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Zinc oxide-catalyzed UV-photodegradation of cyhalothrin: A kinetic analysis Osumba, Seth Otieno Adongo, John Onyango Omolo, Josiah Ouma Kinetics Pesticide Zinc oxide Photodegradation Ultraviolet irradiation Photocatalytic activity In this study, we present kinetic studies of the photodegradation of cyhalothrin (CyH) under ultraviolet (UV) irradiation and the photocatalytic activity of zinc oxide (ZnO) in UV-assisted photodegradation. CyH in an acetone solvent was periodically exposed to UV254 nm radiation light with a surface power density of 48 W/cm2. The photodegradation experiments were conducted by acquiring periodic wavelength-scan spectroscopic data using a double beam ultraviolet-visible (UV-vis) spectrophotometer and plotting the real-time absorbance data to monitor the reaction coordinate. Under our optimized conditions at room temperature of 26.5 °C, atmospheric pressure of 76.6 mmHg, CyH (5.0 ppm) in the 70% acetone solvent with pH = 6.8 and dose of ZnO (25 ppm) exhibited typical photodegradation efficiencies between 81.9 and 90.3 % within the first 1,200 seconds of UV irradiation. Spectroscopic data showed that the ZnO solution significantly elevated the UV-assisted photodegradation rate of CyH by about 7.03 - 7.18 times more than that of UV-only-mediated CyH photodegradation. The result confirmed and characterized the photocatalytic activity of ZnO. Under the optimized measurement conditions, the rate of the ZnO-catalyzed photodegradation of CyH was found to follow the first-order rate law (RSq. = 0.999). Atlanta Publishing House LLC 2025-03-31 info:eu-repo/semantics/article info:eu-repo/semantics/publishedVersion application/pdf https://www.eurjchem.com/index.php/eurjchem/article/view/2598 10.5155/eurjchem.16.1.20-26.2598 European Journal of Chemistry; Vol. 16 No. 1 (2025): March 2025; 20-26 2153-2257 2153-2249 eng https://www.eurjchem.com/index.php/eurjchem/article/view/2598/2896 Copyright (c) 2025 Seth Otieno Osumba, John Onyango Adongo, Josiah Ouma Omolo https://creativecommons.org/licenses/by-nc/4.0