Oxidative degradation kinetics and products of chlortetracycline by manganese dioxide

► CTC could be readily oxidized by δ-MnO2. ► The dosage of δ-MnO2, reaction temperature and pH influenced CTC transformation rate. ► Addition of Mn2+, Zn2+ and substituted phenols remarkably reduced CTC transformation. ► Isomerization, dehydration and N-demethylation products were detected by LC-MS-MS. ► The hydroxyl groups and the dimethylamine moiety of CTC were active reaction sites.