Production and Characterization of KOH‐Activated Shea Shell Charcoal for Cadmium Adsorption From Water

Abstract

Abstract Developing environmental remediation techniques using agricultural and industrial wastes is a sustainable strategy for resource conservation. In this study, shea fruit shell (SFS) was carbonized (SFSC) and then subjected to KOH activation to develop activated SFSC (ASFSC). SFSC and ASFSC were comparatively characterized using Fourier‐transform infrared (FTIR), X‐ray diffraction (XRD), scanning electron microscope (SEM), and TGA‐DTG (Thermogravimetric analysis), while the surface and pore parameters of ASFSC were investigated using Brunauer–Emmett–Teller (BET), Barrett–Joyner–Halenda (BJH), and Dubinin–Radushkevich (D‐R) methods. ASFSC was studied for the adsorption of aqueous Cd 2 ⁺, with equilibrium, kinetics, isotherms, and the effect of co‐ions analyzed. The activation process significantly enhanced the chemical functionality, morphology, microstructure, thermal stability, and surface area (SBET: 105.7 m 2 /g) of ASFSC. High Cd 2 ⁺ adsorption (∼100%) was achieved at equilibrium (pH 7 and 120 min), and the process was endothermic. The adsorption data showed the best fit to the pseudo‐second‐order kinetic model (R 2 : 0.9684) and the Langmuir isotherm model (R 2 : 0.9950, Qmax: 143.76 mg/g), indicating a predominant chemisorption mechanism. High efficiencies (≥97%) were recorded for both Cd 2 ⁺ recovery (using 1 M HNO 3 at 50 °C) and the reactivation of ASFSC over multiple cycles. Additionally, ASFSC was successfully applied in the treatment of mining wastewater.