Adsorption characteristics of gadolinium and dysprosium with microcapsules containing an extractant

The adsorption and separation of gadolinium and dysprosium from aqueous solution were conducted using microcapsules containing a metal extractant, dibenzoylmethane as an extractant. The spherical microcapsules with an average diameter of 196 μm were prepared through encapsulation of the extractant by in situ radical polymerization of divinylbenzene. The results for adsorption equilibrium of each metal were applied to the Langmuir adsorption isotherm model to explain the experimental results. The extent of metal adsorbed on the microcapsules increased as the pH of the metal solution increased. In a binary system of gadolinium and dysprosium, only dysprosium was adsorbed on the microcapsules at pH 6.0; this shows that the separation of these metals can be achieved at pH 6.0. The adsorption rate of the metals was also measured, which indicated that the metal complex formation reaction and the diffusion of the metal complex through the pores of the microcapsules contributed to the overall adsorption process of the metals.