Accelerated Sulfur Oxidation by Ozone on Surfaces of Single Optically Trapped Aerosol Particles

Hsu, Shao-Hong; Lin, Feng-Yu; Huang, Genin Gary; Chang, Yuan‐Pin

doi:10.1021/acs.jpcc.2c06831

Cited by 4 publications

(3 citation statements)

References 87 publications

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“…The following parameters combinations were studied: the SVM type (ε-SVR or ν-SVR); γ was studied between ≈2 −20 and 2 8 using 28 steps in linear or logarithmic scale; and C between ≈ 2 −10 and 2 20 using 30 steps in linear or logarithmic scale (SVM and SVM log ). These values are an extension of the proposed values of Hsu et al (2016) [ 63 ]. In addition to using the database in their real-scale, they were also normalized in the interval [−1,1] (first just normalizing the input variables (SVM n and SVM n log ) and then normalizing the input and the output variables (SVM n2 and SVM n2 log ).…”

Section: Methodssupporting

confidence: 55%

Machine Learning to Predict the Adsorption Capacity of Microplastics

et al. 2023

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Nowadays, there is an extensive production and use of plastic materials for different industrial activities. These plastics, either from their primary production sources or through their own degradation processes, can contaminate ecosystems with micro- and nanoplastics. Once in the aquatic environment, these microplastics can be the basis for the adsorption of chemical pollutants, favoring that these chemical pollutants disperse more quickly in the environment and can affect living beings. Due to the lack of information on adsorption, three machine learning models (random forest, support vector machine, and artificial neural network) were developed to predict different microplastic/water partition coefficients (log Kd) using two different approximations (based on the number of input variables). The best-selected machine learning models present, in general, correlation coefficients above 0.92 in the query phase, which indicates that these types of models could be used for the rapid estimation of the absorption of organic contaminants on microplastics.

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Section: Methodssupporting

confidence: 55%

Machine Learning to Predict the Adsorption Capacity of Microplastics

et al. 2023

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“…In addition to the greater mixing of BPA in the less viscous aqueous aerosol matrix containing NaCl, the effect of salting out could accelerate reactions between OH and BPA as reactions with OH are expected to occur within the near-surface layer of the particle (predicted reacto-diffusive length of OH is ≤1 nm) . This effect by salting out has been observed in other aerosol systems, e.g., in the accelerated oxidation of sulfur by O 3 in the presence of optically trapped sodium thiosulfate/sucrose/aqueous droplets . Furthermore, the larger surface area-to-volume ratio (SA/V) of BPA in the mixed BPA/NaCl aerosol compared to pure BPA could lead to greater reactive loss of BPA as observed in the heterogeneous oxidation of squalane by reaction with OH on squalene-coated ammonium sulfate particles compared to pure squalane particles …”

Section: Resultsmentioning

confidence: 97%

“… 19 This effect by salting out has been observed in other aerosol systems, e.g., in the accelerated oxidation of sulfur by O 3 in the presence of optically trapped sodium thiosulfate/sucrose/aqueous droplets. 57 Furthermore, the larger surface area-to-volume ratio (SA/V) of BPA in the mixed BPA/NaCl aerosol compared to pure BPA could lead to greater reactive loss of BPA as observed in the heterogeneous oxidation of squalane by reaction with OH on squalene-coated ammonium sulfate particles compared to pure squalane particles. 46 …”

Section: Resultsmentioning

confidence: 99%

Heterogeneous and Photosensitized Oxidative Degradation Kinetics of the Plastic Additive Bisphenol-A in Sea Spray Aerosol Mimics

Kruse

Slade

2023

J. Phys. Chem. A

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Plastics have become ubiquitous in the world's oceans, and recent work indicates that they can transfer from the ocean to the atmosphere in sea spray aerosol (SSA). Hazardous chemical residues in plastics, including bisphenol-A (BPA), represent a sizable fraction of consumer plastics and have been measured consistently in air over both terrestrial and marine environments. However, the chemical lifetimes of BPA and mechanisms by which plastic residues degrade with respect to photochemical and heterogeneous oxidation processes in aerosols are unknown. Here, we present the photosensitized and OHinitiated heterogeneous oxidation kinetics of BPA in the aerosol phase consisting of pure-component BPA and internal mixtures of BPA, NaCl, and dissolved photosensitizing organic matter. We found that photosensitizers enhanced BPA degradation in binary-component BPA + photosensitizer aerosol mixtures when irradiated in the absence of OH. OH-initiated degradation of BPA was enhanced in the presence of NaCl with and without photosensitizing species. We attribute this enhanced degradation to greater mobility and thus reaction probability between BPA, OH, and reactive chlorine species (RCS) formed through reaction between OH and dissolved Cl − in the more liquid-like aerosol matrix in the presence of NaCl. Addition of the photosensitizers in the ternary-component BPA + NaCl + photosensitizer aerosol led to no enhancement in the degradation of BPA following light exposure compared to the binary-component BPA + NaCl aerosol. This was attributed to quenching of triplet state formation by dissolved Cl − in the less viscous aqueous aerosol mixtures containing NaCl. Based upon measured second-order heterogeneous reaction rates, the estimated lifetime of BPA with respect to heterogeneous oxidation by OH is one week in the presence of NaCl compared to 20 days in the absence of NaCl. This work highlights the important heterogeneous and photosensitized reactions and the role of phase state, which affect the lifetimes of hazardous plastic pollutants in SSA with implications for understanding pollutant transport and exposure risks in coastal marine environments.

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A Detailed Reaction Mechanism for Thiosulfate Oxidation by Ozone in Aqueous Environments

Deal,

Prophet,

Bernal

et al. 2024

Environ. Sci. Technol.

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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 pHdependent thiosulfate ozonation kinetics. We detect known products and intermediates, including SO 3 2− , SO 4 2− , S 3 O 6 2− , and S 4 O 6 2−, establishing agreement with the literature. However, we identify S 2 O 4 2− as a new reaction intermediate and find that the currently accepted mechanism does not directly explain observed pH effects. Thus, we develop a new mechanism, which incorporates S 2 O 4 2− as an intermediate and uses elementary steps to explain the pH dependence of thiosulfate ozonation. The proposed mechanism is tested using a kinetic model benchmarked to the experiments presented here, then compared to literature data. We demonstrate good agreement between the proposed thiosulfate ozonation mechanism and experiments, suggesting that the insights in this paper can be leveraged in wastewater treatment and in understanding potential climate impacts.

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Accelerated Sulfur Oxidation by Ozone on Surfaces of Single Optically Trapped Aerosol Particles

Cited by 4 publications

References 87 publications

Machine Learning to Predict the Adsorption Capacity of Microplastics

Machine Learning to Predict the Adsorption Capacity of Microplastics

Heterogeneous and Photosensitized Oxidative Degradation Kinetics of the Plastic Additive Bisphenol-A in Sea Spray Aerosol Mimics

A Detailed Reaction Mechanism for Thiosulfate Oxidation by Ozone in Aqueous Environments

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