On The Mechanism of the Extraction of Uranyl Nitrate by TBP (Partition Study)

The method of analysis using the distribution coefficient to confirm the mechanism of extraction was proposed and the formation of the complex UO2(NO3)2·(TBP)2 and HNO3·TBP was confirmed. The extraction behavior of uranium from a nitric acid solution was concluded as a result of the competition of uranium and nitric acid. The thermochemical functions ΔH0, ΔF0 and ΔS0 for the complex formation reaction: UO_2^+2(aq.)+2NO_3-(aq.)+2TBP(org.)=UO_2(NO_3)_2(TBP)_2(org.) were determined roughly from the measurement of the distribution coefficient as follows: ΔH0(25°C) ≅−4.3 kcal., ΔF0 (25°C) ≅−2.0 kcal., ΔS0(∼25°C) ≅−7.7 e.u.