Degradation kinetics and mechanism of beta-lactam antibiotics by the activation of H2O2 and Na2S2O8 under UV-254 nm irradiation

作者：He, Xuexiang; Mezyk, Stephen P.; Michael, Irene; Fatta-Kassinos, Despo; Dionysiou, Dionysios D.^*

来源：Journal of Hazardous Materials, 2014, 279: 375-383.

DOI：10.1016/j.jhazmat.2014.07.008

• beta-Lactam antibiotics
• UV-254 nm
• Hydrogen peroxide
• Persulfate
• Radical reaction mechanism

The extensive production and usage of antibiotics have led to an increasing occurrence of antibiotic residuals in various aquatic compartments, presenting a significant threat to both ecosystem and human health. This study investigated the degradation of selected beta-lactam antibiotics (penicillins: ampicillin, penicillin V, and piperacillin; cephalosporin: cephalothin) by UV-254nm activated H2O2 and S2O82- photochemical processes. The UV irradiation alone resulted in various degrees of direct photolysis of the antibiotics; while the addition of the oxidants improved significantly the removal efficiency. The steady-state radical concentrations were estimated, revealing a non-negligible contribution of hydroxyl radicals in the UV/S2O82- system. Mineralization of the beta-lactams could be achieved at high UV fluence, with a slow formation of SO42- and a much lower elimination of total organic carbon (TOC). The transformation mechanisms were also investigated showing the main reaction pathways of hydroxylation (+16 Da) at the aromatic ring and/or the sulfur atom, hydrolysis (+18 Da) at the beta-lactam ring and decarboxylation (-44 Da) for the three penicillins. Oxidation of amine group was also observed for ampicillin. This study suggests that UV/H2O2 and UV/S2O82- advanced oxidation processes (AOPs) are capable of degrading beta-lactam antibiotics decreasing consequently the antibiotic activity of treated waters.

• 出版日期2014-8-30