Kinetics and mechanism of distribution of Am(III) and Eu(III) between thenoyltrifluoroacetone-triphenylarsine oxide mixture in chloroform and aqueous nitrate medium

Abstract

The kinetics of distribution of Am(III) and Eu(III) between thenoyltrifluoroacetone (HTTA) and triphenylarsine oxide (Ph3AsO) mixture in chloroform and aqueous nitrate medium has been investigated using a stirred Lewis cell at ionic strength of 0.1M. The effect of the concentration of HTTA, Ph3AsO, H+ and NO3− on the rate of distribution of Am(III) and Eu(III) was studied. The results were interpreted by reaction mechanisms where the rate-determining steps are the parallel reactions of Am(OH)2+ or Eu(OH)2+ with one HTTA molecule and one Ph3AsO molecule in the aqueous medium. The values at 25 °C of the rate constantkHLL′ (HL=HTTA andL′=Ph3AsO) are 1.6±0.3·106M−2·s−1 and 2.3±±0.3·108M−2·s−1 for Am(III) and Eu(III), respectively.