A novel partially carbonized Fe3O4@PANI-p catalyst for tetracycline degradation via peroxymonosulfate activation

A novel polyaniline (PANI) partially carbonized core–shell material (Fe3O4@PANI-p) was prepared and used to activate peroxymonosulfate (PMS) for tetracycline (TC) degradation. Partial carbonization of the polyaniline layer introduced carbon catalytic sites into the catalyst. The polyaniline/carbon bilayer structure of the catalyst confined the metal oxides in the shell layer, which improved the catalytic performance of the material and reduced the leaching of metal ions. The effect of various influencing factors, such as PMS dosage, pollutant concentration, and initial pH on TC degradation was further investigated. The TC degradation efficiency was positively correlated with PMS dosage and negatively correlated with TC concentration. In the pH range of 3.0–9.0, the degradation efficiency of TC (C0 = 20 mg/L) reached more than 87.0 % within 90 min, and the highest efficiency was 89.8 %. HCO3– promoted the degradation of TC to a higher efficiency (95.9 %), whereas H2PO4− slightly inhibited it (88.1 %). The effect of humic acid (HA) in water on TC degradation was not significant. After three cycles, the degradation efficiency still reached 77.5 % and the degradation efficiency was restored to 83.7 % after pyrolysis regeneration. According to quenching experiments and electron paramagnetic resonance (EPR) characterization, the main reactive oxygen species (ROS) in the degradation process were singlet oxygen (1O2), followed by superoxide radicals (O2·−), sulfate radicals (SO4·−), and hydroxyl radicals (·OH). The above findings provide a reference for the application of new multilayer core–shell composites for antibiotic wastewater treatment.