Fast degradation, large capacity, and high electron efficiency of chloramphenicol removal by different carbon-supported nanoscale zerovalent iron

It remains unclear that which kind of carbon support is better for improving the reactivity of nanoscale zerovalent iron (nZVI) without the adsorption effects of carbon. Finding appropriate contaminants that could be degraded by nZVI with high capacity and electron utilization is crucial for exploring the applications of nZVI. High degradation rate (up to 3.70 min^-1) and high capacity (up to 3000 mg g^-1) of antibiotic chloramphenicol (C₁₁H₁₂Cl₂N₂O₅, CAP) removal with high electron utilization (>97%) was achieved by different carbon supported nZVI in this study. Carbon powder (CP) was found to be the best support, possessing good distribution and reactivity of nZVI. 99% of CAP was removed by CP-nZVI after 3 min, without the electron consumption via the side reaction between nZVI and water, suggesting that CAP could outcompete with water for the electrons from nZVI. The entire pathway of CAP removal was elucidated based on UPLC-MS/MS analysis. Partial degradation of CAP (denitration and dechlorination) was enough to take away the antimicrobial properties. These results suggest a promising application scenario of carbon supported nZVI for the remediation of CAP-contaminated water to reduce the antibiotic selection pressure of the environment.