2454
Anal. Chem. 1903, 55, 2454-2457
Separation of Actinides in Dlfferent Oxidation States from Neutral Solutions by Solvent Extraction Akira Saito' and Gregory R. Choppin*
Department of Chemistry, Florida State University, Tallahassee, Florida 32306 The behavior of the transuranium elements in the environment is an important question in connection with the nuclear fuel cycle. The neutral or near neutral conditions in environmental systems lead to chemical reactions involving hydrolysis, redox, precipitation, adsorption, and complexation with inorganic and organic ligands. Since some of the adinides can exist simultaneously in more than one oxidation state, each with different chemical behavior, the determination of the oxidation states present in a particular system is of primary importance. The most direct method for such analysis is spectrophotometry which, however, is applicable only to samples of macroconcentrations. In environmental systems, tracer level concentrations of the elements are more often encountered. For such tracer concentrations, methods for oxidation state determination have been reported that we solvent extraction ( I ) , adsorption, and coprecipitation (2). Among these, the solvent extraction techniques seem to be most reliable and widely applicable. For example, the dependency of pH in extraction by 8-diketones allows quite selective separation of cations by careful choice of the aqueous phase pH. An extraction method has been reported that uses thenoyltrifluoracetone (TTA) for the analysis of the actinide ions in IV, V, and VI oxidation states (3) in solutions at pH
