Experimental and theoretical study of kinetic and mechanism of hydroxyl radical-mediated degradation of sulfamethazine
- PDF / 919,659 Bytes
- 8 Pages / 595.276 x 790.866 pts Page_size
- 38 Downloads / 216 Views
RESEARCH ARTICLE
Experimental and theoretical study of kinetic and mechanism of hydroxyl radical-mediated degradation of sulfamethazine Xie Zheng 1,2 & Shijie Chen 1,2 & Lingwei Gao 3 & Yucheng Liu 1,2 & Fenghua Shen 1,2 & Hui Liu 1,2 Received: 6 April 2020 / Accepted: 8 July 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract Hydroxyl radical (•OH)-based advanced oxidation technologies (AOTs) is an effective and clean way to remove sulfonamide antibiotics in water at ambient temperature and pressure. In this study, we systematically investigated the degradation kinetics of sulfamethazine (SMT) by •OH with a combination of experimental and theoretical approaches. The second-order rate constant (k) of SMT with •OH was experimentally determined to be 5.27 ± 0.06 × 109 M−1 s−1 at pH 4.5. We also calculated the thermodynamic and kinetic behaviors for the reactions by density functional theory (DFT) using the B3LYP/6-31G*. The results revealed that •OH addition pathways at the methylene (C4) site on the pyridine ring and the ortho sites (C12 and C14) of the amino group on the benzene ring dominate the reaction, especially C14 site on the benzene ring accounted for 43.95% of SMT degradation kinetics. The theoretical k value which was calculated by conventional transition state theory is 3.96 × 109 M−1 s−1, indicating that experimental observation (5.27 ± 0.06 × 109) is correct. These results could further help AOTs design in treating sulfonamide during wastewater treatment processes. Keywords Hydroxyl radical . Sulfamethazine . UV/H2O2 . Pathway . Kinetics . DFT
Introduction Pharmaceutical such as analgesics, antibiotics, steroid, and hormones are widely used in the medical and health field nowadays. However, they are ineffective and low in biodegradability in the activated sludge process treatment method
Responsible editor: Vítor Pais Vilar Electronic supplementary material The online version of this article (https://doi.org/10.1007/s11356-020-10072-z) contains supplementary material, which is available to authorized users. * Hui Liu [email protected] 1
Institute of Environmental Engineering, School of Metallurgy and Environment, Central South University, Changsha 410083, China
2
Chinese National Engineering Research Center for Control & Treatment of Heavy Metal Pollution, Changsha 410083, China
3
School of Environment, Beijing Key Laboratory for Emerging Organic Contaminants Control, State Key Joint Laboratory of Environmental Simulation and Pollution Control, Tsinghua University, Beijing 100084, China
(Lapworth et al. 2012). For example, the total removal efficiencies (including sorption and biodegradation) of metronidazole, sulfamethoxazole, and carbamazepine in activated sludge process were only 61.7, 56.7, and 9.0% at 24 h, respectively (Min et al. 2018). Thus, these pharmaceuticals are observed frequently in secondary effluent of sewage treatment plant (Benitez et al. 2011; Wei et al. 2019). Sulfamethazine (SMT) is one of the best-seller broad-spectrum antibiotics with a structural
Data Loading...
