Sorption and catalytic oxidation of Fe(II) at the surface of calcite
The effect of sorption and coprecipitation of Fe(II) with calcite on the kinetics of Fe(II) oxidation was investigated. The interaction of Fe(II) with calcite was studied experimentally in the absence and presence of oxygen. The sorption of Fe(II) on calcite occurred in two distinguishable steps: (a...
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ftinfoscience:oai:infoscience.tind.io:167234 2023-06-11T04:10:56+02:00 Sorption and catalytic oxidation of Fe(II) at the surface of calcite Mettler, Suzanne Wolthers, Mariette Charlet, Laurent von Gunten, Urs 2011-07-01T10:10:38Z http://infoscience.epfl.ch/record/167234 https://doi.org/10.1016/j.gca.2009.01.003 unknown http://infoscience.epfl.ch/record/167234 doi:10.1016/j.gca.2009.01.003 ISI:000264518500003 http://infoscience.epfl.ch/record/167234 Text 2011 ftinfoscience https://doi.org/10.1016/j.gca.2009.01.003 2023-05-08T00:44:19Z The effect of sorption and coprecipitation of Fe(II) with calcite on the kinetics of Fe(II) oxidation was investigated. The interaction of Fe(II) with calcite was studied experimentally in the absence and presence of oxygen. The sorption of Fe(II) on calcite occurred in two distinguishable steps: (a) a rapid adsorption step (seconds-minutes) was followed by (b) a slower incorporation (hours-weeks). The incorporated Fe(II) could not be remobilized by a strong complexing agent (phenanthroline or ferrozine) but the dissolution of the outmost calcite layers with carbonic acid allowed its recovery. Based on results of the latter dissolution experiments, a stoichiometry of 0.4 mol% Fe:Ca and a mixed carbonate layer thickness of 25 nm (after 168 It equilibration) were estimated. Fe(II) sorption on calcite could be successfully described by a surface adsorption and precipitation model (Comans & Middelburg, GCA 51 (1987), 2587) and surface complexation modeling (Van Cappellen et al., GCA 57 (1993), 3505; Pokrovsky et al., Langmuir 16 (2000), 2677). The surface complex model required the consideration of two adsorbed Fe(II) surface species, >CO3Fe+ and >CO3FeCO3H0. For the formation of the latter species, a stability constant is being suggested. The oxidation kinetics of Fe(II) in the presence of calcite depended on the equilibration time of aqueous Fe(II) with the mineral prior to the introduction of oxygen. If pre-equilibrated for >15 h, the oxidation kinetics was comparable to a calcite-free system (t(1/2) = 145 +/- 15 min). Conversely, if Fe(II) was added to an aerated calcite suspension, the rate of oxidation was higher than in the absence of calcite (t(1/2) = 41 +/- 1 min and t(1/2) = 100 +/- 15 min, respectively). This catalysis was due to the greater reactivity of the adsorbed Fe(II) species, >CO3FeCO3H0, for which the species specific rate constant was estimated. (c) 2009 Elsevier Ltd. All rights reserved. Text Carbonic acid EPFL Infoscience (Ecole Polytechnique Fédérale Lausanne) Langmuir ENVELOPE(-67.150,-67.150,-66.967,-66.967) Geochimica et Cosmochimica Acta 73 7 1826 1840 |
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EPFL Infoscience (Ecole Polytechnique Fédérale Lausanne) |
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ftinfoscience |
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description |
The effect of sorption and coprecipitation of Fe(II) with calcite on the kinetics of Fe(II) oxidation was investigated. The interaction of Fe(II) with calcite was studied experimentally in the absence and presence of oxygen. The sorption of Fe(II) on calcite occurred in two distinguishable steps: (a) a rapid adsorption step (seconds-minutes) was followed by (b) a slower incorporation (hours-weeks). The incorporated Fe(II) could not be remobilized by a strong complexing agent (phenanthroline or ferrozine) but the dissolution of the outmost calcite layers with carbonic acid allowed its recovery. Based on results of the latter dissolution experiments, a stoichiometry of 0.4 mol% Fe:Ca and a mixed carbonate layer thickness of 25 nm (after 168 It equilibration) were estimated. Fe(II) sorption on calcite could be successfully described by a surface adsorption and precipitation model (Comans & Middelburg, GCA 51 (1987), 2587) and surface complexation modeling (Van Cappellen et al., GCA 57 (1993), 3505; Pokrovsky et al., Langmuir 16 (2000), 2677). The surface complex model required the consideration of two adsorbed Fe(II) surface species, >CO3Fe+ and >CO3FeCO3H0. For the formation of the latter species, a stability constant is being suggested. The oxidation kinetics of Fe(II) in the presence of calcite depended on the equilibration time of aqueous Fe(II) with the mineral prior to the introduction of oxygen. If pre-equilibrated for >15 h, the oxidation kinetics was comparable to a calcite-free system (t(1/2) = 145 +/- 15 min). Conversely, if Fe(II) was added to an aerated calcite suspension, the rate of oxidation was higher than in the absence of calcite (t(1/2) = 41 +/- 1 min and t(1/2) = 100 +/- 15 min, respectively). This catalysis was due to the greater reactivity of the adsorbed Fe(II) species, >CO3FeCO3H0, for which the species specific rate constant was estimated. (c) 2009 Elsevier Ltd. All rights reserved. |
format |
Text |
author |
Mettler, Suzanne Wolthers, Mariette Charlet, Laurent von Gunten, Urs |
spellingShingle |
Mettler, Suzanne Wolthers, Mariette Charlet, Laurent von Gunten, Urs Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
author_facet |
Mettler, Suzanne Wolthers, Mariette Charlet, Laurent von Gunten, Urs |
author_sort |
Mettler, Suzanne |
title |
Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
title_short |
Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
title_full |
Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
title_fullStr |
Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
title_full_unstemmed |
Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
title_sort |
sorption and catalytic oxidation of fe(ii) at the surface of calcite |
publishDate |
2011 |
url |
http://infoscience.epfl.ch/record/167234 https://doi.org/10.1016/j.gca.2009.01.003 |
long_lat |
ENVELOPE(-67.150,-67.150,-66.967,-66.967) |
geographic |
Langmuir |
geographic_facet |
Langmuir |
genre |
Carbonic acid |
genre_facet |
Carbonic acid |
op_source |
http://infoscience.epfl.ch/record/167234 |
op_relation |
http://infoscience.epfl.ch/record/167234 doi:10.1016/j.gca.2009.01.003 ISI:000264518500003 |
op_doi |
https://doi.org/10.1016/j.gca.2009.01.003 |
container_title |
Geochimica et Cosmochimica Acta |
container_volume |
73 |
container_issue |
7 |
container_start_page |
1826 |
op_container_end_page |
1840 |
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1768385676625051648 |