Kinetics of reductive stripping of Np(VI) by acetohydroxamic acid from 30%TBP/kerosene to nitrate medium using a high-speed stirred cell

Abstract

Abstract The kinetics of reductive stripping of Np(VI) by Acetohydroxamic Acid from 30%TBP/kerosene was investigated using a high-speed stirred cell designed by ourselves. The phase separator for sampling was simple and powerful. The interfacial areas of different stirring speeds were determined by microphotograph method at 21 ℃ before the experiments. The effects of the different parameters as well as temperature were investigated systemically. The results showed that, at 21 ℃ the rate equation is − d[Np(VI)]/dt = k(S/V)[Np(VI)]0.78[AHA]0.46[HNO3]−0.20 − k′(S/V)[Np(V)]2.87, where k = (8.7 ± 0.7) × 10−7 (mol/L) –0.04m s –1, k′ = 1.1 ± 0.2 (mol/L) –2.87 m s –1, as c[HNO3] <= 1.0 mol/L, − d[Np(VI)]/dt = k(S/V)[Np(VI)]0.78[AHA]0.46[HNO3]−1.42 − k′(S/V)[Np(V)]2.87, where k = (3.2 ± 0.3) × 10−7 (mol/L)1.18 m s –1, k′ = 1.1 ± 0.2(mol/L) –2.87 m s –1 as c[HNO3] >= 1.0 mol/L, and S is the interfacial area, V the organic phase volume. The reductive stripping process is controlled by chemical reactions (kinetics regime) taking place at the interface. The apparent activation energy is 13.5 ± 0.2 kJ/mol.