Chromatography. Chemistry in Nonaqueous Solutions

The volume covers two aspects of thorium solution chemistry: chromatographic methods and the chemistry in nonaqueous solutions. Chromatographic methods find broad application in the analytical chemistry of thorium, notably in the field of radiochemistry where unweighable or trace amounts of thorium have to be determined. Electrolytic methods like migration are used to separate ions to study the complexing behaviour of thorium in solution. Accordingly, these methods have been adopted as standard procedures in radioanalytical laboratories from mining in- dustry to reprocessing plants and research laboratories. They have the advantage that only trace amounts are needed to obtain results, so that radiation shielding and health considerations are less important. The behaviour of Th4+ in aqueous solution at pH > 3 is dominated by hydrolysis. Studies in nonaqueous solutions avoid this complication. The complexing behaviour towards donor ligands and the isolation of compounds like ThX2.2L is a feature of this type of chemistry. Most organometallic compounds can be obtained only in nonaqueous solutions. Furthermore, the amount of thorium extracted from aqueous solution into organic solutions depends strongly on the behaviour of the Th4+ ion and its complexes in the organic phase. Therefore, the studies of the reactions of thorium ions in organic solutions are of some importance for several industrial processes, such as the recovery of thorium from mining solutions by extraction with tributyl phosphate (TBP) to form Th(NO3)4.2 TBP.