Stanford scientists unveil game changer. low‑cost powder that sanitizes water in seconds
The struggle for clean drinking water, uninfected by dangerous microbes, impacts a minimum of 2 billion individuals globally. Researchers from Stanford University have created a low-cost, non-toxic powder that can be used repeatedly and eliminates microorganisms in water when exposed to sunlight.
"Waterborne diseases cause 2 million fatalities per year, and the victims are primarily under the age of 5," stated the study's co-author, Dr. Tong Wu. "We anticipate our innovative technology will transform water disinfection methods revolutionarily and inspire more breakthroughs in this exciting interdisciplinary field."
Existing technologies have limitations
Traditional water treatment methodologies use disinfecting chemicals, which may generate toxic by-products, and ultraviolet light, which demands considerable time and an electrical power source.
The new disinfectant formulated by Stanford is a non-harmful metallic powder that absorbs UV rays and high-energy sunlight. The powder comprises aluminum oxide, molybdenum sulfide, copper, and iron oxide nanoparticles.
"We only utilized a minimal quantity of these materials," stated the senior author, Professor Yi Cui. "Upon immersion in water, the elements in the powder collaborate." He added that the particle's speedy movement allows them to contact with numerous bacteria thus exterminating them swiftly.
The powder is combined with water polluted with bacteria; once exposed to sunlight, it annihilates the bacteria promptly. After sterilization, the metallic powder can be retrieved with a magnet and reused to purify additional water.
When the powder absorbs sunlight photons, the molybdenum sulfide/copper catalyst acts like a semiconductor/metal junction, enabling photons to displace electrons. The freed electrons then react with the nearby water, creating hydrogen peroxide and hydroxyl radicals, or, highly reactive oxygen forms. The newly produced chemical compounds rapidly destroy bacteria by damaging their cellular structures before they degrade into harmless substances.
For experiments, the Stanford research team employed about 6.76 ounces of room temperature water, contaminated with around 1 million E. coli bacteria per milliliter (cubic centimeter). The co-author, Dr. Bofei Liu, said, "We combined the powder with the polluted water, and a disinfection test conducted under sunlight at the Stanford campus eliminated all living bacteria within 60 seconds."
Due to the powder's iron oxide constituents, a standard magnet can remove the particles from water. The authors successfully reused the same powder 30 times to purify 30 distinct water samples.
"I picture hikers carrying a small quantity of this powder and a mini magnet," expressed Cui. "During daylight, sprinkle it into the water, agitate it a bit under sunlight, and you have potable water within a minute. The magnet can be used to separate the particles for future use."
Further, Prof. Cui remarked, the powder could potentially be utilized in wastewater treatment plants, which currently employ UV lamps for disinfecting treated water.
"In the daylight, the treatment plant could use visible sunlight, which would operate faster than ultraviolet lamps and likely conserve energy," mentioned Cui. He added that the nanoparticles are relatively simple to manufacture."
The study primarily focused on E. coli, known for triggering severe gastrointestinal ailments and life-threatening conditions. The United States Environmental Protection Agency has established zero as the maximum acceptable contamination level for E. coli in drinking water. The Stanford team aims to assess the new water purification method's effectiveness against other disease-causing pathogens, including viruses, protozoa, and parasites.
