Sol-Gel Glass-Encapsulated Crown Ethers for the Separation and Preconcentration of Strontium from Acidic Media

• Published in: Separation science and technology Vol. 50; no. 18; pp. 2873 - 2880
• Main Authors: Momen, M. A., Kaminski, Michael D., Dietz, Mark L.
• Format: Journal Article
• Language: English
• Published: Taylor & Francis 12.12.2015
• Subjects: Chromatography; Crown ethers; Extraction; extraction chromatography; Polymers; Separation; Sol gel process; sol-gel encapsulation; Strontium; Uptakes
• ISSN: 0149-6395; 1520-5754
• DOI: 10.1080/01496395.2015.1085420

Extraction chromatography employing an inert polymeric support impregnated with a crown ether (typically, 4,4',(5')-di-(tert-butylcyclohexano)-18-crown-6 (DtBuCH18C6)), either neat (i.e., undiluted) or as a solution in 1-octanol, has previously been shown to provide an effective means for the isolation of radiostrontium from a variety of sample types for subsequent determination. In this study, sol-gel chemistry has been employed to prepare sorbents in which DtBuCH18C6 is encapsulated in a silica matrix. The resultant materials have been evaluated for their ability to retain strontium ion and compared to a commercially available extraction chromatographic (EXC) resin. Certain of the new materials are shown to provide uptake efficiencies comparable to those obtained with the commercial resins, although unless a porogen is employed, the kinetics of strontium uptake are significantly slower. In contrast to conventional EXC materials, however, strontium uptake by DtBuCH18C6-loaded glasses does not increase in proportion to the amount of extractant present, indicating that not all of the crown ether present is available for interaction with the metal ion.