Chemical and electrochemical oscillatory extraction of F-elements - new procedure development

A new separation extraction system was created based on an oscillatory extraction/stripping process in two extractors coupled by a bulk liquid membrane stream (0.5 M tributylphosphate (TBP) in tetradecane). The cyclic Belousov-Zhabotinsky (BZ) reaction and electrochemical oxidation/reduction were used to induce the cyclic extraction-stripping process. In the part of work devoted to the chemical oscillatory extraction with BZ reaction in aqueous phase equimolar solutions of Nd and Pr, in presence of potassium bromate and malonic acid (HMal), were used. It was demonstrated that in different conditions the concentration of Pr in the liquid membrane decreased faster than the concentration of Nd during oscillatory process in the aqueous phase. It was shown that the separation of the pair Pr/Nd was achieved and the Pr/Nd pair effective separation coefficient is equal to 3. In the part of work devoted to the electrochemical oscillatory extraction, the possibility of periodic oxidation and reduction of cerium ions was established. The possibility of using this approach to separate the rare earth elements (REE) was considered. The conditions in which the enrichment coefficient of the pair Pr/Nd is equal to 6.25 in an organic phase were determined. The possibility to use an oscillatory extraction approach to separate elements with similar partition coefficients was demonstrated. (C) 2003 Elsevier B.V. All rights reserved.