Hydroxyl radical (·OH) plays a crucial role in atmospheric chemistry, regulating the oxidative potential and aerosol composition. This study reveals an unprecedented source of ·OH in the atmosphere: mineral dust-bearing microdroplet aerosols. We demonstrate that Kaolin clay particles in microdroplet aerosols trigger rapid ·OH production upon solar irradiation, with rates reaching an order of at least 10 M s. This production rate is several orders of magnitude higher than that of the bulk phase (2.4 × 10 M s) and previously known pathways. On this basis, the surface-based interfacial ·OH production rate is estimated to be 8.9 × 10 mol m s at the air-water-solid interface of 1 μm sized aerosol particles. The enhanced ·OH formation is attributed to the unique features of air-water-solid interfaces, where the lifespan of photoinduced holes was significantly increased due to the presence of strong electric fields at the air-water interface. We further investigated the impacts of various environmental factors and aerosol properties on ·OH production, including light intensity, relative humidity, particle size, and pH. Our findings provide new insights into atmospheric photochemical processes mediated by mineral dust-bearing microdroplet aerosols, which are important contributors to ·OH source in the atmosphere. This work advances our understanding of atmospheric interfacial chemistry and its profound and lasting implications for air quality and climate.
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http://dx.doi.org/10.1021/jacs.4c14149 | DOI Listing |
J Am Chem Soc
January 2025
Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention, National Observations and Research Station for Wetland Ecosystems of the Yangtze Estuary, IRDR International Center of Excellence on Risk Interconnectivity and Governance on Weather, Department of Environmental Science & Engineering, Fudan University, Shanghai 200433, Peoples' Republic of China.
Hydroxyl radical (·OH) plays a crucial role in atmospheric chemistry, regulating the oxidative potential and aerosol composition. This study reveals an unprecedented source of ·OH in the atmosphere: mineral dust-bearing microdroplet aerosols. We demonstrate that Kaolin clay particles in microdroplet aerosols trigger rapid ·OH production upon solar irradiation, with rates reaching an order of at least 10 M s.
View Article and Find Full Text PDFAnal Chem
January 2025
School of Chemistry, University of Bristol, Bristol BS8 1TS, United Kingdom.
Aerosol droplets are unique microcompartments containing microscopic amounts of material and exhibiting surprising chemical reactivity. Although a diverse set of tools exists to characterize the chemical composition of individual submicron particles in air, comparatively fewer approaches can chemically analyze individual, airborne picolitre droplets. We describe a novel approach for mass spectrometric analysis of individual aqueous picolitre droplets (∼2-180 pL volume) containing down to ∼1 pg analyte mass per droplet.
View Article and Find Full Text PDFProc Natl Acad Sci U S A
December 2024
Department of Chemistry, Purdue University, West Lafayette, IN 47907.
The curious chemistry observed in microdroplets has captivated chemists in recent years and has led to an investigation into their ability to drive seemingly impossible chemistries. One particularly interesting capability of these microdroplets is their ability to accelerate reactions by several orders of magnitude. While there have been many investigations into which reactions can be accelerated by confinement within microdroplets, no study has directly compared reaction acceleration at the liquid|liquid and gas|liquid interfaces.
View Article and Find Full Text PDFNat Commun
December 2024
Department of Atmospheric and Oceanic Sciences, McGill University, Montréal, QC, Canada.
Accurate surface tension measurements are key to understanding and predicting the behavior of atmospheric aerosols, particularly their formation, growth, and phase transitions. In Earth's atmosphere, aerosols often exist in metastable states, such as being supercooled or supersaturated. Standard tensiometry instruments face challenges in accessing these states due to the large sample volumes they require and rapid phase changes near surfaces.
View Article and Find Full Text PDFEnviron Sci Technol
October 2024
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, United States.
The ozone oxidation, or ozonation, of thiosulfate is an important reaction for wastewater processing, where it is used for remediation of mining effluents, and for studying aerosol chemistry, where its fast reaction rate makes it an excellent model reaction. Although thiosulfate ozonation has been studied since the 1950s, challenges remain in developing a realistic reaction mechanism that can satisfactorily account for all observed products with a sequence of elementary reaction steps. Here, we present novel measurements using trapped microdroplets to study the pH-dependent thiosulfate ozonation kinetics.
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