Magnetic core–shell S-Fe@MOF derivative hybrids to activate peroxymonosulfate for highly efficient degradation of tetrabromobisphenol A

Abstract

In recent years, new heterogeneous catalysts derived from metal organic frameworks (MOFs) have been widely used in advanced oxidation processes (AOPs). In this work, zeolite imidazole framework-67 (ZIF-67) and sulfide nanozero-valent iron (S-Fe) were used as precursors to prepare S-Fe/Co bimetallic nanoparticles embedded in graphitized carbon (S-Fe/Co@GC) and used to activate peroxymonosulfate (PMS) to degrade tetrabromobisphenol A (TBBPA). Morphological and structural characterization indicated that S-Fe/Co@GC compared to pre-carbonization, the pore size of the material became larger, formed a graphite carbon skeleton with excellent electrical conductivity. In a 0.2 g/L S-Fe/Co@GC and 0.6 mM PMS system, 96.1% of TBBPA (20 mg/L) was degraded within 30 min, and the degradation yielded a total organic carbon (TOC) removal of 56.2% in 60 min. This excellent catalytic activity was attributed to the synergistic effect of graphitic carbon, sulfide nanozero-valent iron and metallic cobalt. Radical quenching experiments and electron paramagnetic resonance (EPR) technology indicated that reactive oxygen species (ROS) included HO•, SO4•−, O2•− and 1O2, among which O2•− plays a leading role in the degradation of TBBPA. Based on the LC-MS analysis of the degradation intermediates, the degradation pathway of TBBPA in the S-Fe/Co@GC/PMS system was proposed. In addition, S-Fe/Co@GC showed a low ion leaching rate, and the regenerated S-Fe/Co@GC still had high catalytic performance. This work will extend the development of MOFs encapsulate functional nanoparticle materials for environmental remediation.