Coprecipitation of gadolinium with calcium sulphate dihydrate

The present study reports the coprecipitation of gadolinium with calcium sulphate dihydrate, in aqueous solutions of sulphuric acid, at constant ionic strength using a rachotracer technique. The experimental results obtained at ambient temperature, show that the quantity of gadolinium ions coprecipitated in gypsum identified by X-ray diffraction (XRD) and elemental analysis is very small, lower than 4 at. %. The mechanism of coprecipitation of Gd(III) has been discussed, although the elementary processes of the mechanism are not clear. The distribution of gadolinium between precipitate of gypsum and saturated aqueous solutions of H(2)SO(4) has been measured between 30 and 70 degrees C. Experiments of coprecipitation indicate that the coefficient of distribution of Gd(III) depends on the solubility and nature of solid calcium sulphate phase.