Application of a chitosan bimetallic nanocomposite for the simultaneous removal of cadmium, nickel, and lead from aqueous solution
Charlton van der Horst, Bongiwe Silwana, Martin Makombe, Emmanuel I. Iwuoha, Vernon Somerset
Abstract
ABSTRACT Wastewaters often consist of heavy metals and the use of iron-based bimetallic nanocomposites to remove these inorganic pollutants is still unclear. This investigation used a chitosan-iron/silver bimetallic nanocomposites (CS-Fe/AgNPs) to eliminate cadmium (Cd 2+ ), nickel (Ni 2+ ), and lead (Pb 2+ ) from aqueous solution. The chemically synthesized CS-Fe/AgNPs were characterized by scanning electron microscopy, transmission electron microscopy, Fourier transformed infrared spectroscopy, ultraviolet-visible spectroscopy, X-ray diffraction, and thermogravimetric analysis, which confirmed the shape, size, and composition of the bimetallic nanocomposite synthesized. The kinetics, adsorption isotherms, and thermodynamics of Cd 2+ , Pb 2+ , and Ni 2+ were also studied in batch experiments. Analysis of inductively coupled plasma-optical emission spectroscopy was employed to quantify the amount of Cd 2+ , Pb 2+ , and Ni 2+ absorbed by the CS-Fe/AgNPs from an aqueous solution. The results obtained revealed that Pb 2+ , Cd 2+ , and Ni 2+ adsorption capacities using CS-Fe/AgNPs under optimized conditions were 2.01 mg g –1 for Pb 2+ , 1.73 mg g –1 for Cd 2+ , and 1.81 mg g –1 for Ni 2+ , respectively. These results showed that the application of CS-Fe/Ag bimetallic nanocomposite can be applied to remove these heavy metals from wastewaters, simultaneously under optimized conditions such as effects of pH, contact time, and adsorbent dosage.