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)
































