Manihot esculenta Leaves Extract Mediated Silver–Clay Nanocomposite for the Adsorption of Cadmium(II) and Chromium(VI) Ions from Aqueous Media

The increasing prevalence of heavy metal contamination in aqueous environments poses severe risks to both human health and the ecosystem. To address this environmental concern, this study focused on the utilization of a nature-based silver clay nanocomposite (NAgC) for the removal of cadmium (Cd(II)) and chromium (Cr(VI)) ions from aqueous media. The NAgC was synthesized through the reduction of silver ions in a clay matrix by employing the leaf of Manihot esculenta extract as the reducing agent. The NAgC was characterized using Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM), Brunauer, Emmett, and Teller (BET) surface area as well as energy-dispersive X-ray spectroscopy (EDX). The adsorption behavior of the NAgC in batch experiments under varying pH, contact time, initial concentration, and adsorbent dosage were investigated for the removal of cadmium and chromium from aqueous media. The optimum adsorption of cadmium ions was 157.87 mg/g, achieved at an initial concentration of 20 mg/L at 1 g dosage at pH 7 for 60 min, while that of chromium was 137.91 mg/g at a metal concentration of 20 mg/L at 1 g dosage at pH 7 for 60 min. The Freundlich isotherm model adequately explained the adsorption data of both Cd(II) and Cr(VI). However, the pseudo-first order (PFO) adequately interpreted the kinetic data for both Cd(II) and Cr(VI).