Biogenic Silver Kaolinite Nanocomposite for the Sequestration of Lead and Cadmium in Simulated Produced Water

Abstract

Biologically inspired nanocomposites are currently attracting significant recognition in view of their environmentally friendly, cost efficient and sustainable properties. In this study, silver-kaolinite nanocomposite (SKN) was synthesized using aqueous extracts from fresh leaves of Aloe vera as a bioreducing agent and employed for the removal of lead (Pb) and cadmium (Cd) ions from simulated produced water (SPW). Morphological properties of SKN were examined using transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), energy dispersive x-ray (EDX) spectroscopy, Brauner-Emmett-Teller (BET) and ultraviolet-visible (UV-Vis) spectrophotometry with average particle size ranging from 45 to 60 nm. Different physicochemical parameters (initial concentration (10 - 120 mg/L), adsorbent dosage (0.01 - 0.2 g), pH (2 - 8) and contact time (5 - 150 min)) were investigated to ascertain the efficiency of SKN. The results revealed optimum adsorption of 142 and 120 mg/g for lead and cadmium ions respectively at initial metal concentration of 100 mg/L, 0.05 g of SKN dose and pH 6 for 60 min. Freundlich isotherm and pseudo-second order kinetic model adequately interpreted the equilibrium and kinetic data respectively.