The adsorption of Sb(III) in aqueous solution by Fe₂O₃-modified carbon nanotubes

A novel kind of iron oxide supported on carbon nanotubes (CNTs) was prepared for adsorption of antimony (Sb)(III) in aqueous solution. The iron (III) oxide (Fe₂O₃)-modified CNTs were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption and Fourier transform infrared spectrometer. Parameters affecting the adsorption efficiencies, including solution pH value, initial Sb(III) concentration, adsorbent dosage, adsorption time and temperature, were investigated. The results indicate that the removal rate of Sb(III) by Fe₂O₃-modified CNTs is 99.97% under the initial Sb(III) concentration of 1.5 mg/L, adsorbents dosage of 0.5 g/L, temperature of 25 ^oC and pH value of 7.00, which is 29.81% higher than that of the raw CNTs. The adsorption capacity increased correspondingly from 3.01 to 6.23 mg/g. The equilibrium adsorption data can be fitted to the Freundlich adsorption isotherm. In addition, it has been found that the solution pH values and adsorption temperatures have no significant influence on Sb(III) removal.