Preparation Of Ca₆Bi₆O₁₅ And Its Photocatalytic Properties

In recent years,more and more dye pollutants from the textile industry have been produced,which are complicate,toxic and mostly nonbiodegradable and also can not be completely removed by conventional treatment methods.Photocalalytic oxidization technology is a green environmental protection technology in recent dacades,it has many merits in terms of the removal of toxic organic compounds and wastewater treatment,such as high treatment efficiency,simple processing equipment, operation conditions controlled easily,organic pollutants degraded non-selectively,no secondary pollution,etc..So it can provide new thoughts and pathways for industrialization treatment of organic wastewater and will be endowed with extensive application prospect in the organic wastewater treatment.The synthesis and application of photocatalyst is the key of photocatalytic oxidation technology,and the researchers have being searching new photocatalysts with high-activity and low costs.In the article,we synthesize the compound Ca₆Bi₆O₁₅by a simple solid state reaction method,the prepared samples were characterized by powder X-ray diffraction(XRD),scanning electron microscope(SEM),X-ray photoelectron spectroscopy(XPS),and so on.The analysis of X-ray diffraction(XRD)and scanning electron microscope(SEM)indicates that the pure photocatalyst was synthesized at 860℃for 8h,which consist of a single phase of Ca₆Bi₆O₁₅with a layered structure and space group of P1(2).XPS analysis indicated Bi in Ca₆Bi₆O₁₅exists in the valence state of Bi(â…¢).The photocatalytic activity of the prepared samples was evaluated by degradation acid red G as a model dye wastewater under UV irradiation.The complete discoloration of acid red G and the destruction of structure of azo,benzene ring and condensed nucleus in 90 min show a good catalytic oxidation activity of the powder. Moreover,the influences of the calcining temperature and time of the catalysts,the dosage of the catalysts and the initial concentration of acid red G solution on the photocatalytic degradation rate of acid red G were studied.The kinetics of photocatalytic oxidation reaction for acid red G solution was studied in Ca₆Bi₆O₁₅catalyst suspension phase,the results showed that the reaction was first order kinetics and was coincident with Langmuir-Hinsheluwood(L-H) equation.Through the analysis of UV-Vis spectrophotometer,the mechanism of acid red G degradation was discussed.