Selective separation of lanthanides with phenolic resins:: extraction behavior and thermal stability

Catechol, resorcinol, and their admixtures with 8-hydroxyquinoline were converted into polymeric resins by alkaline polycondensation with formaldehyde. The resins were characterized by FTIR spectroscopy, moisture regain, ion-exchange capacity, and distribution coefficient (D) for Eu3+. Thermogravimetric analysis of the polymer samples was studied, and the effect of the sorption of metal ions on their thermal stability was evaluated. Complexation of Eu3+ to the resins was modeled based on metal ion charge neutralization. The selective uptake of Eu3+ from aqueous solutions containing La3+ was investigated, and the ionoselectivities of the resins were compared. The incorporation of 8-hydroxyquinoline in the molecular matrix of the phenolic resins is shown to exert a significant influence upon the competitive sorption of La3+ and Eu3+, leading to their intragroup separation. The separation factors obtained by phenolic ton-exchange resins from aqueous solutions indicate ion-specific resins can be developed for the specific separation of actinide ions from nuclear waste.