As(III) and As(V) adsorption on nanocomposite of hydrated zirconium oxide coated carbon nanotubes.

Novel hydrated zirconium oxide (ZrO(OH)2) coated carbon nanotubes (CNTs) were prepared via a filtration-steam hydrolysis method, and were used to remove As(III) and As(V) from drinking water. This adsorbent was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron microscope (SEM) and transmission electron microscope (TEM). The ZrO(OH)2 coated on the surface of CNTs was amorphous, and the coating thickness was in the range of 1-8 nm. The ZrO(OH)2/CNTs nanocomposite showed high adsorption for both As(III) and As(V) with the maximum adsorption capacities of 78.2 and 124.6 mg/g, respectively, according to the Langmuir fitting. The adsorption capacities of ZrO(OH)2/CNTs at the equilibrium concentration of 10 μg/L were 2.0 mg/g for As(III) and 7.2 mg/g for As(V) at pH 7, much higher than those of ZrO(OH)2 nanoparticles. Meanwhile, the adsorption rates of As(III) and As(V) on the ZrO(OH)2/CNTs were higher than the ZrO(OH)2 nanoparticles. The spent adsorbent can be regenerated by re-coating ZrO(OH)2 as the preparation method, and the adsorbed amounts of As(III) and As(V) on the ZrO(OH)2/CNTs changed little within six cycles. This ZrO(OH)2/CNTs nanocomposite shows a promising application potential for the removal of As(III) and As(V) from drinking water.