Efficient synthesis of magnetic activated carbon from oak pericarp for enhanced dye adsorption: A one-step approach

This study presents a one-step synthetic method utilizing oak pericarp treated with FeCl3 and ZnCl2 as a precursor for the production of magnetic activated carbon (MAC). Characterization techniques including FTIR, SEM-EDX, TGA, XRD, VSM, BET, and pHpzc confirm the integration of biochar characteristics and magnetic properties of iron oxides in the MAC composite. Batch adsorption tests investigate the adsorption capacity of Rhodamine B (RhB) and Rose Bengal (RB) dyes by MAC under varied conditions, including adsorbent dose, contact time, solution pH, ionic strength, temperature, and initial dye concentration. Optimal adsorption conditions for RhB and RB are identified at pH 2 and 7, with adsorbent doses of 0.75 g/L and 1 g/L, and equilibrium times of 180 min and 120 min, respectively. Adsorption isotherm models (Langmuir, Freundlich, and Temkin) are employed, with the Freundlich model providing the best fit. MAC demonstrates a maximum monolayer adsorption capacity of 198.529 mg.g−1 for RhB and 42.551 mg.g−1 for RB at 20 °C. Kinetic data align with the pseudo-second-order model, and thermodynamic parameters confirm the spontaneous and endothermic nature of the adsorption process. In conclusion, this study successfully synthesizes magnetic biochar with enhanced efficacy in dye adsorption. The one-step method proves efficient for treating industrial dye effluents, as evidenced by batch desorption studies over four cycles, establishing the reusability of the MAC.