Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide
The reductive dissolution of hematite by H2S was investigated under conditions of constant partial pressure of H2S (10-4 to 10-2 atm), pH = 3-7 and 25°C, and under conditions where the solubility product of iron sulfide is not exceeded. The reaction proceeds by an initial (relatively fast) formation...
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| Lenguaje: | English |
| Acceso en línea: | http://hdl.handle.net/20.500.12110/paper_07437463_v8_n6_p1671_DosSantosAfonso |
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todo:paper_07437463_v8_n6_p1671_DosSantosAfonso2023-10-03T15:38:51Z Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide Dos Santos Afonso, M. Stumm, W. The reductive dissolution of hematite by H2S was investigated under conditions of constant partial pressure of H2S (10-4 to 10-2 atm), pH = 3-7 and 25°C, and under conditions where the solubility product of iron sulfide is not exceeded. The reaction proceeds by an initial (relatively fast) formation of ≡FeS- and ≡FeSH surface complexes; subsequently, electron transfer and detachment of Fe(II) from the oxide surface occur. The rate law for the dissolution can be interpreted by assuming a surface-controlled reaction depending on the surface concentration of the surface complexes ≡FeS- and ≡FeSH: Rt = ke{≡FeS-} + ke′{≡FeSH} where {≡FeS-} and {≡FeSH} are surface concentrations in mol·m-2. The experimental data are compatible with the constants ke = 30 h-1 and ke′ = 400 h-1 and surface complex formation constants for ≡FeS- (≡FeOH + H2S(g) ⇄ ≡FeS- + H+ + H2O) and ≡FeSH (≡FeOH + H2S(g) ⇄ ≡FeSH + H2O) of log Ks = -2.70 and 2.82, respectively. Preliminary experiments with lepidocrocite and goethite give results on the reaction rates that show the same kind of dependence on solution variables as those with α-Fe2O3 and are compatible with the mechanism proposed here. © 1992 American Chemical Society. JOUR English info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_07437463_v8_n6_p1671_DosSantosAfonso |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| language |
English |
| orig_language_str_mv |
English |
| description |
The reductive dissolution of hematite by H2S was investigated under conditions of constant partial pressure of H2S (10-4 to 10-2 atm), pH = 3-7 and 25°C, and under conditions where the solubility product of iron sulfide is not exceeded. The reaction proceeds by an initial (relatively fast) formation of ≡FeS- and ≡FeSH surface complexes; subsequently, electron transfer and detachment of Fe(II) from the oxide surface occur. The rate law for the dissolution can be interpreted by assuming a surface-controlled reaction depending on the surface concentration of the surface complexes ≡FeS- and ≡FeSH: Rt = ke{≡FeS-} + ke′{≡FeSH} where {≡FeS-} and {≡FeSH} are surface concentrations in mol·m-2. The experimental data are compatible with the constants ke = 30 h-1 and ke′ = 400 h-1 and surface complex formation constants for ≡FeS- (≡FeOH + H2S(g) ⇄ ≡FeS- + H+ + H2O) and ≡FeSH (≡FeOH + H2S(g) ⇄ ≡FeSH + H2O) of log Ks = -2.70 and 2.82, respectively. Preliminary experiments with lepidocrocite and goethite give results on the reaction rates that show the same kind of dependence on solution variables as those with α-Fe2O3 and are compatible with the mechanism proposed here. © 1992 American Chemical Society. |
| format |
JOUR |
| author |
Dos Santos Afonso, M. Stumm, W. |
| spellingShingle |
Dos Santos Afonso, M. Stumm, W. Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide |
| author_facet |
Dos Santos Afonso, M. Stumm, W. |
| author_sort |
Dos Santos Afonso, M. |
| title |
Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide |
| title_short |
Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide |
| title_full |
Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide |
| title_fullStr |
Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide |
| title_full_unstemmed |
Reductive dissolution of iron(III) (hydr)oxides by hydrogen sulfide |
| title_sort |
reductive dissolution of iron(iii) (hydr)oxides by hydrogen sulfide |
| url |
http://hdl.handle.net/20.500.12110/paper_07437463_v8_n6_p1671_DosSantosAfonso |
| work_keys_str_mv |
AT dossantosafonsom reductivedissolutionofironiiihydroxidesbyhydrogensulfide AT stummw reductivedissolutionofironiiihydroxidesbyhydrogensulfide |
| _version_ |
1807321549028458496 |