Solar-Powered Desalination System Bypasses the Release of Hypersaline Waste Brine: Self-Cleaning, Super-Wicking Solar Panels are the Key: Minerals, Including Salt and Lithium, Can Be Recovered

      I posted quite recently about the environmental impacts of waste brine released from desalination plants. The most common forms of desalination, reverse osmosis and thermal distillation, are energy-intensive, require pre-treatment and post-treatment, and release waste brine. Researchers from the University of Rochester’s Institute of Optics have developed a new solar-thermal method of desalination that recovers the leftover salts in the brine rather than releasing them back into the sea in a concentrated form. The method, known as solar-thermal interfacial desalination, adds a “femtosecond laser surface processing technique” to create a “multi-functional superwicking black metal (SWBM) panel.”

     According to TechXplore:

“The technology uses solar panels made of black metal etched with femtosecond lasers to make the surface super light-absorbing and superwicking—or extremely attractive to water.”

“The panels have a laser-treated active region that pulls a thin layer of water across the surface, absorbs nearly all solar radiation, distills the water, and deposits the leftover salts and minerals into the panel's untreated sides or "passive" region so that the salt does not clog the active region and disrupt continuous desalination.”

     The method utilizes something known as the ‘coffee ring effect,’ where, after evaporation, a stain is left on the outside of spilled coffee due to the coffee particles wicking to the outside of the ring. The salts from the seawater can do the same thing, effectively wicking them away from the center of the solar panel where the desalination is taking place and moving them to the outside where they can be collected more easily. The staining phenomenon is similar to the scaling effects of salty water on pipes and containers, such as a teapot.

“To keep their solar panel surface from gumming up in a similar way, Guo's team precisely etched the black metal's grooves so the various salts and minerals in ocean water would simply slough off.”

“Testing their solar-thermal desalination technique using samples of water from the Pacific, Atlantic, and Indian Oceans, Guo and his team were able to make the surface self-cleaning so that it extracted freshwater and directed the remaining salts to the passive region where they could be later collected without reducing the panel's efficiency.”

     With some modifications, the method can also be used to separate lithium from seawater:

“In a related paper in the Journal of Materials Chemistry A, Guo and his colleagues show how they can use the same superwicking solar panels to separate lithium from the rest of other salts in desalination. Embedding nanoparticles made of hydrogen titanate in the tiny grooves of the black metal surface isolates the lithium from other salts and minerals.”

     They tested the lithium separation process on water from the Great Salt Lake and were able to recover 50% of the lithium.

“Guo says now that the superwicking desalination technology has been demonstrated in proofs of concept on small-scale devices, he sees the technology as inherently scalable, capable of improving global access to drinking water and building more sustainable supply chains for precious minerals.”

     As the abstract from that paper notes, minerals recovery from the original process is nearly 100%, and when the hydrogen titanite nanoparticles are added, the extraction efficiency for lithium reaches 50%.

References:

 

Solar-powered desalination system turns ocean water into drinking water without waste. Science X staff. TechXplore. May 27, 2026. Solar-powered desalination system turns ocean water into drinking water without waste

Additive-free and brine-discharge-free solar-thermal desalination with simultaneous complete mineral mining from ocean water. Luheng Tang, Subhash C. Singh, Ran Wei, Tianshu Xu & Chunlei Guo. Light: Science & Applications volume 15, Article number: 246 (May 27, 2026). Additive-free and brine-discharge-free solar-thermal desalination with simultaneous complete mineral mining from ocean water | Light: Science & Applications

Rapid lithium extraction via solar-thermal interfacial evaporation with zero liquid discharge. Luheng Tang, Subhash C. Singh, Mingjiang Maa and Chunlei Guo. Journal of Materials Chemistry A. Issue 25, 2026. Rapid lithium extraction via solar-thermal interfacial evaporation with zero liquid discharge - Journal of Materials Chemistry A (RSC Publishing)