Strong adsorption of arsenic species by amorphous zirconium oxide nanoparticles

A novel oxide adsorbent of amorphous zirconium oxide (am-ZrO2) nanoparticles was synthesized by a simple hydrothermal process for effective arsenic removal from aqueous environment. Due to their high specific surface area (327.1 m2/g), large mesopore volume (0.68 cm3/g), and the presence of high affinity surface hydroxyl groups, am-ZrO2 nanoparticles demonstrated exceptional adsorption performance on both As(III) (arsenite) and As(V) (arsenate) without pre-treatment at near neutral condition. At pH ∼ 7, the adsorption kinetic is fast and the adsorption capacity is high (over 83 mg/g for As(III) and over 32.4 mg/g for As(V), respectively). Under low equilibrium arsenic concentrations (Ce at 0.01 mg/L, the maximum contaminant level (MCL) for arsenic in drinking water), the amount of arsenic adsorbed by am-ZrO2 nanoparticles is over 0.92 mg/g for As(III) and over 5.2 mg/g for As(V), respectively. The adsorption mechanism of arsenic species onto am-ZrO2 nanoparticles was found to follow the inner-sphere complex mechanism. Testing with arsenic contaminated natural lake water confirmed the effectiveness of these am-ZrO2 nanoparticles in removing arsenic from natural water. The immobilized am-ZrO2 nanoparticles on glass fiber cloth demonstrated an even better arsenic removal performance than dispersed am-ZrO2 nanoparticles in water, paving the way for their potential applications in water treatment facility to treat arsenic contaminated water body without pre-treatment.