Kinetics Of Ozonation And Catalytic Ozonation Of Dichlorprop

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 research situation of ozonation of water, the main research target of this study were proposed. What this paper describes mainly include three parts: kinetics and mechanism of ozonation and Mn²⁺ catalytic ozonation of dichlorprop; kinetics of Fe₃O₄-CoO/AL₂O₃ catalytic ozonation of dichlorprop; kinetics of Fe₃O₄-CoO/AL₂O₃ catalytic ozonation of nitrobenzene and oxalic acid.In chapterâ…£, the effect of ozonation and Mn²⁺ catalytic ozonation of dichlorprop (DCPP) was evaluated, and its kinetics and mechanism were also discussed. The rate constants of DCPP with ozone and OH radical calculated by the relative method were (0.733±0.163) L·mol?1·s?1 and 2.367×109 L·mol?1·s?1, respectively. The above results agreed very well with the apparent reaction rate constant of ozonation or Mn²⁺ catalytic ozontaion of DCPP when it was controlled by chemical reaction. The results of the relative method for kinetic study showed that Mn²⁺/O₃ possessed a larger Rct than O₃, indicating that Mn²⁺/O₃ produced more hydroxyl radical, which was also proved by the total organic carbon(TOC) analysis. Intermediates detected by GC-MS and ion chromatography (IC) included 2,4-dichlorophenol, 2-chlorohydroquinone, 2-chloroquinone, 2-hydroxypropionic acid, pyruvic acid, acetic acid and oxalic acid. Therefore, the possible destruction pathway of ozonation and Mn²⁺ catalytic ozonation of DCPP was proposed.In chapterâ…¤, Al₂O₃-supported Fe3O4-CoO catalysts were prepared by incipient wetness impregnation and used to catalyze ozonation of DCPP. The results showed that Fe₃O₄-CoO/AL₂O₃ catalyst could significantly improve ozonation effciency, about 5 times under the same condations. The change of pH had little affect on the efficiency of DCPP removal, and Fe₃O₄-CoO/AL₂O₃ catalytic ozonation system was more suitable for application in acidic condition., Fe₃O₄-CoO/AL₂O₃ catalyst had a better activity in the decomposition of dissolved ozone: the decomposition rate constant reached 3.370×10-3 s-1 while that of the ozone alone was 1.380×10-3 s-1.The experimental results of t-butanol indicated that the Fe₃O₄-CoO/AL₂O₃ catalytic ozonation of DCPP followed a radical-type mechanism. The results of the relative method for kinetic study showed that O₃/Fe₃O₄-CoO/AL₂O₃ possessed a larger Rct than O₃, indicating that O₃/Fe₃O₄-CoO/AL₂O₃ produced more hydroxyl radical.In chapterâ…¥, Fe₃O₄-CoO/AL₂O₃ catalytic ozonation of nitrobenzene(NB) and oxalic acid(OA) were carried out to evalute the characteristics of the catalyst. The results showed that Fe₃O₄-CoO/AL₂O₃ catalytic ozonation of NB followed a radical-type mechanism, and that O₃/Fe₃O₄-CoO/AL₂O₃ had a larger Rct calculated by the relative method than O₃ did, showing that the system of O₃/Fe₃O₄-CoO/AL₂O₃ generated more hydroxyl radical. Similar results could be obtained in the catalytic ozonation of oxalic acid, indicating that the catalytic performance of Fe₃O₄-CoO/AL₂O₃ was universal to a certain degree.