Molecular environment of iodine in naturally iodinated humic substances: Insight from X-ray absorption spectroscopy

Abstract : The molecular environment of iodine in reference inorganic and organic compounds, and in dry humic and fulvic acids (HAs and FAs) extracted from subsurface and deep aquifers was probed by iodine L 3-edge X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) of iodine spectra from HAs and FAs resembled those of organic references and displayed structural features consistent with iodine forming covalent bonds with organic molecules. Simulation of XANES spectra by linear combination of reference spectra suggested the predominance of iodine forming covalent bonds to aromatic rings (aromatic-bound iodine). Comparison of extended X-ray absorption fine structure (EXAFS) spectra of reference and samples further showed that iodine was surrounded by carbon shells at distances comparables to those for references containing aromatic-bound iodine. Quantitative analysis of EXAFS spectra indicated that iodine was bound to about one carbon at a distance d (I–C) of 2.01(4)–2.04(9) A ˚ , which was comparable to the distances observed for aromatic-bound iodine in references (1.99(1)–2.07(6) A ˚), and significantly shorter than that observed for aliphatic-bound iodine (2.15(2)–2.16(2) A ˚). These results are in agreement with previous conclusions from X-ray photoelectron spectros-copy and from electrospray ionization mass spectrometry. These results collectively suggest that the aromatic-bound iodine is stable in the various aquifers of this study.
Complete list of metadatas

Cited literature [85 references]  Display  Hide  Download

https://hal-cea.archives-ouvertes.fr/cea-01270133
Contributor : Delphine Vidart-Dufort <>
Submitted on : Friday, February 5, 2016 - 4:43:26 PM
Last modification on : Thursday, February 7, 2019 - 4:46:17 PM
Long-term archiving on : Saturday, November 12, 2016 - 11:49:24 AM

File

2006_GCA 2006 iodine HAFA.pdf
Files produced by the author(s)

Identifiers

Collections

Citation

Michel L. Schlegel, Pascal E. Reiller, Florence Mercier-Bion, Nicole Barré, Valérie Moulin. Molecular environment of iodine in naturally iodinated humic substances: Insight from X-ray absorption spectroscopy. Geochimica et Cosmochimica Acta Supplement, Pergamon, 2006, 70 (22), pp.5536­5551. ⟨10.1016/j.gca.2006.08.026⟩. ⟨cea-01270133⟩

Share

Metrics

Record views

177

Files downloads

214