A new way to turn seawater into drinking water without wasting it

Energy efficient desalination system produces fresh water without chemical additives and converts remaining salt into useful substances.

Important Points

We produce drinking water from seawater without using chemical additives.

The solar power system uses black metal specially designed to absorb sunlight.

The self-cleaning surface does not discard the salt as harmful salt water waste, but is separated and collected.

This system can extract lithium, which is an important material for rechargeable batteries from salt.

This approach can help to address global water shortages and the global environment of mineral demand.

The United Nations estimates that 22 billion people lack safe controlled drinking water, and the local communities from California to the Middle East rely on desalination plants to change seawater into desalination. General desalination technology, such as reverse osmosis and thermal distillation, consumes large amounts of energy, requires water treatment before and after, and remains concentrated byproducts called brine. Salt water, a by-product, deposits into the sea, increases the salt concentration in the water, and reduces oxygen, causing significant damage to marine life.

However, a new approach developed atチェster University provides a way to overcome these downsides. Urochester Optics Researcher developed a new solar heat desalination method that produces freshwater in an energy efficient way, without leaving the salt water and does not require chemical additives in the pre、ment of water. The team led by Chunlei Guo, a professor of optics and physics, and a senior scientist atchechester’s Laboratory for Laser Energetics, explains how to use the paper published in Light: Science & Applications.

This technology uses a black metal solar panel etched with a femtosecond laser to make its surface very light absorption and ultra-hygroscopic, which means the surface is very pulling. The panel has a laser-processed active area, which removes a thin layer of water throughout the surface, absorbs almost all solar radiation, distills water and deposits remaining salt and minerals into un処理ed sides of the panel or “passive” areas, so the salt does not 。gged the active area and prevents continuous desalination.

Use the effect of "coffee ring"

Mr. Guo said that other researchers have developed a desalination technology by solar heat and demonstrated the effect in laboratory experiments using simulated seawater made only by water and sodium。. When water evaporates, sodium。 crystallizes in a granular, porous form, and the water passes to dissolve the salt. On the other hand, solar panels can be easily cleaned.

However, because the actual ocean has a much more complex structure, these systems tend to be tested on-site.マグネシウム sodium , many other ingredients in the seawater, such as substances based on magnesium and calcium, crystallize porous on the surface of the solar panel and cause eye swelling. In the end, the water will not penetrate. This is the same 、omena that the shower head has been calibrated over time or calibrated on the teapot, but the seawater contains several hundred times the salt of tap water.

“The mining of lithium from the earth is found to be very burdensome from the viewpoint of energy and the environment, so it can be a very important means in the future.

In order to prevent the surface of the solar panel to be sticky similarly, Mr. Guo’s team etched black metal grooves accurately to make it easy to peel off various salts and minerals in the seawater. They also used the physical 、omena that has been suffering from unwanted Java enthusiasts for centuries, i.e. the coffee ring effect.

Guo says, “When coffee is dropped on the surface, it will eventually leave the ring, which is the particle of coffee concentrated on the outer edge,” Guo said. "We use the same principle to proceed to the uns。rated area of salt.

Mr. Guo and his team have successfully tested the solar thermal desalination technology using water samples from Pacific, Atlantic and Indian Ocean and auto-clean the surface. In other words, we extracted fresh water, in the remaining salt into the passive area, so that we can collect it later without decreasing the efficiency of the panel.

Convert waste into resources

One of the clear benefits of the new desalination method is that it can extract almost 100% of the salt in solid form instead of leaving the salt water that should be dis or treated. This can also be used to extract more valuable minerals, such as lithium ion batteries used to power electric vehicles and other electronic devices, as well as to produce rich salt.

Journal the related papers published in Journal of Materials A, Guo shows how to separate lithium from the rest of other salts when desalination using the same super-hygroscopic solar panel. It isolates lithium from other salts and minerals by embedding nanoparticles made of hydrochloride into small grooves with black metal.

“The mining of lithium from the earth is found to be very burdensome from the viewpoint of energy and the environment, so it can be a very important thing in the future to collect lithium from seawater,” Guo says.

Researchers extracted about 50 percent of lithium from the salt remaining in the desalination process using a water sample of Lake Great Salt.

Mr. Guo said that superhygroscopic desalination technology was demonstrated in the conceptual demonstration of small equipment, the technology essentially scalable, and the ability to improve access to global drinking water and build a more sustainable supply chain of precious minerals.

The National Science Foundation, Bill & Melinda Gates Foundation and the World University Network supported this study. Mr. Guo’s colleagues, who contributed to this research, include Dr. Subash Singh, Dr. Ran Wei '24, Dr. Luheng Tang, Mr. Tainshu Xu and Mr. Mingjiang Ma.