Kinetics and Mechanism of As2S3(am) Dissolution under N2
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- 作者：Ruxandra M. Floroiu ; Allen P. Davis ; and Alba Torrents
- 刊名：Environmental Science & Technology
- 出版年：2004
- 出版时间：February 15, 2004
- 年：2004
- 卷：38
- 期：4
- 页码：1031 - 1037
- 全文大小：122K
- 年卷期：v.38,no.4(February 15, 2004)
- ISSN：1520-5851
文摘
Arsenic presence in ground and surface waters poses arisk to ecosystem and human health; consequently, detailedinformation is needed on the factors that govern arsenicfate and transport in the environment. As2S3 is commonlyfound in hydrothermal and geothermal environments, hotsprings, and in gold deposits, but the dominant reactionpathways and rates of dissolution are not well understood.The objectives of this research were as follows: (1) tounderstand the effect of pH on the dissolution of As2S3 undernitrogen-purged conditions, (2) to examine arsenic andsulfur speciation upon dissolution, and (3) to develop kineticdata for modeling the dissolution of As2S3. Studies wereperformed in batch reactors for a range of pH from 2 to 8.Results indicate that As2S3 dissolution is kinetically slowbut very much dependent on pH. A J-shaped dissolution rateversus pH curve is described by the following expression:rate (
M h-1) = 0.9 + 610{OH-}0.3. Rate trends seemto follow As2S3 solubility as a function of pH. A surfacedissolution mechanism is proposed, leading to dissolvedAs(III) species. Results indicate that under anaerobicconditions, an increase in pH will act to promote the arsenicsulfide dissolution rate.
M h-1) = 0.9 + 610{OH-}0.3. Rate trends seemto follow As2S3 solubility as a function of pH. A surfacedissolution mechanism is proposed, leading to dissolvedAs(III) species. Results indicate that under anaerobicconditions, an increase in pH will act to promote the arsenicsulfide dissolution rate.