Three-dimensional porous CuFe2O4 for visible-light-driven peroxymonosulfate activation with superior performance for the degradation of tetracycline hydrochloride

Three dimensional porous CuFe2O4 (CuFe2O4 3DPs) catalysts were prepared using the polymer-assisted freeze-drying method. Then, the formation mechanism of the porous structure, as well as their effects on mass transfer, were comparatively studied and carefully analyzed. The mass transfer rate of the CuFe2O4 3DPs was 21.1 and 9.0 times that of the CuFe2O4 nanosheets (NSs) prepared without polymer assistance, and the CuFe2O4 nanoparticles (NPs) prepared without freeze-drying, respectively. The catalytic performance of the CuFe2O4 3DPs for visible-light (Vis)-driven peroxymonosulfate (PMS) activation technology was studied through the degradation of tetracycline hydrochloride (TCH). A pseudo-first-order kinetics degradation constant of CuFe2O4 3DPs was achieved at 0.071 min−1, which was 3.2 and 2.2 times higher than the CuFe2O4 NSs and CuFe2O4 NPs, respectively. Electron paramagnetic resonance and capture experiments on the CuFe2O4 3DPs/Vis, CuFe2O4 3DPs/PMS, and CuFe2O4 3DPs/Vis/PMS systems demonstrated that the three factors on the CuFe2O4 3DPs/Vis/PMS system exhibited a strong synergistic effect in the degradation process. The photogenerated electrons could directly activate PMS and produce more SO4− and OH species. In addition, the photogenerated electrons could promote cycling between Cu3+/Cu2+, Cu2+/Cu+, and Fe3+/Fe2+, reduce the concentration of H+, accelerate the activation of PMS, and reduce the leaching of Cu and Fe ions. Meanwhile, the degradation pathway of TCH was analyzed and proposed via liquid chromatography-mass spectrometry analysis. The CuFe2O4 3DPs were easily separated and recycled due to their macroscopic self-supporting structure and good mechanical stability, offering good prospects for sustainable development and chemical applications.