Z-scheme FeS/MgIn2S4 heterojunction for solar-light induced peroxymonosulfate elimination of tetracycline hydrochloride

Photocatalysis induced peroxymonosulfate (PMS) oxidation has been confirmed as a potential route to eliminate antibiotics of wastewater. To boost the solar-light driven photocatalysis-PMS activity of MgIn2S4 for tetracycline hydrochloride (TCH) degradation, Z-scheme FeS/MgIn2S4 heterojunction was fabricated via the solvothermal approach. The Z-scheme structure between FeS and MgIn2S4 was likely to separate and migrate photo-generated e(-)/h(+) pairs and to suppress the recombination of charge carriers. In addition, S defects and Fe2+/Fe3+ couples were likely to form active radicals, including SO4-, OH, and O-2(-). For comparison to FeS and MgIn2S4, FeS/MgIn2S4 hybrids exhibited the better photocatalysis-PMS activity for TCH removal. The removal efficiency of TCH over 3-FeS/MgIn2S4 with a nominal Fe/Mg molar ratio was 98.88 % within 140 min, and declined to 90.97 % after five cycle times. The deactivation of 3-FeS/MgIn2S4 was attributed to the valence states variation of surface components under long-term irradiation.