Redox-state-dependent adsorption of arsenic and antimony on hydrothermally synthesized mesoporous boehmite (γ-AlOOH): mechanistic insights from synchrotron-based spectroscopy

) precipitated. Synchrotron-based spectroscopic analyses demonstrated that As(III/V) and Sb(V) form inner-sphere complexes with surface hydroxyl groups, whereas Sb(III) interacts mainly through weaker outer-sphere associations with negligible Al coordination. Molecular-scale structural interpretation further revealed that As(III) and As(V) form bidentate binuclear corner-sharing complexes on the boehmite surface, whereas Sb(V) forms both bidentate edge- and corner-sharing geometries. Therefore, metalloid adsorption was governed by oxidation-state-dependent surface complexation mechanisms, highlighting that efficiently removing As and Sb requires solution conditions tailored to each species. This study provides mechanistic insights into redox-dependent metalloid adsorption and demonstrates hydrothermally engineered boehmite as a high-capacity adsorbent among pristine aluminum oxyhydroxides without post-modification for metalloid remediation in complex aqueous systems.