Cathodic degradation of antibiotics: Characterization and pathway analysis. (1st April 2015)

• Record Type: Journal Article
• Authors: Kong, Deyong; Liang, Bin; Yun, Hui; Cheng, Haoyi; Ma, Jincai; Cui, Minhua; Wang, Aijie; Ren, Nanqi
• Is Part Of: Water research. Volume 72(2015)
• Page Start: 281
• Page End: 292
• Publication Date: 2015-04-01
• Subjects: Antibiotics degradation -- Cathode potential -- Nitro group reduction -- Dehalogenation -- Antibacterial activity elimination; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2015.01.025
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: Antibiotics in wastewaters must be degraded to eliminate their antibacterial activity before discharging into the environment. A cathode can provide continuous electrons for the degradation of refractory pollutants, however the cathodic degradation feasibility, efficiency and pathway for different kinds of antibiotics is poorly understood. Here, we investigated the degradation of four antibiotics, namely nitrofurazone (NFZ), metronidazole (MNZ), chloramphenicol (CAP), and florfenicol (FLO) by a poised cathode in a dual chamber electrochemical reactor. The cyclic voltammetry preliminarily proved the feasibility of the cathodic degradation of these antibiotics. The cathodic reducibility of these antibiotics followed the order of NFZ > MNZ > CAP > FLO. A decreased phosphate buffered solution (PBS) concentration as low as 2 mM or utilization of NaCl buffer solution as catholyte had significant influence on antibiotics degradation rate and efficiency for CAP and FLO but not for NFZ and MNZ. PBS could be replaced by Na2 CO3 –NaHCO3 buffer solution as catholyte for the degradation of these antibiotics. Reductive dechlorination of CAP proceeded only after the reduction of the nitro group to aromatic amine. The composition of the degradation products depended on the cathode potential except for MNZ. The cathodic degradation process could eliminate the antibacterial activity of these antibiotics. The current study suggests that the electrochemical reduction could serve as a potential pretreatment or advanced treatment unit for the treatment of antibiotics containing wastewaters. Graphical abstract: Highlights: Cathodic dehalogenation of chloramphenicol (CAP) and florfenicol (FLO) was achieved. The order of cathodic reducibility of antibiotics was: nitrofurazone > metronidazole > CAP > FLO. Antibiotics degradation products associated with applied cathode potentials. Cathodic degradation of four antibiotics eliminated their antibacterial activity.