Abstract:
Advanced oxidation technology based on persulfate (PS) activation has unique advantages in the degradation of emerging pollutants. Based on the use of nitrogen-doped carbon nanotube (NCNT) materials, ferrous disulfide was wrapped on its surface to prepare ferrous disulfide-modified nitrogen-doped carbon nanotubes (FeS
2@NCNT). With norfloxacin (NOR) as the target pollutant, the materials were characterized and their electrochemical properties were detected. The mechanism and performance of NOR degradation by FeS
2@NCNT-electro-activated peroxymonosulfate (PMS) were studied, and free radical quenching experiments were carried out. The influence of co-existing anions on the system performance and repeatability tests were also investigated. The results showed that: (1) FeS
2@NCNT had excellent electrocatalytic activity and low-impedance characteristics, showing good charge storage capacity and electron transfer ability. (2) In the FeS
2@NCNT/PMS system, the optimal reaction conditions were determined as a current density of 15 mA/cm
2, pH=6.0 and a PMS concentration of 3 mmol/L. Under these conditions, the NOR removal rate reached 93.0% within 60 minutes. (3) Free radical quenching experiments indicated that singlet oxygen (
1O
2) was the main active species for NOR degradation, and superoxide radicals (\mathrmO_2^-\cdot ), hydroxyl radicals (·OH) and sulfate radicals (\mathrmSO_4^-\cdot ) also contributed to some extent. (4) Cl
− and \mathrmSO_4^2- participated in the electron transfer process or acted as electron donors, which had a promoting effect on the system, while \mathrmH_2\mathrmPO_3^-、\mathrmH\mathrmCO_3^- 、\mathrmNO_3^- and humic acid (HA) natural ions had an inhibitory effect on the system's degradation of NOR. Moreover, FeS
2@NCNT could still maintain good catalytic activity after multiple cycles of use, demonstrating the application potential of this composite material in the field of water treatment.