超聲過程中典型含氮副產物生成機制的研究
發(fā)布時間：2019-03-01 16:16
【摘要】：近年來利用超聲波技術處理降解水中的化學污染物尤其是難降解有機污染物的應用取得了很大的進展,它是一項新型的水處理技術,集高溫熱解、高級氧化以及超臨界氧化等多種技術于一身,具有降解效率高、適用范圍廣,且可以與其他水處理技術聯合作用的優(yōu)點。在強化降解或者直接降解水體中有機污染物方面的實驗室水平及應用上研究報道也日益增加,取得了許多有價值的研究成果。但是,目前還沒有關于超聲空化氧化技術在降解水中有機物的過程中生成含氮的有機副產物的系統(tǒng)研究報道,因此本文就超聲波降解有機胺類有機物及降解過程中含氮副產物的產生機理進行了研究。超聲空化氧化過程中無機含氮副產物生成的研究發(fā)現,超聲空化氧化反應過程中能產生無機含氮副產物NO2-和NO3-,產生NO2-和NO3-的機理主要是在超聲空化作用的作用下水體中溶解的N2和O2在空化泡內部發(fā)生反應形成HNO2和HNO3,然后擴散到主體溶液中,并且在主體溶液中空化作用產生的氧化自由基和雙氧水可以氧化NO2-生成NO3-。研究發(fā)現NO2-的生成速率與超聲空化的強度的呈正相關關系,相對于NO2-的生成,在NO3-的生成過程中有更多的二級自由基反應,并且自由基的二次氧化在NO3-的生成過程中有重要的作用。在改變水體中的N2和O2體積比發(fā)現,在比例與空氣中的比例接近時有利于NO2-和NO3-的產生。在超聲波降解有機胺類有機物的研究中,選取了二乙胺和二苯胺作為研究的目標物。在隨后的研究中發(fā)現超聲波對兩者有很好的降解效果,60min的超聲作用,二乙胺和二苯胺的降解效率分別達到了98.9%和99.8%,并且降解反應滿足擬一級動力學模型。在600k Hz時二乙胺和二苯胺的降解效果最好,并且隨著超聲功率的增加而增加,而溶液的初始p H對兩者降解效果的影響甚小。對二苯胺降解路徑分析可知,在超聲波降解二苯胺過程中有亞硝胺產生,并且還存在其他的硝基和羥基取代物。超聲波降解有機胺類有機物過程中有機含氮副產物生成的研究中檢測了二乙胺和二苯胺相應的亞硝胺物質—亞硝基二乙胺(NDEA)和亞硝基二苯胺(NDPh A)及硝基胺類物質的含量變化。結果顯示在這個過程中兩者均有其對應的亞硝胺類物質生成,600k Hz時NDEA和NDPh A的生成量最大,二乙胺和二苯胺的最大轉化率分別達到了0.47%和0.24%,并且生成的量隨著超聲功率的增加而增加。p H對NDEA和NDPh A生成的影響有所不同,NDEA在酸性條件下的生成量比堿性條件下的生成量少,而NDPh A的生成量在酸性條件下大于堿性條件下。分析兩者的產生機理可知,在超聲空化氧化過程中產生亞硝胺類物質主要是通過亞硝化和羥胺成肼的途徑。其中對于二苯胺等芳香胺類有機胺則主要是通過亞硝化途徑產生亞硝胺類物質,而對于二乙胺等脂肪胺則還可以通過羥胺成肼的方式產生。
[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.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：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.
【學位授予單位】：重慶大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TB559;X703
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