EXTRACTION OF CERIUM(III) BY SOLID EXTRACTANT IMPREGNATED WITH DIHEXYL-N,N-DIETHYLCARBAMOYLMETHYLPHOSPHONATE

A solid extractant, a porous styrene-divinylbenzene copolymer (SDB) im pregnated with dihexyl-N, N-diethylcarbamoylmethylphosphonate (CMP), w as developed for the extraction of rare-earth elements. Solid extracta nts supported by SDB particles with different crosslinking and pore vo lume were prepared and the extraction of Ce(III) from aqueous phase co ntaining nitrate ion was examined. SEM observation suggested that the impregnated CMP was dissolved in the SDB polymer network. The CMP cont ent increased by use of SDB particles with lower crosslinking and high er pore volume. The stoichiometric relation for the extraction reactio n was represented by Ce3+ + 3NO3- + 3CMP reversible Ce(NO3)3.3CMP whic h was the same as that for the liquid-liquid extraction. The extractio n rate increased with decrease of particle size. The rate-controlling step was the intraparticle diffusion of Ce(III) for solid extractant o f diameter greater than 0.2 mm. For smaller particles, it changed to t he reaction between CMP and Ce(III).