Complexation of strontium in the synergistic extraction system dicyclohexano-18-crown-6, versatic acid, carbon tetrachloride

Bruce A. Moyer, W. J. McDowell, R. J. Ontko, S. A. Bryan, G. N. Case

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25 Scopus citations

Abstract

The synergism in the extraction of Sr2+ from 0.5M Sr(NO3)2 by 0.05M dicyclohexano-18-crown-6 (DC18C6) + 0.1M Versatic 1519 (abbreviated V-acid or RCOOH, a neo carboxylic acid) in CCl4 has been found to stem from a strong 1:1 interaction between DC18C6 and Sr2+. However, both nitrate and carboxylate can function as the anion for the (DC18C6)Sr2+ moiety. At aqueous conditions corresponding to less than complete loading (i.e., [Sr2+)org < 0.05M for pH < 11.7), (DC18C6)Sr(NO3)2 precipitates as a solid. As the pH is raised in the interval 7 < pH < 11.7 to deprotonate the V-acid, the precipitate (DC18C6)Sr(NO3)2 becomes solubilized first with probable formation of a mixed-anion complex and finally with quantitative (0.05M) formation of the monomeric complex (DC18C6)Sr(OOCR)2·H2O at pH = 11.7 as confirmed by viscometric titration of 0.05M DC18C6 in wet CCl4 with Sr(OOCR)2, Karl-Fischer titrations, vapor-phase osmometry, and IR spectrophotometry.

Original languageEnglish
Pages (from-to)83-93
Number of pages11
JournalSolvent Extraction and Ion Exchange
Volume4
Issue number1
DOIs
StatePublished - Jan 1 1986

Funding

This research was sponsored by the Division of Chemical Sciences, Office of Basic Energy Sciences, U.S. Department of Energy under contract DE-Aa5-840R21400 with Martin Marietta Energy Systems, Inc. and supported i n part (S. A. Bryan) by an appointment to the U.S. Department of Energy Postgraduate Research Training program administered by Oak Ridge Associated Universities. The authors would like to thank George Begun of ORNL for help in obtaining the infrared data, and John Burns of ORNL for insightful discussions on bonding interactions in crown-e ther complexes.

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