Hydrolytic transformation mechanism of tetracycline antibiotics: Reaction kinetics, products identification and determination in WWTPs

Shao-Fen Zhong; Bin Yang; Qian Xiong; Wen-Wen Cai; Zheng-Gang Lan; Guang-Guo Ying

Ecotoxicology and Environmental Safety (Jan 2022)

Hydrolytic transformation mechanism of tetracycline antibiotics: Reaction kinetics, products identification and determination in WWTPs

Shao-Fen Zhong,
Bin Yang,
Qian Xiong,
Wen-Wen Cai,
Zheng-Gang Lan,
Guang-Guo Ying

Affiliations

Shao-Fen Zhong: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China; School of Chemical Engineering and Energy Technology, Dongguan University of Technology, Dongguan 523808, China
Bin Yang: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China; Corresponding authors at: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China.
Qian Xiong: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China
Wen-Wen Cai: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China
Zheng-Gang Lan: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China
Guang-Guo Ying: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China; School of Environment, South China Normal University, Guangzhou 510006, China; Corresponding authors at: SCNU Environmental Research Institute, Guangdong Provincial Key Laboratory of Chemical Pollution and Environmental Safety & MOE Key Laboratory of Theoretical Chemistry of Environment, South China Normal University, Guangzhou 510006, China.

Journal volume & issue: Vol. 229
p. 113063

Abstract

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Antibiotic residues and antibiotic resistance have been widely reported in aquatic environments. Hydrolysis of antibiotics is one of the important environmental processes. Here we investigated the hydrolytic transformation of four tetracycline antibiotics i.e. tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and doxycycline (DC) under different environmental conditions, and determined their parents and transformation products in the wastewater treatment plants (WWTPs). The results showed that the hydrolysis of the four tetracyclines followed first-order reaction kinetics, and the acid-catalyzed hydrolysis rates were significantly lower than the base-catalyzed and neutral pH hydrolysis rates. The effect of temperature on tetracycline hydrolysis was quantified by Arrhenius equation, with Ea values ranged from 42.0 kJ mol−1 to 77.0 kJ mol−1 at pH 7.0. In total, nine, six, eight and nine transformation products at three different pH conditions were identified for TC, CTC, OTC and DC, respectively. The main hydrolysis pathways involved the epimerization/isomerization, and dehydration. According to the mass balance analysis, 4-epi-tetracycline and iso-chlortetracycline were the main hydrolytic products for TC and CTC, respectively. The 2 tetracyclines and 4 hydrolysis products were found in the sludge samples in two WWTPs, with concentrations from 15.8 ng/g to 1418 ng/g. Preliminary toxicity evaluation for the tetracyclines and their hydrolysis products showed that some hydrolysis products had higher predicted toxicity than their parent compounds. These results suggest that the hydrolysis products of tetracycline antibiotics should also be included in environmental monitoring and risk assessment.

Published in Ecotoxicology and Environmental Safety

ISSN: 0147-6513 (Print); 1090-2414 (Online)
Publisher: Elsevier
Country of publisher: United States
LCC subjects: Technology: Environmental technology. Sanitary engineering: Environmental pollution; Geography. Anthropology. Recreation: Environmental sciences
Website: https://www.journals.elsevier.com/ecotoxicology-and-environmental-safety

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