Kinetics of ion exchange in monodisperse resin

Abstract

Ion-exchange kinetics within a conventional strong base resin, Dowexl-8X®, and a resin with uniform particle size, Dowex® Monosphere® Tough Gel® TG550A®, were investigated using neutron activation analysis and radio-tracer techniques. The kinetics of ion exchange were measured in a batch and in a “shallow-bed” flow system. The experimental data were compared with the results of model computations. The diffusivities of several anions within TG550A and Dowexl-8X were deduced. It was found that at 25°C Br-, Cl-, OH-, and Na+ diffuse within TG550A with the diffusion coefficients = 6.0 × 10-7 cm2/s, = 1.2 × 10-6 cm2/s, = 7.0 × 10-8 cm2/s, and = 5 × 10-7 cm2/s. Diffusion of anions within a conventional resin, Dowexl®, was slower: = 3.5 × 10-7 cm2/s, = 6 × 10-7 cm2/s, = 2.7 × 10-8 cm2/s, and = 5 × 10-7 cm2/s. A higher rate of ion diffusion and the bead-size uniformity may make monodisperse Dowex Monosphere Tough Gel TG550A resin attractive for analytical applications. The difference in properties between conventional and monodisperse resins is not sufficient to affect the large volume applications of resins. © 1997 John Wiley & Sons, Inc. J Appl Polm Sci 65:1271–1283, 1997