Study On The Synthesis Of Perovskite Oxides And The Photocatalytic Degradation Of Acid Red B

Perovskite oxides (ABO3) has stable structure and high photocatalytic activity ,further morea catalyst which has more narrow band gap can be synthesized and can absorb more solar energy by altering the type of A and B. A series of perovskite oxides are synthesized by means of blend deposition using the nitrate of A and B as the raw materials, and ammonia or sodium carbonateas sedimentation .A includes alkaline-earth metals such as Mg, Ca, Sr, Ba and rare-earth metalsLa; while B includes transition metal Cr, Mn, Fe, Co and Ni. The result of activity evaluation indicates that the effect of A is low while the effect of B is remarkable comparatively. The normal tendency of change is that the photocatalytic activity improvements with the increases ofatomic number.The activity of CaNiO3 is the highest among the above photocatalysts. The test result ofXRD and TEM shows that the purity of CaNiO3 is comparatively high and the particle shape isapproximately round ball whose diameter is in the range of 150-200nm. The photocatalytic activity of CaNiO3 and TiO2 is compared, and the result shows that the activity of the two photocatalysts are equal under the irradiation of UV while under imitation of sunlight the farmer's activity is higher than the latter's, and that the rate of degradation of acid red B is 63%and 47% respectively. The compound oxides of CaFexNi1-xO3 (x=0.1-0.9) have been synthesized.Among them, the activity of CaFe0.3Ni0.7O3 is the highest and under the imitation of sunlight, the rare of degradation of acid red B can reach 91%. The effect of load of Co and Ag on the CaFe0.3Ni0.7O3 is studied, and indicates that the activity of CaFe0.3Ni0.7O3 supporting Co is muchlower, while the activity of CaFeo.3Ni0.7O3 supporting Ag is increased and that the rate of degradation of acid red B is 96%.The kinetics of degradation of acid red B under UV is studied over CaNiO3 catalyst. Thereaction order is defined to be 1.4. Pre-exponential factor in ko= 1.01 × 107 mol-0.4L0.4min-1, and the activation energy is Ea=35.5 kJ.mol-1.Acid red B degraded in different time is analyzed by IR and UV-VIS spectra analysis. According to result, the mechanism of acid red B degradation is inferred, i.e., double bond of nitrogen is disappeared, firstly and then, naphthalene ring is broken and benzene ring is cracked.The effects of experimental condition on photocatalytic degradation of acid red B are studied. The photocatalysis is improved by adding H2O2 into the solution and the activity is raised with the increase of the amount of H2O2. Increasing the acidity of the solution is benefited to decompose acid red B. The higher the initial concentration of acid red B, the more difficult the photocatalysis.