O / Sub> / MgO Catalytic Oxidation On Phenol

According to the "three letter" of phenol and the particularity of one of the priority control pollutants in China, this paper studied on phenol treatment using ozone oxidation technology. Phenol degradation effect, the reaction rate constant, the degradation process by ozonation alone and catalytic ozonation and mechanism of catalytic ozonation were studied. Thesis respectively investigated the effect of ozone addition amount, catalyst amount, phenol initial concentration, pH and reaction temperature on the influence of phenol degradation and the reaction rate constant. Analyzed the degradation of phenol and the dynamic model of reaction process in the O3and O3/MgO systems. And discussed the catalytic ozonation mechanism for phenol.The experimental studies on the ozone oxidation and ozone oxidation of phenol were conducted. The results showed that:It was a positive correlation between phenol degradation, reaction rate constant and the ozone dosage, pH and reaction temperature in the ozone oxidation system. It was a negative correlation between phenol degradation, reaction rate constant and phenol initial concentration in the ozone oxidation system. When reaction after10min under the ozone dosage of3.6mg/min, pH of6.89, phenol initial concentration of100mg/L, the temperature of20℃, the rate of phenol degradation was61%. And in the O3/MgO system, it was a positive correlation between phenol degradation, reaction rate constant and the ozone dosage, pH and reaction temperature. It was a negative correlation between phenol degradation, reaction rate constant and phenol initial concentration. When reaction after10min under the ozone dosage of3.6mg/min, MgO dosage of40mg/L, pH of6.89, phenol initial concentration of100mg/L, the temperature of20℃, the rate of phenol degradation was80.3%.The two reaction processes of O3and O3/MgO systems were analyzed and compared. The pH in the process of the two systems were declining. And the pH in the process of O3/MgO system was falling faster. This phenomenon indicated that the CO2and other carboxylic acids were produced during the reaction. TOC removal rate during the reaction was lower than the rate of phenol degradation, indicating that intermediates were produced in the phenol degradation process, rather than completely mineralized to CO2and H2O. And the rate of TOC removal and phenol degradation in O3/MgO system were higher than that in single ozonation system, which suggested that MgO promoted the phenol degradation, and also promoted the further degradation of the intermediate product.Phenol degradation processed showed that O3alone attached perferentially to position of phenol, and electropilic hydroxyl radicals attached perferentially to ortho-positions of phenol. It is reasoned that O3molecules oxidation in the alone ozone system was dominan. And OH oxidation in the catalytic ozonation system was dominant. This paper also builded the dynamic model of the two systems. The average relative error between O3system dynamics model calculation value and experimental data was4.26%. The average relative error between O3/MgO system dynamics model calculation value and experimental data was7.16%. They were able to simulate degradation process of phenol wastewater in O3and MgO/03systems.The mechanism of catalytic ozonation was explored by-OH inhibitors of tert-butyl alcohol, Rct values, infrared, and the determination of activation energy. The results showed that:The addition of tert-butyl alcohol reduced the phenol removal rate, indicating that-OH indeed existed in the reaction processes. Rct values in ozone oxidation system and the catalytic ozonation system respectively were1.47×10-9and3.15X10-9. By infrared measuring MgO surface groups, under the same condition, ozone adsorbed species and density of surface hydroxyl on the surface of MgO in phenol system are superior to the pure water system, which showed that phenol in the heterogeneous catalytic ozonation process acted as the promoter by promoting ozone adsorbed onto the surface of the catalyst. The reaction activation energy Ea in O3and MgO/03systems were2.88×104J·mol-1and2.6167X104J·mol-1. The similar Ea in two systems can be considered that the existence of catalyst did not lower the reaction activation energy of O3and organic pollutants in heterogeneous catalytic ozonation process. Therefore, the paper thinked that the existence of the catalyst indeed promoted the decomposition of ozone, produced more·OH, and then maked the degradation of organic matter to achieve better effect. And·OH generation was not only related to the catalyst surface properties, but also related to organic pollutants. In the process of Ozone adsorption on the surface of the catalyst, organic pollutant phenol had played an important role in promoting ozone adsorption on the catalyst surface.