Assessment of Leucaena leucocephala as bio-based adsorbent for the removal of Pb2+, Cd2+ and Ni2+ from water

This study was investigated the removal of Pb 2+ , Cd 2+ and Ni 2+ from single and multicomponent aqueous solutions by Leucaena leucocephala. The point of zero charge and the specific surface area of the bio-based adsorbent were determined, and the Fourier-transform infrared spectroscopy and scanning electron microscopy techniques were used to characterize the biosorbent. The elemental composition before and after the heavy metal adsorption by this material was found using energy dispersive X-ray spectroscopy. The effects of various parameters such as contact time (30–1,440 min), pH (2–10), initial adsorbate concentration (10–500 mg L -1 ) and biosorbent dosage (1–10 mg L –1 ) were examined. Biosorption capacity was found to be dependent on all of the parameters studied. The amount of metal ions sorbed by L. leucocephala increased as the radius of the cations decreased. Kinetic studies show that maximum uptake of Pb 2+ , Cd 2+ and Ni 2+ was reached within 60 min of contact for single and multicomponent solutions of these metallic ions. However, metal removal by biosorbent using a single metal ion solution was higher than that obtained using multicomponent solutions. Furthermore, the biosorption process of the metal ions followed a well-defined pseudo-second- order model. The data’s for the single and simultaneous removal of Pb 2+ , Cd 2+ and Ni 2+ were analyzed according to Langmuir and Freundlich isotherm models. The equilibrium data fit well in Freundlich isotherm model. After the biosorption process, L. leucocephala was treated with nitric acid at different concentrations to evaluate reusability.