It’s a discovery that could fundamentally alter how scientists think about how the air rids itself of pollutants and greenhouse gases, which OH can interact with and eliminate.
Many different types of pollutants are released into the atmosphere as a result of human activity, and without a molecule called hydroxide (OH), many of these pollutants would continue to assemble in the atmosphere.
An extensive electric field that exists at the surface between airborne water droplets and the surrounding air can create OH by a previously unknown mechanism, according to new research published in the Proceedings of the National Academy of Sciences.
The research team, which includes Sergey Nizkorodov, a professor of chemistry at the University of California, Irvine, conducted the research.
It’s a discovery that could fundamentally alter how scientists think about how the air rids itself of pollutants and greenhouse gases, which OH can interact with and eliminate. Nizkorodov stated that without OH, hydrocarbons would continue to accumulate in the atmosphere.
“In the story of atmospheric chemistry, OH is a significant character. It starts the chemical processes that degrade airborne pollutants and aid in clearing the atmosphere of harmful substances like sulphur dioxide and nitric oxide, which are poisonous gases, “said Christian George, the study’s lead author and an atmospheric chemist at the University of Lyon in France.
Therefore, the key to comprehending and reducing air pollution is having a thorough understanding of its sources and sinks.
Until recently, scientists believed that the main cause of OH formation was sunlight. “According to conventional wisdom, OH must be produced through photochemistry or redox chemistry. Metals or sunlight must be present to serve as catalysts, “said Nizkorodov. “The main message of this essay is that none of this is necessary. By special circumstances on the surface of the droplets, OH can spontaneously form in the pure water itself.”
The group expanded on work by Stanford University researchers led by Richard Zare that showed spontaneous hydrogen peroxide formation on the surfaces of water droplets. The latest research aids in the interpretation of the Zare group’s unexpected findings.
The team determined the concentrations of OH in various vials, some of which contained an air-water surface and others of which contained only water and no air, and they monitored OH production in the dark by adding a “probe” molecule to the vials that fluoresced in response to OH.
They discovered that OH production rates in the dark match and sometimes even surpass rates from drivers like exposure to sunlight. Nizkorodov predicted that “enough hydroxide molecules will be created to compete with other known OH sources.”
“OH is still produced at night, even though there is no photochemistry, and it is produced more quickly than it would be otherwise.”
The results, according to Nizkorodov, change our understanding of the origins of OH, which will affect how other researchers construct computer models to try to predict the causes of air pollution. According to Nizkorodov, “it could change air pollution models quite significantly.”
The main assumption in the models is that hydroxide molecule comes from the air and is not directly produced in the droplet.
OH is an important oxidant inside water droplets. Nizkorodov believes that the next step is to conduct meticulously planned experiments in the real atmosphere in various locations around the world to ascertain whether this new hydroxide molecule production mechanism plays a role.
But first, the team anticipates that the findings will create a stir in the field of atmospheric research. Many people who read this won’t at first believe it, so they’ll try to duplicate it or conduct experiments to disprove it, predicted Nizkorodov. “This will undoubtedly be the subject of numerous laboratory experiments.”
He continued by saying that UCI is an ideal location for such research to continue because other labs there, like the one run by chemistry professor Ann Marie Carlton, concentrate their efforts on the function that water droplets play in the atmosphere.
Researchers from the Guangdong University of Technology in China, the Weizmann Institute in Israel, and the University Claude Bernard in France participated in this project, which was funded by the European Research Council.