KINETICS OF ION-EXCHANGE IN MONODISPERSE RESIN

Ion-exchange kinetics within a conventional strong base resin, Dowexl- 8X(R), and a resin with uniform particle size, Dowex(R) Monosphere(R) Tough Gel(R) TG550A(R), were investigated using neutron activation ana lysis and radio-tracer techniques. The kinetics of ion exchange were m easured in a batch and in a ''shallow-bed'' flow system. The experimen tal data were compared with the results of model computations. The dif fusivities of several anions within TG550A and Dowexl-8X were deduced. It was found that at 25 degrees C Br-, Cl-, OH-, and Na+ diffuse with in TG550A with the diffusion coefficients DBr- = 6.0 x 10(-7) cm(2)/s, DCl- = 1.2 x 10(-6) cm(2)/s, DOH- = 7.0 x 10(-8) cm(2)/s, and DNa+ = 5 x 10(-7) cm(2)/s. Diffusion of anions within a conventional resin, D owexl(R), was slower: DBr- = 3.5 x 10(-7) cm(2)/s, DCl- = 6 x 10(-7) c m(2)/s, DOH- = 2.7 x 10(-8) cm(2)/s, and DNa+ = 5 x 10 -7 cm(2)/s. A h igher rate of ion diffusion and the bead-size uniformity may make mono disperse Dowex Monosphere Tough Gel TG550A resin attractive for analyt ical applications. The difference in properties between conventional a nd monodisperse resins is not sufficient to affect the large volume ap plications of resins. (C) 1997 John Wiley & Sons, Inc.