Jl. Cortina et al., Kinetics studies on heavy metal ions extraction by Amberlite XAD2 impregnated resins containing a bifunctional organophosphorous extractant, REACT FUNCT, 38(2-3), 1998, pp. 269-278
Kinetics measurements on the extraction of divalent metal ions (Zn, Cu and
Cd) with impregnated resins, prepared by adsorption of a bifunctional extra
ctant, O-methyl-dihexyl-phosphine-oxide O'-hexyl-2-ethyl phosphoric acid (I
-IL) into polymeric macroporous supports of Amberlite XAD2 (XAD2-HL), were
made. The extraction process is accompanied by fast chemical reaction and i
s characterized by a sharp moving boundary between the reacted shell and th
e shrinking unreacted core within the impregnated resin. Analyses of the re
spective rate data in accordance with two theoretical models used to explai
n the metal extraction kinetics showed that process is controlled by the ra
te of diffusion of the ions penetrating the reacted layer at high metal ion
concentration (1 x 10(-2) mol l(-1)) and controlled by the rate of diffusi
on of the ions across the liquid film surrounding the resin particle at low
metal ion concentration (1x10(-4) mol l(-1)). Particle diffusion coefficie
nts and mass transfer constants across the liquid film were determined from
the graphical representation of the proposed models. (C) 1998 Elsevier Sci
ence BN. All rights reserved.