Kinetics of Ion Exchange in the Chelating Resin Dowex A-1

Abstract

Abstract The kinetics of ion exchanges of Ag+, Zn2+ and Cr3+ at extremely low concentrations on the chelating resin Dowex A-1 has been studied by means of finite volume method. The rate of exchanges for both Ag+ and Zn2+ is dependent on the ionic strength, particle size of the resin and reaction temperature. At higher ionic strength (0.1–0.05) the kinetics is controlled by particle diffusion, whereas at lower ionic one (0.01–0.001) film diffusion is predominant. The apparent activation energy obtained is 3.84 kcal/mol for Ag+ and 3.91 kcal/mol for Zn2+. The exchange rate of Cr3+ obeys a first-order rate equation independent of the ionic strength and particle size of the resin. The apparent activation energy is 15.5 kcal/mol. These results support the view that the ratedetermining step of this reaction is chelate formation reaction.