Adsorption kinetics of cadmium and lead by chitosan

Abstract

An evaluation of the kinetics and capacity of chitosan to trap lead and cadmium ions in aqueous solution was carried out at 25°C using concentration and contact time as parameters. The experiments were done as batch process. Our results show that the adsorption process is concentration-driven with high capacity of chitosan for the adsorption of these metal ions. The infrared spectroscopic study on the chitosan and the metal-chitosan complexes reveals a metal coordination based on the observed characteristic band changes. At initial lead concentrations of 1000, 500, 400, 250 and 100 mg/L, the adsorbed lead ion concentrations are 557, 265, 218, 132 and 65 mg/L, respectively. However, for the cadmium, the adsorbed concentrations are 263, 165, 152, 78 and 45 mg/L, respectively at the same initial concentrations. The lead and cadmium adsorption kinetic behavior could not be described using the Langmuir isotherm over the whole concentration range but Freundlich isotherm conforms to the experimental data.