Hexavalent chromium adsorption from aqueous solution using Cordia Africana leaf based activated carbon

Abstract

Chromium, a prevalent heavy metal pollutant originating from various industrial processes, poses significant risks if not properly treated. In this study, batch adsorption of hexavalent chromium (Cr6+) from water was performed using activated carbon derived from Cordia africana. This application represents a novel approach, as the use of this material for Cr6+ removal has not been previously explored. The adsorbent was analyzed through Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), and the Brunauer–Emmett–Teller (BET), and Fourier Transform Infrared (FTIR) methods, revealing its structural and surface properties. Adsorption kinetics followed the pseudo-first-order model (R² = 0.99), while the Koble Corrigan isotherm (R² = 0.98) most accurately expressed the adsorption behavior. The adsorption experiments achieved a maximum Cr⁶⁺ adsorption capacity of 52.2 mg/g. Thermodynamic studies indicated that the process is spontaneous and endothermic. Reusability tests demonstrated the stability of the adsorbent over five cycles, with removal efficiencies ranging from 99.7 to 75.1%. Overall, Cordia africana leaf-based activated carbon exhibited a promising adsorption capacity, making it a cost-effective and readily available adsorbent suitable for industrial wastewater treatment.