scholarly journals Quantification of SO2 Oxidation on Interfacial Surfaces of Acidic Micro-Droplets: Implication for Ambient Sulfate Formation

2018 ◽  
Vol 52 (16) ◽  
pp. 9079-9086 ◽  
Author(s):  
Hui-Ming Hung ◽  
Mu-Ni Hsu ◽  
Michael R. Hoffmann
Keyword(s):  
So2 Oxidation ◽  
Sulfate Formation ◽  
Interfacial Surfaces

scholarly journals Modelling Atmospheric Mineral Aerosol Chemistry to Predict Heterogeneous Photooxidation of SO<sub>2</sub>

2017 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang ◽  
Jiyeon Park
Keyword(s):  
Mineral Dust ◽  
Uv Light ◽  
Full Range ◽  
Saharan Dust ◽  
Dust Particles ◽  
Oh Radicals ◽  
Desorption Kinetics ◽  
So2 Oxidation ◽  
Photocatalytic Ability ◽  
Sulfate Formation

Abstract. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO2 oxidation, but prediction of this phenomenon is not fully taken into account by current models. In this study, the Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on sulfate formation in various environments. In the model, SO2 oxidation proceeds in three phases including the gas phase, the inorganic-salted aqueous phase (non-dust phase), and the dust phase. Dust chemistry is described as the adsorption-desorption kinetics (gas-particle partitioning) of SO2 and NOx. The reaction of adsorbed SO2 on dust particles occurs via two major paths: autoxidation of SO2 in open air and photocatalytic mechanisms under UV light. The kinetic mechanism of autoxidation was first leveraged using controlled indoor chamber data in the presence of Arizona Test Dust (ATD) particles without UV light, and then extended to photochemistry. With UV light, SO2 photooxidation was promoted by surface oxidants (OH radicals) that are generated via the photocatalysis of semiconducting metal oxides (electron–hole theory) of ATD particles. This photocatalytic rate constant was derived from the integration of the combinational product of the dust absorbance spectrum and wave-dependent actinic flux for the full range of wavelengths of the light source. The predicted concentrations of sulfate and nitrate using the AMAR model agreed well with outdoor chamber data that were produced under natural sunlight. For seven consecutive hours of photooxidation of SO2 in an outdoor chamber, dust chemistry at the low NOx level was attributed to 70 % of total sulfate (60 ppb SO2, 290 μg m−3 ATD, and NOx less than 5 ppb). At high NOx (> 50 ppb of NOx with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was significantly suppressed by the competition between NO2 and SO2 that both consume the dust-surface oxidants (OH radicals or ozone). The AMAR model, derived in this study with ATD particles, will provide a platform for predicting sulfate formation in the presence of authentic dust particles (e.g. Gobi and Saharan dust).

scholarly journals Modeling atmospheric mineral aerosol chemistry to predict heterogeneous photooxidation of SO<sub>2</sub>

2017 ◽  
Vol 17 (16) ◽  
pp. 10001-10017 ◽  
Author(s):  
Zechen Yu ◽  
Myoseon Jang ◽  
Jiyeon Park
Keyword(s):  
Gas Phase ◽  
Mineral Dust ◽  
Uv Light ◽  
Full Range ◽  
Dust Particles ◽  
Oh Radicals ◽  
Desorption Kinetics ◽  
So2 Oxidation ◽  
Photocatalytic Ability ◽  
Sulfate Formation

Abstract. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO2 oxidation, but prediction of this phenomenon is not fully taken into account by current models. In this study, the Atmospheric Mineral Aerosol Reaction (AMAR) model was developed to capture the influence of air-suspended mineral dust particles on sulfate formation in various environments. In the model, SO2 oxidation proceeds in three phases including the gas phase, the inorganic-salted aqueous phase (non-dust phase), and the dust phase. Dust chemistry is described as the absorption–desorption kinetics of SO2 and NOx (partitioning between the gas phase and the multilayer coated dust). The reaction of absorbed SO2 on dust particles occurs via two major paths: autoxidation of SO2 in open air and photocatalytic mechanisms under UV light. The kinetic mechanism of autoxidation was first leveraged using controlled indoor chamber data in the presence of Arizona Test Dust (ATD) particles without UV light, and then extended to photochemistry. With UV light, SO2 photooxidation was promoted by surface oxidants (OH radicals) that are generated via the photocatalysis of semiconducting metal oxides (electron–hole theory) of ATD particles. This photocatalytic rate constant was derived from the integration of the combinational product of the dust absorbance spectrum and wave-dependent actinic flux for the full range of wavelengths of the light source. The predicted concentrations of sulfate and nitrate using the AMAR model agreed well with outdoor chamber data that were produced under natural sunlight. For seven consecutive hours of photooxidation of SO2 in an outdoor chamber, dust chemistry at the low NOx level was attributed to 55 % of total sulfate (56 ppb SO2, 290 µg m−3 ATD, and NOx less than 5 ppb). At high NOx ( >  50 ppb of NOx with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was suppressed by the competition between NO2 and SO2, which both consume the dust-surface oxidants (OH radicals or ozone).

scholarly journals Influence of atmospheric in-cloud aqueous-phase chemistry on global simulation of SO<sub>2</sub> in CESM2

2021 ◽  
Author(s):  
Wendong Ge ◽  
Junfeng Liu ◽  
Kan Yi ◽  
Jiayu Xu ◽  
Yizhou Zhang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
The United States ◽  
Cloud Microphysics ◽  
So2 Oxidation ◽  
Atmospheric Pollutant ◽  
Global Simulation ◽  
Ph Values ◽  
Community Earth System Model ◽  
Sulfate Formation ◽  
Phase Chemistry

Abstract. Sulfur dioxide (SO2) is a major atmospheric pollutant and precursor of sulfate aerosols, which influences air quality, cloud microphysics and climate. Therefore, better understanding the conversion of SO2 to sulfate is essential to simulate and predict sulfur compounds more accurately. This study evaluates the effects of in-cloud aqueous-phase chemistry on SO2 oxidation in the Community Earth System Model version 2 (CESM2). We replaced the default aqueous-phase reactions with detailed HOx-, Fe-, N- and carbonate chemistry and performed a global simulation for 2014–2015. Compared with the observations, the results incorporating detailed aqueous-phase chemistry greatly reduced SO2 overestimation. This overestimation was reduced by 0.1–10 ppbv in most of Europe, North America and Asia and more than 10 ppbv in parts of China. The biases in annual simulated SO2 concentrations decreased by 46 %, 41 %, and 22 % in Europe, the United States and China, respectively. Fe-chemistry and HOx-chemistry contributed more to SO2 oxidation than N-chemistry. Higher concentrations of soluble Fe and higher pH values could further enhance the oxidation capacity. This study emphasizes the importance of detailed aqueous-phase chemistry for the oxidation of SO2. These mechanisms can improve SO2 simulation in CESM2 and deepen understanding of SO2 oxidation and sulfate formation.

scholarly journals Kinetics and mechanism of heterogeneous oxidation of sulfur dioxide by ozone on surface of calcium carbonate

2006 ◽  
Vol 6 (1) ◽  
pp. 579-613 ◽  
Author(s):  
L. Li ◽  
Z. M. Chen ◽  
Y. H. Zhang ◽  
T. Zhu ◽  
J. L. Li ◽  
...  
Keyword(s):  
Heterogeneous Reaction ◽  
Global Climate ◽  
Chemical Properties ◽  
So2 Oxidation ◽  
Heterogeneous Oxidation ◽  
Reactive Component ◽  
Rate Determining Step ◽  
Sulfate Formation ◽  
Heterogeneous Formation ◽  
Diffuse Reflectance Infrared

Abstract. Sulfate particles play a key role in the air quality and the global climate, but the heterogeneous formation mechanism of sulfates on surfaces of atmospheric particles is not well established. Carbonates, which act as a reactive component in mineral dust due to their special chemical properties, may contribute significantly to the sulfate formation by heterogeneous processes. This paper presents a study on the oxidation of SO2 by O3 on CaCO3 particles. Using Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), the formation of sulfite and sulfate on the surface was identified, and the roles of O3 and water in oxidation processes were determined. The results showed that in the presence of O3, SO2 can be oxidized to sulfate on the surface of CaCO3 particles. The reaction is first order in SO2 and zero order in O3. The reactive uptake coefficient for SO2 oxidation by O3 was determined to be (1.4±0.3)×10−7 using the BET area as the reactive area and (7.7±1.6)×10−4 using the geometric area. A two-stage mechanism that involves adsorption of SO2 followed by O3 oxidation is proposed and the adsorption of SO2 on the CaCO3 surface is the rate-determining step. The proposed mechanism can well explain the experiment results. The atmospheric implications were explored based on a box model calculation. It was found that the heterogeneous reaction might be an important pathway for sulfate formation in the atmosphere.

From O2–-Initiated SO2 Oxidation to Sulfate Formation in the Gas Phase

2018 ◽  
Vol 122 (27) ◽  
pp. 5781-5788 ◽  
Author(s):  
Narcisse T. Tsona ◽  
Junyao Li ◽  
Lin Du
Keyword(s):  
Gas Phase ◽  
So2 Oxidation ◽  
Sulfate Formation

scholarly journals Multiphase Reaction of SO<sub>2</sub> with NO<sub>2</sub> on CaCO<sub>3</sub> Particles. 1. Oxidation of SO<sub>2</sub> by NO<sub>2</sub>

2017 ◽  
Author(s):  
Defeng Zhao ◽  
Xiaojuan Song ◽  
Tong Zhu ◽  
Zefeng Zhang ◽  
Yingjun Liu
Keyword(s):  
Gas Phase ◽  
Gas Mixture ◽  
Ambient Atmosphere ◽  
Uptake Coefficient ◽  
Direct Oxidation ◽  
So2 Oxidation ◽  
Micro Raman Spectroscopy ◽  
Multiphase Reaction ◽  
Sulfate Formation ◽  
Reactive Uptake Coefficient

Abstract. Heterogeneous/multiphase reaction of SO2 with NO2 on solid or aqueous particles is thought to be a potentially important source of sulfate in the atmosphere, for example, during heavily polluted episodes (haze), but the reaction mechanism and rate are uncertain. In this study, we investigated the heterogeneous/multiphase reaction of SO2 with NO2 on individual CaCO3 particles in N2 using Micro-Raman spectroscopy in order to assess the importance of the direct oxidation of SO2 by NO2. In the SO2/NO2/H2O/N2 gas mixture, the CaCO3 solid particle was first converted to the Ca(NO3)2 droplet by the reaction with NO2 and the deliquescence of Ca(NO3)2, and then NO2 oxidized SO2 in the Ca(NO3)2 droplet forming CaSO4, which appeared as needle-shaped crystals. Sulfate was mainly formed after the complete conversion of CaCO3 to Ca(NO3)2, that is, during the multiphase oxidation of SO2 by NO2. The precipitation of CaSO4 from the droplet solution promoted sulfate formation. The reactive uptake coefficient of SO2 for sulfate formation is on the order of 10−8, and RH enhanced the uptake coefficient. We estimate that the direct multiphase oxidation of SO2 by NO2 is not an important source of sulfate in the ambient atmosphere compared with the SO2 oxidation by OH in the gas phase.

scholarly journals Effects of stabilized Criegee Intermediates (sCI) on the sulfate formation: A case study during summertime in Beijing-Tianjin-Hebei (BTH), China

2019 ◽  
Author(s):  
Lang Liu ◽  
Naifang Bei ◽  
Jiarui Wu ◽  
Suixin Liu ◽  
Jiamao Zhou ◽  
...  
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Heterogeneous Reaction ◽  
Reaction Rate Constant ◽  
So2 Emissions ◽  
So2 Oxidation ◽  
Formation Pathway ◽  
Criegee Intermediates ◽  
Sulfate Formation ◽  
Stabilized Criegee Intermediates

Abstract. Sulfate aerosols exert profound impacts on climate, ecosystem, visibility, and public health, but the sulfate formation pathway remains elusive. In the present study, a source-oriented WRF-Chem model is applied to simulate a persistent air pollution episode from 04 to 15 July 2015 in Beijing-Tianjin-Hebei (BTH), China to study contributions of four pathways to the sulfate formation. When comparing simulations to measurements in BTH, the index of agreement (IOA) of meteorological parameters, air pollutants and aerosol species generally exceeds 0.6. On average in BTH, the heterogeneous reaction of SO2 involving aerosol water and the SO2 oxidation by OH constitutes the two most important sulfate sources, with a contribution of about 35 %–38 % and 33 %–36 % respectively. The primary emission accounts for around 22 %–24 % of sulfate concentrations due to high SO2 emissions. The SO2 oxidation by stabilized Criegee Intermediates (sCI) also plays an appreciable role in the sulfate formation, with a contribution of around 9 % when an upper limit of the reaction rate constant of sCI with SO2 (κsCI + SO2 = 3.9 × 10−11 cm3 s−1) and a lower limit of the reaction rate constant of sCI with H2O (κsCI + H2O = 1.97 × 10−18 cm3 s−1) are used. Sensitivity studies reveal that there still exist large uncertainties in the sulfate contribution of the SO2 oxidation by sCI. The sulfate contribution of the reaction is decreased to less than 3 % when κsCI + SO2 is decreased to 6.0 × 10−13 cm3 s−1. Furthermore, when κsCI + H2O is increased to 2.38 × 10−15 cm3 s−1 based on the reported ratio of κsCI + SO2 to κsCI + H2O (6.1 × 10−5), the sulfate contribution becomes insignificant, less than 2%. Further studies need to be conducted to better determine κsCI + SO2 and κsCI + H2O to evaluate effects of the sCI chemistry on the sulfate formation.

scholarly journals Effects of stabilized Criegee intermediates (sCIs) on sulfate formation: a sensitivity analysis during summertime in Beijing–Tianjin–Hebei (BTH), China

2019 ◽  
Vol 19 (21) ◽  
pp. 13341-13354 ◽  
Author(s):  
Lang Liu ◽  
Naifang Bei ◽  
Jiarui Wu ◽  
Suixin Liu ◽  
Jiamao Zhou ◽  
...  
Keyword(s):  
Rate Constant ◽  
Reaction Rate ◽  
Heterogeneous Reaction ◽  
Reaction Rate Constant ◽  
So2 Oxidation ◽  
Formation Pathway ◽  
Criegee Intermediates ◽  
Sulfate Formation ◽  
Total Sulfate ◽  
Stabilized Criegee Intermediates

Abstract. Sulfate aerosols have profound impacts on the climate, ecosystem, visibility, and public health, but the sulfate formation pathway remains elusive. In the present study, a source-oriented WRF-Chem model is applied to simulate a persistent air pollution episode from 4 to 15 July 2015 in Beijing–Tianjin–Hebei (BTH), China, to study the contributions of four pathways to sulfate formation. When comparing simulations to measurements in BTH, the index of agreement (IOA) of meteorological parameters, air pollutants, and aerosol species generally exceeds 0.6. On average in BTH, the heterogeneous reaction of SO2 involving aerosol water and the SO2 oxidation by OH constitutes the two most important sulfate sources, with a contribution of about 35 %–38 % and 33 %–36 %, respectively. Primary sulfate emissions account for around 22 %–24 % of the total sulfate concentration. SO2 oxidation by stabilized Criegee intermediates (sCIs) also plays an appreciable role in sulfate formation, with a contribution of around 9 % when an upper limit of the reaction rate constant of sCIs with SO2 (κsCI+SO2=3.9×10-11 cm3 s−1) and a lower limit of the reaction rate constant of sCIs with H2O (κsCI+H2O=1.97×10-18 cm3 s−1) are used. Sensitivity studies reveal that there are still large uncertainties in the sulfate contribution of SO2 oxidation by sCIs. The sulfate contribution of the reaction is decreased to less than 3 % when κSCI+SO2 is decreased to 6.0×10-13 cm3 s−1. Furthermore, when κsCI+H2O is increased to 2.38×10-15 cm3 s−1 based on the reported ratio of κSCI+H2O to κSCI+SO2 (6.1×10-5), the sulfate contribution becomes insignificant at less than 2 %. Further studies need to be conducted to better determine κsCI+SO2 and κsCI+H2O to evaluate the effects of sCI chemistry on sulfate formation.

Heterogeneous SO2 Oxidation in Sulfate Formation by Photolysis of Particulate Nitrate

2019 ◽  
Vol 6 (2) ◽  
pp. 86-91 ◽  
Author(s):  
Masao Gen ◽  
Ruifeng Zhang ◽  
Dan Dan Huang ◽  
Yongjie Li ◽  
Chak K. Chan
Keyword(s):  
So2 Oxidation ◽  
Sulfate Formation

scholarly journals A potential source of atmospheric sulfate from O<sub>2</sub><sup>−</sup>-induced SO<sub>2</sub> oxidation by ozone

2019 ◽  
Vol 19 (1) ◽  
pp. 649-661 ◽  
Author(s):  
Narcisse Tchinda Tsona ◽  
Lin Du
Keyword(s):  
Electron Transfer ◽  
Gas Phase ◽  
Low Energy ◽  
Aerosol Formation ◽  
So2 Oxidation ◽  
Title Reaction ◽  
Chemical Fate ◽  
Atmospheric Fate ◽  
Potential Source ◽  
Sulfate Formation

Abstract. It was formerly demonstrated that O2SOO− forms at collisions rate in the gas phase as a result of SO2 reaction with O2-. Here, we present a theoretical investigation of the chemical fate of O2SOO− by reaction with O3 in the gas phase, based on ab initio calculations. Two main mechanisms were found for the title reaction, with fundamentally different products: (i) formation of a van der Waals complex followed by electron transfer and further decomposition to O2 + SO2 + O3- and (ii) formation of a molecular complex from O2 switching by O3, followed by SO2 oxidation to SO3- within the complex. Both reactions are exergonic, but separated by relatively low energy barriers. The products in the former mechanism would likely initiate other SO2 oxidations as shown in previous studies, whereas the latter mechanism closes a path wherein SO2 is oxidized to SO3-. The latter reaction is atmospherically relevant since it forms the SO3- ion, hereby closing the SO2 oxidation path initiated by O2-. The main atmospheric fate of SO3- is nothing but sulfate formation. Exploration of the reactions kinetics indicates that the path of reaction (ii) is highly facilitated by humidity. For this path, we found an overall rate constant of 4.0×10-11 cm3 molecule−1 s−1 at 298 K and 50 % relative humidity. The title reaction provides a new mechanism for sulfate formation from ion-induced SO2 oxidation in the gas phase and highlights the importance of including such a mechanism in modeling sulfate-based aerosol formation rates.

Sign in / Sign up

Export Citation Format

Share Document