Insight into degradation mechanism of sulfamethoxazole by metal-organic framework derived novel magnetic Fe@C composite activated persulfate

Novel [email protected] composites derived from metal-organic framework (MOF) were synthesized. Being subject to pyrolysis under different temperatures endows these [email protected] diverse physical-chemical properties, including morphology, crystal structure, defect level, magnetism, and most importantly, iron phase composition. [email protected] consists mainly of Fe3C and α-Fe, thus possesses strong ferromagnetic properties, which imparts the ability to be separated and recycled. Its catalytic activity towards the activation of persulfate (PS) and the decomposition of sulfamethoxazole (SMX) was found to be the best among all the [email protected], and this activity can be regenerated by simple heat treatment. Given the mixed form of iron and N-doped carbon, α-Fe/Fe3C species provide electrons for PS to decompose and generate sulfate radical (SO4·−), hydroxyl radical (·OH), and superoxide radical (O2·−), initiating the radical pathway for partial SMX degradation. The positively charged C atoms on PS bonded [email protected], as well as the conversion of O2·− give rise to the generation of singlet oxygen (1O2), which was responsible for the non-radical pathway for SMX degradation. As a consequence, SMX was degraded to intermediates through five degradation pathways, and finally mineralized to inorganic molecules. The results indicate that [email protected] has great potential to serve as a promising activator for persulfate-mediated environmental remediation.