| With the development of society,environmental pollution is becoming increasingly serious.Photocatalytic treatment technology has the advantages of complete degradation of pollutants,no high-temperature and high-pressure reaction conditions,and high reaction rate,and stands out in the field of sewage treatment.Currently,TiO2 is the photocatalyst that most widely used and studied.SiO2 aerogel has a structure similar to TiO2 aerogel and a larger specific surface area,which can support TiO2 aerogel with photocatalytic activity.In view of the above research background,TiO2 aerogel with photocatalytic activity was prepared by using titanium sulfate solution as raw material.On this basis,SiO2/TiO2 composite aerogel was prepared by mixing two kinds of sol containing titanium source and silicon source.RhB was taken as the target substrate to explore the influence of different reaction conditions on photocatalyst catalytic activity.The above two photocatalysts were used to treat sodium oxalate solutions and humic acid solutions of simulated bayer liquor,in order to providing reference and basis for field test.Bayer liquor is an important process fluid in the process of producing alumina by Bayer process.The high content of organic matter in Bayer liquor will affect the normal production of alumina.In this paper,the process of removing organic impurities in Bayer liquid by photocatalytic oxidation method is proposed,and part of the field test is completed on the basis of laboratory test.The main content of this paper is as follows:(1)the use of titanium sulfate as titanium source,were prepared by sol-gel TiO2 photocatalysis aerogel materials,and the material with the light catalytic degradation of RhB,the experimental results show that under ultraviolet light the aerogel materials photocatalytic activity,have stronger than commercial photocatalyst P25,under the same experimental conditions of 10 mg/L of the degradation of rhodamine B effect is about 80%of the P25;Under the conditions of neutral pH,0.6g/L material addition and 10 mg/L substrate initial concentration,the photocatalytic reaction rate was the highest,and the degradation rate reached more than 60%at 1 h and more than 90%at 4 h.The degradation rate of sodium oxalate and humic acid at 4 h was 23%and 12%,respectively.(2)to solve the problem of material reuse activity after serious decline,will contain titanium precursor and two containing silicon precursor sol,stability of wet gel system formed under atmospheric pressure,using the sol gel method successful preparation of SiO2/TiO2 composite aerogels have to close the photocatalytic activity of TiO2 aerogels,and after the first use activity fell 32%,smaller than TiO2 aerogel decline after the first use,showed that after/SiO2 composite aerogel has better stability.(3)in this paper,the organic matter in the production of alumina by bayer process was removed by photocatalytic method,and the optimal pilot treatment conditions were obtained.Under this condition,the COD degradation rate reached 52%after 6 hours of reaction.The experimental results show that the process is feasible in technology. |
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