Efficient removal of sulfamethazine from irrigation water using an ultra-stable magnetic carbon composite catalyst

Antibiotics accumulated in ecosystem can easily enter the agricultural cycle with irrigation water, which brings a huge potential threat to food security. Transition metals are widely utilized in advanced oxidation processes to degrade pollutants, but the poor stability has significantly impeded their application in irrigation water. To solve these problems, the harmless tetrasodium iminodisuccinate is selected to pyrolysis with ferrite and cobalt resources to obtain a composite heterogeneous catalyst composed of porous carbon and Co3Fe7 , CoFe2O4 (IDC@Co3Fe7/CFO). The catalyst exhibits excellent catalytic performance in peroxydisulfate (PDS) activation and shows a high removal efficiency of sulfamethazine up to 100%. The ESR analysis proves SO4 center dot- , center dot OH and center dot O-2(-) are the main active substances, and sulfamethazine can be gradually degraded until mineralization. More importantly, with the formation of Metal-Metal/Metal-Oxygen bonds and the protection of the IDS derived carbon, the dispersion and stability of the metal can be greatly promoted. The composite can maintain the rate of degrading sulfamethazine above 93.44% after 10 times catalytic reactions, with extremely low detection of Fe or Co leaching. This study not only give a super-stable material for the removal of antibiotics in irrigation water, but also provides a novel stratagem for obtaining stable catalytic structures.