| Using ultrasonic to degrade the chemical pollutants, especially the refractory organic pollutants, is a new type of water treatment technology which has been being developed in recent years. It is a technology of high temperature pyrolysis, advanced oxidation and supercritical oxidation, and has the advantages of high efficiency, wide range of applications, and can be combined with other water treatment technologies. The reports on lab research level and application of degradation of organic pollutants in water by ultrasonic are also increasing and many valuable results were obtained. However, there are not reports about nitrogenous by-products generating in the process of using ultrasonic cavitation oxidation technology to degrade organic matter. So the mechanism of degradation of organic amine by ultrasonic and nitrogenous by-products generating in this process will be studied in this paper.The study of inorganic nitrogenous byproducts generated in the process of ultrasonic cavitation oxidation found that NO2- and NO3- can be generated during ultrasonic cavitation oxidation reaction. A possible path of the generation of NO2- and NO3-is that the dissolved N2 and O2 in the water can occur a series of reactions under the ultrasonic cavitation oxidation and form the NO2- and NO3-, then the NO2- in the bulk solution will be oxidized into NO3-by the hydrogen peroxide. The NO2- generation rate was positively correlated to the intensity of ultrasonic cavitation. Relative to the generation of NO2-, there are more secondary free radical reactions in the process of the formation of NO3-, and the secondary oxidation of free radicals have important roles in this process.What’s more, it will be most productive when the N2 / O2 volume proportion is near to the ratio of the air. The results also showed that the water in ultrasonic field can also have gas exchange with air.The research targets are diethylamine and diphenylamine in the study of ultrasonic degradation of organic amine. The subsequent research found that the ultrasound has a good degradation effect on both of them, the efficiency of degradation of diethylamine and diphenylamine in 60 min reached 98.9% and 98.9% respectively, and the degradation reaction is fitting in the pseudo first order kinetics model. The effect of degradation of diethylamine and diphenylamine is best at 600 k Hz, and increases with the increase of ultrasonic power, however, the initial p H of solution has a very slight effect on the degradation.The contents of diethylamine and diphenylamine corresponding nitrosamines– nitroso-diethylamine(NDEA) and nitroso-diphenylamine(NDPh A) are tested in the study of the formation of nitrosamines substances in the process of ultrasonic degradation of organic amine. According to the results, both diethylamine and diphenylamine have its corresponding nitrosamines material generated in the process of degradation, the productions of NDEA and NDPh A are the largest at 600 k Hz, the conversion rate of diethylamine and diphenylamine reached 0.47% and 0.24% respectively, and the amount of them increased with the increasing of ultrasonic power. The influence of p H on the NDEA and NDPh A generation is different, the production of NDEA in acidic conditions is less than that in alkaline conditions, and however, the NDPh A generation under acid condition is greater than that under the alkaline conditions. The mechanism of nitrosamines substances generation in the process of ultrasonic cavitation oxidation is mainly through the way of nitrosation and hydroxylamine into hydrazine. Specific for diphenylamine, the way to produce nitrosamines substances is mainly through nitrosation, while for diethylamine, it can also be produced through hydroxylamine into hydrazine. |
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