Photocatalytic Degradation of Mancozeb Pesticide Residue using Nanoceria Doped Zinc Oxide Nanoparticles under Natural Solar Irradiation

Introduction: Excessive applications of agrochemicals to meet the high food demand from ever-increasing populations are becoming a major issue for both health practitioners and environmental managers. Chemicals such as ethylene bis-dithiocarbamate pesticide mancozeb (MCZ) are known to have deleterious effects on the ecosystem. Aim: This study, aimed at assessing the suitability of cerium-doped zinc oxide (Ce-ZnO) for efficient degradation of MCZ fungicide. Methods: The photocatalysts were synthesized using the coprecipitation method with zinc nitrate hexahydrate, cerium nitrate hexahydrate, and sodium hydroxide. The synthesized nanocomposites were further characterized by Powder X-ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FTIR), Scanning Electron Microscopy (SEM), and Energy Dispersive Xray Spectroscopy (EDAX). The average crystallite size of the as-synthesized particles was found to be 31.42 nm, with very sharp PXRD peaks revealing the pure crystal nature of the particles. The photocatalytic degradation activity was evaluated following a series of experiments under natural environmental conditions. The optimal conditions for the degradation of MCZ fungicide using Ce-ZnO were found to be 10 ppm initial concentration of MCZ, 20 mg dose of the Ce- ZnO photocatalyst, 180 minutes irradiation time, and 10-11 atmospheric UV index. Results: At the optimum conditions, the degradation efficiency was found to be about 90% after 180 minutes. The reported photocatalytic degradation of MCZ using Ce-ZnO fits a pseudo-firstorder kinetic model with an R2 value of 0. 9677. Similarly, the reusability of the as-synthesized photocatalyst was evaluated and found to be active for five rounds with little change in the activity. Conclusion: Thus, the degradation method in the current study can be suitable for the degradation and removal of MCZ in agricultural runoff in the field.