Ea. Saad, KINETIC-STUDIES OF EXTRACTION FOR A MIXTURE OF SOME EUROPIUM PHOSPHONATE COMPLEXES AND 2-BENZOYL OR 2-ANILINOPYRIDINE IN N-HEXANE, Microchemical journal, 58(1), 1998, pp. 6-12
The kinetics and mechanism of solvent extraction of Eu3+ from an aqueo
us phase of 0.1 M ionic strength (Na+, HClO4) at pH 3.2 and 25 degrees
C by a mixture of ethylhydrogen benzyl phosphonate (HEBzP), ethylhydr
ogen benzoyl phosphonate (HEBoP), and 2-benzoylpyridine (BP), or 2-ani
linopyridine was studied using a stirred Lewis cell. The extraction wa
s investigated over a wide range of extractant concentrations and pH.
The kinetic data were treated according to the mass transfer with chem
ical reaction (MTWCR) model, in which the extraction rate was shown to
be controlled by a mechanism involving. diffusion of the extractant i
nto the aqueous phase boundary layer followed by addition of the first
ligand to the europium ion. The rate constants K-HL = 2.49 +/- 0.02 X
10(3) M-2 min(-1), K-L = 10.35 +/- 0.05 x 10(2) M-2 min(-1), and K-LS
= 1.105 +/- 0.12 x 10(3) M-2 min(-1) (HL, HEBzP; S, AP). (C) 1998 Aca
demic Press.