Oligo and polyuronic acids interactions with hypervalent chromium

Juan C. González, Silvia I. García, Sebastián Bellú, Ana María Atria, Juan Manuel Salas Pelegrín, Antal Rockenbauer, Lazlo Korecz, Sandra Signorella, Luis F. Sala

Research output: Contribution to journalArticle

13 Citations (Scopus)

Abstract

Selective oxidation of galacturonic residues of oligo and polyuronic acids by CrVI affords CO2/HCO2H, oxidized uronic acid, and CrIII as final redox products. Kinetic studies show that the redox reaction proceeds through a mechanism combining CrVI → CrIV → CrII and CrVI → CrIV → CrIII pathways. The mechanism is supported by the observation of free radicals, CrO22+ and CrV as reaction intermediates. The EPR spectra show that five- and six coordinated oxo-CrV intermediates are formed. Penta-coordinated oxo-CrV species are present at any [H+], whereas hexa-coordinated ones are only observed at pH <1. At low pH CrV predominating species are coordinated by carboxylate groups and Oring (giso = 1.9783/5). At pH 7.5, the predominating ones are those coordinated by alcoholate groups of the ligand (giso = 1.9800). Polygal can reduce CrVI and efficiently trap CrIII. This behaviour represents an interesting model for the study of biomaterials, which possess a high proportion of polygal, in order to remove chromium from polluted waters.

Original languageEnglish
Pages (from-to)2719-2729
Number of pages11
JournalPolyhedron
Volume28
Issue number13
DOIs
Publication statusPublished - Sep 2 2009

Keywords

  • Chromium
  • EPR
  • Kinetics
  • Redox chemistry
  • Uronic acids

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Inorganic Chemistry
  • Materials Chemistry

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  • Cite this

    González, J. C., García, S. I., Bellú, S., Atria, A. M., Pelegrín, J. M. S., Rockenbauer, A., Korecz, L., Signorella, S., & Sala, L. F. (2009). Oligo and polyuronic acids interactions with hypervalent chromium. Polyhedron, 28(13), 2719-2729. https://doi.org/10.1016/j.poly.2009.05.018