Efficient removal of Cr (VI) and Co (II) from aqueous solution by activated carbon from <i>Manihot esculenta</i> Crantz agricultural bio-waste

Abstract Heavy metals are one of the most dangerous and critical threats to human and environment. In this study, the adsorption efficiency of activated carbon from cassava peels considered as agricultural waste (CPR) was evaluated for removal of heavy metals Cr (VI) and Co (II) from aqueous media. Cassava peel carbon (CPC) was obtained by acid treatment. Structural and morphological properties were investigated using Fourier Transform Infra-Red (FTIR), Scanning Electron Microscopy (SEM), Brunauer-Emmet-Teller surface area (BET) and X-Ray Diffraction (XRD). The adsorption experiments were conducted in batch mode under natural solution pH and complexation of the heavy metals, which allows the use of UV-Visible spectroscopy technique. CPC adsorbent exhibited a high adsorption capacity, according to Langmuir model, for Cr (VI) (166.35 mg/g) and Co (II) (301.63 mg/g) at 25 °C. Kinetic and adsorption isotherms followed the pseudo second-order and Langmuir isotherm models for both metals, respectively. Thermodynamic study confirmed the spontaneity and endothermic nature of both metals adsorption onto CPC surface.