Heterogeneous reaction of SO2 on TiO2 particles

Shang, Jing; Li, Jia; Zhu, Tong

doi:10.1007/s11426-010-4160-3

Cited by 57 publications

(76 citation statements)

References 26 publications

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“…For example, the uptake of NO 2 on TiO 2 particles is enhanced under irradiation (Gustafsson et al, 2006;Ndour et al, 2008;El Zein and Bedjanian, 2012), leading to the formation of HONO, the photolysis of which produces NO and OH and may perturb the stratospheric NO x and HO x cycles. Heterogeneous chemical oxidation of SO 2 could enhance the formation of sulfate coating on mineral particles (Shang et al, 2010). Future studies will address this aspect.…”

Section: Discussionmentioning

confidence: 95%

Heterogeneous reaction of N2O5 with airborne TiO2 particles and its implication for stratospheric particle injection

et al. 2014

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Abstract. Injection of aerosol particles (or their precursors) into the stratosphere to scatter solar radiation back into space has been suggested as a solar-radiation management scheme for the mitigation of global warming. TiO 2 has recently been highlighted as a possible candidate particle because of its high refractive index, but its impact on stratospheric chemistry via heterogeneous reactions is as yet unknown. In this work the heterogeneous reaction of airborne submicrometre TiO 2 particles with N 2 O 5 has been investigated for the first time, at room temperature and different relative humidities (RH), using an atmospheric pressure aerosol flow tube. The uptake coefficient of N 2 O 5 onto TiO 2 , γ (N 2 O 5 ), was determined to be ∼ 1.0 × 10 −3 at low RH, increasing to ∼ 3 × 10 −3 at 60 % RH. The uptake of N 2 O 5 onto TiO 2 is then included in the UKCA chemistry-climate model to assess the impact of this reaction on stratospheric chemistry. While the impact of TiO 2 on the scattering of solar radiation is chosen to be similar to the aerosol from the Mt Pinatubo eruption, the impact of TiO 2 injection on stratospheric N 2 O 5 is much smaller.

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Section: Discussionmentioning

confidence: 95%

Heterogeneous reaction of N2O5 with airborne TiO2 particles and its implication for stratospheric particle injection

et al. 2014

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“…The uptake coefficient with the presence of water and UV illumination was 1 magnitude higher than that without water and UV illumination. Under UV illumination, the photo-generated electrons and holes can react with surface adsorbed oxygen and water, and produce active oxygen species (such as superoxide anions (O 2  ) and hydroxyl radicals (·OH)), which can further oxidize surface-adsorbed SO 2 to produce sulfate [39,40].…”

Section: Organics/so 2 -Particles Reaction Under Uv Illuminationmentioning

confidence: 99%

The roles of heterogeneous chemical processes in the formation of an air pollution complex and gray haze

2011

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Urban and regional air pollutions are characterized by high concentrations of secondary pollutants such as photo-oxidants (mainly ozone) and fine particulate matter, which are formed through chemical reactions of the primary pollutants emitted from various sources. The accumulation of these pollutants under stagnant meteorological conditions results in the formation of gray haze, reducing visibility and causing major impacts on human health and climate. In an air pollution complex, the coexistence of high concentrations of primary and secondary gaseous and particulate pollutants provides a large amount of reactants for heterogeneous reactions on the surface of fine particles; these reactions change the oxidizing capacity of the atmosphere, as well as chemical compositions along with the physicochemical and optical properties of particulate matter, thereby accelerating formation of the air pollution complex and gray haze. Using in situ technologies, such as diffuse reflectance infrared Fourier-transform spectroscopy and single-particle Raman spectroscopy, we systematically investigated the reaction kinetics and mechanisms of gaseous pollutants (i.e., NO 2 , SO 2 , O 3 , and formaldehyde) on the surfaces of the major components of atmospheric particles such as CaCO 3 , kaolinite, montmorillonite, NaCl, sea salt, Al 2 O 3 , and TiO 2 . We found that the main reaction products were sulfate, nitrate, or formate, which can change the hygroscopicity and light extinction parameters of those particles significantly. By analyzing the reaction kinetics of these heterogeneous reactions, we identified synergetic mechanisms of the three ternary reaction systems, i.e., NO 2 -particlesH 2 O, SO 2 -particlesO 3 , and organics/SO 2 -particles-UV illumination. These synergetic mechanisms can provide experimental and theoretical bases for understanding the feedback mechanisms and nonlinear processes in the formation of an air pollution complex and gray haze.

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“…In the presence of UV light, the particle water content can act as an acceptor for h + vb and produce surface OH radicals, promoting heterogeneous photochemistry of SO 2 on mineral dust. In the presence of UV light, Shang et al (2010) reported that sulfate production on the surface of TiO 2 increased by 5 times because of the increase in RH from 20 to 80 %. Park and Jang (2016) also reported the exponential increase in γ SO 2− 4 as the RH increased from 20 to 80 % for both autoxidation and photooxidation of SO 2 in the presence of ATD particles.…”

Section: Introductionmentioning

confidence: 99%

Modeling atmospheric mineral aerosol chemistry to predict heterogeneous photooxidation of SO2

Jang

Park

2017

Atmos. Chem. Phys.

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Abstract. The photocatalytic ability of airborne mineral dust particles is known to heterogeneously promote SO 2 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, SO 2 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 SO 2 and NO x (partitioning between the gas phase and the multilayer coated dust). The reaction of absorbed SO 2 on dust particles occurs via two major paths: autoxidation of SO 2 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, SO 2 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 SO 2 in an outdoor chamber, dust chemistry at the low NO x level was attributed to 55 % of total sulfate (56 ppb SO 2 , 290 µg m −3 ATD, and NO x less than 5 ppb). At high NO x (> 50 ppb of NO x with low hydrocarbons), sulfate formation was also greatly promoted by dust chemistry, but it was suppressed by the competition between NO 2 and SO 2 , which both consume the dust-surface oxidants (OH radicals or ozone).

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Heterogeneous reaction of SO2 on TiO2 particles

Cited by 57 publications

References 26 publications

Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

The roles of heterogeneous chemical processes in the formation of an air pollution complex and gray haze

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

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Heterogeneous reaction of SO2 on TiO2 particles

Cited by 57 publications

References 26 publications

Heterogeneous reaction of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; with airborne TiO&lt;sub&gt;2&lt;/sub&gt; particles and its implication for stratospheric particle injection

Heterogeneous reaction of N&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;5&lt;/sub&gt; with airborne TiO&lt;sub&gt;2&lt;/sub&gt; particles and its implication for stratospheric particle injection

The roles of heterogeneous chemical processes in the formation of an air pollution complex and gray haze

Modeling atmospheric mineral aerosol chemistry to predict heterogeneous photooxidation of SO&lt;sub&gt;2&lt;/sub&gt;

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Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

Heterogeneous reaction of N<sub>2</sub>O<sub>5</sub> with airborne TiO<sub>2</sub> particles and its implication for stratospheric particle injection

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