Studies of the Behavior of Trivalent Uranium in an Aqueous Solution. III : Extraction from a Hydrochloric Acid Solution by Bis(n-butyl) Orthophosphoric Acid and by Bis-(2-ethylhexyl) Orthophosphoric Acid

The distribution of U(III) between hydrochloric acid solutions and benzene solutions of bis(n-butyl) orthophosphoric acid or cyclohexane solutions of bis(2-ethylhexyl) orthophosphoric acid has been investigated by using the uranium-237 isotope as a tracer. It has been found that the log-log plot of the distribution ratio vs. the concentration of dimeric organophosphoric acids, and that of the distribution ratio vs. the hydrogen ion concentration, always show a good linearity, with a slope of 3. This indicates that the complex-forming reaction is as follows:U^3++3(HA)_2\ightleftarrowsU(HA_2)_3+3H^+where (HA)2 represents the dimeric solvent, (HDBP)2 or (HDEHP)2. The above results are in agreement with the conclusions reached in the cases of other trivalent actinide and lanthanide elements by other investigators.