本文選題：1 + 3��； 參考：《山東大學》2017年碩士論文

【摘要】：本文在調研與考查環(huán)境空氣中VOCs污染特征的基礎上,選擇在環(huán)境空氣中具有較高污染濃度并且具有較高二次有機氣溶膠生成潛勢的VOCs物種——1,3,5-三甲苯作為研究目標物種,利用中國環(huán)境科學研究院的大型室外光化學煙霧箱模擬實驗系統(tǒng),在接近真實環(huán)境空氣條件下開展1,3,5-三甲苯的大氣光化學氧化過程的模擬實驗研究,重點考察[1,3,5-三甲苯]/[NOx]初始濃度比值以及氣象因子對1,3,5-安甲苯大氣光化學氧化過程的影響。文獻調研表明典型區(qū)域環(huán)境空氣中芳香烴在VOCs中占16.21%～53.73%,1,3,5-三甲苯占所觀測芳香烴濃度的1.99%～9.29%,其SOAFP占具有SOAFP物種的5.01～15.23%。實際觀測中,北京市典型城區(qū)環(huán)境空氣中芳香烴占84種VOCs濃度的15%左右,1,3,5-三甲苯占觀測期間間芳香烴濃度的2.00%,其SOAFP占具有SOAFP物種的7.02%。文獻調研與實際觀測表明典型城市環(huán)境空氣中1,3,5-三甲苯為具有較高濃度的苯系物物種,并且為二次有機氣溶膠的重要前體物,因此本文選取1,3,5-三甲苯作為目標VOCs物種開展大氣光化學反應模擬實驗研究。在進行1,3,5-三甲苯大氣光化學氧化模擬實驗之前,對煙霧箱箱體的密閉性、混合性和壁效應等性能進行表征。CO在3.5 min即可混合均勻;O3的衰減速率常數K=2.47×10-6s-1,半衰期t1/2=77.87 h;顆粒物總數濃度壁損失常數為7× 10-5 s-1,生命周期為4.0h;1 3.5-三甲苯的壁衰減反應速率常數K=6×10-6s-1,半衰期t1/2=32.08h。以上表征實驗的結果表明,大型室外光化學煙霧箱模擬系統(tǒng)基本可以滿足模擬實驗的需求。本文開展10次不同污染氣象條件下的1,3,5-三甲苯大氣光化學氧化模擬實驗,其中于夏季和冬季在不同氣象條件下分別開展6次和4次實驗,實驗中對[1.3,5-三甲苯]/[NOx]初始濃度比進行調變,變化范圍在1.08-16.47之間。1,3,5-二甲苯大氣光化學氧化模擬實驗結果分析表明,當[1,3.5-三甲苯]/[NOx]初始濃度比在1-2時,1,3.5-三甲苯大氣光化學反應中反應物的消耗和產物的生成速率隨比值的增加而增加;當[1,3,5-三甲苯]/[NOx]初始濃度比在7-16時,1,3,5-三甲苯大氣光化學反應中反應物的消耗和產物的生成速率不隨初始濃度比的變化而變化。夏季模擬實驗中二次有機氣溶膠數濃度和體積濃度隨紫外輻射的延長表現出上升趨勢,并在達到模擬實驗中的最高值后出現小幅度下降,隨后在結束模擬實驗前一直呈上升趨勢;冬季模擬實驗中二次有機氣溶膠體積濃度隨紫外輻射強度的變化而變化,而二次有機氣溶膠數濃度則隨紫外輻射的延長而逐漸上升,當達到實驗中的最高值后出現小幅度的下降,隨后在關箱前一直呈上升趨勢,并且冬季模擬實驗的二次有機氣溶膠產率高于夏季。模擬實驗中的醛酮化合物產物主要包括甲醛、乙醛、丙酮、丙醛、正丁醛和m-甲基苯甲醛,1,3,5-三甲苯光氧化氣態(tài)產物濃度冬季低于夏季。夏季模擬實驗的二次有機氣溶膠產物中含有2,4,6-三甲基苯酚、3,5-二甲基-2-呋喃、甲基乙二醛酸、2-甲基-2,3-二羥基-4-羰基-戊烯酸、2,4-二甲基-2,3,4-三羥基-5,6-二羰基-庚酸等5種化合物,冬季模擬實驗二次有機氣溶膠產物中則含有2,4,6-三甲基苯酚、3,5-二甲基-2-呋喃和2,4-二甲基-2,3,4-三羥基-5,6-二羰基-庚酸等3種化合物。根據對1,3,5-三甲苯大氣光化學氧化過程產物的情況可以判斷1,3,5-三甲苯存在分子重排現象,部分1,3,5-三甲苯發(fā)生了開環(huán)反應;產物中分子量較大的物質可能會轉變?yōu)榉菗]發(fā)性有機物分配到有機氣溶膠中;而分子量較低的物種由于具有更多官能團或不飽和鍵,易與OH自由基、O3和NO3發(fā)生進一步的氧化反應;另外一些高極性和低揮發(fā)性的小分子量物質也容易分配到有機氣溶膠中。1,3,5-三甲苯光化學反應實驗結果表明,影響1,3,5-三甲苯光化學反應過程的包括[1,3,5-三甲苯]/[NOx]初始比、溫度、光輻照等因素。[1,3,5-三甲苯]/[NOx]初始比影響1,3,5-三甲苯光化學反應歷程;較高的溫度有利于提高二次有機氣溶膠產率,但較低的溫度有利于顆粒物粒徑和數濃度的增長;較強的紫外輻射可以提高1,3,5-三甲苯的光化學反應速率,促進二次有機氣溶膠濃度的生成。以上研究結果說明在制定環(huán)境空氣中大氣顆粒物控制政策時,需要高度重視VOCs/NOx的比例,即VOCs與NOx的協(xié)同控制。
[Abstract]:On the basis of investigating and examining the characteristics of VOCs pollution in the ambient air, this paper selects the VOCs species, 1,3,5- three toluene, which has high pollution concentration in the ambient air and has high two times of organic aerosol generation potential as the target species, and uses the large-scale outdoor photochemical smog box simulation of the Chinese Academy of Environmental Sciences. In the experimental system, the experimental study on the atmospheric and chemical oxidation process of 1,3,5- three toluene under the actual ambient air conditions is studied. The initial concentration ratio of [1,3,5- three toluene]/[NOx] and the influence of meteorological factors on the atmospheric photochemical oxidation process of 1,3,5- an toluene are mainly investigated. Hydrocarbons accounted for 16.21% ~ 53.73% in VOCs, and 1,3,5- trimethol accounted for 1.99% ~ 9.29% of the observed aromatic hydrocarbon concentration, and its SOAFP accounted for 5.01 ~ 15.23%. of SOAFP species. The aromatic hydrocarbons in the ambient air in the typical urban areas of Beijing accounted for 15% of the 84 VOCs concentrations, and 1,3,5- trimethol accounted for 2% of the observed aromatic hydrocarbon concentration during the observation period, and its SOAFP accounted for it. The 7.02%. literature survey and actual observation of SOAFP species show that 1,3,5- trimethol in the typical urban environment is a species with high concentration of benzene, and is an important precursor of two organic aerosols. Therefore, this paper selects 1,3,5- three toluene as a target VOCs species to carry out a simulated experimental study of large gas photochemical reaction. 1, Before the simulation experiment of 3,5- tri benzol atmospheric photochemical oxidation, the properties of the airtight, mixing and wall effect of the smoke box body were characterized by.CO at 3.5 min, and the decay rate constant of O3 was K=2.47 * 10-6s-1, the half life t1/2=77.87 h; the concentration wall loss constant of the total particles was 7 * 10-5 s-1, the life cycle was 4.0h; 1 3.5-. The reaction rate constant of the three toluene is K=6 x 10-6s-1, and the results of the half life longer than t1/2=32.08h. show that the large-scale outdoor photochemical smoke box simulation system can basically meet the needs of the simulated experiment. In this paper, the simulated experiment on the photochemical oxidation of 1,3,5- three toluene in the atmosphere under different weather conditions is carried out in this paper, in which summer is in summer. 6 and 4 experiments were carried out at different meteorological conditions in season and winter. The initial concentration ratio of [1.3,5- three toluene]/[NOx] was adjusted in the experiment. The variation range of the variation range of.1,3,5- dimethylbenzene atmospheric photochemical oxidation experiment between 1.08-16.47 showed that when the initial concentration of [1,3.5- three toluene] / [NOx] was 1-2, 1,3.5- tri methylbenzene was large The consumption of reactants and the production rate of the products increased with the ratio of the gas photochemical reaction. When the initial concentration of [1,3,5- three toluene]/[NOx] was 7-16, the consumption of reactants and the production rate of the products were not changed with the variation of the initial concentration ratio in the atmospheric photochemical reaction of 1,3,5- trimethol. In the summer simulation experiment, two organic compounds were used. The concentration and concentration of aerosol number and concentration increase with the increase of ultraviolet radiation, and then decrease slightly after the maximum value of the simulated experiment. Then, it has been increasing before the simulation experiment. In the winter simulation experiment, the volume concentration of two organic aerosols varies with the intensity of ultraviolet radiation, and two times. The number of organic aerosols increased gradually with the extension of UV radiation. When the maximum value of the experiment was reached, the number of organic aerosols decreased slightly, and then increased in front of the closed box, and the two organic aerosol yield in the simulated experiment was higher than that in the summer. The aldehyde and ketone compounds in the simulated experiment mainly include formaldehyde and acetaldehyde. The concentration of acetone, propionic aldehyde, n-butyl aldehyde and m- methyl benzaldehyde, 1,3,5- trimethyl benzaldehyde in the photooxidation of gaseous products in winter is lower than that in summer. The two organic aerosol products in the simulated experiment contain 2,4,6- three methyl phenol, 3,5- two methyl -2- furan, methyl ethyl two alalonic acid, 2- methyl -2,3- two hydroxyl -4- carbonyl pentaenoic acid, 2,4- two methyl -2,3,4- three hydroxyl -5. 6- two carbonyl - heptanoic acid and other 5 compounds. In the two organic aerosol products in winter simulation experiments, there are 3 compounds of 2,4,6- three methyl phenol, 3,5- two methyl -2- furan and 2,4- two methyl -2,3,4- three hydroxyl -5,6- two carbonyl heptanoic acid. In the presence of benzene molecular rearrangement, partial 1,3,5- trimethylamine has an open ring reaction, and the larger molecules in the products may change into organic aerosols with non volatile organic compounds, and the species with lower molecular weight have more oxidation reactions with OH radicals, O3 and NO3 because of more functional groups or unsaturated bonds. Some other high polar and low volatile small molecular weight substances are also easily distributed to the.1,3,5- trimethol photochemical reaction in organic aerosols. The results show that the effect of the initial ratio of [1,3,5- three toluene]/[NOx], temperature, and light irradiation on the initial ratio of.[1,3,5- three toluene]/[NOx] affects the initial ratio of.[1,3,5- three to 1,3,5-. The photochemical reaction process of trimethol can increase the yield of two organic aerosol, but the lower temperature is beneficial to the increase of particle size and number concentration. The strong UV radiation can increase the photochemical reaction rate of 1,3,5- three toluene and promote the formation of two organic aerosol concentration. When controlling atmospheric particulate matters in ambient air, we need to attach great importance to the VOCs/NOx ratio, that is, the coordinated control of VOCs and NOx.
【學位授予單位】：山東大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：X513;O648.18

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