, a characteristic known as superwicking.

A laser-treated active region on the panel draws a thin layer of seawater across its surface. The material captures nearly all incoming solar energy, heating the water and driving evaporation. As the water is distilled, dissolved salts and minerals are moved away from the active area and deposited in untreated sections of the panel known as the passive region.

By directing salt away from the evaporation zone, the system prevents buildup that could otherwise interfere with continuous freshwater production.

Using the Coffee Ring Effect To Prevent Clogging

Guo notes that several solar-thermal desalination technologies have shown promising results in laboratory experiments using simplified seawater made from water and sodium chloride.

In those tests, sodium chloride forms porous, grain-like crystals as water evaporates. Water can still flow through these structures, allowing the salt to dissolve again, and the panels are relatively easy to clean.

Real seawater is far more complicated.

In addition to sodium chloride, ocean water contains a wide range of dissolved minerals. Magnesium- and calcium-based compounds, for example, often crystallize into dense, crust-like deposits that block water flow. Over time, these deposits can clog desalination surfaces and stop the process from working effectively.

The same phenomenon occurs in everyday life when mineral deposits build up inside a showerhead or form scale inside a teapot. Seawater simply contains far greater concentrations of dissolved salts.

To overcome this problem, the Rochester team carefully engineered microscopic grooves into the black metal surface. The design encourages salts and minerals to move away from critical operating areas instead of accumulating there.

The researchers also took advantage of a familiar physical process known as the coffee ring effect.

“If you drop coffee on a surface, eventually the water evaporates, and there’s a ring left at the outer edge that is the concentrated coffee particles,” says Guo. “We use that same principle to advance the salts to the passive region.”

When tested with seawater collected from the Pacific, Atlantic, and Indian Oceans, the system continuously produced fresh water while automatically directing salts toward the passive region. This self-cleaning behavior maintained performance and allowed the salts to be collected later without reducing efficiency.

Turning Salt Waste Into Valuable Resources

One of the most significant advantages of the technology is that it avoids generating liquid brine.

Instead, nearly all dissolved salts are recovered in solid form. These materials could potentially be used as a source of table salt or as feedstock for recovering more valuable elements.

Among the most promising targets is lithium, a critical component in lithium-ion batteries used in electric vehicles and many consumer electronics.

In a related study published in the Journal of Materials Chemistry A, Guo and colleagues demonstrated that the same superwicking solar panels can also help separate lithium from other salts during desalination.

The researchers embedded hydrogen titanate nanoparticles into the microscopic grooves of the black metal surface. These particles selectively capture lithium while leaving other salts behind.

“Mining lithium from the earth has proven to be very taxing from an energy and environmental standpoint, so pulling lithium directly from saltwater could be a very important future route,” says Guo.

Using water samples from Utah’s Great Salt Lake, the team successfully recovered approximately 50 percent of the lithium present in the salt mixture left behind after desalination.

A Potential Solution for Water and Mineral Supply Challenges

Although the technology has so far been demonstrated on small proof-of-concept devices, Guo believes it can be scaled up for larger applications.

If successfully expanded, the approach could help increase access to drinking water around the world while also creating a more sustainable source of important minerals such as lithium.

References:

“Additive-free and brine-discharge-free solar-thermal desalination with simultaneous complete mineral mining from ocean water” by Luheng Tang, Subhash C. Singh, Ran Wei, Tianshu Xu and Chunlei Guo, 27 May 2026, Light: Science & Applications.
DOI: 10.1038/s41377-026-02315-4

“Rapid lithium extraction via solar-thermal interfacial evaporation with zero liquid discharge” by Luheng Tang, Subhash C. Singh, Mingjiang Ma and Chunlei Guo, 13 February 2026, Journal of Materials Chemistry A.
DOI: 10.1039/D5TA08968A

The research was supported by the National Science Foundation, the Bill & Melinda Gates Foundation, and the Worldwide Universities Network.

Additional contributors from the University of Rochester’s Institute of Optics included Senior Scientist Subash Singh, alumnus Ran Wei ’24 (PhD), PhD students Luheng Tang and Tainshu Xu, and Mingjiang Ma.

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