Silica-based solvent impregnated adsorbents for separation of rare earth metals

Silica-based solvent impregnated adsorbents are prepared, employing 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester as an extractant. Two kinds of silica particles are used as supports; (i) those whose surface is coated by a styrene/divinylbenzene copolymer and (ii) those whose hydroxyl-terminated pentadimethyl siloxane group is immobilized on the surface. The adsorbent based on silica particles coated by styrene/divinylbenzene can be repeatedly used for adsorption–elution processing, while the adsorption capacity of the adsorbent based on silica particles modified by the siloxane group is decreased by repeated cycles. The adsorbent is applicable to chromatographic operation for Dy/Nd, and quantitative adsorption–elution is achieved.