Peroxymonosulfate Activation by CoFe2O4/MgAl-LDH Catalyst for the Boosted Degradation of Antibiotic

Owing to outstanding hydrophilicity and ionic interaction, layered double hydroxides (LDHs) have emerged as a promising carrier for high performance catalysts. However, the synthesis of new specialized catalytic LDHs for degradation of antibiotics still faces some challenges. In this study, a CoFe2O4/MgAl-LDH composite catalyst was synthesized using a hydrothermal coprecipitation method. Comprehensive characterization reveals that the surface of MgAl-LDH is covered with nanometer CoFe2O4 particles. The specific surface area of CoFe2O4/MgAl-LDH is 82.84 m2<middle dot>g-1, which is 2.34 times that of CoFe2O4. CoFe2O4/MgAl-LDH has a saturation magnetic strength of 22.24 A<middle dot>m2<middle dot>kg-1 facilitating efficient solid-liquid separation. The composite catalyst was employed to activate peroxymonosulfate (PMS) for the efficient degradation of tetracycline hydrochloride (TCH). It is found that the catalytic performance of CoFe2O4/MgAl-LDH significantly exceeds that of CoFe2O4. The maximum TCH removal reaches 98.2% under the optimal conditions ([TCH] = 25 mg/L, [PMS] = 1.5 mmol/L, CoFe2O4/MgAl-LDH = 0.20 g/L, pH 7, and T = 25 degrees C). Coexisting ions in the solution, such as SO42-, Cl-, H2PO4-, and CO32-, have a negligible effect on catalytic performance. Cyclic tests demonstrate that the catalytic performance of CoFe2O4/MgAl-LDH remains 67.2% after five cycles. Mechanism investigations suggest that O2 center dot-and 1O2 produced by CoFe2O4/MgAl-LDH play a critical role in the catalytic degradation.