Adsorption kinetics of an ion-exchange column

Abstract

The adsorption Kinetics of Ca2+ and Mg2+ from single-ion and mixed-ion solutions on a strong-acid cation resin (Dowex50-X8) was investigated. The process was carried out in the fluidized-bed column at room temperature. In the beginning, total adsorption capacities were determined using batch experiments. The results showed that this resin had the total adsorption capacity about 1.13 meq/ml. A no adsorption test was also carried out to examine the characteristics of the flow in the column. It was found that this system exhibits a good fluidized-bed pattern. The results of the single ion adsorption tests indicated that the exchange rate of Ca2+ for H+ on the resin was higher than that of Mg2+. For the mixed-ion system with a Ca2+ and Mg2+ initial concentration ratio of 1:1, the exchange rate of Ca2+ for H+ on the resin was also higher than that of Mg2+. The complicated adsorption behavior of the fluidized-bed operation can be explained using a simple model. The model was developed based on the assumption that the operation can be represented with a mixed flow reactor, a plug flow reactor and the response time of the pH electrode.