Extraction of Cerium (III) by Solid Extractant Impregnated with Dihexyl-N,N-Diethylcarbamoylmethylphosphonate

Abstract

A solid extractant, a porous styrene-divinylbenzene copolymer (SDB) impregnated with dihexyl-N,N-diethylearbamoylmethylphosphonate (CMP), was developed for the extraction of rare-earth elements. Solid extractants supported by SDB particles with different crosslinking and pore volume were prepared and the extraction of Ce(III) from aqueous phase containing nitrate ion was examined.
SEM observation suggested that the impregnated CMP was dissolved in the SDB polymer network. The CMP content increased by use of SDB particles with lower crosslinking and higher pore volume. The stoichiometric relation for the extraction reaction was represented by

Ce³⁺ + 3NO₃^– + 3CMP ↔ Ce (NO₃) ₃·3CMP

which was the same as that for the liquid-liquid extraction.
The extraction rate increased with decrease of particle size. The rate-controlling step was the intraparticle diffusion of Ce(III) for solid extractant of diameter greater than 0.2 mm. For smaller particles, it changed to the reaction between CMP and Ce(III).