Study On Advanced Degradation Of Organics In Water Based On Photocatalysis Integrated Device

The advanced treatment of the nocuous organics in water is vital to environmental protection. Compared with the conventional physical and biological treatment, photocatalysis has been become an effective advanced water treatment for its broad applicability and sensitiveness to the low-concentration solution. Nowadays, photocatalysis has been gradually developed for the industry application. However, there still exist many difficulties for the adjusting of the parameters in the amplifying procedure. Although a great deal of information of organics photodegradation have been provided by many research groups, these data are not enough for the requirement of practical needs because of the diversity and the uncertain concentration of the organic species. Therefore, the prediction methods for the properties of the photocatalysts, reaction rates and photoreactor efficiency are needed to widen the utilization of the photocatalysis for the practical applications. In addition, the cost of the modified catalyst must be taken into consideration. So it is most important to set up the relations between the organics, the catalyst and the reactor parameters for industry application. In this work, the advanced treatment of nocuous organics in water based on photocatalysis integrated device are detailed discussed accounting to four aspects, which are the sieving of catalysts, the prediction of the reaction rate, the efficiency of photoreactors and the modification of the catalyst for the photogradtion of the chloride organics. At first, the cluster analysis is carried out accounting to the photodegradation achievements of nocuous organics which are hard to photodegrade and the proper catalysts, radiation condition or annexing agents are then deduced. Based on these, the photocatalysis reaction rate of many kinds of reaction systems is studied by using the Langmuir-Hinshelwood(L-H) kinetic equation. It proves that kinetic constant can be used to analyze and forecast some experiment phenomenon. As the aspect of the prediction of reaction rates, the photodegradation rates of 14 organics are compared. From the experimental data, the intrinsic kinetics of the photodegradation of CHCl3 is set up. Combined with the degradation rate of 14 organics, the degradation rates of these organics in a certain concentration can be predicted. The Dissolved Oxygen (DO) and radiation distribution in reactors are difficult to be confined in the different systems , the comparison of reactors'efficiency can not be achieved. It is found that aerating has influence on the CHCl3 photodegradation by detecting the change of DO in chloroform photodegradation reaction. In the continuous plant, the decrease of liquid phase's flow rate and the expandability of tray aperture are beneficial to the integration of gas phase in the reactor. The absorbed radiation of the reactors also has an important influence on the reaction efficiency. In this work, the absorbed radiation model of the mutil-tubular photoreactor is established. On this basis, chloroform's instinct kinetics equation 0.4930.25710R = kCeαVR can be deduced. This equation is used in predicting the efficiency of photoreactors and the deviation is less than 11%. Among all the organics, chloride organics has an enormous harm to the water environment. It has been proved that the noble mental modified TiO2 is efficient to the mineralization of the chloride organics, but the cost limits its commercial application. In this work, the low content Pt doping TiO2 fiber is presented for the first time and is more effective in the photodegradation of chloroform. In contrast to the normal content deposition, TiO2 fiber doped with Pt can form "bi-extreme value"effect. This result shows that the difference of the Pt forms on the fibers led to the different react process in the chloroform photodegradation. What's more, TiO2 fiber in low content Pt deposition has cooperative effect on the catalyst property, which is related to the crystal structure and the surface properties of the supporting materials. By using ICP, the rate of the Pt doping on TiO2 fiber is similar to the doping theory reported in references. Based on the above discussion, the dye waste water in Shengze city as a reactant model is chosen to be advanced treated by photocatalysis. It is detected that the main contaminants in the dye waste water are benzene and substituted bezene. With thecluster analysis of organics photocatalysis, the pure TiO2 and transition metal ions that have high activities on oxidation effect are fit for this system, which is verified by the experiment. The L-H kinetics equation of this system is proposed in which CODCr stands for the organics content. The results show that the TiO2 fiber is the optimal catalyst with the commercial application in the object system. In this thesis, we used the single-lamp-mutil-tubular piston flow reactor as the pilot plant. Compared with the experiment in the lab, with the same light intensity density, the degradation efficiency of the pilot plant is 8.1 times than that of a batch one. By detecting the treated water, every item is far below the first-lever of National Discharge Standard. The total cyanide and Volatile phenol is close to Santtary Standard Of Drinking Water Quality. The photodegradation results of the dye water have reached the expected object. The optimal way of photodegradation of actual water presented by this thesis is found successfully.