Separation of Cobalt From Europium with Mesoporous Hybrid Silica-Poly(Styrene) Impregnated Chelating Resin

This article describes resins for extraction chromatography capable of separating cobalt from europium. Radionuclides Eu-152 and Co-57 were used to represent the REEs and heavy metals. Resins were prepared by immobilizing poly(styrene) on porous silica particles and impregnating the particles with an organic extractant: Octyl(phenyl)-N,N-disiobutylcarbamoylmethylphosphineoxide (CMPO), bis(2,4,4-trimethylphentyl)dithiophosphinic acid (Cyanex-301), 2-thenoyl trifluoroacetone (HTTA), tributylphosphate (TBP) or dibenzo-21-crown-7 (DB21C7). The specific adsorption of Eu(III) and Co(II) was studied by measuring distribution coefficients and uptake percentages as a function of contact time, solution pH and metal ion concentration. The new resins, especially Cyanex 301/SiO2-P, provide rapid kinetics and high adsorption selectivity for Co(II). The efficient and selective adsorption of Eu(III) on SiO2-P impregnated with CMPO, a bifunctional organophosphorus compound and HTTA, a β-diketone compound, is attributed to strong complex formation between the soft donor atom of each chelating ligand and trivalent ion.