| Groundwater pollution caused by the accident would have incalculable pollution of groundwater, For example, explosion caused by underground water pollution accidents, and accidental release into the oil storage facilities, etc. As such sudden accident, resulting in the concentration of organic pollutants in groundwater transiently increased, then the groundwater will need in a shorter period of time can quickly degrade organic pollutants, which can minimize groundwater resource damage.In this study, prepared by impregnation of transition metal/silica catalyst carrier, will contain the active component (or with the catalyst composition) of the liquid (or gas) contained in the solid carrier material soaked surface. Preparation of this study, a new Mn-Fe/silica catalyst carrier, and the organic toxic pollutants pollutant nitrobenzene and chlorobenzene as the common object of study, through a series of experiments on the ozone/Fe-Mn/vector gel Removal of catalytic oxidation of organic pollutants compared the effectiveness of systematic experimental study. The study of its oxidation mechanism was discussed, the development of the ozone/ Mn-Fe/carrier catalytic degradation of silicone hard biochemical degradation of organic compounds in water wastewater treatment technologies.(1) Through screening, a highly efficient and new Mn-Fe/silica catalyst carrier had been prepared. Used in the experiment preparation of new catalysts are:The carrier first buy silicone cleaning, drying, will be immersed into the silica gel carrier has said a good first end of the Mn and Fe dissolved 3:1 in 10% of the nitrate solution, the solution and the silica gel carrier plasmid ratio was 1:2.5, and then impregnated at 40℃at least 24h. Remove and drain, then into the oven to bake 85℃to 8 hours or so. remove into a muffle furnace, transferred to 450℃, roasted to 6 hours, and other natural cooling to room temperature, rinse with distilled water, washed several times back and forth to the cleaning liquid is almost no metal ions were detected so far, placing well-ventilated place to dry for use. The whole process takes about 2 days.(2) Carrier silica gel times and 250 times magnification under an electron scanning microscope phase carrier surface can be observed, there are many pores, and SiO2 crystals. By Mn-Fe/silica catalyst carrier SEM-EDS joint representation found the presence of Mn greatly increased the load of metal Fe. Mn and Fe metal in the load process has significant synergistic effect, so we prepared a catalyst with high activity.(3) O3/Mn-Fe/silica gel carrier performance of catalytic oxidation of organic pollutants①O3/Mn-Fe/carrier gel and catalytic oxidation of chlorobenzene degradation of nitrobenzene had a good effect. In this experiment, ozone alone the removal of chlorobenzene and nitrobenzene were 93.4%(5min) and 32.07%(30min), and under the same conditions O3/Mn-Fe/chloride carrier system on silica gel the removal of benzene and nitrobenzene were up 98.9%(5min) and 69.7%(30min), were increased by 6.5% and 37.63%, the amount of catalyst have a certain influence on the experiment, there is the best dosage is 20g/L;②In 30 min, the adsorption of catalyst removal rate of nitrobenzene was 9.6%, while there is still a catalyst for desorption. It can be speculated that the adsorption of organic matter degradation for a certain contribution, however, organic matter catalytic ozonation of ozone on the degradation of performance is not a catalyst for oxidation of organic matter and sorption of organic compounds the simple sum; can speculate that the adsorption of organic compounds have some contribution to the degradation, however, catalytic ozonation on the degradation efficiency of organic matter is not the catalyst of ozone oxidation and adsorption of the simple sum;③The removal rate of nitrobenzene dosage of ozone increased with the increase;④increasing initial concentration of nitrobenzene as the positive effect;⑤pH value on the oxidation system of impact is relatively large. When the water sample pH=9, the reaction is very fast,10Min had more than 60% in, but then the degradation is carried out very slowly, pH=7, although the beginning of the slow degradation, but the whole growth is very obvious. In 30Min, the water samples had very similar degradation under alkaline conditions results. Therefore, if the water in the actual operation was neutral, could be considered appropriate to extend the response time;(4) The main component of the catalyst in the new system is still SiO2, and metal oxides highly dispersed in the carrier's backbone. On the surface of the catalyst there is a lot of hydroxyl, Fe-Mn/carrier catalytic ozonation of nitrobenzene gel process follows the mechanism of hydroxyl radical. The main active site is MnOx/FeOx/metal oxide silicon carriers and their mutual synergies. Among them, the catalyst is the surface hydroxyl groups O3 decomposition catalyst surface active sites, O3 adsorption on the catalyst surface, decomposition, desorption process of hydroxyl radicals determines the rate of oxidation, and·OH will rapidly through the interface spread to the occurrence of organic pollutants in wastewater and fast, chemical control of the oxidation reaction.(5) For the laboratory simulation of water in the continuous operation of one hour after the water is lower than the basic chlorobenzene 100mg/L, more than 86% chlorobenzene removal. When the tests to 100 hours later, the effect of catalytic ozonation is more clear and stable, the basic concentration of chlorobenzene in the 40mg/L is about 2 hours in continuous operation, the degradation of nitrobenzene in the water began to slow trend, nitrobenzene removal rate was 57.92% at this time. When the tests to 100 hours later, the effect of catalytic ozonation is more clear and stable, the basic concentration of nitrobenzene in the 145mg/L or so, run the effect is stable. In dealing with actual contaminated groundwater, wastewater can be seen in experiments has been dramatically improved color, odor also much smaller. Although it also contains, like nitrobenzene, chlorobenzene,etc., but has been reduced a lot, indicating that the catalyst in the actual handling of water samples is also largely carried out in the laboratory can be achieved when the treatment effect, by other elements in water samples little influence can be ignored. Silica gel as a carrier to carrier system was the Mn-Fe/silica catalyst carrier technology is simple, high hardness, wear resistance, and removal of organic matter stability, long-term operation without further adding other agents to save operating costs. 03/Mn-Fe/carrier catalytic oxidation of silicon is very promising new technology. |
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