Photochemical Properties of Precipitated Solid Aerosol Produced by Burning of Titanium Microparticles under Ambient Air

Захаренко, В. С.; Khromova, S. A.

doi:10.4236/msa.2010.12017

Cited by 2 publications

(1 citation statement)

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“…Figures and illustrate that the illumination of Mauritanian sand and Icelandic volcanic ash films leads to the production of gas-phase CO 2 , even in the absence of added oxalic acid. Although the release of CO 2 upon illumination has previously been observed for TiO 2 , and a variety of other semiconductors, the present work provides, to our knowledge, the first demonstration of this phenomenon on real environmental substrates.…”

Section: Discussionsupporting

confidence: 50%

Heterogeneous Photochemistry of Oxalic Acid on Mauritanian Sand and Icelandic Volcanic Ash

Styler

Donaldson

2012

Environ. Sci. Technol.

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Teragram quantities of crustal and volcanic aerosol are released into the atmosphere on an annual basis. Although these substrates contain photoactive metal oxides, little is known about the role that they may play in catalyzing the heterogeneous phototransformation of semivolatile organic species. In the present study, we have investigated oxalic acid photochemistry at the surface of Fe(2)O(3), TiO(2), Mauritanian sand, and Icelandic volcanic ash in the presence and absence of oxygen using a photochemical Knudsen cell reactor. Illumination of all sample types resulted in the production of gas-phase CO(2). In the case of Mauritanian sand, the production of gas-phase CO(2) scaled with the loss of surface oxalic acid. In the absence of oxygen, the production of CO(2) by the sand and ash films scaled with the absorption spectrum of iron oxalate, which suggests that the reaction is at least in part iron-mediated. The presence of oxygen suppressed CO(2) production at the Fe(2)O(3) surface, enhanced CO(2) production at the Mauritanian sand surface, and did not have a net effect upon CO(2) production at the Icelandic ash surface. These different oxygen dependencies imply that oxalic acid photochemistry at the authentic surfaces under study was not solely iron-mediated. Experiments at the TiO(2) surface, which showed enhanced CO(2) production from oxalic acid in the presence of oxygen, suggest that Ti-mediated photochemistry played an important role. In summary, these results provide evidence that solid-phase aerosol photochemistry may influence the atmospheric lifetime of oxalic acid in arid regions, where its removal via wet deposition is insignificant.

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Section: Discussionsupporting

confidence: 50%