Characterization of adsorptive capacity and mechanisms on adsorption of copper, lead and zinc by modified orange peel

A novel adsorbent was prepared by modifying orange peel with sodium hydroxide and calcium chloride. The morphological and characteristics of the adsorbent were evaluated by infrared spectroscopy (IR), scanning electron microscopy (SEM) and N-2-adsorption techniques. The adsorption behavior of Cu2+, Pb2+ and Zn2+ on modified orange peel (SCOP) was studied by varying parameters like pH, initial concentration of metal ions. Equilibrium was well described by Langmuir equation with the maximum adsorption capacities for Cu2+, Pb2+ and Zn2+ of 70.73, 209.8 and 56.18 mg/g, respectively. Based on the results obtained in batch experiments, breakthrough profiles were examined using a column packed with SCOP for the separation of small concentration of Pb2+ from an excess of Zn2+ followed by elution tests. Ion exchange with Ca2+ neutralizing the carboxyl groups of the pectin was found to be the predominant mechanism.