Enhancement of Fe@porous carbon to be an efficient mediator for peroxymonosulfate activation for oxidation of organic contaminants: Incorporation NH2-group into structure of its MOF precursor

Metal-organic frameworks (MOFs) derived metal@porous carbon showed good performance in peroxymonosulfate (PMS) activation for refractory organic chemical degradation from aqueous. However, the effect of structure and physical-chemical properties of metal@porous carbon on PMS activation and its involved reaction mechanism were still unclear. Herein, Fe@porous carbon derived from MOF MIL-53(Fe) was used as target, to discuss the role of NH2-group incorporation on the development of structure and physical-chemical properties of obtained Fe@porous carbon, and reaction mechanism for PMS activation. The incorporation of NH2-group significantly decreased the synthesis temperature of Fe@porous carbon and increased the encapsulation of Fe-0 in the porous carbon. Furthermore, the addition of nitrogen in porous carbon and rigid encapsulation structure reduced the defects of the Fe@porous carbon. These improvements of the structure and chemical properties were favored for enhancement of the catalytic activity and stability of the obtained Fe@porous carbon in the activation of PMS. Electron paramagnetic resonance (EPR) experiments indicated that SO4 center dot-, center dot OH and O-1(2) were involved. The radical pathway involving SO4 center dot- and center dot OH was the prevailing pathway while the nonradical pathway involving O-1(2) was the recessive pathway. Based on intermediate identification, the degradation pathway of acyclovir (ACV) was proposed as SO4 center dot- and center dot OH derived process, and eight of intermediates were first reported. It was interesting to note that iron species, carbon structure, and nitrogen element in the catalysts derived from MIL-53(Fe) or NH2-MIL-53(Fe) clearly showed different role and reaction pathway. This work not only provided an efficient Fe@N-doped porous carbon for activation PMS to degrade refractory organic chemicals for water purification, but also suggested a valuable insight for the design of metal@porous carbon derived from MOF.