Study On Photocatalytic Degradation Of Chlorobenzene On The Modified Layered Perovskite-type K₂La₂Ti₃O₁₀ Under Simulated Sunlight

Chlorobenzene is one kind of the halogenated aromatic compounds with extensive application, and it can be used to synthesis many organic materials intermediates. Although chlorobenzene has extensive uses, but because of its low boiling point at normal temperature and pressure likely to be volatile and persistent in the environment, as well as resistantance to degradation and other features, it will seriously pollute water, soil and air atmosphere. Meanwhile, chlorobenzene will continuously accumulate in human body, and then endanger human health seriously. However, the traditional methods of removing chlorobenzene such as methods of aerobic and anaerobic microorganisms, reduction and method of ultrasonic oxidation can not remove chlorobenzene effectively. Therefore, this paper focuses on the method of photocatalysis under simulated sunlight to remove chlorobenzene, and investigate the catalyst activity of modified catalysts.In this paper, perovskite-type layered catalyst K2La2Ti3O10 was prepared by the sol-gel method, and then the catalyst preparation conditions were discussed. The results suggested that the target catalyst could be prepared successfully by sol-gel method as described above. When the calcination temperature was 950 ℃, the calcination time was 2 hours, the catalyst reached the highest activity, and chlorobenzene degradation rate could reach 38.0% after 180 minutes of illumination.The catalysts were modified by ion-exchange method. For catalyst Fe3+/K2La2Ti3O10, the optimal condition for ion-exchange concentration was 0.15 mol/L, for exchange temperature was 60 ℃ and for calcination temperature was 500 ℃, and at this point, the chlorobenzene degradation rate reached 49.1%. For catalyst Cu2+/K2La2Ti3O10, when the ion-exchange concentration was 0.10 mol/L, the exchange temperature was 20 ℃ and calcination temperature was 500 ℃, the chlorobenzene degradation reached the highest point, which was 51.1%. For catalyst H2La2Ti3O10, acidification time was an important factor affecting the catalytic activity, and the catalyst reached the highest activity when acidification time was 48 hours. At this time, the degradation rate of chlorobenzene reached 43.2%.This paper studied kinetics of degradation reaction of chlorobenzene on catalyst K2La2Ti3O10、Fe3+/K2La2Ti3O10、Cu2+/K2La2Ti3O10 and H2La2Ti3O10, the effect of reaction conditions and amount of CO2 introduced into reactor on the degradation rate of chlorobenzene. Research concluded that four kinds of catalyst reaction systems were all in line with a kinetic model, and Cu2+/K2La2Ti3O10 catalyst had a maximum degradation rate of reaction of chlorobenzene. The initial concentration of chlorobenzene and the amount of catalyst also affected the degradation efficiency, and there existed an optimum value. The introduce of CO2 contributed to the degradation of chlorobenzene, and when the ratio of CO2 was 50%, the degradation rate of chlorobenzene reached the highest, which was 68.0%. The photocatalytic degradation products of chlorobenzene included benzaldehyde. This illustrated that the method of photocatalytic degradation of chlorobenzene provided a new method for the recycling of chlorobenzene.