Aly. Y. Okasha Hesham G. Ibrahim, Mokhtar S. Elatrash and Ahmed A. Marie
Abstract
Heavy metals are well recognized as potential health hazards as they can neither be degraded nor biologically detoxified. This experimental study aims to investigate the possible use of Libyan local soil (Ashkida soil), mined in the Southern Province of Libya as a low cost adsorbent for the removal of cadmium ions from aqueous solution. In this work, the effects of various parameters such as adsorbent dosage, initial cadmium concentration, agitation rate, contact time and solution pH value on the adsorption efficiency were investigated through batch experiments at room temperature. The results indicated that the optimum conditions for cadmium removal from aqueous solutions were 60 min, 10 g/l and 500 rpm as a contact time, adsorption dose and agitation rate, respectively, and natural pH value. The results were fitted to the Freundlich, langmuir, Temkin and Dubinin-Radushkevich isotherms. Satisfactory agreement between experimental data and the model-predicted values was expressed by the correlation coefficient (R2) and the total mean error (E%). The Freundlich model represented the sorption process better than others. The calculated monolayer adsorption capacity (qmax)
was 31.25 mg/g. A comparison of kinetic models applied to the adsorption of cadmium ions on the adsorbent was evaluated for the simple first order, the pseudo first order and second order kinetic models. Kinetic parameters, rate constant, equilibrium sorption capacities and related correlation coefficients for each kinetic model were calculated and
discussed. Results showed that the pseudo second order kinetic model was found to correlate the experimental data well. A linear relationship between the equilibrium rate constant of pseudo second order model and the system temperature suggests that the adsorption process is controlled by an endothermic reaction. However, an efficient cadmium ions removal can be achieved at ambient temperature.
Publication Date
6/10/2012
Publisher
International Journal of Environment and Bioenergy
علي يوسف عكاشة | Aly Y. Okasha | 11234