The Research On Oxidation Absorption On Of Using Oxone Activated By Catalyst On Go

Recently, the advanced oxidation technology based on sulfate radicals has aroused people’s attention and has been widely used. In comparation with the traditional hydroxyl radicals, the sulfate radicals have higher redox potential, the wider range of pH application, the less amount of iron to deal with, the higher degree of mineralization, the simple operation and no harm to environment. Homogeneous catalytic oxidation system has faster reaction and simple operation, but the manganese ion may cause the second pollution to the environment and the catalyst is hard to be recycled. Due to the shortage of the homogeneous system, the heterogeneous catalytic system was studied and applied, and the drawbacks of the homogeneous catalytic system were solved effectively. In this paper, the Mn3O4and Co3O4were supported on expanded graphite to form the composite catalyst Mn3O4/GO and Co3O4/GO, and the research on the oxidation of NO. At the same time, from the method of catalyst preparation, the loading, the heat treating temperature and heat treating time were discussed. Also the stability of the catalyst and the dynamics analysis conditions under the condition of optimal reaction was also researched. The major research contents as followings.(1) The preparation and characterization of the catalystThe expanded graphite was prepared from expandable graphite with a instant high temperature. Then using the expanded graphite as the presoma, in aqueous solution system by using solvent impregnated step to form the composite catalysts of Mn3O4/GO which was used as a catalyst during the oxidation of NO. The GO, Mn3O4and Mn3O4/GO was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS). The results showed that the Mn3O4with small particles was supported on GO successfully, and the purity of the catalyst was high. The surface of GO is smooth and have the fold on the edges, and there are a lot of functional groups containing oxygen, such as hydroxyl group, epoxy group. The Mn3O4was in the presence of nano composites Mn3O4/GO, but the XRD diffraction peak was smaller. At the same time there was a large number of Mn3O4in the GO, resulted in the disappear of ghaphene. The Mn3O4lattice is5.7621A, and the EDS confirmed that the compound is composed of C, O, Mn three elements.(2) The activity and stability of the composite Mn3O4/GOThe preparative composite catalyst was applied on the research of the oxidation of NO with the heterogeneous system. The good catalytic activity of composite catalyst of Mn3O4can be found. The studies shown that the oxidation activity was relate to the catalyst of catalyst loading, heat treatment temperature and heat treatment time in the process of catalyst preparation, but also with the pH, PMS concentration catalyst concentration and temperature. Considering the reaction efficiency and the economic and practical factors, the optimum reaction conditions were determined as follows. Under the catalyst loading50%, heat treatment temperature180℃and the heat treatment time7h, the optimal operation condition for oxidation is considered to be the pH4.00, the dosage of0.5mM Mn3O4/GO,6mM PMS and25℃. In the optimal condition,70.58%oxidation of NO coubld be obtained. After7rounds of oxidation of the catalyst, the oxidation efficiency could be reached45%because of the stable performance of the catalyst, and the concentration of the Mn2+leached from the solution was still very low, it showed that the Mn2O3from Mn3O4determines the degradation rate instead of Mn2+.(3) The dynamic analysis under the optimum oxidation conditionAt the same time, under the best conditions of the loading, heat treatment temperature and heat treatment time, the pre-first order kinetics was researched. The results showed that there were a good linear relation between pH, PMS,[Mn2+], temperature and the reaction rate constant, and according to the Eyring-Polanyi equation, the Ea, the activation enthalpy (△H) and entropy of activation (△S) and gibbs free energy of reaction (△G) were calculated through the establishment of In (k/T) and linear figure1/T.(4) The research of catalytic oxidation of NO by Co3O4/GO/PMSThe GO, Co304and Co3O4/GO was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), Raman, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS). The results showed that the Co3O4with small particles was supported on GO successfully. The optimal operation condition for catalytic oxidation of NO is considered to be the dosage of6mM PMS,0.75mM Co3O4/GO, pH4.00and25℃.