Understanding the sorption behavior of trivalent lanthanides on amide functionalized multi walled carbon nanotubes

An attempt was made to understand the sorption behavior of trivalent lanthanides (La, Nd, Gd, Er and Lu) onto amide functionalized multiwalled carbon nanotubes (CNT-DHA). The Kd values were found to follow the trend: Lu3 + > La3 + ~ Gd3 + > Nd3 + > Er3 +, which was attributed to a combination of the water exchange mechanism and the hydration number of trivalent lanthanides in solution. Analysis of sorption isotherm via Langmuir, Temkin, Freundlich and Dubinin-Radushkevich isotherm revealed the sorption process was physisorption and cooperative. Based on the linear regression analysis, the sorption processes were found to proceed via Freundlich isotherms. The sorption process followed pseudo second order kinetics with the trend in rate constants Nd3 + > Er3 + > La3 + > Lu3 + > Gd3 +. CNT-DHA was found to be radiolytically stable with a slight decrease in sorption performance. Quantitative back extraction of Ln3 + from loaded CNT-DHA was effectively done by EDTA solution.