Study On Degradation Of Guaiacol By Catalytic Ozonation

Guaiacol (GL) is one of Lignin model compound that the main pollutants in papermaking wastewater. Its structure is composed of three parts: benzene ring, hydroxyl group, methoxy group. As an organic pollutant, it is difficult to completely degradation by physical, chemical, biological and so on. Heterogeneous catalytic ozonation was used to degrade the guaiacol solution in this study. In the experiment of catalytic ozonation, the choice of catalyst is very important. The primary task of this heterogeneous catalytic ozonation process is to select a suitable catalyst.In the process of catalyst exploration, it was found that different catalysts have different catalytic efficiency in the degradation of guaiacol solution by heterogeneous catalytic ozonation. The catalytic ozonation degradation of guaiacol solution by ?-Al2O3 and AlOOH and the kinetic analysis showed that the catalytic effect of AlOOH on the degradation of guaiacol solution was better than that of ?-Al2O3. The removal efficiency of guaiacol (200mg/L) can reach 100% and the COD removal efficiency of the guaiacol solution can reach 89.31% by AlOOH catalytic ozonation, while the removal efficiency of COD in the guaiacol solution Only can reach 52.7% by ?-Al2O3 catalytic ozonation. The efficiency of catalytic ozonation is significantly affected by the catalytic performance of the catalyst. The catalytic performance of ?-Al2O3 and AlOOH was found to be very different,but y-Al2O3 was obtained from the pyrolysis of AlOOH at high temperature. That is to say,AlOOH was the precursor of ?-Al2O3. The specific surface area of AlOOH was higher than the ?-Al2O3 by specific surface area analysis. The larger specific surface area was favorable for the contact reaction of ozone and organic matter on the surface, which enhanced the effect of catalytic ozone oxidation.The introduction of the catalyst in the catalytic ozonation is mainly to improve the utilization of ozone in the ozonization experiments alone, and the reaction with the organics is selective. AlOOH can promote the reaction of ozonation. The degradation of guaiacol solution by heterogeneous catalytic ozonation is better than that ozonation alone, and the adsorption of AlOOH to organic matter is almost zero. A series of experiments were conducted to investig te the influence of oxidation condition on the degradation of guaiacol and COD removal efficiency by Orthogonal method, such as ozone flow rate, initial pH of reaction system, catalyst dosage, catalyst particle size. The results showed that the removal efficiency of guaiacol (200mg/L) was 100% and the COD removal efficiency was 89.3%after 40 min reaction at pH = 5.4 when the ozone concentration, ozone flow rate, and the dosage of AlOOH were 13.32 mg/L,0.51 L/min and 5 g/L,respectively. The particle size of the catalyst had little effect on the degradation of the guaiacol. However, the results showed that the grinding time had a certain effect on the particle size distribution by the scanning electron microscopy and particle size analysis. If you want to heterogeneous catalytic ozone oxidation technology was used in industrial, it is very important to analysis the performance of ALOOH before and after the reaction. The analysis of AlOOH that before and after the reaction by the particle size analyzer, scanning electron microscope and X-ray diffraction analysis shows that the catalyst will be a little change After the reaction,but the impact is not great.In the process of catalyzed ozonation guaiacol with AlOOH, the solution changed from a colorless to yellow showed that some intermediate products had produced. There are two intermediates can be characterized by FPLC and FT-IR. The structure of the guaiacol during the heterogeneous catalytic ozonation is destroyed, resulting in a variety of intermediates, which substances continue to be oxidized to be mineralized into CO2 and H2O. The degradation mechanism of catalytic ozonation is discussed by UV- visible spectrum, liquid chromatography analysis and addition of hydroxyl radical scavenger t-butanol (TBA). The results showed that Both hydroxyl radical and O3 played an important role on the degradation process of guaiacol. And the hydroxyl groups on the surface of AlOOH resulting in more hydroxyl radicals.