Successful fabrication of iron-manganese (Fe-Mn) layered double bimetallic oxide for the degradation of sulfathiazole via peroxymonosulfate activation: Performance, degradation mechanism and pathway

Peroxymonosulfate (PMS) activation technology represents an efficient approach to generate reactive oxygen species for treating pharmaceutical pollutants, and the fabrication of effective catalysts is of great significance for PMS activation technology. In this study, iron-manganese (Fe-Mn) layered double oxides (LDO) with flaky structure formed by metal oxide nanoparticles were synthesized by coprecipitation-calcination method and used to activate oxidant PMS to generate reactive oxygen species so as to realize the degradation of sulfathiazole (STZ). Benefiting from the well-dispersed structure and synergistic effect between bimetallic oxides, about 90% of STZ (20 mg L−1) could be removed with the dosage of catalyst (LDO-400, 0.4 g L−1) and PMS (0.4 g L−1) in 40 min catalysis process. Quenching experiments and in-situ electron paramagnetic resonance (EPR) analysis revealed that radical pathways dominated by surface-bound SO4−• and •OH were involved in the removal of STZ in LDO-400/PMS system. Besides, EPR and linear sweep voltammetry (LSV) analysis indicated the non-radical pathways containing 1O2 and electron transfer also contributed to STZ degradation. Five consecutive cycles were conducted to prove the stability and reusability of LDO-400. The intermediates in the STZ degradation process were identified to propose the STZ degradation pathways. Particularly, ecological structure-activity relationship (ECOSAR) predicted the relatively low ecological risk of LDO-400/PMS system for STZ degradation. This study not only proves the advantages of synergistic effect between bimetallic oxides, but also enriches the design strategy of environmental remediation.