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

Abstract

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 (K _d ) 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 TmI₃·3THF. A study of the co-crystallization of ¹⁰⁹Cd and ⁶⁵Zn, as well as ⁸⁵Sr²⁺ microquantities with the TmI₃·3THF solid phase in the presence of Tm²⁺ from THF solutions showed that in contrast to ⁸⁵Sr²⁺, ¹⁰⁹Cd and ⁶⁵Zn microquantities co-crystallized with the TmI₃·3THF 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 M₂ ³⁺ (M=Cd and Zn).