Research On Photocatalytic Degradation Of Chlorobenzene And Toluene By Visible Light

People have begun to pay attention to Volatile Organic Pollutants, and chlorobenzene and toluene are important volatile organic compounds, which have more menace. As other phenyl materials, due to the structure stability of benzene, chlorobenzene and toluene are difficult to be degraded by the common techniques. Gas-phase photocatalytic oxidation is a promising and effective method. K₂La₂Ti₃O₁₀(KLTO) has high activity for photocatalytic degradation of organic contaminations. This paper prepared KLTO, and modified it with metal ion, and prepared several other catalysts including superconducting material (GdBCO), to degrade chlorobenzene and toluene which have high activity in visible light.With the irradiation of visible light, by the products of metal ion-KLTO to degrade chlorobenzene, the order is Co-KLTO>Zn-KLTO>Mn-KLTO>Cu-KLTO>Cr-KLTO≥Ni-KLTO≥Fe-KLTO, and Co-KLTO has the highest degradation rate of 50.2%. For toluene, the order is Ni-KLTO>Cu-KLTO>Mn-KLTO>Zn-KLTO≥Co-KLTO>Fe-KLTO≥Cr-KLTO, and Ni-KLTO has the highest degradation rate of 45.3%. For other metal oxides, FeVO₄ has the highest degradation rate of 45.9% for chlorobenzene, and CoAl₂O₄ has the highest degradation rate of 48.7% for toluene. Superconducting material (GdBCO) was used in this experiment, and it had a degradation rate of 48.5% for chlorobenzene.The results of XRD measurement indicate that the structures and composing of all kinds of photocatalysts. The results of UV-Vis Diffuse Reflectance Spectra show that the Einstein shifts of absorbance spectra of different catalysts have the same trend with the results of the experiment. This approved the correctness of experiment data. The results of BET show that the specific surface area of metal ion exchanged products have increased.Finally, the paper studyed the reaction degraded rate of chlorobenzene and toluene by different catalysts, and the results indicate that the rate of photocatalysts degradation can be expressed in first-order kinetics model to Langmuir-Hinshelwood kinetic equation under most catalysts. The first-order kinetics indicates that in the process of degradation, there is a step that decides other steps, and it was consistent with reaction mechanism. It also explained the differences of two different sequences of metal ion exchange products' catalytic activity. Through the infrared analysis of Co-KLTO, Ni-KLTO which have the highest catalytic activity of chlorobenzene and toluene, and there's no other organisms, and it indicate the process of photocatalytic reactions was completed oxidation, finally generating CO₂.