Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid

Aqueous oxalic acid forms surface CrIII-oxalato complexes with suspended chromium(III) oxide particles; the FTIR spectra demonstrate that both carboxylate groups of the ligand are bound to surface CrIII. Surface complexation is followed by changes in the surface redox potential toward more negative...

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Detalles Bibliográficos
Autores principales: Iglesias, Alberto, Weisz, Ariel Dan
Publicado: 1997
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v36_n27_p6423_GarciaRodenas
http://hdl.handle.net/20.500.12110/paper_00201669_v36_n27_p6423_GarciaRodenas
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_00201669_v36_n27_p6423_GarciaRodenas
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spelling paper:paper_00201669_v36_n27_p6423_GarciaRodenas2023-06-08T14:40:26Z Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid Iglesias, Alberto Weisz, Ariel Dan Aqueous oxalic acid forms surface CrIII-oxalato complexes with suspended chromium(III) oxide particles; the FTIR spectra demonstrate that both carboxylate groups of the ligand are bound to surface CrIII. Surface complexation is followed by changes in the surface redox potential toward more negative values and by the dissolution of the oxide. The dissolving steady state potential is in the range -60 to -210 mV against SHE. During surface conditioning, traces of oxidants at the interface are reduced, and some reduced metal ions accumulate. Minor amounts of dissolved CrII are generated and can be collected at a vicinal ring electrode set at -60 mV. In agreement, dissolution kinetics suggest that generation of CrII by ligand-to-metal charge transfer within the surface complexes produces a large increase in the rate of phase transfer, as expected from the properties of CrIII and CrII. Added chromous salts also catalyze the dissolution through intervalence charge transfer within an oxalato-bridged CrIII-L-CrII surface dimeric complex. The rate of dissolution at 65 °C follows a Langmuir-Hinshelwood dependence on oxalic acid concentration, a power law (order 0.31) dependence on proton concentration, and an a + b[CrII]0.64 dependence on [Cr(II)]. The Langmuir-Hinshelwood parameters are interpreted in terms of the stability constant of the surface CrIII-oxalato complex. © 1997 American Chemical Society. Fil:Iglesias, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Weisz, A.D. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. 1997 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v36_n27_p6423_GarciaRodenas http://hdl.handle.net/20.500.12110/paper_00201669_v36_n27_p6423_GarciaRodenas
institution Universidad de Buenos Aires
institution_str I-28
repository_str R-134
collection Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA)
description Aqueous oxalic acid forms surface CrIII-oxalato complexes with suspended chromium(III) oxide particles; the FTIR spectra demonstrate that both carboxylate groups of the ligand are bound to surface CrIII. Surface complexation is followed by changes in the surface redox potential toward more negative values and by the dissolution of the oxide. The dissolving steady state potential is in the range -60 to -210 mV against SHE. During surface conditioning, traces of oxidants at the interface are reduced, and some reduced metal ions accumulate. Minor amounts of dissolved CrII are generated and can be collected at a vicinal ring electrode set at -60 mV. In agreement, dissolution kinetics suggest that generation of CrII by ligand-to-metal charge transfer within the surface complexes produces a large increase in the rate of phase transfer, as expected from the properties of CrIII and CrII. Added chromous salts also catalyze the dissolution through intervalence charge transfer within an oxalato-bridged CrIII-L-CrII surface dimeric complex. The rate of dissolution at 65 °C follows a Langmuir-Hinshelwood dependence on oxalic acid concentration, a power law (order 0.31) dependence on proton concentration, and an a + b[CrII]0.64 dependence on [Cr(II)]. The Langmuir-Hinshelwood parameters are interpreted in terms of the stability constant of the surface CrIII-oxalato complex. © 1997 American Chemical Society.
author Iglesias, Alberto
Weisz, Ariel Dan
spellingShingle Iglesias, Alberto
Weisz, Ariel Dan
Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid
author_facet Iglesias, Alberto
Weisz, Ariel Dan
author_sort Iglesias, Alberto
title Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid
title_short Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid
title_full Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid
title_fullStr Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid
title_full_unstemmed Surface complexation description of the dissolution of chromium(III) hydrous oxides by oxalic acid
title_sort surface complexation description of the dissolution of chromium(iii) hydrous oxides by oxalic acid
publishDate 1997
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_00201669_v36_n27_p6423_GarciaRodenas
http://hdl.handle.net/20.500.12110/paper_00201669_v36_n27_p6423_GarciaRodenas
work_keys_str_mv AT iglesiasalberto surfacecomplexationdescriptionofthedissolutionofchromiumiiihydrousoxidesbyoxalicacid
AT weiszarieldan surfacecomplexationdescriptionofthedissolutionofchromiumiiihydrousoxidesbyoxalicacid
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