Department of Chemistry, University of Ioannina, Ioannina 45110, Greece.
Department of Chemistry, University of Ioannina, Ioannina 45110, Greece; Institute of Environment and Sustainable Development, University Research Center of Ioannina (URCI), Ioannina 45110, Greece.
Sci Total Environ. 2023 Apr 20;870:161877. doi: 10.1016/j.scitotenv.2023.161877. Epub 2023 Jan 28.
Nowadays, the increased consumption of antibiotics, such as metronidazole (MTZ), leads to their introduction in wastewater as well as in the receiving surface waters due to their incomplete removal by conventional wastewater treatment plants. Heterogeneous photocatalysis is a versatile technology that can efficiently degrade such organic contaminants. In the present research, the photocatalytic degradation of MTZ with TiO P25 was studied under lab and pilot (CPC reactor) conditions. The antibiotic was efficiently removed at high rates in both cases (100 % and 91 %) following pseudo-first order kinetics with rate constants equal to 0.0452 min (±RSD% = 0.68 % - 2.57 %) and 0.0462 L KJ (±RSD% = 8.94 % - 21.64 %) respectively. Also, by scavenging lab scale experiments, the contribution of the generated reactive species was investigated and hydroxy radicals (HO) were proposed as the predominant species. By applying high resolution mass spectrometry techniques, the transformation products (TPs) were identified and possible transformation pathways were proposed. The ecotoxicity of the TPs was assessed in silico using the ECOSAR software with the results revealing that most of them were less toxic than the parent compound. Similarly, the mutagenicity, developmental toxicity and bioconcentration factors of the TPs were predicted by utilizing the T.E.S.T. software and in their majority, were found to be less mutagenic and developmentally toxic than MTZ. The ecotoxicity monitoring with the Vibrio fischeri bioassay in both laboratory and pilot scale experiments indicated that through heterogeneous photocatalysis it is possible to reduce the toxicity of wastewater containing MTZ. Finally, the stability and reusability of the photocatalyst was investigated through three consecutive catalytic cycles with the results showing that the performance of TiO decreased after each use. For the heterogeneous photocatalysis with TiO to be a "real life" applicable technique, further studies focusing on catalyst regeneration and optimization of the catalytic conditions must be conducted.
如今，由于常规废水处理厂无法完全去除抗生素（如甲硝唑），导致其在废水中以及受纳地表水中的含量增加。多相光催化是一种高效的技术，可以有效地降解这些有机污染物。在本研究中，采用 TiO2 P25 研究了甲硝唑在实验室和中试（CPC 反应器）条件下的光催化降解情况。在这两种情况下，甲硝唑均能以高去除率被有效去除（分别为 100%和 91%），遵循准一级动力学，速率常数分别为 0.0452 min（±RSD%=6.8%-2.57%）和 0.0462 L·KJ（±RSD%=8.94%-21.64%）。此外，通过实验室规模的清除实验，研究了生成的活性物质的贡献，并提出羟基自由基（HO）为主要物质。采用高分辨率质谱技术，鉴定了转化产物（TPs）并提出了可能的转化途径。利用 ECOSAR 软件对 TPs 的生态毒性进行了计算机模拟评估，结果表明大多数 TPs 的毒性低于母体化合物。同样，利用 T.E.S.T.软件预测了 TPs 的致突变性、发育毒性和生物浓缩因子，大多数 TPs 的致突变性和发育毒性均低于甲硝唑。利用发光菌 Vibrio fischeri 生物测定法在实验室和中试规模实验中进行的生态毒性监测表明，通过多相光催化可以降低含有甲硝唑的废水的毒性。最后，通过三个连续的催化循环考察了光催化剂的稳定性和可重复使用性，结果表明 TiO2 的性能在每次使用后都会下降。为了使 TiO2 的多相光催化成为一种“现实生活”适用的技术，必须进一步研究催化剂的再生和催化条件的优化。
