| Title: | Abiotic formation of methyl iodide on synthetic birnessite: a mechanistic study |
| Address: | "Ecole Nationale Superieure d'Ingenieurs de Poitiers - Universite de Poitiers, Institut de Chimie des Milieux et des Materiaux UMR 7285, 1, rue Marcel Dore, 86022 Poitiers Cedex, France. Electronic address: s.allard@curtin.edu.au" |
| DOI: | 10.1016/j.scitotenv.2013.05.079 |
| ISSN/ISBN: | 1879-1026 (Electronic) 0048-9697 (Linking) |
| Abstract: | "Methyl iodide is a well-known volatile halogenated organic compound that contributes to the iodine content in the troposphere, potentially resulting in damage to the ozone layer. Most methyl iodide sources derive from biological activity in oceans and soils with very few abiotic mechanisms proposed in the literature. In this study we report that synthetic manganese oxide (birnessite delta-MnO2) can catalyze the formation of methyl iodide in the presence of natural organic matter (NOM) and iodide. Methyl iodide formation was only observed at acidic pH (4-5) where iodide is oxidized to iodine and NOM is adsorbed on delta-MnO2. The effect of delta-MnO2, iodide and NOM concentrations, nature of NOM and ionic strength was investigated. High concentrations of methyl iodide were formed in experiments conducted with the model compound pyruvate. The Lewis acid property of delta-MnO2 leads to a polarization of the iodine molecule, and catalyzes the reaction with natural organic matter. As manganese oxides are strong oxidants and are ubiquitous in the environment, this mechanism could significantly contribute to the global atmospheric input of iodine" |
| Keywords: | Atmospheric iodine Iodide Iodine Manganese oxide Natural organic matter Volatile halogenated organic compound; |
| Notes: | "PubMed-not-MEDLINEAllard, Sebastien Gallard, Herve eng Netherlands 2013/06/28 Sci Total Environ. 2013 Oct 1; 463-464:169-75. doi: 10.1016/j.scitotenv.2013.05.079. Epub 2013 Jun 23" |
