As(III) and As(V) Adsorption by Hydrous Zirconium Oxide Nanoparticles Synthesized by a Hydrothermal Process Followed with Heat Treatment

Hydrous zirconium oxide (ZrO 2 · x H 2 O) were synthesized by a low-cost hydrothermal process followed with heat treatment. ZrO 2 · x H 2 O nanoparticles ranged from 6 nm to 10 nm and formed highly porous aggregates, resulting in a large surface area of 161.8 m 2 g –1 . The batch tests on the laboratory water samples demonstrated a very high degree of As(III) and As(V) removal by ZrO 2 · x H 2 O nanoparticles. The adsorption mechanism study demonstrated that both arsenic species form inner-sphere surface complexes on the surface of ZrO 2 · x H 2 O nanoparticles. Higher arsenic removal effect of these ZrO 2 · x H 2 O nanoparticles were demonstrated, compared with commercially available Al 2 O 3 and TiO 2 nanoparticles. Ionic strength and competing ion effects on the arsenic adsorption of these ZrO 2 · x H 2 O nanoparticles were also studied. Testing with natural lake water confirmed the effectiveness of ZrO 2 · x H 2 O nanoparticles in removing arsenic species from natural water, and the immobilization of ZrO 2 •xH 2 O nanoparticles on glass fiber cloth minimized the dispersion of nanoparticles into the treated body of water. The high adsorption capacity of ZrO 2 · x H 2 O nanoparticles is shown to result from the strong inner-sphere surface complexing promoted by the high surface area, large pore volume, and surface hydroxyl groups of zirconium oxide nanoparticles.