Biohybrid Organic‐Inorganic Nanocomposites: Mentha Piperita‐Derived Macromolecular Capping Agents for Enhanced Lead Ion Adsorption From Petroleum‐Contaminated Waters

ABSTRACT Zinc oxide nanoparticles (ZnO NPs) were synthesized via an eco‐friendly approach utilizing natural plant‐derived macromolecular components as both reducing and stabilizing agents. The resulting nanomaterial was evaluated as an efficient adsorbent for the removal of Pb 2+ ions from aqueous solutions. The fabricated material was analyzed via X‐ray diffraction (XRD) for crystal structure, scanning electron microscopy (SEM) for surface morphology, and energy‐dispersive spectroscopy (EDS) examination to investigate the chemical constituents. These methods ensured the success of the nanoparticle preparation and their stability. The behavior of the nanoparticles in lead adsorption from solutions was investigated by a number of experiments to evaluate the effects of major operating parameters, pH, contact time, and amount of adsorbent. The adsorption efficiency was highly determined by these factors, as the results indicated. A pH close to neutral, a contact time of 90 min, and an increase in ZnO dose showed better removal results. A pseudo‐second‐order model was also used for data analysis to determine the kinetics, and good agreement with experimental values was obtained, indicating that the adsorption is controlled by a chemical reaction and limited by active sites on the surface. The adsorption at equilibrium was found to be best represented by the Langmuir model, and the fits with this model were excellent, indicating that adsorption takes place on a uniform surface in a monolayer. Maximum adsorption capacity (Qm) was 48.5 mg/g, and the Langmuir constant (KL) was 0.072 L/mg, R 2 = 0.992.