Product identification and the mechanisms involved in the transformation of cefazolin by birnessite (δ-MnO 2 )

•Acid-catalyzed decarboxylation was found in the reaction of cefazolin with δ-MnO2.•Oxidation of thioether and olefin occurred in cefazolin transformation by δ-MnO2.•Catalytic oxidation and hydrolysis took place during cefazolin transformation.•The formation of the transformation products species was pH dependent.