Green Synthesis of Zinc Oxide Nanoparticles for Tetracycline Adsorption: Experimental Insights and DFT Study

An eco-friendly approach was used to fabricate zinc oxide nanoparticles (ZnO NPs) using thyme, Thymus vulgaris L., leaf extract. The produced ZnO nanoparticles were characterized by XRD and SEM analysis. The ZnO NPs showed remarkable adsorption efficiency for tetracycline (TC) from water systems, with a maximum removal rate of 95% under optimal conditions (10 ppm, 0.10 g of ZnO NPs, pH 8.5, and 30 min at 25 °C). The adsorption kinetics followed the pseudo-2nd-order model, and the adsorption process fitted the Temkin isotherm model. The process was spontaneous, endothermic, and primarily chemisorptive. Quantum chemistry calculations, utilizing electrostatic potential maps and HOMO-LUMO gap analysis, have confirmed the stability of the TC clusters. This study suggests that green synthesis using plant extracts presents an opportunity to generate nanoparticles with properties suitable for real-world applications.