Green synthesis of rGO/ZnO/Fe₂O₃ using caulerpa peltata extract for enhanced malachite green removal
Abstract
This study reports the green synthesis of rGO/ZnO/Fe₂O₃ nanocomposites using Caulerpa peltata extract as a natural reducing and stabilizing agent for enhanced malachite green (MG) removal from aqueous solutions. Structural characterization confirmed successful composite formation, where XRD analysis revealed the coexistence of crystalline ZnO and Fe₂O₃ phases integrated within the rGO matrix, while FTIR, Raman, and thermogravimetric analyses indicated successful reduction, increased defect density, and improved thermal stability. Raman analysis showed an increase in ID/IG ratio from 1.197 to 1.283 after composite formation, suggesting additional active defect sites. Adsorption studies demonstrated superior performance of rGO/ZnO/Fe₂O₃ with a maximum adsorption capacity of 305.212 mg g⁻¹ compared to 190.582 mg g⁻¹ for rGO. The adsorption process followed pseudo-second-order kinetics and showed spontaneous, exothermic behavior. Furthermore, the composite maintained removal efficiencies above 94% after ten adsorption–desorption cycles, indicating excellent operational stability and reusability for sustainable wastewater treatment applications. KEY WORDS: Reduced graphene oxide, Green synthesis, Caulerpa peltate, Malachite green adsorption, rGO/ZnO/Fe₂O₃ nanocomposite Bull. Chem. Soc. Ethiop. 2026, 40(12), 2701-2716. = DOI: https://dx.doi.org/10.4314/bcse.v40i12.14