Preptration Of Bi-based Pyrochlore And Its Degradation Properties To Tetracycline

Tetracycline(TC)is one of the commonly used antibiotics and is widely used in agriculture,medicine,animal husbandry and aquaculture and frequently detected in water and sediments.Due to its high toxicity,persistent and incomplete metabolism in nature,it is difficult to be removed in the environment,which poses a potential threat to human health.Bi-based pyrochlore is a promising enviromnental-friendly photocatalyst with high visible light reflectance and has potential for photodegradation of TC.So far,there have been few studies on the degradation of TC wastewater by pyrochlore,and the degradation performance and influencing factors are still need to study.Different types of phosphorescent catalysts have significant differences in the degradation and selectivity of contaminants.Bi2Sn2O7 and Bi2Zr2O7 prepared by sol-gel method and the synthesized nanoparticles analyzed by various characterization methods such as XRD.SEM.TEM.UV-vis DRS and BET specific surface area.Under visible light,the degradation performance of Bi2Zr2O7 on methylene blue dye and tetracycline wastewater is 35%and 40.5%higher than that of Bi2Sn2O7,respectively.Bi2Zr2O7 is an effective photocatalyst.In this study,Bi2Zr2O7 synthesized by direct combustion method.CTAB soft template method and sol-gel method,named as BZO-1,2,3.The synthesized nanoparticles analyzed by XRD.SEM.TEM.XPS.UV-vis DRS and BET specific surface area methods.The three synthetic Bi2Zr2O7 catalysts have different structures,morphology and band gaps.Bi2Zr2O7 nanoparticles(BZO-3)synthesized by sol-gel method have large specific surface area(30.7m2/g)and narrow band gap(2.39eV).and have good TC degradation performance under visible light.The degradation efficiency is as high as 81.3%.They also showed good stability and reusability in recycling experiments.According to the particle capture experiment and the characterization results,it is proposed that the enhanced photocatalytic performance mainly benefits from the photogenerated holes of the active materials.To improve the TC degradation performance of Bi-based pyrochlore photocatalyst under visible light further.g-C3N4 powder added during the preparation to synthesize Bi2Zr2O7/g-C3N4(BZO/CN)composite.The synthesized BZO/CN materials characterized by XRD,XPS,DRS,SEM.TEM and BET specific surface area methods.Mass spectrometry(MS)used to analyze the intermediates and degradation products of the reaction process by mass spectrometry.The degradation pathway of TC photodegradation was proposed.The particle-capture experiments based on composite materials show that the enhanced photocatalytic performance mainly attributed to photogene rated holes and superoxide radicals of active materials.TC mainly degrades on the surface of photocatalysts,and combines various characterization results to propose photocatalytic reaction mechanism of TC degradation.The enhancement of photocatalytic performance was mainly due to photogene rated holes of reactive species and TC mainly degraded on the surface of the photocatalyst.Pathways of TC photodegradation derived from the result of analyses of the reaction intermediates.In conclusion.BZO/CN nanoparticle found effective as photocatalyst for TC photodegradation by visible light,which is an interesting founding.