Highly efficient visible-light photocatalytic performance of Ag/AgIn5S8 for degradation of tetracycline hydrochloride and treatment of real pharmaceutical industry wastewater

The deposition of Ag nanoparticles (NPs) on semiconductors has been demonstrated to be an efficient route to improve the separation of photogenerated electrons and holes due to plasma resonance effect, but the photocatalytic efficiency of the available Ag-based photocatalysts is still low and far from practical application. In this study, a novel photocatalyst with Ag NPs deposited on the surface of AgIn5S8 (Ag/AgIn5S8) was fabricated via solvothermal method and further photo-reduction approach. The amount of deposited Ag nanoparticles has an obvious effect on the charge separation and visible-light photocatalytic activity of Ag/AgIn5S8, and 2.5% Ag/AgIn5S8 nanocomposites exhibit the highest visible-light photocatalytic activity with 95.3% degradation efficiency of tetracycline hydrochloride (TC% HCl) compared with that of the other samples due to the surface plasmon resonance of Ag NPs, proper bandgap of AgIn5S8 and the synergistic effect between them. The main reactive species in TC% HCl degradation are center dot OH and center dot O-2(-). The possible degradation pathway of TC% HCl and photocatalytic mechanism of Ag/AgIn5S8 were proposed according to high performance liquid chromatographytandem mass spectrometry (HPLC-MS) analysis, main reactive species, and conduction band and valence band of AgIn5S8. Moreover, Ag/AgIn5S8 nanohybrids were applied to treat real pharmaceutical industry wastewater, and it was found that the mineralization efficiency and COD removal of real pharmaceutical industry wastewater can reach 56.3% and 77.6%, respectively. The above results indicate Ag/AgIn5S8 photocatalysts have a promising prospect in the treatment of real pharmaceutical industry wastewater.