Oxidation of beta-lactam antibiotics by peracetic acid: Reaction kinetics, product and pathway evaluation

摘要

Peracetic acid (PAA) is a disinfection oxidant used in many industries including wastewater treatment. beta-Lactams, a group of widely prescribed antibiotics, are frequently detected in wastewater effluents and surface waters. The reaction kinetics and transformation of seven beta-lactams (cefalexin (CFX), cefadroxil (CFR), cefapirin (CFP), cephalothin (CFT), ampicillin (AMP), amoxicillin (AMX) and penicillin G (PG)) toward PM were investigated to elucidate the behavior of beta-lactams during PAA oxidation processes. The reaction follows second-order kinetics and is much faster at pH 5 and 7 than at pH 9 due to speciation of PM. Reactivity to PAA follows the order of CFR similar to CFX > AMP similar to AMX > CFT CFP similar to PG and is related to beta-lactam's nucleophilicity. The thioether sulfur of beta-lactams is attacked by PAA to generate sulfoxide products. Presence of the phenylglycinyl amino group on beta-lactams can significantly influence electron distribution and the highest occupied molecular orbital (HOMO) location and energy in ways that enhance the reactivity to PM. Reaction rate constants obtained in clean water matrix can be used to accurately model the decay of beta-lactams by PM in surface water matrix and only slightly overestimate the decay in wastewater matrix. Results of this study indicate that the oxidative transformation of beta-lactams by PM can be expected under appropriate wastewater treatment conditions. 2017 Published by Elsevier Ltd.