Removal of UO2 2+ from aqueous solution by plasma functionalized MWCNTs

The study was undertaken to evaluate the feasibility of functionalized multi-walled carbon nanotubes (MWCNTs) for the removal of UO₂ ²⁺ from aqueous solutions. The MWCNTs was treated by oxygen plasma and characterized by FTIR and XPS. The characterization indicates that MWCNTs is successfully functionalized of oxygen groups such as –COOH on its surface (denote as P-MWCNTs). The sorption of UO₂ ²⁺ from aqueous solution on P-MWCNTs was studied as a function of contact time, solid contents, pH, ionic strength and temperature under ambient conditions using batch experiment. Two simplified kinetic models of pseudo-first-order and pseudo-second-order were tested to determine kinetic parameters such as rate constants, equilibrium sorption capacities and related correlation coefficients for kinetic models of the sorption process. It can be seen that the UO₂ ²⁺ sorption on P-MWCNTs could be described more favorably by the pseudo-second-order model. The thermodynamic parameters (?G°, ?S°, ?H°) calculated from the temperature-dependent sorption isotherms indicated that the sorption of UO₂ ²⁺ on P-MWCNTs were an endothermic and spontaneous processes. The results of the present study suggest that P-MWCNTs can be used beneficially in treating industrial effluents containing radioactive and heavy metal ions.