Investigating the toxicity of photocatalytic degradation products from metronidazole using ZnO/polyaniline and TiO2/polyaniline nanocomposites: A bioassay study
Mahdi Farzadkia, Ali Esrafili, Esrafil Asgari, Ahmad Jonidi Jafari, Roshanak Rezaei Kalantary
Abstract
The increasing use of nanomaterials in various applications has raised concerns about their potential impact on the environment and human health. In this study, bioassays using the freshwater crustacean Daphnia magna were employed to evaluate the toxicity of ZnO/Polyaniline and TiO 2 /Polyaniline nanocomposites, as well as the photocatalytic degradation products of metronidazole (MNZ), an antibiotic drug. The results indicate that both ZnO/Polyaniline and TiO 2 /Polyaniline nanocomposites exhibit moderate toxicity, with ZnO/Polyaniline being slightly more toxic than TiO 2 /Polyaniline. Photocatalytic degradation of MNZ using these nanocomposites significantly reduced the solution's toxicity, suggesting that the degradation products are less harmful than the parent compound. However, some residual toxicity remained even after complete degradation, indicating incomplete mineralization and the presence of intermediate degradation products of MNZ. Therefore, this study highlights the importance of evaluating the environmental impact of nanomaterials and their photocatalytic products to ensure their safe and sustainable use. • Toxicity assessment of ZnO/PANI and TiO 2 /PANI nanocomposites and their MNZ photocatalytic degradation products using Daphnia magna. • Toxicity comparison of MNZ pre- and post-photocatalytic degradation using nanocomposites. • Identifying toxicity concerns of ZnO/PANI and TiO 2 /PANI nanocomposites in photocatalytic wastewater treatment.