Mechanistic Insights into Cu(Ii) Removal from Aqueous Solution by Camellia Oleifera Shell–Reduced Graphene Oxide

Abstract

Copper pollution of the aquatic environment is becoming a severe health challenge due to its non-biodegradable nature. In this study, for the first time, the reduced graphene oxide (rGO) was prepared from Camellia oleifera shell (COS) extract in a low-cost and environmentally friendly method, and successfully applied for Cu(II) removal from aqueous solutions. 85.8% removal efficiency (18.7mg/g) of 10 mg/L initial concentration of Cu(II) was achieved using 0.5 g/L dosage of COS-reduced graphene at a pH of 5.1 and reaction temperature of 20 °C. Characterization techniques including Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to study the synthesized COS-rGO, while thermodynamic and kinetic studies were employed to study the mechanism of Cu(II) adsorption on COS-rGO. The adsorption of Cu(II) on COS-rGO obeyed the pseudo-second-order kinetics as a spontaneous exothermic reaction. Our results also confirmed that Cu(II) removal by COS-rGO was a result of chemical adsorption following a rate-controlled process based on Langmuir adsorption model. Here, we present the green synthesis of COS-rGO as a potential technique for developing the cost-effective adsorbent from waste material that can be used for the heavy metal mitigation in water.

Keywords: Cu (II), Reduced Graphene oxide, Camellia oleifera shell, Green synthesis, Adsorption, Water pollution