A ‘Water-Purifying’ Solar Panel?

Sometimes the craziest-sounding inventions can have the biggest impact.

Researchers at the University of Rochester are collaborating with the armed forces on something that falls in that “so crazy it just might work” category—combining solar power and water purification to combat water shortages during the coronavirus pandemic. Bear in mind, to them, this technology is far from crazy, as they’ve put in years of study to cultivate it. Plus, the innovation stems from dire needs in a time of crisis.

“Amid the coronavirus pandemic, people in developed countries are assured of ample supplies of clean water to wash their hands as often as needed to protect themselves from the virus,” a U of R news release July 13 said. “And yet, nearly a third of the world’s population is not even assured of clean water for drinking.”

The researchers have now found a way to address this problem by using sunlight—a resource that everyone can access—to evaporate and purify contaminated water with greater than 100 percent efficiency.

How is this possible?

In a paper in Nature Sustainability, researchers in the laboratory of Chunlei Guo, professor of optics, demonstrate how a burst of femtosecond laser pulses etch the surface of a normal sheet of aluminum into a superwicking (water-attracting), super energy-absorbing material.

When placed in water at an angle facing the sun, the surface:

  • Draws a thin film of water upwards over the metal’s surface
  • Retains nearly 100 percent of the energy it absorbs from the sun to quickly heat the water
  • Simultaneously changes the inter-molecular bonds of the water, significantly increasing the efficiency of the evaporation process even further.

Using sunlight to boil has long been recognized as a way to eliminate microbial pathogens and reduce deaths from diarrheal infections. But boiling water does not eliminate heavy metals and other contaminants.

Experiments by the lab show that their new method reduces the presence of all common contaminants, such as detergent, dyes, urine, heavy metals, and glycerin, to safe levels for drinking.

2 Responses to “A ‘Water-Purifying’ Solar Panel?”

  1. Jerome Silverman Reply July 17, 2020 at 4:34 pm

    If etching is the key, chemically deeply etched aluminum is commonly used as the cathode in aluminum electrolytic capacitors. Is this the reinvention of the wheel?

  2. Only etching cannot make it a solar absorber. Laser etching makes deep grooves along with deposition of dense nanoparticles on the surface that makes it to absorb > 95 % of solar radiation. Chemically etched Al does not absorb the sunlight.

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