Synthesis, Characterisation and Application of Chromic Oxide-Lophira Alata Carbonized Sawdust Nanocomposite (COLACSN) in Removing Cd2+ and Pb2+ ions from aqueous solution

Abstract

The aim of this research is to examine the efficiency of removing cadmium-II and lead-II ions from aqueous solution using chromic oxide-lophira alata carbonised sawdust nanocomposite (COLACSN) synthesized by modified co-precipitation and thermal degradation method. The physicochemical characterization of chromic oxide-lophira alata carbonised sawdust nanocomposite was evaluated with the use of x-ray diffractograms (XRD), scanning electron microscope (SEM) and Fourier-Transform infrared spectrophotometer (F-TIR). The nanocomposite was amorphous with some degree of crystallinity, smooth and spherical in shape with a particles size of 12.05 nm in apparently soft agglomerates. The quantity of cadmium-II and lead-II ions before and after treatment of the aqueous solution was evaluated using atomic absorption spectrometer (AAS). Adsorption experiments were conducted in batches and the adsorption property of COLACSN was studied using isotherm models and Response Surface Methodology (RSM). The adsorption isothermal study revealed that the adsorption manner was physical and favorable for the accumulation of Cd²⁺ and Pb²⁺ ions on to chromic oxide-lophira alata carbonised sawdust nanocomposite. The chromic oxide-lophira alata carbonised sawdust nanocomposite had high adsorption capacity for Pb²⁺ ions. The accumulation process of Pb²⁺ ions was exothermic and possesses a high interaction with the adsorbent chromic oxide-lophira alata carbonised sawdust nanocomposite. The optimization analysis revealed that the Pb²⁺ ions were more adsorbed compared to Cd²⁺ ions with optimum adsorption capacities of 191.50mg/g and 66.20mg/g respectively. These values agreed with the k_F values obtained from Freundlich isotherm. This implies that the chromic oxide-lophira alata carbonised sawdust nanocomposite was more effective in the removal of Pb²⁺ ions.