Synthesis And Visible Light Photocatalytic Performance Of AgBr/Zn₃?OH?₂V₂O₇·2H₂O

At present,photocatalytic technology has attracted more and more attention with the increasingly serious global environmental problems and resources shortage,and the exploration of highly efficient visible-light-responded photocatalysts is becoming a hot topic in this field.Vanadate compounds have good photocatalytic activity.As one of the most important vanadate materials,zinc pyrovanadate possess the unique porous framework structure,but its practical application is limited due to low utilization of sunlight.In this paper,our work is focused on expanding the zinc pyrovanadate absorption range and improving its visible light photocatalytic activity by combining the narrow band gap of silver bromide with zinc pyrovanadate.X-AgBr/ZVO composite catalyst with different mass ration were prepared by hydrothermal-precipitation method and characterized by XRD,SEM and other method.The preparation conditions of the composite catalyst with better visible light photocatalytic activity were screened through the degradation of methylene blue,and the influencing factors of photocatalytic degradation of methylene blue and methyl orange and the reuse performance of the catalyst were also investigated.The main contents of this paper were shown as following:(1)The screening congdition was that the precursor pH=10,heated at 120? for 10h,the quality of silver bromide and zinc pyrovanadate ratio was 0.20.Under the same conditions,the degradation of methylene blue(10mg/L)by 1.0g/L catalyst was 220%higher than that of zinc pyrovanadate,respectively.(2)Methylene blue served as target contaminat,and photocatalytic degradation experiments were carried out with the selected catalyst under visible light.Results showed that:The decolorization rate could reach about 90%within 120 min,when the catalyst dosage was 1.5g/L,the initial concentration of methylene blue was 10mg/L and the pH was in the range of 4-10;NaCl inhibited the degradation of methylene blue,while Na2SO4 promoted the degradation of methylene blue;The photocatalytic activity of the catalyst was stable,and after 4 times of repeated use,the decolorization rate caused by photocatalysis was not changed much.(3)Photocatalytic degradation of methyl orange were performed to investigate the influence of different conditions.Results showed that:When the initial concentration of methyl orange was 20mg/L,the pH was also original,the catalyst dosage was 1.5g/L,the decolorization rate of methyl orange reached the maximum after 5h;pH had little effect on the photocatalytic degradation of methyl orange;Na2SO4 promoted the degradation of methyl orange;The decolorization rate decreased with the increase of the number of reused.(4)The photocatalytic degradation process of methylene blue and methyl orange with different initial concentrations conformed to the first-order reaction kinetics model,and the apparent reaction rate constant decreased with the increase of initial concentration of solution.