Treatment of Wastewater-CPL by Biochar-Based Fenton-Like Catalyst in the Presence of Micro-nano Bubbles

Biochar-based Fe–Ce bimetallic Fenton-like heterogeneous catalyst was prepared and applied to the degradation of wastewater produced during the synthesis of caprolactam (wastewater-CPL) in the presence of micro-nano bubbles (MNB). The prepared materials were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, field emission scanning electron microscope (SEM), and X-ray photoelectron spectroscopy (XPS), which confirmed the successful loading of Fe and Ce and the formation of Fe2O3 and CeO2. The treatment effects of different reaction systems were compared, indicating that biochar-based catalyst + H2O2 + MNB system had the best treatment effect that the COD removal rate can reach 93.26%. The influencing factors of the system were discussed, and finally it was concluded that the condition of Fe:Ce was 3:1, hydrogen peroxide concentration was 1.2 M, pH was 2, catalyst dosage was 1 g/L, and temperature was 35 ℃. The treatment effects of adding MNB were compared; the treatment effect of MNB + H2O2 on wastewater was about 60% higher than that of H2O2 alone. The reusability of the catalyst was determined, and it was observed that high catalytic performance could be retained after five cycles. Finally, the water quality of the effluent was analyzed, and it was proved that the treatment of wastewater-CPL had a good effect. This study provided a new idea for the treatment of wastewater-CPL.