A study of the behavior of cadmium and zinc microquantities in sorption and coprecipitation processes in tetrahydrofuran solutions

The sorption of 109Cd and 65Zn microquantities with NaX and NaA zeolites in the presence of divalent lanthanides (Ln2+) (Ln=Tm, Dy, and Nd) from tetrahydrofuran (THF) solutions was studied. It was found that in contrast to 137Cs+, 109Cd and 65Zn, as well as 85Sr2+ microquantities were sorbed by zeolites very poorly: ∼99% of the species remained in solution. The distribution coefficients (Kd) of 109Cd and 65Zn were ∼0.3 and ∼0.4 ml/g, respectively. When Tm2+ was used as a reducer, it partially oxidized in solution to Tm3+ to form precipitates of the composition TmI3 x 3THF. A study of the co-crystallization of 109Cd and 65Zn, as well as 85Sr2+ microquantities with the TmI3 x 3THF solid phase in the presence of Tm2+ from THF solutions showed that in contrast to 85Sr2+, 109Cd and 65Zn microquantities co-crystallized with the TmI3 x 3THF solid phase. The co-crystallization coefficients (D) for 109Cd and 65Zn depended on the ratio Tm3+/Tm2+ in solution and increased with its increasing. The assumption was made that in the presence of Tm2+, 109Cd2+ and 65Zn2+ form M+ ions, which quickly react with M2+ ions to form dimers of the composition M23+ (M=Cd and Zn). (author)