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Reactions at Oxide Surfaces. 1. Oxidation of As(III) by Synthetic Birnessite

Scott, Michael J. and Morgan, James J. (1995) Reactions at Oxide Surfaces. 1. Oxidation of As(III) by Synthetic Birnessite. Environmental Science and Technology, 29 (8). pp. 1898-1905. ISSN 0013-936X. doi:10.1021/es00008a006.

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The rates and mechanisms of the reactions between aqueous As(III) and synthetic birnessite (δ-MnO_2) particles were studied. The experimental results at pH 4 indicate that the depletion of As(III) from solution is rapid, with a time scale of minutes. The oxidation product As(V) is released almost as quickly, while the release of the reduction product Mn(II) is slightly slower. The results also show that the concentration of dissolved oxygen has no effect on the rate of reaction. These observations suggestthat (i) birnessite directly oxidizes As(III) through a surface mechanism, (ii) the adsorption of As(III) is the slowest step in the production of As(V), and (iii) the reaction products As- (V) and Mn(II) are released via different mechanisms. The time-dependent behavior of the aqueous reactants and products over a pH range from 4 to 8.2, and a temperature range from 15 to 35 °C is also discussed. The rates of As(III) oxidation by inorganic redox reactions with manganese dioxides are compared to observed As(III) oxidation rates in natural aquatic systems.

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Additional Information:© 1995 American Chemical Society. Received for review August 15, 1994, Accepted April 18, 1995. This research was funded in part by the Andrew W. Mellon Foundation, by the United States Department of the Interior, Geological Survey, through the State Water Resources Research Institute (Project 14-08-0001-G1550), and by the University of California Water Resources Center [Project UCAL-WRC-W-22605-89(03)].
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Andrew W. Mellon FoundationUNSPECIFIED
University of California Water Resources CenterUCAL-WRC-W-22605-89(03)
Issue or Number:8
Record Number:CaltechAUTHORS:20180313-083650021
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Official Citation:Reactions at Oxide Surfaces. 1. Oxidation of As(III) by Synthetic Birnessite. Michael J. Scott and James J. Morgan. Environmental Science & Technology 1995 29 (8), 1898-1905 DOI: 10.1021/es00008a006
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:85268
Deposited By: Tony Diaz
Deposited On:13 Mar 2018 17:22
Last Modified:15 Nov 2021 20:27

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