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...
Published in: | Geochimica et Cosmochimica Acta |
---|---|
Main Authors: | , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
Elsevier
2009
|
Subjects: | |
Online Access: | https://doi.org/10.1016/j.gca.2009.01.003 |
id |
fteawag:oai:dora:eawag_6005 |
---|---|
record_format |
openpolar |
spelling |
fteawag:oai:dora:eawag_6005 2024-09-15T18:01:42+00:00 Sorption and catalytic oxidation of Fe(II) at the surface of calcite Mettler, Suzanne Wolthers, Mariëtte Charlet, Laurent von Gunten, Urs 2009 https://doi.org/10.1016/j.gca.2009.01.003 eng eng Elsevier Geochimica et Cosmochimica Acta--Geochim. Cosmochim. Acta--journals:1114--0016-7037--0046-564X eawag:6005 journal id: journals:1114 issn: 0016-7037 e-issn: 0046-564X ut: 000264518500003 local: 13520 scopus: 2-s2.0-61849182048 doi:10.1016/j.gca.2009.01.003 Text Journal Article 2009 fteawag https://doi.org/10.1016/j.gca.2009.01.003 2024-08-05T03:04:28Z 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 h 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, >CO 3 Fe + and >CO 3 FeCO 3 H 0 . 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, >CO 3 FeCO 3 H 0 , for which the species specific rate constant was estimated. Article in Journal/Newspaper Carbonic acid DORA Eawag Geochimica et Cosmochimica Acta 73 7 1826 1840 |
institution |
Open Polar |
collection |
DORA Eawag |
op_collection_id |
fteawag |
language |
English |
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 h 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, >CO 3 Fe + and >CO 3 FeCO 3 H 0 . 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, >CO 3 FeCO 3 H 0 , for which the species specific rate constant was estimated. |
format |
Article in Journal/Newspaper |
author |
Mettler, Suzanne Wolthers, Mariëtte Charlet, Laurent von Gunten, Urs |
spellingShingle |
Mettler, Suzanne Wolthers, Mariëtte Charlet, Laurent von Gunten, Urs Sorption and catalytic oxidation of Fe(II) at the surface of calcite |
author_facet |
Mettler, Suzanne Wolthers, Mariëtte 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 |
publisher |
Elsevier |
publishDate |
2009 |
url |
https://doi.org/10.1016/j.gca.2009.01.003 |
genre |
Carbonic acid |
genre_facet |
Carbonic acid |
op_relation |
Geochimica et Cosmochimica Acta--Geochim. Cosmochim. Acta--journals:1114--0016-7037--0046-564X eawag:6005 journal id: journals:1114 issn: 0016-7037 e-issn: 0046-564X ut: 000264518500003 local: 13520 scopus: 2-s2.0-61849182048 doi:10.1016/j.gca.2009.01.003 |
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 |
_version_ |
1810438783725731840 |