Structural model of arsenic(III) adsorbed on gibbsite based on DFT calculations

This study investigates the adsorption behavior of As(III) on gibbsite (g-Al(OH)3), focusing on the mechanisms governing this process. The mobility of arsenic species in the environment, particularly As(III), poses significant concerns, as its adsorption behavior contradicts its high mobility. To understand this discrepancy, density functional theory (DFT) calculations were employed to analyze two distinct adsorption mechanisms of H3AsO3 on gibbsite. The results reveal that As(III) is not adsorbed through an acid/base mechanism but rather via a non-dissociative approach, where O–H bonds remain intact during adsorption. This finding suggests that the formation of inner-sphere complexes does not compromise the remobilization potential of As(III), providing insight into its environmental behavior. The implications of these findings are crucial for better understanding arsenic contamination in soils and developing remediation strategies.