Periodate activation by atomically dispersed Mn on carbon nanotubes for the production of iodate radicals and rapid degradation of sulfadiazine

Sulfonamides, such as sulfadiazine (SDZ), are widely used antibiotics that pose a significant threat to the environment due to their poor biodegradability and potential to induce antibiotic resistance. In this study, a new catalyst with atomically dispersed Mn on carbon nanotubes (MnN@CNT) was applied for the first time to activate periodate (PI) for rapid degradation of SDZ. MnN@CNT/PI system achieved 100% SDZ removal in 15 min, and the kinetic rate constant (knor) reaches 406.1 min−1·g−2·L2, higher than those of the reported catalytic PI systems. Multiple reactive oxygen species (ROS), including IO3•, O2–•, 1O2, high-valent Mn-oxo complexes, and •OH, were detected, with IO3• being the most predominant. The Mn atom bridged the electron from the carbon support to IO4- via the Mn-O bond, which induced the prolonged I-O bond and thus the generation of IO3•. SDZ was degraded through S-N bond cleavage, pyrimidine destruction, SO2 extrusion, and N-N coupling. The intermediate products of the SDZ degradation process showed little antibacterial activity, indicating the greatly reduced risk of the treated water to induce antibiotic resistance in the environment. The superior performance of MnN@CNT/PI in the environmental water samples suggests its high application potential for selective degradation of SDZ in complex waters. The research presents a novel advanced catalytic oxidation technology for efficiently removing sulfonamides and similar antibiotics from water for adequate environmental and ecological protection.