Determination of the optimal conditions for the adsorption of cadmium ions and phenol on chestnut(Castanea sativa) shell

Adsorption of cadmium ions and phenol from aqueous solutions on chestnut (Castanea
sativa) shell was studied. An incomplete 33 factorial design was applied to investigate the
influence of the initial cadmium ions (20-60-100 mg l-1) or phenol concentration (0.01-0.255-
0.5 g l-1), temperature (10-25-40ºC for cadmium and 10-35-60ºC for phenol) and pH (5.5-7.0-
8.5 for Cd2+ ions and 2.5-6.0-9.5 for phenol) on the amount of contaminant adsorbed and on
the adsorption percentage. Statistical analysis of the results showed the significance of the
individual factors and their interactions on both adsorption processes. The best conditions for
high cadmium ions and phenol removal within the experimental ranges of the variables
studied were the natural pH (around 5.5) and a temperature of 25ºC for cadmium ions and
60ºC for phenol. Under these conditions, adsorption equilibrium was modelled by the
Freundlich isotherm for cadmium ions and by the Langmuir isotherm for phenol.