Quantitative Analysis of Cs Extraction by Some Dialkoxycalix[4]Arene-Crown-6 Extractants

ABSTRACT

Cesium extraction from acidic media by seven dialkoxy-calix[4]arene-crown-6 compounds in several diluents was studied. 2-Nonanone was found to be a suitable diluent for cesium extraction. Nitric acid concentration variation reveals a maximum distribution ratio, whose position depends on extractant and diluent. This maximum was explained quantitatively by a competitive extraction of H⁺. An analytical mass-action extraction model accounting for activity effects is proposed that fits correctly the different datasets. The analysis showed a nitrate hyper-stoichiometry in alkyl ketone diluents. This effect yields efficient back-extraction at low acidity. Benzo substitution on the crown ether lowers nitric acid extraction, improves sodium separation, but also degrades potassium and rubidium separation.

KEYWORDS:

• Cesium
• liquid-liquid extraction
• calixarenes crown-ethers
• diluent
• nitric acid
• nitrates

Acknowledgments

Authors would like to thank Dr. Bruce A. Moyer for the fruitful discussions.