The Preparation Of Br-Bi₂WO₆ And Photocatalytic Degradation Of Rhodamine B And Teracycline

Bi2WO6 is considered as an excellent visible light photocatalytic material,being widely utilized in photocatalytic degradation of organic pollutants.However,the traditional hydrothermal method to synthesize Bi2WO6 material was limited by the long-prepared time and high energy consumption.Although rapid preparation of Bi2WO6 could be achieved via the microwave-assisted hydrothermal method,but low photocatalysis activity of Bi2WO6 still limited to use that method.In this study,the Bi2WO6 doped with bromine ion(Br-),which achieved excellent photocatalytic activity,was synthesized by rapid microwave-assisted hydrothermal method.The effects of Br-content and microwave reaction time on preparation of material were investigated.The cationic dye Rhodamine B(Rh-B)and antibiotic tetracycline(TC)were chosen as target pollutants to evaluate the photocatalytic property of Br-Bi2WO6,moreover,the optimized conditions of photodegradation were also investigated..The structural properties of Br-Bi2WO6 were analysed by a series of characterizations techniques.Meantime,the reusability and photocatalytic reaction models of Br-Bi2WO6 were also investigated.The main conclusions were as follows:The photocatalytic performance of Br-Bi2WO6 materials were improved with the increase of Br-content and microwave reaction time.Better photocatalytic activity and low energy consumption were exhibited in the prepared conditions of 20%Br-content and 120 min microwave reaction time.The Orthogonal phase of Bi2WO6 could be demonstrated by XRD technology and RAMAN spectrum,furthermore there was no other crystalline phase could be detected.The larger specific surface area,stronger property of visible light absorption and higher photocatalytic property were achieved by doping Br-.Br-Bi2WO6 prepared under optimized conditions,which exhibited well dispersion and eximious crystallinity,possessed specific surface area of 21.15 m2·g-1,a band gap of 2.72 eV.With the increase of photocatalyst dosage,Rh-B removal increased,however,the removal would decrease with the increase of increased while decreased with the increase of initial concentration of Rh-B.Well photodegradation of Rh-B were exhibited in 20%Br-Bi2WO6 when the pH of solution ranged in 5?9.Cetyltrimethyl ammonium bromide(CTAB)could effectively improve the photocatalytic activity of the catalyst when CTAB concentration was lower than 30 mg·L-1.The photocatalytic degradation processes of Rh-B were fitted with the pseudo-first order kinetic model,the respective reaction rate constant of 20%Br-Bi2WO6 was 0.018 min-1,however,the reaction rate constant of Bi2WO6 prepared by traditional hydrothermal method was 0.010 min-1.Active species capture experiment showed that e-and ·O2-had a decisive role in the photocatalytic reaction.Different structure and properties of TC were affected by different pH value.The Br-Bi2WO6 possessed good photocatalytic degradation for TC within pH 4?8 range.Owing to complexation,the photocatalytic degradation of TC could be improved with the existence of Cu(II).The photocatalytic degradation processes of TC by 20%Br-Bi2WO6 and Bi2WO6 followed the pseudo-first order kinetic model.The respective reaction rate constant of 20%Br-Bi2WO6 and Bi2WO6 were 0.026 and 0.024 min-1.Active species capture experiments showed that e-and ·O2-had a decisive role in the photocatalytic reaction of TC degradation.In summary,Br-Bi2WO6 materials were successfully synthesized by the microwave assisted-hydrothermal method.Compared with traditional hydrothermal method,the microwave irradiation and Br-doping method was beneficial for preparing the Bi2WO6 with well photocatalytic activity in short time.In general,this study provided reference for developing new preparation technology of Bi2WO6.In addition,the photocatalytic degradation Rh-B and TC is useful to research the optimized photocatalytic conditions and provide the alternative reference for dyes and antibiotics removal from wastewaters.