Studies on the formation of composite complexes by means of an extractive technique

Abstract

AbstractFor the interpretation of the data obtained on the extraction of metal complexes to organic solvents from aqueous solutions of low and constant ionic strength, the following minimum number of variables has to be considered: the concentrations of the metal atom (M), main ligand (the base A‐), HA, OH−, H2O, organic solvent molecules (Org) and the temperature. This has been done in an attempt to determine the compostion of the composite complexes of type MAn(OH)p(HA)r(Org)•(H2O)t formed in a given system.In this complex s and t can be determined only in special cases, and it is not possible to distinguish by equilibrium methods between isomers with the same values for x = n + r and y = n + p. These isomers can be represented by the formula M(HA)x(H)−y.It can be shown that in principal a distinction can be made between complexes of the type MAn, MAn(OH)p or MAn(OH)p(HA)r.A general method to calculate formation constants for the complex M(HA)x(H)−y from extraction data has been developed. It is also shown that from a comparison of the distribution ratios of the metal between water and several different organic solvents it is possible to determine if the metal forms a complex with the organic solvent molecules.The equations have been applied on the distribution of U(VI) and Th between several different organic solvents and water in the presence of acetylacetone.