Experimental and Theoretical Investigation of Zinc Oxide Nanoparticles for the Removal of Toxic Mercury(II) Ions from Wastewater

Hg(II) contamination in industrial wastewater poses serious environmental and public health concerns due to its toxicity and persistence. This study investigates the synthesis and application of ZnO as eco-friendly adsorbents for the efficient removal of Hg(II) ions from aqueous solutions. fabricate zinc oxide nanoparticles (ZnO NPs) using thyme, Thymus vulgaris L., leaf extract method and characterized using Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and scanning electron microscopy (SEM) to elucidate their structural and surface properties. Adsorption behavior was evaluated through batch experiments, and the results were analyzed using Langmuir and Freundlich isotherm models, revealing high adsorption capacities and monolayer adsorption characteristics. Monte Carlo simulations provided molecular-level insight into the strong interactions between Hg(II) ions and the composite surface, supported by negative adsorption energy values and high chemical hardness of the adsorbent system. The synergistic combination of ZnO NPs led to improved hydrophilicity, enhanced active binding sites, and efficient Hg(II) removal. These findings demonstrate the potential of ZnO NPs as a sustainable and high-performance material for heavy metal remediation in water treatment applications. In parallel, blind molecular docking of thymol onto human B-cell lymphoma 2 (Bcl-2) (PDB 6O0K) revealed preferential binding within the BH3 groove (ΔG ≈ −6 kcal mol⁻¹), suggesting disruption of the release of Bcl-2/Bax complex and potential release of pro-apoptotic factors.