Many coastal communities rely on desalination, and the United Nations estimates 2.2 billion people lack safely managed drinking water. Standard methods such as reverse osmosis and thermal distillation use a lot of energy, need chemical pre- and post-treatment, and create concentrated brine. Discharging that brine raises local salt levels and lowers oxygen in the sea, which harms marine life.
Researchers at the University of Rochester developed a different solar-powered approach. They use black metal panels etched with femtosecond lasers to make the surface highly light-absorbing and superwicking. A laser-treated active region pulls a thin layer of water across the panel, absorbs sunlight, distills the water and moves salts to an untreated passive region so the active area does not clog.
To handle many salts found in real seawater, the team shaped tiny grooves so minerals slough off and used the coffee ring effect to move salts to the passive region. Tests with Pacific, Atlantic and Indian Ocean samples produced fresh water while directing leftover salts into the passive area for later collection. The method deposits nearly 100% of salts as solids, and embedding hydrogen titanate nanoparticles helped isolate lithium; tests with Great Salt Lake samples recovered about 50% of the lithium.
Lead researcher Chunlei Guo and colleagues published results in Light: Science & Applications and Journal of Materials Chemistry A. Guo says the technology has been shown in small proof-of-concept devices and is inherently scalable, and the approach could reduce energy use, avoid chemical additives and cut brine waste.
Difficult words
- desalination — Process to remove salt from seawater
- brine — Very salty water left after desalination
- femtosecond — Extremely short time interval in lasers
- superwicking — Very strong movement of liquid along surface
- coffee ring effect — Pattern that moves solids to surface edges
- passive region — Area where salts collect and wait
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Discussion questions
- What advantages does the solar-powered desalination method offer over standard methods mentioned in the article?
- How would directing salts to a passive region change how a desalination site handles waste?
- What local conditions would you check before installing this technology in your area?
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