High-Efficiency Adsorption and Sustainable Desorption of Anionic Dyes Using a Novel AC–Fe₂O₃/ZnO Nanocomposite

Abstract

This study proposes the preparation of a novel adsorbent material, AC-ZnO-Fe₂O₃, synthesized using activated carbon derived from plastic waste and metal oxides produced via co-precipitation methods. The structural and physicochemical characteristics of the prepared adsorbent were examined using FTIR, XRD, BET, and EDX analyses. Particle size estimation performed by SEM revealed values of 63.29 nm for activated carbon (AC), 91.69 nm for Fe₂O₃, 68.79 nm for ZnO, and 72.11 nm for the composite (AC-ZnO-Fe₂O₃). Zeta potential measurement recorded a negative surface charge of it-42.2 mV. The batch adsorption technique was employed to evaluate the removal efficiency of two anionic dyes, Eosin Blue (EB) and Fuchsin Acid (FA), under varying operational conditions, including equilibrium time, temperature, pH, and agitation speed.  Under optimal conditions, the removal efficiencies reached 77.17% and 88.21% for EB and FA, respectively. Adsorption isotherm analyses demonstrated that the Freundlich model provided the best results. In addition, thermodynamic parameters were calculated, and a negative ∆G^ᴼ value was obtained, indicating a spontaneous adsorption process and confirming the endothermic nature of the reaction. Finally, Desorption experiments were conducted to achieve high recovery efficiencies of 98.46% For EB and 75.81% For FA, using water as the solvent.