Study On Preparation Of WO₃/Titanate Composites And Visible Light Catalytic Activity

Organic dyes in the wastewater emitted from industrial plants such as paper,plastic,textiles,food and cosmetics are harmful to the environment.These organic pollutants are structurally stable and difficult to degrade.Therefore,it is an urgent and important task for the removal of organic dyes from wastewater.In recent years,the application of photocatalytic oxidation technology be concerned in water pollution control field.Tungsten trioxide and titanate semiconductor has been applied to photocatalysis.However,their electronic?e-?and hole?h+?are easily composite,also the light response range is limited.In order to overcome this difficulty,in this paper,the tungsten trioxide and titanate were composited.The degradation of organic pollutants in aqueous solution was studied by using WO₃/ titanate as photocatalyst.In this paper,WO₃/Ba Ti O₃,WO₃/Sr Ti O₃ and WO₃/Ba0.5Sr0.5Ti O₃ be prepared by microwave hydrothermal method.Photocatalytic degradation of organic pollutants in water by visible light and the catalytic activities of the three catalysts were compared.The properties were characterized by XRD,SEM,FTIR and PL.Effects of microwave synthesis time,microwave synthesis pressure,the precursor of p H,calcination temperature of the catalyst,the molar ratio of WO₃ and titanate catalyst,visible light irradiation time for degradation efficiency of organic pollutants.Degradation kinetics of rhodamine B?Rh B?,direct yellow-4R?DY-4R?,methyl parathion?MP?,methylene blue?MB?solution were Compared.The results showed that in WO₃/ titanate / visible light system,organic pollutants can be effectively degraded.The order of activity of the three catalysts as follows,WO₃/Ba0.5Sr0.5Ti O₃ > WO₃/Sr Ti O₃ > WO₃/Ba Ti O₃.The order of particle size is from large to small as follows:O₃/Ba Ti O₃ > WO₃/Sr Ti O₃ > WO₃/Ba0.5Sr0.5Ti O₃.When the microwave hydrothermal pressure,the microwave hydrothermal time,the precursor p H,and the calcination temperature were 1.5 MPa,30 min,1.0 and 700?,respectively,the highest activity of WO₃ catalyst was obtained.When the molar ratio of WO₃ and titanate of 2:1,the catalyst dosage of 2.4 g/L and the illumination power of 315 W,the degradation rate about 100% when 10 mg/L Rh B solution is illumination about 8 h.In addition,8 mg/L DY-4R degradation of 12 h,can be completely removed.Howere,Rh B,DY-4R,MP and MA,the degradation rate constant of WO₃/titanate / visible light in the system?k?were 0.63,0.40,0.20 and 0.14 h-1,respectively.Degradation rate as follow,Rh B > DY-4R > MB > MP.When the WO₃/ titanate was reused for three times,it still had some degradation effect.Therefore,the visible light photocatalytic degradation of WO₃/titanate has a good application prospect in organic wastewater treatment.