Redox stability of As(III) on schwertmannite surfaces
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- 作者：Susanta Paikaray ; Joseph Essilfie-Dughan ; J枚rg G枚ttlicher ; Kilian Pollok ; Stefan Peiffer
- 关键词：Mine drainage ; As redox stability ; As immobilization ; Surface precipitation ; Iron oxyhydroxy sulphate
- 刊名：Journal of Hazardous Materials
- 出版年：30 January, 2014
- 年：2014
- 卷：265
- 期：Complete
- 页码：208-216
- 全文大小：1878 K
文摘
As(III)-enriched mine discharge often drains through Fe(III)-mineral abundant land covers which makes the understanding of its fate and redox behaviour extremely important. We therefore conducted batch kinetic and equilibrium studies at pH 3.0 卤 0.05 in anoxic media coupled with spectroscopic and microscopic examinations at variable conditions to understand possible As(III) binding mechanisms and the redox stability of As(III) on schwertmannite, a prominent ferric mineral in acid mine drainage environments. Schwertmannite acted as an efficient scavenger for As(III) compared to goethite at identical sorbent:solute ratios. As K-edge X-ray absorption near-edge structure (XANES) demonstrated partial oxidation of sorbed As(III) to As(V) on both the minerals depending on the Fe(III)/As(III) ratios (goethite acted as a better oxidant than schwertmannite). Sorbed As(III) and As(V) coordinated in a bidentate binuclear binding mechanism with As(III)/As(V)-O and As(III)/As(V)-Fe interatomic distances as 1.78/1.69 and 3.37/3.31 脜, respectively. Scanning (SEM-EDX) and transmission (TEM) electron microscopic, and IR spectroscopic measurements revealed the formation of As-containing surface coatings by sorbed As on schwertmannite.