The role of soluble constituents of atmospheric aerosols in, aqueous phase oxidation mechanism of SO2

1997 ◽  
Vol 28 ◽  
pp. S111-S112
Author(s):  
I. Grgić ◽  
M. Poznič ◽  
V. Hudnik
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Oxidation Mechanism ◽  
Phase Oxidation

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 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

SO2 oxidation and nucleation studies at near-atmospheric conditions in outdoor smog chamber

2013 ◽  
Vol 10 (3) ◽  
pp. 210 ◽  
Author(s):  
Yang Zhou ◽  
Elias P. Rosen ◽  
Haofei Zhang ◽  
Weruka Rattanavaraha ◽  
Wenxing Wang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Particle Growth ◽  
Particle Formation ◽  
Particle Nucleation ◽  
Smog Chamber ◽  
Atmospheric Conditions ◽  
So2 Oxidation ◽  
Phase Oxidation ◽  
Exponential Power

Environmental context Nucleation, a fundamental step in atmospheric new-particle formation, is a significant source of atmospheric aerosols. Most laboratory experiments investigate H2SO4 nucleation based on indoor chambers or flow tube reactors, and find discrepancies with field observations. Here a large outdoor smog chamber is used to study the relationship between SO2 and nucleation rates, and demonstrate the importance of aqueous phase oxidation of SO2 by H2O2 and other oxidants. Abstract Particle formation under different initial ambient background conditions was simulated in a dual outdoor smog chamber for the SO2 and O3–SO2 systems with and without sunlight, as well as a propylene–NOx–SO2–sunlight system. An exponential power of 1.37 between nucleation rates at 1nm (J1) and SO2 gas phase concentrations was obtained for the SO2–sunlight system and a minimum of 0.45ppbSO2 is required by this relationship to initiate nucleation (J1 is equal to 1cm–3s–1). An investigation of the O3–SO2–sunlight/dark system showed that the presence of O3 contributed to the particle nucleation and growth at night; however, it only enhanced the particle growth in the daytime when H2SO4 photochemistry was present. In the presence of an OH• scavenger, the O3–SO2 system did not show particle nucleation, suggesting that the scavenger cut off this pathway of SO2 oxidation. A lower nucleation rate and higher particle grow rate were also observed for SO2 oxidation in the presence of propylene and NOx. However a higher SO2 decay rate was obtained for the propylene system especially under high relative humidity, which was not observed in the O3–SO2 system. This suggests that aqueous phase oxidation of SO2 from H2O2, RO2• and other oxidants produced in the propylene–NOx system contribute to the particle growth.

Liquid-liquid extraction of succinate using a dicopper cryptate

2020 ◽  
Author(s):  
Riccardo Mobili ◽  
Sonia La Cognata ◽  
Francesca Merlo ◽  
Andrea Speltini ◽  
Massimo Boiocchi ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Visible Spectrum ◽  
Tca Cycle ◽  
Residual Concentration ◽  
Waste Products ◽  
Liquid Liquid Extraction ◽  
The Tca Cycle ◽  
Quantitative Extraction ◽  
Uv Visible

<div> <p>The extraction of the succinate dianion from a neutral aqueous solution into dichloromethane is obtained using a lipophilic cage-like dicopper(II) complex as the extractant. The quantitative extraction exploits the high affinity of the succinate anion for the cavity of the azacryptate. The anion is effectively transferred from the aqueous phase, buffered at pH 7 with HEPES, into dichloromethane. A 1:1 extractant:anion adduct is obtained. Extraction can be easily monitored by following changes in the UV-visible spectrum of the dicopper complex in dichloromethane, and by measuring the residual concentration of succinate in the aqueous phase by HPLC−UV. Considering i) the relevance of polycarboxylates in biochemistry, as e.g. normal intermediates of the TCA cycle, ii) the relevance of dicarboxylates in the environmental field, as e.g. waste products of industrial processes, and iii) the recently discovered role of succinate and other dicarboxylates in pathophysiological processes including cancer, our results open new perspectives for research in all contexts where selective recognition, trapping and extraction of polycarboxylates is required. </p> </div>

scholarly journals Aging of atmospheric aerosols and the role of iron in catalyzing brown carbon formation

2021 ◽  
Author(s):  
Hind A. A. Al-Abadleh
Keyword(s):  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Atmospheric Aerosols ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Atmospheric Oxidation ◽  
Carbon Formation ◽  
Brown Carbon ◽  
Volatile Organic

Extensive research has been done on the processes that lead to the formation of secondary organic aerosol (SOA) including atmospheric oxidation of volatile organic compounds (VOCs) from biogenic and anthropogenic...

scholarly journals Properties of aerosols and formation mechanisms over southern China during the monsoon season

2016 ◽  
Author(s):  
Weihua Chen ◽  
Xuemei Wang ◽  
Jason Blake Cohen ◽  
Shengzhen Zhou ◽  
Zhisheng Zhang ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Transport Model ◽  
Atmospheric Transport ◽  
Southern China ◽  
Monsoon Season ◽  
Sea Salt ◽  
Urban Site ◽  
Chemical Components ◽  
Formation Mechanisms

Abstract. Measurements of size-resolved aerosols from 0.25 to 18 μm were conducted at three sites (urban, suburban and background sites) and used in tandem with an atmospheric transport model to study the size distribution and formation of atmospheric aerosols in southern China during the monsoon season (May–June) in 2010. The mass distribution showed the majority of chemical components were found in the smaller size bins (< 2.5 μm). Sulfate, was found to be strongly correlated with aerosol water, and anti-correlated with atmospheric SO2, hinting at aqueous-phase reactions being the main formation pathway. Nitrate was the only major species that showed a bi-modal distribution at the urban site, and was dominated by the coarse mode in the other two sites, suggesting that an important component of nitrate formation is chloride depletion of sea salt transported from the South China Sea. In addition to these aqueous-phase reactions and interactions with sea salt aerosols, new particle formation, chemical aging, and long-range transport from upwind urban or biomass burning regions were also found to be important in at least some of the sights on some of the days. This work therefore summarizes the different mechanisms that significantly impact the aerosol chemical composition during the Monsoon over southern China.

scholarly journals Constraining condensed-phase formation kinetics of secondary organic aerosol components from isoprene epoxydiols

2016 ◽  
Vol 16 (3) ◽  
pp. 1245-1254 ◽  
Author(s):  
T. P. Riedel ◽  
Y.-H. Lin ◽  
Z. Zhang ◽  
K. Chu ◽  
J. A. Thornton ◽  
...  
Keyword(s):  
Aqueous Phase ◽  
Atmospheric Aerosols ◽  
Rate Constants ◽  
Reaction Rate ◽  
Secondary Organic Aerosol ◽  
Organic Aerosol ◽  
Heterogeneous Reactions ◽  
Model Calculations ◽  
Reaction Rate Constants ◽  
Aerosol Mass

Abstract. Isomeric epoxydiols from isoprene photooxidation (IEPOX) have been shown to produce substantial amounts of secondary organic aerosol (SOA) mass and are therefore considered a major isoprene-derived SOA precursor. Heterogeneous reactions of IEPOX on atmospheric aerosols form various aerosol-phase components or "tracers" that contribute to the SOA mass burden. A limited number of the reaction rate constants for these acid-catalyzed aqueous-phase tracer formation reactions have been constrained through bulk laboratory measurements. We have designed a chemical box model with multiple experimental constraints to explicitly simulate gas- and aqueous-phase reactions during chamber experiments of SOA growth from IEPOX uptake onto acidic sulfate aerosol. The model is constrained by measurements of the IEPOX reactive uptake coefficient, IEPOX and aerosol chamber wall losses, chamber-measured aerosol mass and surface area concentrations, aerosol thermodynamic model calculations, and offline filter-based measurements of SOA tracers. By requiring the model output to match the SOA growth and offline filter measurements collected during the chamber experiments, we derive estimates of the tracer formation reaction rate constants that have not yet been measured or estimated for bulk solutions.

scholarly journals The role of transition metal ions on HO<sub>x</sub> radicals in clouds: a numerical evaluation of its impact on multiphase chemistry

2004 ◽  
Vol 4 (1) ◽  
pp. 95-110 ◽  
Author(s):  
L. Deguillaume ◽  
M. Leriche ◽  
A. Monod ◽  
N. Chaumerliac
Keyword(s):  
Transition Metal ◽  
Metal Ions ◽  
Aqueous Phase ◽  
Numerical Evaluation ◽  
Transition Metal Ions ◽  
Cloud Chemistry ◽  
Sensitivity Tests ◽  
Fe Speciation ◽  
Deposition Processes

Abstract. A new modelling study of the role of transition metal ions on cloud chemistry has been performed. Developments of the Model of Multiphase Cloud Chemistry (M2C2; Leriche et al., 2001) are described, including the transition metal ions reactivity emission/deposition processes and variable photolysis in the aqueous phase. The model is then applied to three summertime scenarios under urban, remote and marine conditions, described by Ervens et al. (2003). Chemical regimes in clouds are analyzed to understand the role of transition metal ions on cloud chemistry and especially, on HxOy chemistry, which consequently influences the sulphur and the VOCs chemistry in droplets. The ratio of Fe(II)/Fe(III) exhibits a diurnal variation with values in agreement with the available measurements of Fe speciation. In the urban case, sensitivity tests with and without TMI chemistry, show an enhancement of OH concentration in the aqueous phase when TMI chemistry is considered.

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