Goethite-MoS2 hybrid with dual active sites boosted peroxymonosulfate activation for removal of tetracycline: The vital roles of hydroxyl radicals and singlet oxygen

MoS2-based materials have recently attracted much attention in advanced oxidation processes based on peroxymonosulfate (PMS). Herein, a series of goethite-MoS2 hybrids (G-MoS2) with dual sites (Fe and Mo) were applied as PMS activators to remove tetracycline (TC). The pseudo-first-order rate constant for TC degradation in 0.1G-MoS2/PMS system was 3.25 times that in MoS2/PMS system. Electron paramagnetic resonance spectra and density functional theory calculation demonstrated that PMS was more likely to be adsorbed and activated on the surface of 0.1G-MoS2 compared with pristine MoS2. Moreover, the total contributions of •OH and 1O2 were over 95% for TC removal in both MoS2/PMS and 0.1G-MoS2/PMS systems. However, the contribution of •OH (66.72%) was enhanced, and that of 1O2 (32.17%) was weakened in 0.1G-MoS2/PMS system compared with those in MoS2/PMS system. This work could provide new strategies to construct high-efficiency PMS catalysts and further understand the role of main reactive species in catalyst/PMS system.