Preparation And Photocatalytic Properties Of Ce³⁺ And W⁶⁺ Doped Nano-TiO₂

With the rapid development of economy,the pollution of water resources by industrial wastewater,domestic wastewater and agricultural wastewater has become increasingly serious,resulting in many compounds in water resources that are difficult to decompose,thus causing great harm to the ecology.Photocatalytic technology can avoid the harm of wastewater by degrading these compounds.Ti O₂is a new photocatalytic material,which has stable physical and chemical activity,no toxicity.However,Ti O₂has a wide band gap,a small absorption range of sunlight,and a high recombination rate of electron hole pair,which affects its photocatalytic properties.In this paper,nano-Ti O₂was prepared by sol-gel method,and the process route was optimized.The effect of doping Ce³⁺and W⁶⁺on the photocatalytic properties of nano-Ti O₂was emphatically discussed.The main research contents and conclusions were as follows.1.Nano-Ti O₂was prepared by sol-gel method,and a better process route was obtained by optimizing the process parameters.When the volume ratio of tetrabutyl titanate to absolute ethanol was 1:6,the magnetic stirring temperature was 30?,the dosage of hydrochloric acid was 1 m L,and the aging time was 48 h,stable white Ti O₂sol and the nano-Ti O₂with high crystallinity could be obtained.2.The influence of the doping amount of Ce³⁺on the morphology and photocatalytic properties of nano-Ti O₂was studied.The results show that when the doping ratio is higher than 8%,there are more massive nano-Ti O₂in the sample.When the doping ratio is lower than 0.4%,there are some spherical nano-Ti O₂in the sample.Under the condition of simulated sunlight,with the degradation of methylene blue solution as the standard,it is found that the concentration of Ce³⁺will affect the photocatalytic properties of the sample,in which the proportion of Ce³⁺doping is 8%,the photocatalytic activity of the sample is the best,and the degradation rate can reach32.9%.It is found that the heat treatment temperature is 350?500?,Ce³⁺can inhibit the transformation of nano-Ti O₂from anatase type to rutile type,and there is only a single anatase type nano-Ti O₂.Moreover,the heat treatment temperature also has a great impact on the photocatalytic properties of nano-Ti O₂.As the temperature increased from 350?to 500?,the photocatalytic activity of the sample first decreased and then increased.When the heat treatment temperature is 350?,the photocatalytic activity of the sample is the best,and the degradation rate can reach32.6%.3.The influence of the doping amount of W⁶⁺on the morphology and photocatalytic properties of nano-Ti O₂was studied in detail.The results showed that the doping amount of W⁶⁺can improve the morphology of nano-Ti O₂,not only can improve the crystallinity of nano-Ti O₂,but also refine the grains of nano-Ti O₂.Under the condition of simulated sunlight,the efficiency of degrading methylene blue by nano-Ti O₂without W⁶⁺is only 64.1%.When the concentration of doped W⁶⁺is lower than 5%,it will promote the degradation of methylene blue.Among them,the degradation efficiency of 3%W⁶⁺sample is the best,which can reach 92.3%.When the heat treatment temperature increased from 350?to 500?,the amount of anatase and rutile in W⁶⁺doped nano-Ti O₂increased at the same time,and W⁶⁺had a strong promoting effect on the growth of anatase.At the same time,it was found that the degradation of methylene blue was promoted by heat treatment temperature.When the heat treatment temperature is 350?,the degradation rate of 1%W⁶⁺doped nano-Ti O₂is only 10.2%.When the heat treatment temperature is 500?,the photocatalytic properties of the sample is the best,and the degradation efficiency can reach 78.6%.