Arsenite and Arsenate Adsorption Behavior Employing Different Crystal Forms of Iron Oxyhydroxide Coexisting with Soil

Abstract

In order to evaluate a potential adsorbent to remove arsenic in soil, the asenite/arsenate adsorption properties in soil were examined by employing three different crystalline types of iron oxyhydroxides, α-FeOOH (goethite), β-FeOOH (akaganeite) and γ-FeOOH (lepidocrocite). A weathered granite soil (Masatsuchi) and a clay were used in the experiment. These soils showed a rather lower arsenic uptake than FeOOH. The arsenite/arsenate uptakes by the FeOOHs strongly depended on the pH of the equilibrium solution. The arsenic uptakes at pH = 7 with or without the soils were well-fitted by Freundlich’s equation. The arsenite/arsenate uptakes by α-FeOOH and the arsenate uptake by γ-FeOOH were negatively affected by coexistence of the soils, presumably due to leaching components such as sulfate ions from the soils, though the similar arsenite/arsenate uptakes around several mg-As/g were observed by these three types of FeOOHs.