Rochester lab's solar desalination skips brine, harvests lithium from seawater

Researchers at the University of Rochester’s Institute of Optics have built a solar-thermal desalination system that sidesteps the two biggest headaches of conventional plants: high energy use and toxic brine discharge. The device uses black metal panels etched by femtosecond lasers to be both intensely light-absorbing and superwicking, drawing a thin film of seawater across an active region where it evaporates. By exploiting the coffee-ring effect, the panel pushes leftover salts outward to a passive zone where they crystallize as solids rather than crusting over and clogging the surface, a failure mode that has tripped up earlier solar stills tested on real ocean water.

The team validated the approach with samples from the Pacific, Atlantic, and Indian Oceans, reporting self-cleaning operation and near-total recovery of dissolved salts in solid form. A companion paper describes embedding hydrogen titanate nanoparticles in the panel’s grooves to selectively isolate lithium; in tests on Great Salt Lake water they pulled out roughly half the available lithium. Lead researcher Chunlei Guo frames the work as a route to both potable water and a less destructive lithium supply for batteries, and argues the proof-of-concept devices should scale. Funding came from NSF, the Gates Foundation, and Worldwide Universities Network.