NOVEL POLYETHYLENE GLYCOL-BASED AQUEOUS BIPHASIC SYSTEMS FOR THE EXTRACTION OF STRONTIUM AND CESIUM

The partitioning behavior of Sr2+ and Cs+ in aqueous biphasic systems formed by the addition of polyethylene glycol (PEG)-2000 to either NaO H, (NH4)(2)SO4, or K2CO3 was investigated. Phase diagram data reveal t hat on a weight percent basis the salting out effects of the three sal ts increase in the order (NH4)(2)SO4 < K2CO3 < NaOH. In the presence o f traditional extractants 12-crown-4, 15-crown-5, or 18-crown-6, only the partitioning of Sr2+ from (NH4)(2)SO4 media using 18-crown-6 resul ted in the expected 1:1 extractant dependency. All other measured dist ribution ratios in the presence or absence of extractants and regardle ss of salt system appear to be governed by cation enthalpy of hydratio n and system composition. The distribution ratio for cesium, D-Cs is g reater than D-Sr due to cesium's lower enthalpy of hydration. D-M vs. percent salt and percent PEG both reveal an increase in D-M with decre asing salt or PEG.