New solar desalination breakthrough makes fresh water without toxic brine

Recorded: May 31, 2026, 11 p.m.

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New solar desalination breakthrough makes fresh water without toxic brine
This sunlight-powered desalination breakthrough turns seawater into fresh water while harvesting valuable minerals.

Date:
May 31, 2026
Source:
University of Rochester
Summary:
Scientists have developed a solar desalination system that turns seawater into drinking water without creating environmentally damaging brine. Special laser-textured metal panels use sunlight to evaporate water while automatically moving salt deposits away from the working surface, preventing clogging. The process was successfully tested with water from three oceans and can recover nearly all salts as solids. Those leftover materials could even become a source of valuable lithium for batteries.
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In Professor Chunlei Guo’s lab at the University of Rorchester, researchers developed a solar desalination device featuring laser-etched superwicking black metal, a technology that produces fresh water from seawater while capturing salts and minerals instead of generating harmful brine waste. Credit: University of Rochester / J. Adam Fenster

According to the United Nations, 2.2 billion people still do not have access to safely managed drinking water. To help meet growing demand, many regions, from California to parts of the Middle East, rely on desalination plants that convert seawater into fresh water.

Traditional desalination methods such as reverse osmosis and thermal distillation can be expensive and energy intensive. They often require chemical treatments before and after processing the water and generate large volumes of concentrated saltwater known as brine. When discharged back into the ocean, brine can damage marine ecosystems by increasing salinity and reducing oxygen levels.
Researchers at the University of Rochester have developed a new approach that could address several of these challenges. Their solar powered desalination system produces fresh water efficiently, operates without chemical pretreatment, and avoids creating brine waste. The research was led by Chunlei Guo, a professor of optics and physics and a senior scientist at the University's Laboratory for Laser Energetics. The team described the technology in the journal Light: Science & Applications.
Laser-Treated Solar Panels Drive the Process
The system relies on specially engineered solar panels made from black metal that has been textured with femtosecond lasers. This treatment gives the surface two important properties. It absorbs nearly all incoming sunlight and strongly attracts water, a characteristic known as superwicking.
A laser patterned active region draws a thin layer of seawater across the panel. As sunlight is absorbed, the water evaporates and is distilled into fresh water. At the same time, dissolved salts and minerals are guided away from the active area and deposited onto untreated sections of the panel called passive regions.
By moving the salts away from the evaporation zone, the design prevents buildup that could otherwise interfere with continuous operation.

Using the Coffee Ring Effect to Prevent Clogging
Guo notes that several solar thermal desalination technologies have shown promising results in laboratory studies using simplified seawater composed only of water and sodium chloride.
In those experiments, sodium chloride crystals form in a loose, porous structure as water evaporates. Water can continue flowing through these crystals, dissolving them and making the systems relatively easy to clean.
Real seawater is far more complicated.
In addition to sodium chloride, oceans contain many other dissolved minerals. Materials containing magnesium and calcium often form hard, dense crusts when they crystallize. These deposits can block water flow and eventually shut down the desalination process.
The problem is similar to mineral scale building up inside a tea kettle or clogging a shower head over time, except seawater contains far higher concentrations of dissolved salts.

To overcome this challenge, the Rochester team carefully designed microscopic grooves on the black metal surface. The pattern encourages salts and minerals to move away from the active region before they can accumulate.
The researchers also took advantage of a familiar physical phenomenon 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 the team tested the technology using water samples collected from the Pacific, Atlantic, and Indian Oceans, the surface effectively cleaned itself. Fresh water was continuously extracted while salts were directed toward the passive regions, where they could later be collected without reducing performance.
Recovering Valuable Minerals Instead of Creating Waste
One of the most significant advantages of the system is what happens to the leftover salt.
Conventional desalination produces liquid brine that must be treated, disposed of, or discharged into the environment. The new process instead recovers nearly all dissolved salts in solid form.
Those recovered materials could become valuable resources. In addition to producing table salt, the process could help extract important minerals such as lithium, a key ingredient 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 separate lithium from other salts.
To accomplish this, the researchers embedded hydrogen titanate nanoparticles into the microscopic grooves of the black metal surface. These particles selectively isolate lithium from other dissolved minerals.
"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 from Utah's Great Salt Lake, the team successfully recovered about 50 percent of the lithium contained in the salts remaining after desalination.
Potential for Large Scale Fresh Water Production
Although the technology has so far been demonstrated only in proof of concept devices, Guo believes the approach can be scaled up significantly.
If successfully expanded, the system could help increase access to clean drinking water while also creating more sustainable sources of critical minerals.
The research was supported by the National Science Foundation, the Bill & Melinda Gates Foundation, and the Worldwide Universities Network. Additional contributors from the 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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Scientists at the University of Rochester, led by Professor Chunlei Guo, have developed a novel solar desalination system that converts seawater into fresh water while simultaneously recovering valuable salts and minerals, effectively eliminating the creation of harmful brine waste. This breakthrough addresses the limitations of traditional desalination methods, such as reverse osmosis and thermal distillation, which are energy-intensive, require chemical treatments, and result in large volumes of concentrated saltwater that can damage marine ecosystems upon discharge. The new system is powered by specialized solar panels constructed from black metal that has been laser-etched with femtosecond lasers. This laser treatment imparts two critical properties to the surface: it strongly absorbs incoming sunlight and exhibits superwicking characteristics, which attract water.

The operational mechanism relies on this laser-patterned surface to draw a thin layer of seawater across the panel. As sunlight is absorbed, the water evaporates and is distilled into fresh water. Crucially, the design is engineered to guide dissolved salts and minerals away from the active evaporation zone and deposit them onto untreated sections of the panel known as passive regions. This spatial separation is designed specifically to prevent the accumulation of mineral scale, which typically causes clogging and operational shutdowns in other thermal desalination technologies.

To ensure continuous flow, the researchers utilized the principle of the coffee ring effect. By creating microscopic grooves on the black metal surface, the pattern encourages salts and minerals to migrate away from the active area, effectively directing them toward the passive regions. This design mimics how water evaporates and concentrates impurities at the edge of a liquid, facilitating the separation of salts. Testing with samples from the Pacific, Atlantic, and Indian Oceans demonstrated that the surface could effectively clean itself throughout the process, continuously extracting fresh water while channeling salts away for later collection.

A significant advantage of this approach is the recovery of salts in a solid form rather than generating liquid brine. Beyond producing common table salt, the system is designed to recover other important minerals. The researchers enhanced this by embedding hydrogen titanate nanoparticles into the microscopic grooves of the metal surface; these nanoparticles selectively isolate lithium from other dissolved salts. This process allows for the extraction of critical materials. For instance, when tested with water from Utah's Great Salt Lake, the team successfully recovered approximately fifty percent of the lithium contained within the remaining salts. This method offers a potentially sustainable route for mining lithium directly from saltwater, addressing the high energy and environmental costs associated with traditional terrestrial lithium mining.

The potential for this technology extends to large-scale fresh water production and sustainable resource management. Although the research is currently at the proof-of-concept stage, the approach is believed to be scalable. If fully expanded, the system could facilitate access to clean drinking water while simultaneously establishing a method for extracting essential critical minerals from ocean water, offering a more sustainable solution for meeting global water and energy demands.