Urea-assisted one-step synthesis of cobalt ferrite impregnated ceramic membrane for sulfamethoxazole degradation via peroxymonosulfate activation

In this study, a novel CoFe₂O₄ nanocatalyst impregnated Al₂O₃ ceramic membrane was prepared via a urea-assisted one-step combustion method. The catalytic membrane was characterized by field emission scanning electron microscopy (FESEM) with energy dispersive X-Ray analysis (EDX) and applied for the catalytic degradation of sulfamethoxazole (SMX) via peroxymonosulfate (PMS) activation under a dead-end membrane filtration mode for the first time. Results indicate that CoFe₂O₄ could be impregnated into the macropores throughout the whole Al₂O₃ ceramic membrane via this method and the CoFe₂O₄ loading amount could be controlled by the multiple impregnation cycles. The membrane filtration operation mode significantly enhances the accessibility of the catalytic active sites to PMS and SMX in microreactor environment and thus the CoFe₂O₄ impregnated membrane displays excellent catalytic activity for the SMX degradation. The pure water permeability flux can maintain at ∼3000 L m⁻² h⁻¹ bar⁻¹ (LMHB) with the catalyst loading amount of 0.015 g/g Al₂O₃. In the membrane filtration system, the removal rate of SMX with the initial concentration of 10 mg L⁻¹ can achieve to ∼98%, 70% and 40% with the residence time of 90, 36 and 18 s. The catalytic membrane shows a great tolerance at wide pH range (3–11), the existence of humic acid and anions. Meanwhile, the membrane shows self-cleaning property by retaining >90% of initial flux after 3 treatment cycles. Electron paramagnetic resonance (EPR) and radical quenching experiments indicate that both sulfate radical and hydroxyl radical are generated and sulfate radical is the dominant active species in the process.