Sorption and speciation of arsenic by ze

This study investigates the sorption and speciation of arsenic in groundwater remediation utilizing zero-valent iron (ZVI) through batch and column experiments. The batch tests revealed that arsenite was effectively oxidized to arsenate, which was subsequently immobilized via co-precipitation with Fe(II)-bearing corrosion products, leading to As(V) becoming the prevalent surface species. In the column experiments, after introducing influent containing arsenite for 22 pore volumes, As(III) was found to be the dominant species on the ZVI surface throughout the column segments. Notably, significant oxidation of arsenite to arsenate occurred predominantly near the inlet. This effect was attributed to prolonged contact between ZVI and high concentrations of arsenite, which resulted in corrosion product accumulation. Supporting evidence from XPS indicated a reduction in the relative intensity of the As(III) peaks while the oxidation mechanism was primarily proposed. Furthermore, geochemical calculations and SEM-EDX analyses suggested that both arsenite and arsenate co-precipitated with Fe(II)-bearing minerals and carbonates, contributing to the overall understanding of arsenic behavior in remediation processes.