The role of bentonite particle size distribution on kinetic of cation exchange capacity

Natural bentonites are not fairly usable in processes where high cation exchange capacity is needed. In order to improve the cation exchange capacity of natural bentonite, alkali materials such as sodium carbonate are used in the activation process. Various factors affect the activation rate. One of the most important parameters that influence the kinetic of the activation process is particle size of starting raw materials. Therefore, in this study the effect of particle size distribution of starting material on sodium bentonite manufacturing was investigated in presence of sodium carbonate. The alkali treatment was isothermally carried out and the cation exchange capacity of activated clay was determined by methylene blue test. The values of activation energy and frequency factor, as number of active sites, were calculated. The kinetic results indicated that the activation mechanism in presence of sodium carbonate is controlled by density of active sites. The optimum activation time was computed for each condition, and FTIR, XRD and TG measurements were carried out to confirm qualitatively the kinetic results at optimum conditions.