Stanford and SLAC scientists have developed an affordable, recyclable powder that can rapidly eliminate thousands of waterborne bacteria every second when sunlight is present. This groundbreaking disinfectant holds tremendous potential for the approximately 2 billion individuals globally who lack access to clean drinking water. [1]

Over 2 billion people worldwide regularly consume water contaminated with disease-causing microorganisms. [1]

Figure 1. Main Phases of using the powder.

Figure 1 shows the main phases of using the powder. A groundbreaking study published in Nature Water reveals that scientists from Stanford University and SLAC National Accelerator Laboratory have successfully developed an inexpensive, eco-friendly powder that, when exposed to regular sunlight, effectively eradicates thousands of waterborne bacteria per second. This remarkable discovery holds immense potential as a major breakthrough for approximately 30 percent of the global population, who currently lack access to safe drinking water. The Stanford and SLAC team's findings, released on May 18, mark a significant milestone in the field of water disinfection. [1]

“Waterborne diseases are responsible for 2 million deaths annually, the majority in children under the age of 5,” said study co-lead author Tong Wu, a former postdoctoral scholar of materials science and engineering (MSE) in the Stanford School of Engineering. “We believe that our novel technology will facilitate revolutionary changes in water disinfection and inspire more innovations in this exciting interdisciplinary field.” [1]

Traditional methods of water treatment often involve the use of chemicals, which can generate harmful byproducts, or rely on ultraviolet (UV) light, which is time-consuming and necessitates an electricity supply. [1]

In contrast, the recently developed disinfectant at Stanford University introduces a safe metallic powder that utilizes the combined power of UV and high-energy visible light emitted by the sun. Composed of nano-scale flakes of aluminum oxide, molybdenum sulfide, copper, and iron oxide, this innovative powder offers a harmless and effective solution. [1]

“We only used a tiny amount of these materials,” said senior author Yi Cui, the Fortinet Founders Professor of MSE and of Energy Science & Engineering in the Stanford Doerr School of Sustainability. “The materials are low cost and fairly abundant. The key innovation is that, when immersed in water, they all function together.” [1]

Fast, nontoxic, and recyclable

Once exposed to sunlight, the molybdenum sulfide/copper catalyst within the metallic powder acts as a junction between a semiconductor and metal. This configuration allows the absorbed photons to release electrons. The liberated electrons subsequently engage with the surrounding water, leading to the production of hydrogen peroxide and hydroxyl radicals. These oxygen derivatives are highly detrimental to biological organisms. The rapid generation of these chemicals proves lethal to bacteria as they inflict severe damage upon the bacteria's cell membranes, effectively eliminating them. [1]

For the study, the Stanford and SLAC team used a 200 milliliter [6.8 ounce] beaker of room-temperature water contaminated with about 1 million E. coli bacteria per mL [.03 oz.]. [2]

“We stirred the powder into the contaminated water,” said co-lead author Bofei Liu, a former MSE postdoc. “Then we carried out the disinfection test on the Stanford campus in real sunlight, and within 60 seconds no live bacteria were detected.” [2]

The powdery nanoflakes can move around quickly, make physical contact with a lot of bacteria and kill them fast, he added. The chemical byproducts generated by sunlight also dissipate quickly. [2]

“The lifetime of hydrogen peroxide and hydroxy radicals is very short,” Cui said. “If they don’t immediately find bacteria to oxidize, the chemicals break down into water and oxygen and are discarded within seconds. So you can drink the water right away.” [2]

The powder used is eco-friendly and can be recycled. Including iron oxide in the nanoflakes allows them to be extracted from water using a regular magnet. The researchers foresee the powder being useful for other applications beyond providing billions of safe water to impoverished people. Hikers, campers, and largescale water treatment plants too. The team plans to test the powder on other water-borne pathogens like viruses, protozoa, and parasites. [2]

Source: Stanford

References:

1. https://news.stanford.edu/2023/05/18/new-technology-uses-ordinary-sunlight-disinfect-drinking-water/
2. https://interestingengineering.com/innovation/water-purification-powder-sunlight

Cite this article:

Hana M (2023), Sunlight Superpowers: Harnessing the Magic of Light to Purify Drinking Water!, AnaTechmaz, pp.442