Oxidized multiwalled carbon nanotubes (MWCNTs) were characterized by SEM and FTIR. The sorption of Th(IV) on MWCNTs was studied
as a function of contact time, pH, ionic strength, Th(IV) concentration and temperature. The results indicate that the sorption
of Th(IV) on MWCNTs is strongly dependent on pH and weakly dependent on ionic strength. The sorption thermodynamics of Th(IV)
on MWCNTs was carried out at 293.15, 313.15 and 333.15 K, respectively, and the thermodynamic parameters (standard free energy
changes (ΔG0), standard enthalpy change (ΔH0) and standard entropy change (ΔS0)) were calculated from the temperature dependent sorption isotherms. The sorption of Th(IV) on MWCNTs is a spontaneous and
endothermic process. The oxidized MWCNTs may be a promising candidate for the preconcentration and solidification of Th(IV),
or its analogue actinides from large volumes of aqueous solutions.