Adsorption of Cu²⁺, As³⁺ and Cd²⁺ ions from aqueous solution by eggshell

Abstract

The adsorption of Cu2+, Cd2+ and As3+ ions on eggshell from aqueous solution was studied under batch conditions at 30, 40, 50 and 60oC and concentrations of 10, 20, 30, 60 and 80 mg/l. The partition coefficient for the ions between aqueous solution and chicken eggshell increased with time and with increase in the concentration of metal ions in solution, but decreased with increase in temperature which is suggestive of physical adsorption on the eggshell. Activation energies of 8.50, 9.25 and 11.74 kJmol-1 were obtained for the adsorption of Cu2+, As3+ and Cd2+ respectively which also suggest physical adsorption. Sorption of As3+ and Cd2+ from solution onto the eggshell adsorbent was found to follow pseudo-first order mechanism while that of Cu2+ was found to follow the pseudo-second order mechanism. Experimental data obtained for the adsorption of the metal ions by eggshell fit the Freundlich adsorption isotherm.