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 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 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 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.

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.

Kinetic study of key species and reactions of atmospheric pressure pulsed corona discharge in humid air

2021 ◽  
Author(s):  
Yongkang Peng ◽  
Xiaoyue Chen ◽  
Yeqiang Deng ◽  
Lan Lei ◽  
Zhan Haoyu ◽  
...  
Keyword(s):  
Chemical Reactions ◽  
Chemical Reaction ◽  
Atmospheric Pressure ◽  
Discharge Plasma ◽  
Reaction Rates ◽  
Global Model ◽  
Discharge Process ◽  
Humid Air ◽  
Pressure Discharge ◽  
Atmospheric Pressure Discharge

Abstract The traditional corona discharge fluid model considers only electrons, positive and negative ions, and the discharge parameters are determined using the simplified weighting method involving the partial pressure ratio. Atmospheric pressure discharge plasma in humid air involves three main neutral gas molecule types: N2, O2, and H2O(g). However, in these conditions, the discharge process involves many types of particles and chemical reactions, and the charge and substance transfer processes are complex. At present, the databases of plasma chemical reaction equations are still expanding based on scholarly research. In this study, we examined the key particles and chemical reactions that substantially influence plasma characteristics. In summarizing the chemical reaction model for the discharge process of N2–O2–H2O(g) mixed gases, 65 particle types and 673 chemical reactions were investigated. On this basis, a global model of atmospheric pressure humid air discharge plasma was developed, with a focus on the variation of charged particles densities and chemical reaction rates with time under the excitation of a 0–200 Td pulsed electric field. Particles with a density greater than 1% of the electron density were classified as key particles. For such particles, the top ranking generation or consumption reactions (i.e., where the sum of their rates was greater than 95% of the total rate of the generation or consumption reactions) were classified as key chemical reactions On the basis of the key particles and reactions identified, a simplified global model was derived. A comparison of the global model with the simplified global model in terms of the model parameters, particle densities, reaction rates (with time), and calculation efficiencies demonstrated that both models can adequately identify the key particles and chemical reactions reflecting the chemical process of atmospheric pressure discharge plasma in humid air. Thus, by analyzing the key particles and chemical reaction pathways, the charge and substance transfer mechanism of atmospheric pressure pulse discharge plasma in humid air was revealed, and the mechanism underlying water vapor molecules’ influence on atmospheric pressure air discharge was elucidated.

scholarly journals The formation of nitro-aromatic compounds under high NO<sub><i>x</i></sub> and anthropogenic VOC conditions in urban Beijing, China

2019 ◽  
Vol 19 (11) ◽  
pp. 7649-7665 ◽  
Author(s):  
Yujue Wang ◽  
Min Hu ◽  
Yuchen Wang ◽  
Jing Zheng ◽  
Dongjie Shang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Aromatic Compounds ◽  
Total Concentration ◽  
Fine Particulate Matter ◽  
Oxidation Products ◽  
Urban Atmosphere ◽  
Formation Pathway ◽  
Relative Contribution ◽  
Phase Oxidation ◽  
Nitro Aromatic

Abstract. Nitro-aromatic compounds (NACs), as important contributors to the light absorption by brown carbon, have been widely observed in various ambient atmospheres; however, their formation in the urban atmosphere was little studied. In this work, we report an intensive field study of NACs in summer 2016 at an urban Beijing site, characterized by both high-NOx and anthropogenic VOC dominated conditions. We investigated the factors that influence NAC formation (e.g., NO2, VOC precursors, RH and photolysis) through quantification of eight NACs, along with major components in fine particulate matter, selected volatile organic compounds, and gases. The average total concentration of the quantified NACs was 6.63 ng m−3, higher than those reported in other summertime studies (0.14–6.44 ng m−3). 4-Nitrophenol (4NP, 32.4 %) and 4-nitrocatechol (4NC, 28.5 %) were the top two most abundant NACs, followed by methyl-nitrocatechol (MNC), methyl-nitrophenol (MNP), and dimethyl-nitrophenol (DMNP). The oxidation of toluene and benzene in the presence of NOx was found to be a more dominant source of NACs than primary biomass burning emissions. The NO2 concentration level was found to be an important factor influencing the secondary formation of NACs. A transition from low- to high-NOx regimes coincided with a shift from organic- to inorganic-dominated oxidation products. The transition thresholds were NO2 ∼ 20 ppb for daytime and NO2∼25 ppb for nighttime conditions. Under low-NOx conditions, NACs increased with NO2, while the NO3- concentrations and (NO3-)/NACs ratios were lower, implying organic-dominated products. Under high-NOx conditions, NAC concentrations did not further increase with NO2, while the NO3- concentrations and (NO3-)/NACs ratios showed increasing trends, signaling a shift from organic- to inorganic-dominated products. Nighttime enhancements were observed for 3M4NC and 4M5NC, while daytime enhancements were noted for 4NP, 2M4NP, and DMNP, indicating different formation pathways for these two groups of NACs. Our analysis suggested that the aqueous-phase oxidation was likely the major formation pathway of 4M5NC and 3M5NC, while photo-oxidation of toluene and benzene in the presence of NO2 could be more important for the formation of nitrophenol and its derivatives. Using the (3M4NC+4M5NC) ∕ 4NP ratios as an indicator of the relative contribution of aqueous-phase and gas-phase oxidation pathways to NAC formation, we observed that the relative contribution of aqueous-phase pathways increased at elevated ambient RH and remained constant at RH > 30 %. We also found that the concentrations of VOC precursors (e.g., toluene and benzene) and aerosol surface area acted as important factors in promoting NAC formation, and photolysis as an important loss pathway for nitrophenols.

A gadolinium MOF acting as a multi-responsive and highly selective luminescent sensor for detecting o-, m-, and p-nitrophenol and Fe3+ ions in the aqueous phase

RSC Advances ◽  
2016 ◽  
Vol 6 (66) ◽  
pp. 61725-61731 ◽  
Author(s):  
Qing-Hua Tan ◽  
Yan-Qin Wang ◽  
Xiao-Yu Guo ◽  
Hou-Ting Liu ◽  
Zhi-Liang Liu
Keyword(s):  
Aqueous Phase ◽  
Aqueous System ◽  
Luminescent Sensor ◽  
System P

A new Gd-MOF constructed with a π-conjugated ligand shows highly luminescent selective sensing of o-, m-, and p-nitrophenol and Fe3+ ions in an aqueous system.

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