Formation of iodinated organic compounds by oxidation of iodide-containing waters with Manganese Dioxide
MetadataShow full item record
This study shows that iodinated organic compounds can be produced when iodide-containing waters are in contact with manganese oxide birnessite (d-MnO2) in the pH range of 5-7. In the absence of natural organic matter (NOM), iodide is oxidized to iodate that is also adsorbed onto d-MnO2. In thepresence of iodide and NOM, adsordable organic iodine compounds (AOI) are formed at pH<7 because of the oxidation of iodide to iodine by d-MnO2 and the reactions of iodine with NOM. In addition, iodoacetic acid and iodoform have been identified as specific iodinated byproducts. Formation ofiodoform is not observed for high NOM/d-MnO2 ratios due to inhibition of the catalytic effect of d-MnO2 by NOM poisoning. Experiments with model compounds such as resorcinol and 3,5- heptanedione confirmed that the d-MnO2/I- system is very effective for the formation of iodinated organic compounds.These results suggest that birnessite acts as a catalyst through the oxidation of iodide to iodine and the polarization of the iodine molecule, which then reacts with NOM moieties.
Showing items related by title, author, creator and subject.
Allard, Sebastien; Gallard, H.; Fontaine, C.; Croue, J. (2010)This paper demonstrates that manganese oxides can initiate the formation of methyl iodide, a volatile compound that participates to the input of iodine into the atmosphere. The formation of methyl iodide was investigated ...
Allard, Sebastien; Gallard, H. (2013)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 ...
Allard, Sebastien; Von Gunten, Urs; Salhi, E.; Nicolau, R.; Gallard, H. (2009)The oxidation of iodide by synthetic birnessite (δ-MnO2) was studied in perchlorate mediain the pH range 4-8. Iodine (I2) was detected as an oxidation product that was subsequently further oxidized to iodate (IO3). The ...