LibGuides: Advanced Oxidation Processes (AOP): Detergent of the Atmosphere

Hydroxyls Radicals - Nature's Detergent - the Basis of Advanced Oxidation Processes

Nobel Laureate Dr. Paul Crutzen, coined the phrase "detergent of the atmosphere" to describe the air-cleaning function of the Hydroxyl Radical (OH).

What happens to the millions of tonnes of gases that nature and humankind lob into the atmosphere every year? Fortunately, their rate of accumulation is countered by the atmosphere’s ability to cleanse itself of most of these so-called trace gases, especially those in chemically reduced form. Through chemical changes initiated by sunlight (photo-oxidation or photolysis), such trace gases are transformed into products that are more easily removed by rain and snow, or that deposit directly onto the earth’s surface.

Reidel, K. & Lassey, K. (2008). Atmospheric chemistry: Detergent of the atmosphere. Water & Atmosphere 16(1), p.22. https://odorox.it/wp-content/uploads/2020/05/All.pdf

How does it Work?

Thousands of megatons of natural and anthropogenic gases are released into the Earth's atmosphere annually. Photochemical-based chemical reactions, initiated by Hydroxyl (OH) radicals, oxidize the majority of these gases into products that are more easily removed through the precipitation cycle and dry deposition at the Earth's surface.

Mother Natures Key Oxidant

The hydroxyl radical (OH) is the most important oxidant in the troposphere and lower stratosphere. It initiates removal from the atmosphere of toxic gases such as carbon monoxide (CO), radiatively active gases such as methane (CH₄), tropospheric ozone precursors such as volatile organic compounds (VOCs), and NOx (NO + NO₂), and stratospheric ozone-depleting compounds such as hydrochlorofluorocarbons (HCFCs). Therefore, it plays a key role in the atmospheric oxidation capacity, air quality, and climate.

Li, M., Karu, E., Brenninkmeijer, C., Fischer, H., Lelieveld, J., & Williams, J. (2018). Tropospheric OH and stratospheric OH and Cl concentrations determined from CH4, CH3Cl, and SF6 measurements. Npj Climate and Atmospheric Science, 1(1). https://search.ebscohost.com/login.aspx?direct=true&db=edssjs&AN=edssjs.90224608&site=eds-live&scope=site&custid=s5672116&authtype=sso

Recommended Reading

Atmospheric Chemistry and Physics by John H. Seinfeld; Spyros N. Pandis
Call Number: Kelowna Circulation Collection QC 879.6 .S45 2006
ISBN: 0471720178
Publication Date: 2006-08-11
Thoroughly restructured and updated with new findings and new features The Second Edition of this internationally acclaimed text presents the latest developments in atmospheric science. It continues to be the premier text for both a rigorous and a complete treatment of the chemistry of the atmosphere, covering such pivotal topics as: * Chemistry of the stratosphere and troposphere * Formation, growth, dynamics, and properties of aerosols * Meteorology of air pollution * Transport, diffusion, and removal of species in the atmosphere * Formation and chemistry of clouds * Interaction of atmospheric chemistry and climate * Radiative and climatic effects of gases and particles * Formulation of mathematical chemical/transport models of the atmosphere All chapters develop results based on fundamental principles, enabling the reader to build a solid understanding of the science underlying atmospheric processes. Among the new material are three new chapters: Atmospheric Radiation and Photochemistry, General Circulation of the Atmosphere, and Global Cycles. In addition, the chapters Stratospheric Chemistry, Tropospheric Chemistry, and Organic Atmospheric Aerosols have been rewritten to reflect the latest findings. Readers familiar with the First Edition will discover a text with new structures and new features that greatly aid learning. Many examples are set off in the text to help readers work through the application of concepts. Advanced material has been moved to appendices. Finally, many new problems, coded by degree of difficulty, have been added. A solutions manual is available. Thoroughly updated and restructured, the Second Edition of Atmospheric Chemistry and Physics is an ideal textbook for upper-level undergraduate and graduate students, as well as a reference for researchers in environmental engineering, meteorology, chemistry, and the atmospheric sciences. Click here to Download the Solutions Manual for Academic Adopters: http://www.wiley.com/WileyCDA/Section/id-292291.html

J. Lelieveld, F. J. Dentener, W. Peters, & M. C. Krol. (2004). On the role of hydroxyl radicals in the self-cleansing capacity of the troposphere. Atmospheric Chemistry and Physics, 4(9/10), 2337–2344.
Thousands of megatons natural and anthropogenic gases are released and subsequently removed from the troposphere each year. Photochemical reactions, initiated by hydroxyl (OH) radicals, oxidise most gases to products which are more easily removed by precipitation and dry deposition at the earth's surface. Since human-induced pollution emissions strongly affect OH formation and loss, large global changes in OH concentrations are possible. Global models and observations of trace gas distributions from global networks have been used to study geographical and temporal changes in tropospheric OH. Here we present a synopsis of recent studies, indicating that global mean OH has changed remarkably little in the past century, even though regional changes have probably been substantial. Globally, depletion of OH by reactive carbon gases has been compensated by increased OH formation by nitrogen oxides, an act of 'inadvertent geo-engineering'. However, OH analyses for the past 1-2 decades, partly based on methyl chloroform measurements, are inconclusive. Some work, assuming that methyl chloroform emissions have largely ceased, suggests a very strong downward global OH trend in the 1990s, inconsistent with modelling studies. The discrepancy could be much reduced by assuming continued small emissions of methyl chloroform. We recommend the continuation of high precision monitoring of this compound and improved analyses based on detailed meteorological-chemical models.

Chemistry of the Climate System by Detlev Möller; Detlev Möller
Call Number: E-Book
ISBN: 9783110330809
Publication Date: 2014-08-19
Climate change is a major challenge facing the modern world. The chemistry of air and it's influence on the climate system forms the main focus of this monograph. The book presents a problem-based approach to presenting global atmospheric processes, evaluating the effects of changing air composition as well as possibilities for interference within these processes and indicates ways for solving the problem of climate change through chemistry. The new edition includes innovations and latest research results.

Free Radical Generator and Methods of Use. (2020). (Patent Application)
Devices suitable for use in an advanced oxidation method for organic and inorganic pollutants deploying OH* radicals and ozone is disclosed. Optionally, a first discharge device, providing OH* radicals and second discharge device providing ozone, are combined to provide desirable chemical and biocidal characteristics. Further, efficient mixing systems for transferring the radicals to the target fluid are disclosed.