Surface Hydroxyl\nGroups Functionalized Porous CeO<sub>2</sub> for Enhanced Selective\nAdsorption of As(III)

The adsorption technique has been considered as one of\nthe promising\nmethods to remove arsenic ions in aqueous systems. However, the adsorbents\nare usually poorly selective and have low capacity. Herein, a kind\nof porous CeO<sub>2</sub> containing surface hydroxyl group which\nsynthesized facilely possesses the great performance of selective\nadsorption of As(III) with 98.57% removal against 14 other coexisting\nmetal ions. The results showed that the processes of As(III) and As(V)\nuptake were heterogeneous monolayer adsorptions and included external\nand intraparticle diffusions. The adsorption capacities at pH 2.5\nreached 111.24 and 56.89 mg/g for As(III) and As(V), respectively.\nIn addition, it also showed that As(III) could be oxidized to As(V)\nin the adsorption process. Density functional theory calculations\nrevealed that the OH group in H<sub>3</sub>AsO<sub>3</sub><sup>0</sup> and the As atom in H<sub>3</sub>AsO<sub>4</sub><sup>0</sup> have\naffinity with lattice oxygen (O<sup>2–</sup>) in CeO<sub>2</sub>, while the O atom in H<sub>2</sub>AsO<sub>4</sub><sup>–</sup> preferred the Ce atom in CeO<sub>2</sub>. This study provides a\nnovel porous CeO<sub>2</sub> containing hydroxyl groups for selective\nand efficient removal of arsenic and elucidates the mechanism of As(III)\nand As(V) adsorptions.