Extraction of strontium and barium by nitrobenzene solution of dicarbolide in the presence of polyethylene glycols

Abstract

Extraction of microamounts of Sr2+ and Ba2+ from 0.2-1.0M-HClO4 by the nitrobenzene solutions of dicarbolide H+[Co(C2B9H11)2]- in the presence of polyethylene glycols (PEG) (Mr = 200, 300, 400) has been investigated. It has been found that the extraction of the protonized polyethylene glycol molecule (H+ + L ##e HL+, where the bar denotes species present in the organic phase) and the extraction of the complex between the extracted ion and polyethylene glycol, i.e., M2+ +L + 2 H+ ##e ML2+ + 2 H+, are the predominant reactions in this system. The respective equilibrium constants have been determined. The hydration numbers of HL+ and ML2+ ions in the organic phase have been obtained from the determination of water content by Karl Fischer titration method. The extraction constants and stability constants in the organic phase increase in the sequence H+ < Sr2+ < Ba2+ and PEG 200 < PEG 300 < PEG 400, while the hydration numbers decrease in the same sequence. Correlations between the hydration numbers and the extraction constants for these cations have been found.

N,N,N’,N’-Tetrabutyl-1,10-phenanthroline- 2,9-dicarboxamide as Very Effective Extraction Agent for Trivalent Europium and Americium

“…A subroutine UBBE, based on the relations given above, the mass balance of the N,N,N',N'-tetrabutyl-1,10phenanthroline-2,9-dicarboxamide (L) ligand and the electroneutrality conditions in both phases of the system under consideration, was formulated 36,37 and introduced into a more general least-squares minimizing program LETAGROP 38 used for determination of the "best" values of the extraction constants K ex (ML The values log K D = 2.2 (see Table 5, footnote a), logβ(HL + org ) = 9.4 ( Tables 3 and 4. From these tables it is evident that the extraction data can be best explained assuming the complexes ML a The values of the extraction constants are given for each complex.…”

Nature of strontium extraction by synergistic mixtures of chlorinated cobalt dicarbollide and polyethers

“…DCC in H-form is known to be a superacid and dissociates completely in polar organic solvents [2]. The authors [4] showed that during the extraction process the hydrated proton of H-DCC acid in organic phase (H § O, n = 5,5) is exchanged to the strongly hydrated strontium cation, Sr(H20)2+n, (n = 12,1-12,3). Addition of PEG into this system results in the displacement of a portion of water molecules from the hydrate shells of the proton and strontium, to form the cation complexes of the composition H+.(PEG-400).…”

“…Therefore, the distribution coefficient of Sr 2+ increases by a factor of 103 in the presence of PEG. According to [4], each oxyethyl group of PEG is capable of displacing one water molecule from hydrate shell of the strontium cation.…”

“…The authors [4] studied the extraction of Sr and Ba from nitric and perchloric acid media using DCC nitrobenzene solutions in the presence of different PEGs. The water content in extracts was concurrently determined by Fisher titration.…”

“…Later, this extraction system was extensively investigated [2] and successfully used in commercial HLW reprocessing [3]. The most comprehensive description of DCC -PEG system is given in [4].…”