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

Abstract

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.