Assessment of the removal of cadmium present in wastewater using soil-admixture membrane

Cadmium and its compounds present in waste water are well known potential environmental hazards. The present contribution deals with the removal of cadmium ion using clay soil mixed with different admixture (cement, gypsum, lime, bentonite) as adsorbent in laboratory scale experiment. The removal of cadmium was studied both in batch and continuous method. The influence of cadmium initial concentration, pH, amount of adsorbent on adsorption capacity, temperature was studied in batch method. The maximum dye adsorption was observed at pH 5.5. Different adsorption isotherm models (Langmuir, Freundlich, Tempkin isotherm) were used to describe the distribution of cadmium between the liquid and solid phases in batch studies and it was observed that Langmuir adsorption isotherm better represents the experimental data. The Arrhenius equation was used to evaluate the activation parameter. The activation energy was estimated as 67.25 kJ mole(-1) which indicate that the adsorption of cadmium using soil was chemical adsorption process. These adsorption studies were applied in continuous experiment also. In continuous experiment it was observed that the % removal was 95-99%. A mathematical treatment of this adsorption phenomenon has been developed and it was observed that the experimental results showed satisfactory agreement with the theoretical predicted results. (C) 2010 Elsevier B.V. All rights reserved.