Soil arsenic removal by a permeable reactive barrier of iron coupled to an electrochemical process

This paper presents a study in which it is tested the effectiveness of zero-valent iron for arsenic remediation of a soil treatment leachate, experimental approach considers to investigate Fe° permeable reactive barrier performance for the treatment of arsenic polluted soil obtained from a mining area in central Mexico. By applying electro-remotion using a series of continuous-flow columns, allowed to obtain experimental data for critical parameters optimization to electro remediate the polluted soil, as electroosmotic flow occurs across the columns. A flow-through electrochemical reactor with major capacity was used to scale up the treatment. This experimental disposition was used with a soil sample in which porosity was enhanced by the presence of glass-fiber (relation of 1:1). Application of a 45 mA current during 7 h in an electrochemical treatment allowed obtaining arsenic removal efficiencies around 94 % at pH 7 and close to 41 % at pH 11. Polarography results indicates there is a strong interaction of Fe(OH)_3(s) - AsO₄^3- in specific conditions, which results the highest electroremotion of As(III) at neutral pH.