- Oxidation of cefalexin by permanganate: Reaction kinetics, mechanism, and residual antibacterial activity
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The oxidation of cefalexin (CFX), a commonly used cephalosporin antibiotic, was investigated by permanganate (PM) in water. Apparent second-order rate constant of the reaction between CFX and PM was determined to be 12.71 ± (1.62) M-1·s-1 at neutral pH. Lower pH was favorable for the oxidation of CFX by PM. The presence of Cl- and HCO3- could enhance PM-induced oxidation of CFX, whereas HA had negligible effect on CFX oxidation by PM. PM-induced oxidation of CFX was also significant in the real wastewater matrix. After addition of bisulfite (BS), PM-induced oxidation was significantly accelerated owing to the generation of Mn(III) reactive species. Product analysis indicated oxidation of CFX to three products, with two stereoisomeric sulfoxide products and one di-ketone product. The thioether sulfur and double bond on the six-membered ring were the reactive sites towards PM oxidation. Antibacterial activity assessment indicated that the activity of CFX solution was significantly reduced after PM oxidation.
- Qian, Yajie,Gao, Pin,Xue, Gang,Liu, Zhenhong,Chen, Jiabin
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