[Base Activation of Peroxymonosulfate for the Degradation of Ciprofloxacin in Water].

Abstract

The degradation of ciprofloxacin (CIP) in a base activated peroxymonosulfate (PMS) system was investigated. Results showed that a base activated PMS system can efficiently remove CIP. Singlet oxygen (¹ O₂) and superoxide anion radical (O₂^-·) were confirmed to be the major reactive oxygen species through radical quenching experiments. The NaOH concentration, PMS concentration, reactive temperature, and coexisting anions also affected CIP removal. Both NaOH and PMS concentration presented a dual effect, which was highly concentration dependent. An improvement in reactive temperature accelerated CIP degradation, and the calculated activation energy (E_a) was determined to be 5.09 kJ·mol^-1 through the fitting of the Arrhenius equation. Different anions had different effects on CIP degradation. No obvious change in CIP concentration was observed when Cl^-, SO₄^2-, and NO₃^- were introduced. H₂PO₄^2- inhibited the degradation, but CO₃^2- significantly promoted it. Ten oxidation products were identified through UPLC-MS/MS analysis, and the piperazine ring in the molecular structure of CIP was preferentially attacked by reactive oxygen species in the base activated PMS system.