Arsenic removal from water by nanometer iron oxide coated single-wall carbon nanotubes

Single-wall carbon nanotubes (SWCNTs) were prepared by arc discharge evaporation of a carbon electrode containing Fe catalyst so that there are an amount of iron nanoparticles attached tightly on SWCNTs. The iron oxide nanoparticle coated SWCNT composite was prepared in situ by oxidizing the above as-grown SWCNTs in air at 350°C, which was used as an adsorbent for As5+ removal from water. It was found that the maximum As5+ adsorption capacity of the composite was 42.30 mg g−1 at pH 8 and 49.65 mg g−1 at pH 4, respectively. The kinetics data were best fitted with a pseudo-second order, thus suggesting chemical adsorption on the surface and pores of iron oxide nanoparticles. The adsorption isotherm obtained at pH 8 was best fitted to the Freundlich model, therefore a non-ideal adsorption on heterogeneous surfaces for As5+ ions on iron oxide nanoparticles was proposed. The firm web structure with high adsorption capacity makes the composite a promising adsorbent for arsenic removal in contaminated water.