Dried sheep manure (SM) has been found to be an effective
adsorbent for the removal of copper and cadmium ions from dilute aqueous
solutions. Batch adsorption experiments using different concentrations of copper
and cadmium ions (2.0?20.0 mg/ml) were carried out for different periods of
agitation. Adsorption uptakes were found to increase with an increase in the
initial metal ion concentration, SM concentration and solution pH for both
copper and cadmium ions.
Maximum uptakes for 100 ppm Cu2+ and 100 ppm Cd2+ ions were found to be
17.8 mg/g and 10.8 mg/g, respectively. The equilibrium uptakes for both copper
and cadmium ions were attained within the first 10 min. The Langmuir isotherm
model failed to represent the adsorption of both copper and cadmium ions on
SM. In contrast, the Freundlich isotherm model fitted the experimental data for
both copper and cadmium ions very well. The presence of EDTA in the solution
decreased the equilibrium uptake of both copper and cadmium ions significantly.