Adsorption of arsenate on lanthanum-impregnated activated alumina: In situ ATR-FTIR and two-dimensional correlation analysis study

Lanthanum modified materials have been widely used for the removal of hazardous anions. In this study, in situ ATR-FTIR and two-dimensional correlation analysis were employed to investigate the adsorption mechanism of arsenate (As(V)) on lanthanum-impregnated activated alumina (LAA). Our results showed that electrostatic interaction attracted As(V) anions to the LAA surface, and then As(V) could form monodentate configuration on the LAA surface at pH 5-9. The result of 2D-COS showed that two coexistent adsorbed As(V) species, H2AsO4- and HAsO4-2, were adsorbed on the LAA surface without specific sequence at different pH conditions, indicating a negligible role of the incorporated protons of As(V) on the adsorption affinity to LAA surface. The results of this study reveal insights into LAA surface complexes on the molecular scale and provide theoretical support to new metal oxides design for efficient arsenic removal.