On coextraction of plutonium (4) and uranium (6) microamounts in tri-n-butylphosphate in the field of high saturation of extragent

More exact +-(5-10)% and new data have been obtained by equilibrium coextraction of macroquantities of uranium (4) (up to 300 g/l) and plutonium (4) (up to 100 g/l) from a 30%-solution of tributylphosphate with n-dodecane as the diluent at 26 +- 1 deg C. The equilibrium concentration data for plutonium (4) in concentrations greater than 30 g/l are reported for the first time. The Koch-Oxenfeld equations with accuracy of +-(20-25)% quaranteed by their authors are found to describe a much more limited region of the system. The largest deviation of these equations from the empirical data is observed for plutonium concentrations > 10-30 g/l. It has been definitely established that the distribution coefficient for Pu is independent of its concentrations within the entire range while the concentration of uranium in aqueous phase remains constant at 15-300 g/l. It has been found that the saturation of organic phase with respect to the total uranium and plutonium concentrations is independent of the ratio of these elements in the system. The equations for the calculation of coextraction isotherms for uranium (4) and plutonium (4), which are obtained by mathematical analysis of experimental results, describe the equilibrium corresponding to the region of practically total use of the extracting agent capacity with accuracy of not less than +-10%