scholarly journals Aqueous phase oxidation of bisulfite influenced by nitrate photolysis

2020 ◽  
Author(s):  
Lu Chen ◽  
Lingdong Kong ◽  
Songying Tong ◽  
Kejing Yang ◽  
Shengyan Jin ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Cloud Droplets ◽  
Radical Chain ◽  
Sulfate Production ◽  
Halogen Chemistry ◽  
Phase Oxidation ◽  
Aqueous Oxidation ◽  
Insight Into ◽  
Solid Aerosol

Abstract. Nitrate aerosol is ubiquitous in the atmosphere, and it can exit in both solid aerosol particles and fog and cloud droplets. Nitrate in the aqueous and particulate phase can undergo photolysis to produce oxidizing active radicals, which will inevitably affect various atmospheric chemical processes. However, the role of nitrate aerosols in these atmospheric photochemical processes remains unclear. In this study, the effects of nitrate photolysis on the aqueous phase oxidation of bisulfite under different conditions were investigated. Results show that nitrate photolysis can significantly promote the oxidation of bisulfite to sulfate. It is found that pH plays a significant role in the reaction, and ammonium sulfate has significant impacts on regulating the pH of solution and the enhancement of sulfate production. We also found an apparent synergism among halogen chemistry, nitrate and its photochemistry and S(IV) aqueous oxidation, especially the oxidation of halide ions by the nitrate photolysis and by the intermediate peroxymonosulfuric acid (HSO5−) produced by the free radical chain oxidation of S(IV) in acidic solution leads to the coupling of the redox cycle of halogen with the oxidation of bisulfite, which promotes the continuous aqueous oxidation of bisulfite and the formation of sulfate. In addition, it is also found that O2 is of great significance on nitrate photolysis for the conversion of HSO3−, and H2O2 generation during the nitrate photolysis is verified. These results provide a new insight into the heterogeneous aqueous phase oxidation pathways and mechanisms of SO2 in cloud and fog droplets and haze particles.

scholarly journals Laboratory studies of the aqueous-phase oxidation of polyols: submicron particles vs. bulk aqueous solution

2014 ◽  
Vol 14 (9) ◽  
pp. 13649-13680 ◽  
Author(s):  
K. E. Daumit ◽  
A. J. Carrasquillo ◽  
J. F. Hunter ◽  
J. H. Kroll
Keyword(s):  
Aqueous Phase ◽  
Liquid Water ◽  
Water Soluble ◽  
Bulk Phase ◽  
Submicron Particles ◽  
Laboratory Studies ◽  
Cloud Droplets ◽  
Fenton Chemistry ◽  
Phase Oxidation ◽  
Aqueous Oxidation

Abstract. Oxidation in the atmospheric aqueous phase (cloud droplets and deliquesced particles) has received recent attention as a potential pathway for the formation of highly oxidized organic aerosol. Most laboratory studies of aqueous-phase oxidation, however, are carried out in bulk solutions rather than aqueous droplets. Here we describe experiments in which aqueous oxidation of polyols (water-soluble species with chemical formula CnH2n+2On) is carried out within submicron particles in an environmental chamber, allowing for significant gas-particle partitioning of reactants, intermediates, and products. Dark Fenton chemistry is used as a source of hydroxyl radicals, and oxidation is monitored using a high-resolution aerosol mass spectrometer (AMS). Aqueous oxidation is rapid, and results in the formation of particulate oxalate; this is accompanied by substantial loss of carbon to the gas phase, indicating the formation of volatile products. Results are compared to those from analogous oxidation reactions carried out in bulk solution. The bulk-phase chemistry is similar to that in the particles, but with substantially less carbon loss. This is likely due to differences in partitioning of early-generation products, which evaporate out of the aqueous phase under chamber conditions (in which liquid water content is low), but remain in solution for further aqueous processing in the bulk phase. This work suggests that the product distributions from oxidation in aqueous aerosol may be substantially different from those in bulk oxidation experiments. This highlights the need for aqueous oxidation studies to be carried out under atmospherically relevant partitioning conditions, with liquid water contents mimicking those of cloud droplets or aqueous aerosol.

scholarly journals Laboratory studies of the aqueous-phase oxidation of polyols: submicron particles vs. bulk aqueous solution

2014 ◽  
Vol 14 (19) ◽  
pp. 10773-10784 ◽  
Author(s):  
K. E. Daumit ◽  
A. J. Carrasquillo ◽  
J. F. Hunter ◽  
J. H. Kroll
Keyword(s):  
Aqueous Phase ◽  
Liquid Water ◽  
Water Soluble ◽  
Bulk Phase ◽  
Submicron Particles ◽  
Laboratory Studies ◽  
Cloud Droplets ◽  
Fenton Chemistry ◽  
Phase Oxidation ◽  
Aqueous Oxidation

Abstract. Oxidation in the atmospheric aqueous phase (cloud droplets and deliquesced particles) has received recent attention as a potential pathway for the formation of highly oxidized organic aerosol. Most laboratory studies of aqueous-phase oxidation, however, are carried out in bulk solutions rather than aqueous droplets. Here we describe experiments in which aqueous oxidation of polyols (water-soluble species with chemical formula CnH2n+2On) is carried out within submicron particles in an environmental chamber, allowing for significant gas–particle partitioning of reactants, intermediates, and products. Dark Fenton chemistry is used as a source of hydroxyl radicals, and oxidation is monitored using a high-resolution aerosol mass spectrometer (AMS). Aqueous oxidation is rapid, and results in the formation of particulate oxalate; this is accompanied by substantial loss of carbon to the gas phase, indicating the formation of volatile products. Results are compared to those from analogous oxidation reactions carried out in bulk solution. The bulk-phase chemistry is similar to that in the particles, but with substantially less carbon loss. This is likely due to differences in partitioning of early-generation products, which evaporate out of the aqueous phase under chamber conditions (in which liquid water content is low), but remain in solution for further aqueous processing in the bulk phase. This work suggests that the product distributions from oxidation in aqueous aerosol may be substantially different from those in bulk oxidation experiments. This highlights the need for aqueous oxidation studies to be carried out under atmospherically relevant partitioning conditions, with liquid water contents mimicking those of cloud droplets or aqueous aerosol.

scholarly journals Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

2016 ◽  
Vol 16 (3) ◽  
pp. 1693-1712 ◽  
Author(s):  
C. R. Hoyle ◽  
C. Fuchs ◽  
E. Järvinen ◽  
H. Saathoff ◽  
A. Dias ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Rate Constants ◽  
Nuclear Research ◽  
Aqueous System ◽  
Cloud Droplets ◽  
European Organization ◽  
Reaction Rate Constants ◽  
Oxidation Rates ◽  
Phase Oxidation ◽  
Bulk Solutions

Abstract. The growth of aerosol due to the aqueous phase oxidation of sulfur dioxide by ozone was measured in laboratory-generated clouds created in the Cosmics Leaving OUtdoor Droplets (CLOUD) chamber at the European Organization for Nuclear Research (CERN). Experiments were performed at 10 and −10 °C, on acidic (sulfuric acid) and on partially to fully neutralised (ammonium sulfate) seed aerosol. Clouds were generated by performing an adiabatic expansion – pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted using oxidation rate constants previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and −10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system can be well represented by using accepted rate constants, based on bulk measurements. To the best of our knowledge, these are the first laboratory-based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rate constants to temperatures below 0 °C is correct.

scholarly journals Aqueous phase oxidation of sulphur dioxide by ozone in cloud droplets

2015 ◽  
Vol 15 (23) ◽  
pp. 33843-33896 ◽  
Author(s):  
C. R. Hoyle ◽  
C. Fuchs ◽  
E. Järvinen ◽  
H. Saathoff ◽  
A. Dias ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Pressure ◽  
Reaction Rates ◽  
Aqueous System ◽  
Excess Pressure ◽  
Cloud Droplets ◽  
Oxidation Rates ◽  
Phase Oxidation ◽  
Bulk Solutions ◽  
Seed Aerosol

Abstract. The growth of aerosol due to the aqueous phase oxidation of SO2 by O3 was measured in laboratory generated clouds created in the CLOUD chamber at CERN. Experiments were performed at 10 and −10 °C, on acidic (sulphuric acid) and on partially to fully neutralised (ammonium sulphate) seed aerosol. Clouds were generated by performing an adiabatic expansion – pressurising the chamber to 220 hPa above atmospheric pressure, and then rapidly releasing the excess pressure, resulting in a cooling, condensation of water on the aerosol and a cloud lifetime of approximately 6 min. A model was developed to compare the observed aerosol growth with that predicted by oxidation rates previously measured in bulk solutions. The model captured the measured aerosol growth very well for experiments performed at 10 and −10 °C, indicating that, in contrast to some previous studies, the oxidation rates of SO2 in a dispersed aqueous system are well represented by accepted rates, based on bulk measurements. To the best of our knowledge, these are the first laboratory based measurements of aqueous phase oxidation in a dispersed, super-cooled population of droplets. The measurements are therefore important in confirming that the extrapolation of currently accepted reaction rates to temperatures below 0 °C is correct.

scholarly journals Sulfur isotope fractionation during heterogeneous oxidation of SO<sub>2</sub> on mineral dust

2012 ◽  
Vol 12 (11) ◽  
pp. 4867-4884 ◽  
Author(s):  
E. Harris ◽  
B. Sinha ◽  
S. Foley ◽  
J. N. Crowley ◽  
S. Borrmann ◽  
...  
Keyword(s):  
Relative Humidity ◽  
Clay Minerals ◽  
Aqueous Phase ◽  
Isotope Fractionation ◽  
Mineral Dust ◽  
Surface Oxidation ◽  
Sulfur Cycle ◽  
Fractionation Factor ◽  
Sulfate Production ◽  
Aqueous Oxidation

Abstract. Mineral dust is a major fraction of global atmospheric aerosol, and the oxidation of SO2 on mineral dust has implications for cloud formation, climate and the sulfur cycle. Stable sulfur isotopes can be used to understand the different oxidation processes occurring on mineral dust. This study presents measurements of the 34S/32S fractionation factor α34 for oxidation of SO2 on mineral dust surfaces and in the aqueous phase in mineral dust leachate. Sahara dust, which accounts for ~60% of global dust emissions and loading, was used for the experiments. The fractionation factor for aqueous oxidation in dust leachate is αleachate = 0.9917±0.0046, which is in agreement with previous measurements of aqueous SO2 oxidation by iron solutions. This fractionation factor is representative of a radical chain reaction oxidation pathway initiated by transition metal ions. Oxidation on the dust surface at subsaturated relative humidity (RH) had an overall fractionation factor of αhet = 1.0096±0.0036 and was found to be almost an order of magnitude faster when the dust was simultaneously exposed to ozone, light and RH of ~40%. However, the presence of ozone, light and humidity did not influence isotope fractionation during oxidation on dust surfaces at subsaturated relative humidity. All the investigated reactions showed mass-dependent fractionation of 33S relative to 34S. A positive matrix factorization model was used to investigate surface oxidation on the different components of dust. Ilmenite, rutile and iron oxide were found to be the most reactive components, accounting for 85% of sulfate production with a fractionation factor of α34 = 1.012±0.010. This overlaps within the analytical uncertainty with the fractionation of other major atmospheric oxidation pathways such as the oxidation of SO2 by H2O2 and O3 in the aqueous phase and OH in the gas phase. Clay minerals accounted for roughly 12% of the sulfate production, and oxidation on clay minerals resulted in a very distinct fractionation factor of α34 = 1.085±0.013. The fractionation factors measured in this study will be particularly useful in combination with field and modelling studies to understand the role of surface oxidation on clay minerals and aqueous oxidation by mineral dust and its leachate in global and regional sulfur cycles.

scholarly journals Promoting Role of Bismuth on Hydrotalcite-Supported Platinum Catalysts in Aqueous Phase Oxidation of Glycerol to Dihydroxyacetone

Catalysts ◽  
2018 ◽  
Vol 8 (1) ◽  
pp. 20 ◽  
Author(s):  
Wenjie Xue ◽  
Zenglong Wang ◽  
Yu Liang ◽  
Hong Xu ◽  
Lei Liu ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Platinum Catalysts ◽  
Supported Platinum ◽  
Supported Platinum Catalysts ◽  
Phase Oxidation

scholarly journals libcloudph++ 1.1: aqueous phase chemistry extension of the Lagrangian cloud microphysics scheme

2018 ◽  
Author(s):  
Anna Jaruga ◽  
Hanna Pawlowska
Keyword(s):  
Programming Languages ◽  
Aqueous Phase ◽  
Numerical Models ◽  
Cloud Condensation Nuclei ◽  
Cloud Microphysics ◽  
Chemical Processes ◽  
Cloud Droplets ◽  
Microphysics Scheme ◽  
Phase Oxidation ◽  
Phase Chemistry

Abstract. This paper introduces a new scheme available in the library of algorithms for representing cloud microphysics in numerical models named libcloudph++. The scheme extends the Lagrangian microphysics scheme available in libcloudph++ to the aqueous phase chemical processes occurring within cloud droplets. The representation of chemical processes focuses on the aqueous phase oxidation of the dissolved SO2 by O3 and H2O2. The Lagrangian Microphysics and Chemistry (LMC) scheme allows tracking the changes in the cloud condensation nuclei (CCN) distribution caused by both collisions between cloud droplets and aqueous phase oxidation. The scheme is implemented in C++ and equipped with bindings to Python which allow reusing the created scheme from models implemented in other programming languages. The scheme can be used on either CPU or GPU, and is distributed under the GPL3 license. Here, the LMC scheme is tested in a simple 0-dimensional adiabatic parcel model and then used in a 2-dimensional prescribed flow framework. The results are discussed with the focus on changes to the CCN sizes and compared with other model simulations discussed in the literature.

scholarly journals libcloudph++ 2.0: aqueous-phase chemistry extension of the particle-based cloud microphysics scheme

2018 ◽  
Vol 11 (9) ◽  
pp. 3623-3645 ◽  
Author(s):  
Anna Jaruga ◽  
Hanna Pawlowska
Keyword(s):  
Aqueous Phase ◽  
Numerical Models ◽  
Cloud Condensation Nuclei ◽  
Cloud Microphysics ◽  
Chemical Processes ◽  
Cloud Droplets ◽  
Microphysics Scheme ◽  
Phase Oxidation ◽  
Phase Chemistry ◽  
Phase Chemical

Abstract. This paper introduces a new scheme available in the library of algorithms for representing cloud microphysics in numerical models named libcloudph++. The scheme extends the particle-based microphysics scheme with a Monte Carlo coalescence available in libcloudph++ to the aqueous-phase chemical processes occurring within cloud droplets. The representation of chemical processes focuses on the aqueous-phase oxidation of the dissolved SO2 by O3 and H2O2. The particle-based microphysics and chemistry scheme allows for tracking of the changes in the cloud condensation nuclei (CCN) distribution caused by both collisions between cloud droplets and aqueous-phase oxidation. The scheme is implemented in C++ and equipped with bindings to Python. The scheme can be used on either a CPU or a GPU, and is distributed under the GPLv3 license. Here, the particle-based microphysics and chemistry scheme is tested in a simple 0-dimensional adiabatic parcel model and then used in a 2-dimensional prescribed flow framework. The results are discussed with a focus on changes to the CCN sizes and comparison with other model simulations discussed in the literature.

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