School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, International Joint Laboratory on Key Techniques in Water Treatment, Xinxiang, Henan 453007, PR China.
School of Environment, Henan Normal University, Key Laboratory for Yellow River and Huai River Water Environmental and Pollution Control, Ministry of Education, Henan Key Laboratory for Environmental Pollution Control, International Joint Laboratory on Key Techniques in Water Treatment, Xinxiang, Henan 453007, PR China.
Sci Total Environ. 2021 Nov 10;794:148707. doi: 10.1016/j.scitotenv.2021.148707. Epub 2021 Jun 25.
The abuse of antibiotics threatens the water environment and human health. Green treatment method is needed to degrade antibiotics such as biochar. Few studies have examined the environmentally persistent free radicals (EPFRs) and defective structure of biochar during the biochar-mediated catalytic degradation of antibiotics. In this study, biochar prepared from poplar and pine sawdust was used to activate peroxymonosulfate (PMS) to generate instant radicals (SO and •OH) and degrade tetracycline (TC), chlortetracycline (CTC) and doxycycline (DOX). The preparation temperatures ranged from 300 °C to 900 °C. EPFRs were the main activator of PMS at 300-500 °C, and the defective structure of biochar was the main activator at 800-900 °C. The concentrations of EPFRs ranged from 1.75 × 10 spins/g to 6.44 × 10 spins/g. According to the electron paramagnetic resonance (EPR) parameter (g-factor), the main types of EPFRs were carbon-centered radicals (g < 2.0030) or carbon-centered radicals with oxygen atoms (2.0030 < g < 2.0040). Optimization of the degradation experiment revealed that the removal rate of antibiotics peaked when the preparation temperature was 500 °C and 900 °C. In the biochar/PMS system, the antibiotics removal rate of 90% was achieved in 40 min with an average apparent rate constant (k) of 0.0588 min. Analysis of the mechanism revealed that the free radical pathway (EPFRs and defective structure) can effectively activate PMS to generate SO and •OH. However, control experiments suggested that the non-free radical pathway (singlet oxygen) had little effect on antibiotic degradation. After five cycles, the removal rate of antibiotics by biochar was still greater than 70%, indicating that biochar retains a high degradation ability. These results indicate that optimizing the preparation conditions can effectively expand the application range of the biochar/PMS system and improve the degradation of antibiotic wastewater.
抗生素的滥用威胁着水环境和人类健康。需要采用绿色处理方法来降解抗生素，例如生物炭。很少有研究考察过抗生素的生物炭介导催化降解过程中，环境持久性自由基（EPFRs）和生物炭缺陷结构的变化。在这项研究中，使用由杨木和松木锯末制备的生物炭来激活过一硫酸盐（PMS）以生成瞬时自由基（SO 和 •OH）并降解四环素（TC）、金霉素（CTC）和强力霉素（DOX）。制备温度范围为 300°C 至 900°C。在 300-500°C 时，EPFRs 是 PMS 的主要激活剂，而在 800-900°C 时，生物炭的缺陷结构是主要的激活剂。EPFRs 的浓度范围为 1.75×10 自旋/g 至 6.44×10 自旋/g。根据电子顺磁共振（EPR）参数（g 因子），主要的 EPFR 类型为碳中心自由基（g < 2.0030）或含有氧原子的碳中心自由基（2.0030 < g < 2.0040）。通过优化降解实验发现，当制备温度为 500°C 和 900°C 时，抗生素的去除率达到峰值。在生物炭/PMS 体系中，在 40 min 内即可达到 90%的抗生素去除率，平均表观速率常数（k）为 0.0588 min。通过分析机制发现，自由基途径（EPFRs 和缺陷结构）可以有效地激活 PMS 以生成 SO 和 •OH。然而，对照实验表明，非自由基途径（单线态氧）对抗生素降解的影响较小。经过五次循环后，生物炭对抗生素的去除率仍大于 70%，表明生物炭保持了较高的降解能力。这些结果表明，优化制备条件可以有效地扩展生物炭/PMS 体系的应用范围，提高抗生素废水的降解效果。
