As(III) and As(V) Adsorption by Hydrous Zirconium Oxide Nanoparticles Synthesized by a Hydrothermal Process Followed with Heat Treatment
2012
Hang, Cui | Li, Qi | Gao, Shian | Shang, Jian Ku
Hydrous zirconium oxide (ZrO₂·xH₂O) were synthesized by a low-cost hydrothermal process followed with heat treatment. ZrO₂·xH₂O nanoparticles ranged from 6 nm to 10 nm and formed highly porous aggregates, resulting in a large surface area of 161.8 m² g–¹. The batch tests on the laboratory water samples demonstrated a very high degree of As(III) and As(V) removal by ZrO₂·xH₂O nanoparticles. The adsorption mechanism study demonstrated that both arsenic species form inner-sphere surface complexes on the surface of ZrO₂·xH₂O nanoparticles. Higher arsenic removal effect of these ZrO₂·xH₂O nanoparticles were demonstrated, compared with commercially available Al₂O₃ and TiO₂ nanoparticles. Ionic strength and competing ion effects on the arsenic adsorption of these ZrO₂·xH₂O nanoparticles were also studied. Testing with natural lake water confirmed the effectiveness of ZrO₂·xH₂O nanoparticles in removing arsenic species from natural water, and the immobilization of ZrO₂•xH₂O nanoparticles on glass fiber cloth minimized the dispersion of nanoparticles into the treated body of water. The high adsorption capacity of ZrO₂·xH₂O 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.
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