Abstract
Two-phase potentiometric titrimetry was used to survey the extraction of alkali metal cations from aqueous chloride solution by the lipophilic, ionizable lariat ether bis-(t-octylbenzo)-14-crown-4-acetic acid (BOB14C4AA) in o-xylene. Analysis of the data indicates that ion-exchange extraction by the crown-carboxylic acid at low loading (i.e., low conversion of BOB14C4AA to its salt form) is stronger for lithium ion than for the other alkali metals. Little or no selectivity occurs at high loadings. In comparison with the long-chain carboxylic acid 2-methyl-2-heptylnonanoic acid (HMHN), BOB14C4AA extracts lithium and sodium at significantly lower pH; in the loading range of 0.1 to 0.7, the pH shift is 1.4-1.8 pH units for sodium ion and 1.7-2.3 pH units for lithium ion. The titration data are interpreted in terms of aggregated organic-phase species. In the case of lithium extraction, clear evidence was found for a species in which neutral BOB14C4AA participates in the organic-phase complexation of the metal cation.
| Original language | English |
|---|---|
| Pages (from-to) | 1-23 |
| Number of pages | 23 |
| Journal | Separation Science and Technology (Philadelphia) |
| Volume | 28 |
| Issue number | 1-3 |
| DOIs | |
| State | Published - Jan 1 1993 |
Funding
This research was funded by the Division of Chemical Sciences, Office of Basic Energy Sciences U. S. Department of Energy under contract DE-AC05-840R21400 with Martin Marietta Energy Systems, Inc. The support of the U. S. Department of Energy Oak Ridge Science and Engineering Research Program administered by the Oak Ridge Associated Universities was responsible for the participation of S. A. Garmon. The authors wish to thank their coworkers J. H. Bums and W. J. McDowell for their contributions in the research that led to these studies, and to Mrs. Susan A. Sachleben for her contributions in the development of the synthesis of BOB14C4AA.