Ozonation And Catalytic Ozonation Of Acetophenone

The physical chemistry properties of ozone and its application in water treatment are reviewed, and the emphasis of discussion is put on metal ( or metal oxide) catalytic ozonation technology developing recently. On the basis of the present research situation of ozonation, the research task of this work was proposed. The contents of the dessertation mainly include three parts: kinetics and mechanism of ozonation of acetophenone; CuO-Ru/Al₂O₃ catalytic ozonation of acetophenone; honeycomb-like ceramic catalytic ozonation of acetophenone.In chapterâ…£, acetophenone (ACP) was degraded by ozone, and the rate constants of ACP reaction with ozone and·OH radicals were calculated using the relative method. The results indicated that ACP could be degraded effectively by ozone, and that the rate constants of ACP with ozone and OH radicals were (0.163±0.036) L·mol^-1·s^-1 and 7.07×109 L·mol^-1·s^-1, respectively. The experimental results at different pHs showed that application of two calculated reaction rate constants could well forecast the evolution of ACP concenation during ozonation. Intermediates detected by GC-MS and ion chromatography (IC) included phenol, 2-hydroxyacetophenone, tartaric acid, acetic acid and oxalic acid etc.In chapterâ…¤, two-component CuO-Ru based on active Al₂O₃ (CuO-Ru/Al₂O₃) catalyst was prepared by incipient wetness impregnation and used to catalyze ozonation of ACP. The results showed that doping Ru could significantly improve the catalytic activity of CuO/Al₂O₃ during ozonation of ACP. The value of pH almost had no affect on the ozonation efficiency. However, a comparison of chemical oxygen demand (COD) removal between ozonation alone and catalytic ozonation indicated that CuO-Ru/Al₂O₃ catalyst was more suitable for application in neutral or acidic condition. CuO-Ru/Al₂O₃ catalyst could accelerate decomposition rate of ozone in water, and its decomposition rate constant reached 2.58×10^-3 s^-1 while that of the ozone alone in double-water was 1.19×10^-3 s^-1. The experimental result of t-butanol indicated that the CuO-Ru/Al₂O₃ catalytic ozonation of ACP followed a radical-type mechanism. CuO-Ru/Al₂O₃ catalyst also had high activity during ozonation of oxalic acid.In chapterâ…¥, ACP was degraded by ozonation alone and honeycomb-like ceramic catalytic ozonation. The results showed that the presence of honeycomb-like ceramic catalyst significantly improved the ozoantion efficiency. The experimental result of adding tert-butanol indicated that honeycomb-like ceramic-catalyzed ozonation of ACP in aqueous solution follows the mechanism of·OH oxidation. The kinetics of honeycomb-like ceramic-catalytic ozonation of ACP included two stages. For the first stage, the values of apparent reaction rate constant was 8.77×10-4 s^-1 and the Rct was 10.34×10-10. For the second stage, the values of apparent reaction rate constant was 4.63×10^-3 s^-1 and the Rct was 172.34×10-10. It is speculated that in the catalytic ozonation process the Ti⁴⁺ leaching from ceramic honeycomb is the dominant factor for the enhancement of ozonation efficiency. Compared with ozonation alone, addition of Ti⁴⁺ could improve the degradation rate of COD by 62.8%, which further corroborated the above-speculated possible mechanism. The results of the degradation of ACP by ozonation alone, Ti⁴⁺/O₃ and Ti⁴⁺/H₂O₂/O₃ showed that only Ti⁴⁺ addition could not improve ozonation efficiency, and that combination of Ti⁴⁺and H₂O₂ was necessary. The analytic results of ozone concentration in water indicated that its decomposition rate was accelerated in the presence of Ti⁴⁺ ion and H₂O₂ in strong acid solution .