Fe@C activated peroxymonosulfate system for effectively degrading emerging contaminants: Analysis of the formation and activation mechanism of Fe coordinately unsaturated metal sites

Carbon-encapsulated Fe nanocomposites ([email protected]), obtained by pyrolysis of metal-organic frameworks (MOFs), can activate peroxymonosulfate (PMS) to remove emerging contaminants (ECs). Unfortunately, the current MOFs-derived catalysts always inevitably produce more iron-oxide compounds that unfavorable for PMS activation. In this work, according to the thermogravimetric curve of Fe(II)-MOF-74, to discuss the role of pyrolysis temperature on the structural characteristics of [email protected] The results demonstrated that [email protected] could obtain abundant coordinately unsaturated metal sites and exhibited the best activation performance. Radical-quenching experiments and EPR measurements confirm that the generated sulfate radical (SO4−˙) and singlet oxygen (1O2) only degraded approximately 35% of TBBPA. Meanwhile, negatively charged complex intermediates formed by the weak interaction between [email protected] and PMS was proposed as the dominant reactive species, and approximately 65% of TBBPA was degraded. This work optimizes the synthesis strategy and mechanism of [email protected] and provides a methodological reference for the design of Fe-based catalysts.