Silver Phosphate Series Photocatalytic Degradation Of RhB Catalyst

Silver phosphate（Ag₃PO₄）has the characteristics of narrow band gap,high quantum yield and strong photocatalytic activity,so it has been widely used in photocatalytic degradation of dyes.However,Ag₃PO₄ has poor stab ility and poor reusability.In order to improve these deficiencies of Ag₃PO₄a nd make the effect of silver phosphate in photocatalytic degradation of Rho damine B（Rh B）dye better,In this paper,the method of doping with KNb O₃was firstly adopted to improve the photocatalytic activity and reuse perfor mance of Ag₃PO₄.Secondly,SBA-15 was used as a carrier to improve the s pecific surface area,photocatalytic activity and reuse performance of Ag₃P O₄.The catalysts were characterized by XRD,FTIR,UV-Vis,N₂ adsorption-desorption,SEM,PL,VB-XPS and XPS.The results are as follows:（1）Ag₃PO₄ doping modification can regulate the band gap,by adding KNb O₃ in the process of preparing Ag₃PO₄ to form（X）KNb O₃-Ag₃PO₄ cat alyst.It can be seen from the characterization that the absorption wavelengt h range of（0.3%）KNb O₃-Ag₃PO₄ is expanded,and the intensity of absorpti on peak is also increased,which enhances the absorption of ultraviolet light.The light absorption wavelength has a blue shift,and the probability of ph oto-generated electron hole recombination is reduced.The band gap widths of Ag₃PO₄,KNb O₃ and（0.3%）KNb O₃-Ag₃PO₄ catalysts were calculated b y Kubelka-Mink formula,and the approximate positions of conduction ban d and valence band of these three catalysts were determined by VB-XPS.T he surface elemental state of（0.3%）KNb O₃-Ag₃PO₄ catalyst was also inves tigated.In order to investigate the photocatalytic performance of the catalys t,the photocatalytic performance of（X）KNb O₃-Ag₃PO₄ catalyst was invest igated by photocatalytic degradation of 100m L Rh B solution with 40mg/L concentration using UV lamp as the light source and catalyst dosage of 0.06g.The optimal doping amount of KNb O₃-Ag₃PO₄ catalyst was studied.（0.3%）KNb O₃-Ag₃PO₄ catalyst degradation rate of Rh B can reach 100%in40min,and the optimal doping amount of KNb O₃ is determined to be0.3%.By linear fitting of the degradation data of Rh B over KNb O₃,Ag₃PO₄ and（0.3%）KNb O₃-Ag₃PO₄ catalysts,it can be verified that the photocatal ytic degradation of Rh B by these three catalysts is in line with the first orde r kinetics,and（0.3%）KNb O₃-Ag₃PO₄ catalyst has the highest activity.The reproducibility test of Ag₃PO₄ and（0.3%）KNb O₃-Ag₃PO₄ catalyst showed t hat the degradation rate could still reach 80%after the fifth repetition,and t he reusability of（0.3%）KNb O₃-Ag₃PO₄ catalyst was higher than that of Ag₃PO₄.·O₂^-and h⁺were the main active species in the photocatalytic degrada tion system by capturing（0.3%）KNb O₃-Ag₃PO₄,and the reaction mechanis m of degradation of Rh B by KNb O₃-Ag₃PO₄ was analyzed.（2）Ag₃PO₄/SBA-15 catalyst was synthesized by introducing Ag₃PO₄ i nto the preparation process of SBA-15 with Ag₃PO₄ as the active compone nt and SBA-15 as the carrier.The results showed that the catalyst had a 2-D hexagonal channel structure and a single mesoporous structure,which mai ntained the wheat ear morphology of SBA-15 molecular sieve.Compared with Ag₃PO₄/SBA-15,after UV irradiation,the light absorption wavelength of Ag₃PO₄/SBA-15 is blue shifted,the photogenerated carrier increases,an d its oxidation performance is enhanced.The effective specific surface area of Ag₃PO₄ in the reaction increases,so（A）the active site of Ag₃PO₄/SBA-15 also increases,and it has the channel of SBA-15.Fluorescence spectra s howed that 20%Ag₃PO₄/SBA-15 catalyst had the lowest recombination pro bability of photogenerated electrons and holes.The band gap width of Ag₃P O₄/SBA-15 and Ag₃PO₄ was calculated by Kubelka-Mink formula.The app roximate positions of valence band and conduction band of Ag₃PO₄/SBA-15 and Ag₃PO₄ were determined by VB-XPS.The photocatalytic degradatio n of Rh B by Ag₃PO₄/SBA-15 catalyst was investigated.The photocatalytic degradation of Under the conditions of 0.06g of catalyst,100mg/L of Rh B and 100m L of solution,the degradation rate can reach 100%after 80min of reaction.which was significantly higher than that of the catalysts with other load of Ag₃PO₄,SBA-15 and other catalysts.It proved that the photocataly tic performance of 20%Ag₃PO₄/SBA-15.