Z-type ZnAl-LDO/Ag2S heterojunction activated peroxysulfate to degrade tetracycline hydrochloride under visible light efficiently

This study used electrostatic self-assembly and chemical deposition to construct a visible-light-driven Z-type ZnAl-LDO/Ag2S heterojunction composite material with active phase Zn/Al LDO. Then it is used as an efficient catalyst for photocatalysis (PC) coupled with sulfate radical based-advanced oxidation processes (SR-AOPs) to degrade tetracycline hydrochloride (TC-HCl) under visible light. The effects of ZnAl-LDO molar ratio, calcination temperature, Ag2S deposition amount, initial concentration of persulfate (PMS), initial solution pH, and catalyst dosage on the reaction were investigated. The results show that the combination of photocatalysis and SR-AOPs can significantly improve the degradation ability of pollutants. Under the action of 0.5 g/L ZnAl-LDO/Ag2S, pH = 7 and 6 mM PMS, within 35 min, 20 mg/L 100 mL of tetracycline hydrochloride can be completely degraded. The results of the scavenging experiment and ESR analysis show that SO4− and OH radicals are the leading free radicals that degrade tetracycline hydrochloride and verify the degradation mechanism. The ZnAl-LDO/Ag2S/PMS system has good structure and performance stability. This research has established the foundation for the design and optimization of the Photo-SR system and further promoted the broad application of the system in environmental treatment.