Molecular-level insights into surface complexation of arsenite, selenium and cadmium on {2 0 1} TiO2

•{201} TiO2 was developed for Se(IV) and As(III) removal for the first time.•High adsorption capacity for Se (0.25 mmol/g) and As (0.32 mmol/g) was achieved.•Se(IV)/As(III) formed bidentate binuclear complexes at bridge-Ti4C of {201} TiO2.•Cd(II) enhanced Se/As adsorption on {201} TiO2 by forming ternary complexes.•Change in hybrid orbital energy drives the antagonistic and synergistic adsorption.