KINETICS AND MECHANISM OF DISTRIBUTION OF AM(III) AND EU(III) BETWEENTHENOYLTRIFLUOROACETONE TRIPHENYLARSINE OXIDE MIXTURE IN CHLOROFORM AND AQUEOUS NITRATE MEDIUM

The kinetics of distribution of Am(III) and Eu(III) between thenoyltri fluoroacetone (HTTA) and triphenylarsine oxide (Ph3AsO) mixture in chl oroform and aqueous nitrate medium has been investigated using a stirr ed Lewis cell at ionic strength of 0.1M. The effect of the concentrati on 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 mec hanisms where the rate-determining steps are the parallel reaction of Am(OH)2+ or Eu(OH)2+ with one HTTA molecule and one Ph3AsO molecule in the aqueous medium. The values at 25-degrees-C of the rate constant k (HLL'), (HL = HTTA and L' = Ph3AsO) are 1.6 +/- 0.3 . 10(6) M-2 . s-1 and 2.3 +/-+/- 0.3 . 10(8) M-2 . s-1 for Am(III) and Eu(III), respecti vely.