First Investigations on the Removal of Tungsten Species from Water Using Multi-walled Carbon Nanotubes

A first study on the adsorptive removal of tungsten species from the aqueous phase by using the multi-walled carbon nanotubes (MWCNTs) is reported. The MWCNTs were employed for the uptake of tungsten species at pH 6 in batch experiments. It was observed that 100% of tungsten species were removed in 2 h, by employing 75 mg of MWCNTs from the aqueous solution containing 10 ppm of tungsten. Adsorption equilibrium data were fitted by the three isotherm models namely the Langmuir, Freundlich, and Sips isotherms and best described by a three-parameter Sips model. The maximum experimental adsorption capacity of MWCNTs for tungsten was 17.64 mg/g, while the adsorption capacity anticipated by the Langmuir and Sips isotherm models was 20.58 and 25.18 mg/g, respectively. The adsorption kinetic data was adequately fitted by a pseudo-second-order model. Our present findings ascertained that MWCNTs could be a potential adsorbent for the removal of tungsten species from the aqueous phase.