Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
576952 | Journal of Hazardous Materials | 2014 | 9 Pages |
Abstract
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 ± 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 Ã
, 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.
Keywords
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Chemical Health and Safety
Authors
Susanta Paikaray, Joseph Essilfie-Dughan, Jörg Göttlicher, Kilian Pollok, Stefan Peiffer,