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Arsenic(III) Oxidation by Iron(VI) (Ferrate) and Subsequent Removal of Arsenic(V) by Iron(III) Coagulation

Title
Arsenic(III) Oxidation by Iron(VI) (Ferrate) and Subsequent Removal of Arsenic(V) by Iron(III) Coagulation
Authors
Lee Y.Um I.-H.Yoon J.
Ewha Authors
엄익환
SCOPUS Author ID
엄익환scopusscopus
Issue Date
2003
Journal Title
Environmental Science and Technology
ISSN
0013-936XJCR Link
Citation
vol. 37, no. 24, pp. 5750 - 5756
Indexed
SCI; SCIE; SCOPUS WOS scopus
Abstract
We investigated the stoichiometry, kinetics, and mechanism of arsenite [As(III)] oxidation by ferrate [Fe(VI)] and performed arsenic removal tests using Fe(VI) as both an oxidant and a coagulant. As(III) was oxidized to As(V) (arsenate) by Fe(VI), with a stoichiometry of 3:2 [As(III):Fe(VI)]. Kinetic studies showed that the reaction of As(III) with Fe(VI) was first-order with respect to both reactants, and its observed second-order rate constant at 25 °C decreased nonlinearly from (3.54 ± 0.24) × 105 to (1.23 ± 0.01) × 103 M-1 s-1 with an increase of pH from 8.4 to 12.9. A reaction mechanism by oxygen transfer has been proposed for the oxidation of As(III) by Fe(VI). Arsenic removal tests with river water showed that, with minimum 2.0 mg L-1 Fe(VI), the arsenic concentration can be lowered from an initial 517 to below 50 μg L-1, which is the regulation level for As in Bangladesh. From this result, Fe(VI) was demonstrated to be very effective in the removal of arsenic species from water at a relatively low dose level (2.0 mg L -1). In addition, the combined use of a small amount of Fe(VI) (below 0.5 mg L-1) and Fe(III) as a major coagulant was found to be a practical and effective method for arsenic removal.
DOI
10.1021/es034203+
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자연과학대학 > 화학·나노과학전공 > Journal papers
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