Abstract
Ion exchange and its industrial applications to water treatment are briefly reviewed. The emphasis has been placed on column operation and the performance of strong acid cation, and mixed base anion, resins. A new approach to explain the complicated behaviour of mixed base resins is reported, which is based on diffusion kinetics and equilibria. A computer program has been developed to evaluate a model incorporating these parameters, by comparing the results of calculation against existing and new experimental data. Because of the number of variables which affect the performance of mixed base resins, a satisfactory quantitative approach to this problem has not been made hitherto. In the course of this work the 'sulphate/bisulphate' explanation for the increased capacity of resins for sulphate ions as compared with chloride ions has been shown to be generally invalid. Two alternative explanations, one for weak and mixed base resins, the other for strong base resins, are proposed. A quantitative study of some of the variables affecting the regeneration of strong acid cation resins is reported, and optimum values for these variables are suggested. Some of this information has been available qualitatively but has not previously been published in detail.