超声过程中典型含氮副产物生成机制的研究
发布时间：2019-03-01 16:16
【摘要】：近年来利用超声波技术处理降解水中的化学污染物尤其是难降解有机污染物的应用取得了很大的进展,它是一项新型的水处理技术,集高温热解、高级氧化以及超临界氧化等多种技术于一身,具有降解效率高、适用范围广,且可以与其他水处理技术联合作用的优点。在强化降解或者直接降解水体中有机污染物方面的实验室水平及应用上研究报道也日益增加,取得了许多有价值的研究成果。但是,目前还没有关于超声空化氧化技术在降解水中有机物的过程中生成含氮的有机副产物的系统研究报道,因此本文就超声波降解有机胺类有机物及降解过程中含氮副产物的产生机理进行了研究。超声空化氧化过程中无机含氮副产物生成的研究发现,超声空化氧化反应过程中能产生无机含氮副产物NO2-和NO3-,产生NO2-和NO3-的机理主要是在超声空化作用的作用下水体中溶解的N2和O2在空化泡内部发生反应形成HNO2和HNO3,然后扩散到主体溶液中,并且在主体溶液中空化作用产生的氧化自由基和双氧水可以氧化NO2-生成NO3-。研究发现NO2-的生成速率与超声空化的强度的呈正相关关系,相对于NO2-的生成,在NO3-的生成过程中有更多的二级自由基反应,并且自由基的二次氧化在NO3-的生成过程中有重要的作用。在改变水体中的N2和O2体积比发现,在比例与空气中的比例接近时有利于NO2-和NO3-的产生。在超声波降解有机胺类有机物的研究中,选取了二乙胺和二苯胺作为研究的目标物。在随后的研究中发现超声波对两者有很好的降解效果,60min的超声作用,二乙胺和二苯胺的降解效率分别达到了98.9%和99.8%,并且降解反应满足拟一级动力学模型。在600k Hz时二乙胺和二苯胺的降解效果最好,并且随着超声功率的增加而增加,而溶液的初始p H对两者降解效果的影响甚小。对二苯胺降解路径分析可知,在超声波降解二苯胺过程中有亚硝胺产生,并且还存在其他的硝基和羟基取代物。超声波降解有机胺类有机物过程中有机含氮副产物生成的研究中检测了二乙胺和二苯胺相应的亚硝胺物质—亚硝基二乙胺(NDEA)和亚硝基二苯胺(NDPh A)及硝基胺类物质的含量变化。结果显示在这个过程中两者均有其对应的亚硝胺类物质生成,600k Hz时NDEA和NDPh A的生成量最大,二乙胺和二苯胺的最大转化率分别达到了0.47%和0.24%,并且生成的量随着超声功率的增加而增加。p H对NDEA和NDPh A生成的影响有所不同,NDEA在酸性条件下的生成量比碱性条件下的生成量少,而NDPh A的生成量在酸性条件下大于碱性条件下。分析两者的产生机理可知,在超声空化氧化过程中产生亚硝胺类物质主要是通过亚硝化和羟胺成肼的途径。其中对于二苯胺等芳香胺类有机胺则主要是通过亚硝化途径产生亚硝胺类物质,而对于二乙胺等脂肪胺则还可以通过羟胺成肼的方式产生。
[Abstract]:In recent years, great progress has been made in the application of ultrasonic technology to the treatment of chemical pollutants in degraded water, especially the refractory organic pollutants. It is a new type of water treatment technology with high temperature pyrolysis. Advanced oxidation and supercritical oxidation have many advantages, such as high degradation efficiency, wide application range, and can be combined with other water treatment technologies. The research reports on the laboratory level and application of enhanced degradation or direct degradation of organic pollutants in water have also been increasing day by day, and many valuable research results have been obtained. However, there is no systematic report on the formation of nitrogen-containing organic by-products in the process of degradation of organic compounds in water by ultrasonic cavitation oxidation. Therefore, the mechanism of ultrasonic degradation of organic amines and nitrogen-containing by-products in the degradation process was studied in this paper. The formation of inorganic nitrogen by-products during ultrasonic cavitation oxidation was studied. It was found that inorganic nitrogen by-products NO2- and NO3-, could be produced during ultrasonic cavitation oxidation. The mechanism of producing NO2- and NO3- is that the N _ 2 and O _ 2 dissolved in the water react in the cavitation bubble to form HNO2 and HNO3, and then diffuse into the main solution under the action of ultrasonic cavitation. And the oxidation free radicals and hydrogen peroxide produced by cavitation in the main solution can oxidize NO2- to form NO3-.. It was found that there was a positive correlation between the rate of NO2- formation and the intensity of ultrasonic cavitation. Compared with the formation of NO2-, there were more second-order free radical reactions in the formation of NO3-. The secondary oxidation of free radicals plays an important role in the formation of NO3-. When the volume ratio of N _ 2 and O _ 2 in water is changed, it is found that the ratio of N _ 2 to O _ 2 is close to the ratio of air to NO2-. In the study of ultrasonic degradation of organic amines, diethylamine and diphenylamine were selected as the target materials. It was found that ultrasound had a good degradation effect on both of them. The degradation efficiency of 60min was 98.9% for diethylamine and 99.8% for diphenylamine, respectively. The degradation reaction met the pseudo-first-order kinetic model, and the degradation efficiency of diethylamine and diphenylamine reached 98.9% and 99.8%, respectively. The degradation effect of diethylamine and diphenylamine was the best at 600k Hz, and increased with the increase of ultrasonic power. However, the initial pH of the solution had little effect on the degradation effect of both. The degradation path analysis of p-diphenylamine shows that nitrosamine is produced in the ultrasonic degradation of diphenylamine, and there are other nitro and hydroxyl substituents. Study on the formation of by-products containing nitrogen in the degradation of Organic Amines by Ultrasonic Wave the nitroso-diethylamine (NDEA) and nitroso-diphenylamine (NDPh A) and nitro-diphenylamine (Nitroso-diethylamine) and nitro-diphenylamine were detected in the process of ultrasonic degradation of organic amines. Changes in the content of amines. The results showed that both of them had their corresponding nitrosamines in this process. The maximum amounts of NDEA and NDPh A were obtained at 600k Hz, and the maximum conversion rates of diethylamine and diphenylamine were 0.47% and 0.24%, respectively, and the maximum conversion rates of diethylamine and diphenylamine were 0.47% and 0.24%, respectively. The effect of pH on the formation of NDEA and NDPh A is different, and the amount of NDEA generated in acidic condition is less than that in alkaline condition, and the amount of NDEA in acidic condition is less than that in alkaline condition, and the amount of production increases with the increase of ultrasonic power. However, the amount of NDPh A produced in acidic condition was higher than that in alkaline condition. The mechanism of the formation of nitrosamines in the process of ultrasonic cavitation oxidation is mainly through nitrosation and hydrazine formation by hydroxylamine. For aromatic amines such as diphenylamine, nitrosamines are produced mainly through nitrosation, while aliphatic amines such as diethylamine can be produced by hydroxylamine to hydrazine.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB559;X703
[Abstract]:In recent years, great progress has been made in the application of ultrasonic technology to the treatment of chemical pollutants in degraded water, especially the refractory organic pollutants. It is a new type of water treatment technology with high temperature pyrolysis. Advanced oxidation and supercritical oxidation have many advantages, such as high degradation efficiency, wide application range, and can be combined with other water treatment technologies. The research reports on the laboratory level and application of enhanced degradation or direct degradation of organic pollutants in water have also been increasing day by day, and many valuable research results have been obtained. However, there is no systematic report on the formation of nitrogen-containing organic by-products in the process of degradation of organic compounds in water by ultrasonic cavitation oxidation. Therefore, the mechanism of ultrasonic degradation of organic amines and nitrogen-containing by-products in the degradation process was studied in this paper. The formation of inorganic nitrogen by-products during ultrasonic cavitation oxidation was studied. It was found that inorganic nitrogen by-products NO2- and NO3-, could be produced during ultrasonic cavitation oxidation. The mechanism of producing NO2- and NO3- is that the N _ 2 and O _ 2 dissolved in the water react in the cavitation bubble to form HNO2 and HNO3, and then diffuse into the main solution under the action of ultrasonic cavitation. And the oxidation free radicals and hydrogen peroxide produced by cavitation in the main solution can oxidize NO2- to form NO3-.. It was found that there was a positive correlation between the rate of NO2- formation and the intensity of ultrasonic cavitation. Compared with the formation of NO2-, there were more second-order free radical reactions in the formation of NO3-. The secondary oxidation of free radicals plays an important role in the formation of NO3-. When the volume ratio of N _ 2 and O _ 2 in water is changed, it is found that the ratio of N _ 2 to O _ 2 is close to the ratio of air to NO2-. In the study of ultrasonic degradation of organic amines, diethylamine and diphenylamine were selected as the target materials. It was found that ultrasound had a good degradation effect on both of them. The degradation efficiency of 60min was 98.9% for diethylamine and 99.8% for diphenylamine, respectively. The degradation reaction met the pseudo-first-order kinetic model, and the degradation efficiency of diethylamine and diphenylamine reached 98.9% and 99.8%, respectively. The degradation effect of diethylamine and diphenylamine was the best at 600k Hz, and increased with the increase of ultrasonic power. However, the initial pH of the solution had little effect on the degradation effect of both. The degradation path analysis of p-diphenylamine shows that nitrosamine is produced in the ultrasonic degradation of diphenylamine, and there are other nitro and hydroxyl substituents. Study on the formation of by-products containing nitrogen in the degradation of Organic Amines by Ultrasonic Wave the nitroso-diethylamine (NDEA) and nitroso-diphenylamine (NDPh A) and nitro-diphenylamine (Nitroso-diethylamine) and nitro-diphenylamine were detected in the process of ultrasonic degradation of organic amines. Changes in the content of amines. The results showed that both of them had their corresponding nitrosamines in this process. The maximum amounts of NDEA and NDPh A were obtained at 600k Hz, and the maximum conversion rates of diethylamine and diphenylamine were 0.47% and 0.24%, respectively, and the maximum conversion rates of diethylamine and diphenylamine were 0.47% and 0.24%, respectively. The effect of pH on the formation of NDEA and NDPh A is different, and the amount of NDEA generated in acidic condition is less than that in alkaline condition, and the amount of NDEA in acidic condition is less than that in alkaline condition, and the amount of production increases with the increase of ultrasonic power. However, the amount of NDPh A produced in acidic condition was higher than that in alkaline condition. The mechanism of the formation of nitrosamines in the process of ultrasonic cavitation oxidation is mainly through nitrosation and hydrazine formation by hydroxylamine. For aromatic amines such as diphenylamine, nitrosamines are produced mainly through nitrosation, while aliphatic amines such as diethylamine can be produced by hydroxylamine to hydrazine.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TB559;X703
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