Fabrication of novel Z-scheme SrTiO3/MnFe2O4 system with double-response activity for simultaneous microwave-induced and photocatalytic degradation of tetracycline and mechanism insight

In this work, a novel Z-scheme SrTiO3/MnFe2O4 catalytic system with microwave-ultraviolet (MW-UV) double-response activity was constructed using MW hydrothermal method for the degradation of tetracycline in water, as a target pollutant. The effects of several parameters including mass ratio (SrTiO3:MnFe2O4), irradiation time, MW power, and catalyst reuse cycles on the catalytic activity of SrTiO3/MnFe2O4 under MW-UV were also investigated. The degradation mechanism on the Z-scheme SrTiO3/MnFe2O4/MW-UV catalytic system was proposed. The results reveal that the combination of MW-induced catalytic and UV photocatalytic oxidation technology achieves superior SrTiO3/MnFe2O4 catalytic performance. The Z-scheme SrTiO3/MnFe2O4 system displays high catalytic activity under MW-UV. Particularly, the generated MW plasma accelerates electron transfer and separation of e(-)-h(+) pair, which promotes the enhancement of redox capacity and the degradation of organic pollutants. At the 1.0:1.0 mass ratio, SrTiO3/MnFe2O4 has higher catalytic activity, and TC (22.0 mg/ L) can be completely degraded within 20.0 min under MW (300 W)-UV (200 W) irradiation. Moreover, the catalytic activity of SrTiO3/MnFe2O4 remains high after five reuse cycles. During the degradation, the center dot OH plays a major role, while the center dot O-2(-) and h(+) play relatively minor roles. Therefore, SrTiO3/MnFe2O4 /MW-UV technology demonstrates to be promising in the treatment of antibiotics at different concentrations in water and wastewater.