Research shows how gentle water can turn hard hydrogen peroxide


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A new study has put a remarkable and unexpected chemical origin on a more solid footing.

Back in 2019, Stanford University researchers and colleagues Shocking discovery revealed He hydrogen peroxide-a caustic substance used to disinfect surfaces and bleach hair – forms spontaneously in microscopic droplets of ordinary, gentle water. Researchers have since aimed to find out how the new reaction occurs, as well as exploring potential applications, such as environmentally friendly cleaning methods.

The latest study has shown that when microscopic droplets of water are sprayed a solid surface, a phenomenon known as contact electrification occurs. The electric charge jumps between the two materials, liquid and solid, producing unstable molecular fragments called reactive oxygen species. Pairs of these species are known as hydroxyl radicals, and which have the chemical formula OH, then can combine to form hydrogen peroxide, H.2hey2in small but detectable amounts.

The new study further demonstrated that this process occurs in a humid environment when water touches soil particles as well as fine particles in the atmosphere. Those additional findings suggest that water can turn into small amounts of reactive oxygen species, such as hydrogen peroxide, wherever microdroplets naturally form, including fog, mist and raindrops, consolidating results from related Doing 2020 study,

“We now have a real understanding that we didn’t have before about the reason for the formation of this hydrogen peroxide,” said senior author Richard Zare, the Marguerite Blake Wilbur Professor in Natural Sciences and Professor of Chemistry at the Stanford School. of Humanities and Sciences. “Furthermore, it appears that the electroporation that generates hydrogen peroxide is a universal phenomenon at the water-solid interface.”

Zare led the work, collaborating with researchers from two Chinese universities, Jianghan University and Wuhan University, as well as the Chinese Academy of Sciences. The study was published on August 1 in Proceedings of the National Academy of Science (PNAS).

On the origin of hydrogen peroxide

For the study, the researchers built a glass device with micro-channels in it where water could be forcibly injected. The channels formed an airtight water-concrete boundary. The researchers scented the water with a fluorescent dye that glows in the presence of hydrogen peroxide. One experiment showed the presence of the harsh chemical in a glass microfluidic channel, but also in a large sample of water not containing the dye. Additional experiments elaborated that hydrogen peroxide forms quickly, within seconds, at the boundary between water and solid.

To find out whether hydrogen peroxide (H.) has an extra oxygen atom2hey2) came from reaction with glass or within water (H2o) By themselves, the researchers treated the vitreous lining of some microfluidic channels. These treated channels contained the heavy isotope, or version of oxygen, known as oxygen-18 or . is called 18A comparison of the post-reaction mixture of water and hydrogen peroxide liquids from O. treated and untreated channels showing 18O refers to the solid as a source of oxygen, in the former, in hydroxyl radicals and eventually in hydrogen peroxide.

The new findings may help settle some debate in the scientific community since Stanford researchers initially announced the novel detection of hydrogen peroxide in microscopic droplets of water three years ago. Other studies have emphasized the major contribution of hydrogen peroxide production through chemical interactions with the gas ozone, o3, and a process called cavitation, when bubbles of vapor rise up in regions of low pressure within accelerated liquids. Zare pointed out that both of those processes apparently produced hydrogen peroxide and comparatively higher amounts.

“All of these processes contribute to hydrogen peroxide production, but the present work confirms that this production is also intrinsic to the way microdroplets form and interact with solid surfaces through contact electroporation,” Zare said.

Turning the Tables on Seasonal Respiratory Viruses

Zare explained how and under what conditions water can turn into reactive oxygen species, such as hydrogen peroxide, offering a host of real-world insights and applications. Most compelling is to understand the formation of hydroxyl radicals And hydrogen peroxide As an overlooked contributor to the well-known seasonality of many viral respiratory diseases, including colds, flu, and potentially COVID-19, when the disease eventually becomes completely endemic.

Viral respiratory infections are spread as water droplets in the air when sick people cough, sneeze, sing, or even talk. These infections tend to increase in winter and decrease in summer, a tendency somewhat for people who spend indoors and in close, permeable proximity during cold weather. However, between work, school, and sleeping through the night, people actually spend the same amount of time indoors during the warmer weather months. Zare said the new study’s findings provide a possible explanation for why colds are related to more flu cases: The main variable at work is humidity, the amount of water in the air. In the summer, higher relative levels of indoor humidity — tied to higher humidity in the warmer air outside — potentially facilitate reactive oxygen species in droplets having enough time to kill the virus. Conversely, in winter – when the air inside buildings heats up and loses its moisture content – ​​the droplets evaporate reactive oxygen species Can act as a disinfectant.

“Contact electroporation provides a chemical basis for partly explaining why there is seasonality for viral respiratory diseases,” Zare said. Accordingly, Zare said, future research should examine any association between indoor humidity levels in buildings and the presence and spread of infections. If the links arise further, simply adding humidifiers to heating, ventilation and cooling systems can reduce disease transmission.

“Taking a new approach to disinfecting surfaces is one of the great practical consequences of this work, including the fundamental chemistry of water in the environment,” Zare said. “It just goes to show that we think we know a lot about WaterOne of the most commonly found substances, but then we become humble.”

Zare is also a member of Stanford Bio-X, Cardiovascular Institute, Stanford Cancer Institute, Stanford Chem-H, Stanford Woods Institute for the Environment and Wu Tsai Neurosciences Institute.

Chemists discover microscopic droplets of water that spontaneously produce hydrogen peroxide

more information:
Bolei Chen et al, Hydroxyl radical recombination in sprayed microdroplets due to electroporation of water-solid contact leads to hydrogen peroxide production, Proceedings of the National Academy of Science (2022). DOI: 10.1073/pns.2209056119

Citation: Research shows how benign water can turn into hard hydrogen peroxide (2022, Aug 2), Aug 2 2022 Obtained from harsh. .html

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