Degradation of norfloxacin by sulfur-doped iron-cobalt oxides activated perodisulfate: Synergism between free radicals and singlet oxygen

Abstract

• The production of sulfur-doped CoFe 2 O 4 (S-CoFe 2 O 4 ) was successfully achieved. • S-CoFe 2 O 4 exhibited an excellent catalytic performance for perodisulfate activation. • Synergistic effects of free radicals and singlet oxygen on norfloxacin removal. • The mechanism of norfloxacin removal in S-CoFe 2 O 4 /PDS system is proposed. The present investigation involved the synthesis of sulfur-doped CoFe 2 O 4 (S-CoFe 2 O 4 ) catalysts by a straightforward co-precipitation and calcination technique. These catalysts were subsequently employed for the degradation of norfloxacin (NOR) utilizing activated perodisulfate (PDS). At the optimal level of sulfur doping, the efficiency of NOR removal in the S-CoFe 2 O 4 -3/PDS system can achieve a high percentage of 98.2%. Furthermore, the study also examined the impact of starting pH, catalyst dosage, PDS dose, several common inorganic anions, and humic acid on the breakdown of NOR. The study of free radicals and singlet oxygen activation mechanisms in the S-CoFe 2 O 4 /PDS system is facilitated through the implementation of free radical quenching experiments and electron paramagnetic resonance (EPR) techniques. The suggested breakdown mechanism of NOR in the S-CoFe 2 O 4 /PDS system was determined through the analysis of degradation products using high-performance liquid chromatography-mass spectrometry (HPLC-MS). The Biotoxicity Analysis Software (TEST) was employed to assess the toxicity of NOR and its breakdown products.