Magnetic Fe3S4/MoS2 with visible-light response as an efficient photo-Fenton-like catalyst: Validation in degrading tetracycline hydrochloride under mild pH conditions

Magnetic Fe3S4/MoS2 composites with a visible light response were prepared, and their degradation activity was tested using tetracycline hydrochloride (TCH) as a simulated pollutant. The mass ratios of Fe3S4 and MoS2, pH change, temperature, H2O2 concentration, and catalyst addition were investigated to determine the mechanism of TCH degradation. The results show that the removal rate of TCH by the Fe3S4/MoS2 composites is much higher than that of the pure Fe3S4 or MoS2 under pH values ranging from 1.2 to 13.2. The removal rate of TCH by Fe3S4/MoS2 was 376.37 and 5.45 times higher than that of pure Fe3S4 and MoS2 when the mass ratio of Fe3S4 and MoS2 was 1:1 at pH 7.2. The main free radicals and metal leaching changes are analyzed. The removal mechanism of TCH was proposed by the free radical scavenger test and the metal leaching test. The mechanism proposed in this paper shows that the high catalytic activity of Fe3S4/MoS2 composite is due to the acidic microenvironment near the surface of the composite, which reduces the production of ferric hydroxide sludge.