The Preparation Of Si-FeOOH And The Research Of It On The Catalytic Ozonation Of Organics In Water

The refractory organic compounds were degraded using catalytic ozonationtechnology in water. This technology has the characteristic of good effect and highdegree of mineralization. Among this, the selection of catalyst is very important tothe application of this technology. Therefore, this paper is intended to prepare a kindof efficient and durable catalyst which has the characteristic of less dissolution ofmetal ion and good settling performance. This catalyst can be used in catalyticozonation technology to deal with refractory organic matter.In this paper, Si-FeOOH was separately prepared through hydrothermal methodand co-precipitation method. And it was analyzed by the characterization methods ofX-ray diffraction (XRD), scanning electron microscope (SEM), FTIR and specificsurface area (BET). At the same time, the catalytic activity was preliminarilydiscussed in the catalytic ozonation of nitrobenzene. And the dissolution quantity ofiron was determined by atomic absorption spectrometer and the dissolution quantityof iron of Si-FeOOH had so little difference between hydrothermal method andco-precipitation method. Therefore, coprecipitation method was more suitable forpractical application through comprehensive consideration.The preparation conditions of Si-FeOOH prepared by co-precipitation methodwere studied in this paper. The best preparation conditions of Si-FeOOH wereselected. These conditions were that the Si/Fe, activation temperature and dryingtemperature were respectively0.33,70℃and105℃and the dissolution quantityof iron was far less than the dissolution quantity of iron of FeOOH under the samepreparation conditions. It illustrated that the dissolution of iron was effectivelycontrolled due to the addition of Si. At the same time, the conclusion that thesettlement performance of Si-FeOOH was better than FeOOH was obtained whensedimentation performance of FeOOH and Si-FeOOH were compared. ThenSi-FeOOH had a good performance of repetition use.The other influencing factors of reaction system were studied. The effect ofSi-FeOOH catalytic ozonation of nitrobenzene and ibuprofen was the best when thereaction system was in the neutral condition. Then the better was in alkalinecondition and the worst one was in acid condition. The degree of mineralization ofnitrobenzene and ibuprofen in catalytic ozonation was higher than ozonation alone.The various inorganic anions in natural water contained Cl-, CO32-, SO42-, PO43-,HCO3-and NO3-can produce the different influence. Among these, Cl-, CO32-,SO42-and PO43-produced inhibition for the degradation and the inhibitory effect of PO43-was the strongest. HCO3-produced the promoting effect under the lowconcentration and the inhibition under the high concentration. NO3-was almost noimpact on the degradation reaction. the reaction mechanism of catalytic ozonation ofnitrobenzene when Si-FeOOH existed was preliminarily discussed. It was concludedthis degradation reaction followed the hydroxyl free radical mechanism.