Interaction of zirconium with pertechnetic acid in the course of extraction from nitric acid solutions with tributyl phosphate in diluent in the presence of uranyl nitrate at various temperatures and its mathematical description

Database on the extraction of zirconium and technetium, present separately and simultaneously, into 30% TBP is presented. With increasing temperature, the distribution ratio of Zr without Tc increases, and that of Tc without Zr decreases; however, because of the coextraction, the temperature dependence of the distribution ratios of these elements, present simultaneously, is leveled off. In the presence of uranyl nitrate, the effect of Tc on the extraction of Zr is preserved, whereas the effect of Zr on the extraction of Tc decreases to fully disappear in the case of the solvent saturation with uranyl nitrate. The interactions in the system are described within the framework of a new approach to modeling using five additional chemical equations. Their apparent equilibrium constants and coefficients of the temperature dependence are determined. The temperature coefficients are determined for the constants of six previously introduced equations of the extraction of zirconium and technetium, including the extraction in the presence of uranyl nitrate. © 2015 Pleiades Publishing, Inc.