Construction of core-shell Fe3O4@MoS2 activates peroxymonosulfate for the degradation of tetracycline: Structure-activity relationship, performance and mechanisms

Peroxymonosulfate (PMS) is an excellent oxidant that can produce multiple radicals. A novel core-shell composite Fe3O4 @MoS2-x (F@M-x) heterostructure was synthesized to degrade tetracycline (TC) by PMS activation. In F@M/PMS catalytic system, more Fe(III) is reduced into Fe(II) by doping MoS2 nanoflowers formed core-shell structure, resulting in the catalytic process being significantly enhanced. Due to the strong complexation tendency of TC towards Fe(II), the Fe(II)-TC complexes* accumulated between the core and shell, which significantly accelerates the PMS activation and TC abatement compared to free Fe(II). The EPR and quenching experimental results revealed that O2•− and 1O2 were detected as the main active species for TC degradation in the F@M/PMS system. Furthermore, the possible TC degradation pathways were proposed and the toxicity estimation of intermediates was evaluated by Toxicity QSAR prediction. These results will be useful for the improvement of PMS-based AOPs activation and expand the application of Fe(II)/PMS systems in the treatment of water containing new organic micro-pollutants.