Photochemical behavior of benzophenone sunscreens induced by nitrate in aquatic environments
| Autor: | Jiali Ge, Zerong Han, Xinghao Wang, Danyu Huang, Zunyao Wang, Xiaolin Wang |
|---|---|
| Rok vydání: | 2019 |
| Předmět: |
Environmental Engineering
Photobacterium phosphoreum 0208 environmental biotechnology Kinetics 02 engineering and technology 010501 environmental sciences Photochemistry 01 natural sciences Mineralization (biology) Chemical kinetics Benzophenones chemistry.chemical_compound Nitrate Nitration Benzophenone Waste Management and Disposal 0105 earth and related environmental sciences Water Science and Technology Civil and Structural Engineering Nitrates Photolysis Quenching (fluorescence) biology Chemistry Ecological Modeling biology.organism_classification Pollution 020801 environmental engineering Sunscreening Agents Water Pollutants Chemical Chromatography Liquid |
| Zdroj: | Water Research. 153:178-186 |
| ISSN: | 0043-1354 |
| DOI: | 10.1016/j.watres.2019.01.023 |
| Popis: | Benzophenones (BPs), which are widely used UV filters, have aroused considerable public concern owing to their potential endocrine-disrupting activities. Herein, we systematically investigated their photochemical behavior and fate, which is mediated by nitrate in aquatic environments. The results showed that 10 μM of 3 BPs can be completely degraded within 4 h of simulated sunlight irradiation in a 10 mM nitrate solution at pH 8.0, and 2,4-dihydroxybenzophenone (BP-1) has a 31.6% mineralization rate after 12 h irradiation. Their photolytic rates (kobs) presented a significant linear correlation with the logarithmic values of the nitrate concentration for 0.1–10 mM (R2 > 0.98), and in three actual waters, the rates of BP-1 were also positively related to the intrinsic nitrate concentration. Furthermore, higher transformation rates under alkaline condition were observed, especially for BP-1, with its kobs at pH 10 being 8.3-fold higher than that at pH 6.0. Moreover, dissolved oxygen (DO) also has an impact on the reaction kinetics to some degree. According to the quenching experiments, we found that three reactive oxygen species (ROS), namely, •OH, •NO, and •NO2, participated in this photolysis of BPs, and the contribution of •OH accounted for 32.1%. Furthermore, we selected BP-1 as the model molecule to study the transformation pathways and toxicity changes in this system. Four main transformation pathways including hydroxylation, nitrosylation, nitration, and dimerization were proposed, based on liquid chromatography quadrupole time-of-flight mass spectrometry (LC-Q-TOF-MS) analysis and density functional theory (DFT). According to the toxicity test, the formed intermediates were more toxic to Photobacterium phosphoreum than the parent BP-1. Therefore, these results can help reveal primary phototransformation mechanisms and evaluate the potential ecological risks of BPs in aquatic environments. |
| Databáze: | OpenAIRE |
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