Constant access to a supply of freshwater is critical for life on this planet, as well as for the growth of industry, agriculture and modern-day economies. But natural water supplies are depleting in many parts of the world, with around 2.2 billion people lacking safely managed drinking water, according to United Nations estimates.
Many countries rely on converting ocean water into freshwater using desalination plants. But the reverse osmosis and thermal distillation techniques currently used are energy intensive and leave behind brine that raises the salt level of the water (and reduces oxygen levels), which can harm sea life.
Researchers from the University of Rochester have taken a new approach by developing a solar-thermal desalination process that’s less energy intensive, doesn’t generate brine and doesn’t require chemical additives to pre-treat the water.
“Today, about one quarter of the global population lacks safely managed drinking water; but at the same time the oceans contain an enormous resource of both water and valuable minerals,” explains lead researcher Chunlei Guo. “We wanted to develop a technology that could address these challenges together, producing freshwater sustainably while turning what is traditionally considered waste into a resource.”
The novel desalination technology, described in Light: Science & Applications, is based on a multi-functional superwicking black metal (SWBM) panel created via femtosecond laser processing. Desalination involves evaporating and distilling the water, removing the salt in the process. To do this, materials that absorb sunlight and heat up, while wicking water, are required. The SWBM panel proved effective at both.
The SWBM panel is highly attractive to water and can pull a thin film of water upwards across its surface, while absorbing almost all solar energy. This uphill pulling of water against gravity means that the panel can be placed in any orientation, enabling effective solar tracking.
The evaporated and distilled water can be extracted from the panel and the remaining salts are directed away from the panel’s active region and deposited in its passive (untreated) regions. This not only self-cleans the active region of the panel, but enables continuous desalination to produce distilled drinking water.
To read more, click here.