Facile fabrication of Fe/Fe3C embedded in N-doped carbon nanofiber for efficient degradation of tetracycline via peroxymonosulfate activation: Role of superoxide radical and singlet oxygen

The toxic metal ions leaching and metal nanoparticles agglomeration were the critical issues for metal-based carbon materials during the peroxymonosulfate (PMS) activation processes. Herein, a facile strategy was first proposed that zero-dimensional Fe/Fe3C nanoparticles were embedded in one-dimensional N-doped carbon nanofiber (Fe/Fe3C@NCNF) to solve the above challenges. The as-obtained Fe/Fe3C@NCNF-800 possessed a low Ea value (11.7 kJ/mol) and exhibited high activity for activating PMS to degrade tetracycline (TC) in a wide range of pH 3-11. As expected, the iron ions leaching concentration of Fe/Fe3C@NCNF-800 was very low (0.082 mg/L). Meanwhile, the Fe/Fe3C@NCNF-800 was easily recovered from the reaction solution due to its magnetic properties. Both superoxide radicals (O2∙-) and non-radical of singlet oxygen (1O2) were the primary reactive oxygen species (ROS) in the Fe/Fe3C@NCNF-800/PMS system via quenching tests and electron spin resonance spectroscopy (ESR). The catalytic mechanism suggested that the Fe/Fe3C and graphitic N were the main active sites in the Fe/Fe3C@NCNF-800 for PMS activation. This work provided a facile method for the preparation of Fe-based carbon materials with high catalytic ability, low metal leaching and easy recycling, showing a broad prospect for environmental applications.