Adsorption of cadmium from aqueous solutions by vermiculite and perlite.

摘要

The present study involves an investigation of two low cost adsorbents, vermiculite and perlite, for the removal of cadmium from aqueous solutions. The effects of contact time, pH, and temperature on the adsorption process were determined. Residual cadmium concentration reached equilibrium in four hours in the case of vermiculite; equilibrium was reached in six hours with perlite. The cadmium removal increased with pH until a pH value of 9, but the optimum pH was 6 for both the adsorbents. The rate of cadmium adsorption by vermiculite and perlite was rapid until one hour of the reaction time. Batch adsorption experiments conducted at 7 ± 1°C, 14 ± 1°C, and 22 ± 1°C showed that the adsorption capacity of vermiculite and perlite increased with increase in temperature to some extent and decreased for a further increase in temperature. The maximum removals of cadmium obtained from the batch studies by vermiculite and perlite were 96% and 55%, respectively. Column studies showed that vermiculite and perlite were less effective in removing cadmium when compared with batch studies. Vermiculite performed better in adsorbing cadmium from aqueous solutions than perlite. Overall, the results showed that vermiculite and perlite could be considered as potential adsorbents for cadmium removal from aqueous solutions.