A chemical model of the solvent extraction systen: water–uranyl nitrate–nitric acid–tri-n-butyl phosphate–diluent

Abstract

A chemical model founded on the equilibrium constant expression for a solvent-extraction reaction has been proposed for the extraction of uranyl nitrate with tri-n-butyl phosphate. The model utilizes the chemical activities of the extraction species in the aqueous phase. Introduction of self-association of the extratant on the coextraction of nitric acid compensates to some extent for the neglect of the corresponding activity coefficients in the organic phase. The model fits well the distribution results over the whole concentration range of the extraction isotherm. Extraction and dimerization constants obtained by means of the model are in agreement with literature data.