Adsorption of cadmium from aqueous solutions by vermiculite

The present study involves an investigation of a low-cost adsorbent, vermiculite for the removal of cadmium from aqueous solutions. The effects of pH and contact time on the adsorption process were examined. The optimum pH for adsorption was found to be 6. Residual cadmium concentration reached equilibrium in four hours and the rate of cadmium adsorption by Vermiculite was rapid in the first hour of the reaction time. Ho's pseudo second order model best described the reaction rate. Batch adsorption experiments conducted at room temperature (22 +/- 1degreesC) showed that the adsorption pattern followed the Freundlich isotherm model. The maximum removal of cadmium obtained from batch studies was 96%. Thomas model was used to describe the adsorption data from column studies. Overall, the results showed that vermiculite could be considered as a potential adsorbent for cadmium removal from aqueous solutions.