(NH4)2Mo3S13/MnFe2O4 hybrid with multiple active sites boosted activation of peroxymonosulfate for removal of tetracycline

Advanced oxidation processes (AOPs) based on peroxymonosulfate (PMS) activation have attracted much attention in wastewater treatment. Here, a series of (NH4)(2)Mo3S13/MnFe2O4 (MSMF) composites were prepared and used as PMS activators to remove tetracycline (TC) for the first time. When the mass ratio of (NH4)(2)Mo3S13 to MnFe2O4 was 4.0 (MSMF4.0), the composite showed remarkable catalytic efficiency for activating PMS to remove TC. Over 93% of TC was removed in MSMF4.0/PMS system in 20 min. The aqueous (OH)-O-center dot as well as the surface SO4 center dot- and (OH)-O-center dot were the primary reactive species for TC degradation in MSMF4.0/PMS system, and the comprehensive experimental results excluded the contributions of aqueous SO4 center dot-, O-2(center dot)-, and O-1(2), high-valent metal-oxo species, and surface-bound PMS. The Mn(II)/Mn(III), Fe(II)/Fe(III), Mo(IV)/Mo(VI), and S2-/SOx2- all contributed to the catalytic process. MSMF4.0 also showed excellent activity and stability after five cycles and significant degradation efficiency for a variety of pollutants. This work will provide theoretical basis for applying MnFe2O4-based composites in PMS-based AOPs.