One-step synthesis of “nuclear-shell” structure iron-carbon nanocomposite as a persulfate activator for bisphenol A degradation

[Display omitted] •Fe@CNs is prepared by a one-step synthesis using sodium alginate as a template.•The carbon shell and network provide double-protection for Fe3C nanoparticles.•The Fe@CNs catalyst shows a high BPA degradation efficiency and TOC removal rate.•BPA degradation includes both radical and non-radical pathways. In this study, a “nuclear-shell” structure iron-carbon nanocomposite catalyst (Fe@CNs) was prepared by a one-step synthesis method using sodium alginate as a template to activate persulfate (PS) for bisphenol A (BPA) degradation. The TEM image of Fe@CNs showed that the Fe nanoparticles were encapsulated in the carbon matrix with doubly protected by both the “carbon shell” and adherent graphite structures (“carbon network”). According to the X-ray diffraction pattern and elemental composition analysis, the encapsulated Fe nanoparticles were designated as Fe3C. Catalytic results show that the Fe@CNs composite has good advanced oxidation catalytic performance and can remove 96% of BPA within 30 min. The effects of coexisting anions and water matrix on the removal of BPA and TOC were also investigated. Free radical quenching experiments confirmed that several free radicals (including OH, SO4−, O2− and 1O2) acted together to cause BPA decomposition. In addition, the catalytic activity of Fe@CNs used in the cycle experiments was mainly recovered after thermal regeneration. Based on the detected intermediates, we proposed a potential BPA degradation pathway and degradation mechanism in the Fe@CNs/PS reaction system. This is a new attempt to synthesize a “nuclear-shell” structure of Fe@CNs using sodium alginate hydrogel as a template in a facile one-step pyrolysis.