Biomass-derived activated carbon supported ZnO nanocomposite synthesized via Averrhoa carambola leaf extract for the adsorption of methylene blue dye from aqueous solution

This study presents a biomass-driven green approach for wastewater treatment. It allied the potential of Averrhoa carambola L. (star fruit) leaf extract, a readily available plant-based resource, to facilitate the synthesis of activated carbon-loaded zinc oxide (AC@ZnO). This biomass-mediated synthesis offers a more sustainable and environmentally benign route compared to traditional chemical methods for nanomaterial production. The study precisely evaluated the material's performance through both photocatalytic degradation and adsorption. Characterization X-ray diffraction and FTIR confirmed the successful formation of Zinc Oxide (ZnO) and AC@ZnO. A batch adsorption process was employed, systematically varying contact time, biosorbent dosage, dye concentration, and pH to assess their impact on adsorption capacities. Results indicated that MB adsorption was more effective in an alkaline pH environment. Adsorption kinetics were best described by the Boyd, intraparticle diffusion, and pseudo-second-order kinetic models. Equilibrium data fit well with the Harkins-Jura, Freundlich, D-R, and Langmuir isotherm models. Notably, AC@ZnO demonstrated superior photocatalytic activity compared to ZnO, highlighting the synergistic effect of ZnO and activated carbon. This research successfully demonstrates the efficacy of a biomass-enabled AC@ZnO nanocomposite as a promising material for the removal of MB dye from wastewater, showcasing the potential of integrating plant-derived resources into advanced nanomaterials for sustainable environmental applications.