Adsorption of uranium (VI) by amidoxime modified multiwalled carbon nanotubes

Amidoxime (AO) modified multi-walled carbon nanotubes (AO-MWCNTs) was prepared and used for adsorption of U(VI) from aqueous solution. MWCNTs were firstly irradiated at dose of 200 kGy, then acrylonitrile (AN) was grafted onto MWCNTs, and finally converted to AO to obtain AO-MWCNTs. The characterization of FTIR, SEM and XPS indicated that amidoxime was successfully grafted to the surface of MWCNTs. Adsorption of U(VI) onto AO-MWCNTs followed to the pseudo second- order kinetics model and the Langmuir isotherm model. The maximum adsorption capacity was calculate to be 67.9 mg g−1 at 298 K and pH 5.0 according to the Langmuir model. The optimum pH was in the range of 3.0–5.0. The adsorption equilibrium was achieved within 60 min. The absorption mechanisms were proposed. The AO-MWCNTs synthetized by RIGP techniques are suitable adsorbent for the separation of U (VI) from aqueous solution.