本文選題：1 + 3　； 參考：《山東大學(xué)》2017年碩士論文

【摘要】：本文在調(diào)研與考查環(huán)境空氣中VOCs污染特征的基礎(chǔ)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(jī)氣溶膠生成潛勢(shì)的VOCs物種——1,3,5-三甲苯作為研究目標(biāo)物種,利用中國(guó)環(huán)境科學(xué)研究院的大型室外光化學(xué)煙霧箱模擬實(shí)驗(yàn)系統(tǒng),在接近真實(shí)環(huán)境空氣條件下開(kāi)展1,3,5-三甲苯的大氣光化學(xué)氧化過(guò)程的模擬實(shí)驗(yàn)研究,重點(diǎn)考察[1,3,5-三甲苯]/[NOx]初始濃度比值以及氣象因子對(duì)1,3,5-安甲苯大氣光化學(xué)氧化過(guò)程的影響。文獻(xiàn)調(diào)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(guān)測(cè)芳香烴濃度的1.99%～9.29%,其SOAFP占具有SOAFP物種的5.01～15.23%。實(shí)際觀(guān)測(cè)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(guān)測(cè)期間間芳香烴濃度的2.00%,其SOAFP占具有SOAFP物種的7.02%。文獻(xiàn)調(diào)研與實(shí)際觀(guān)測(cè)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(jī)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(biāo)VOCs物種開(kāi)展大氣光化學(xué)反應(yīng)模擬實(shí)驗(yàn)研究。在進(jìn)行1,3,5-三甲苯大氣光化學(xué)氧化模擬實(shí)驗(yàn)之前,對(duì)煙霧箱箱體的密閉性、混合性和壁效應(yīng)等性能進(jìn)行表征。CO在3.5 min即可混合均勻;O3的衰減速率常數(shù)K=2.47×10-6s-1,半衰期t1/2=77.87 h;顆粒物總數(shù)濃度壁損失常數(shù)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(yīng)速率常數(shù)K=6×10-6s-1,半衰期t1/2=32.08h。以上表征實(shí)驗(yàn)的結(jié)果表明,大型室外光化學(xué)煙霧箱模擬系統(tǒng)基本可以滿(mǎn)足模擬實(shí)驗(yàn)的需求。本文開(kāi)展10次不同污染氣象條件下的1,3,5-三甲苯大氣光化學(xué)氧化模擬實(shí)驗(yàn),其中于夏季和冬季在不同氣象條件下分別開(kāi)展6次和4次實(shí)驗(yàn),實(shí)驗(yàn)中對(duì)[1.3,5-三甲苯]/[NOx]初始濃度比進(jìn)行調(diào)變,變化范圍在1.08-16.47之間。1,3,5-二甲苯大氣光化學(xué)氧化模擬實(shí)驗(yàn)結(jié)果分析表明,當(dāng)[1,3.5-三甲苯]/[NOx]初始濃度比在1-2時(shí),1,3.5-三甲苯大氣光化學(xué)反應(yīng)中反應(yīng)物的消耗和產(chǎn)物的生成速率隨比值的增加而增加;當(dāng)[1,3,5-三甲苯]/[NOx]初始濃度比在7-16時(shí),1,3,5-三甲苯大氣光化學(xué)反應(yīng)中反應(yīng)物的消耗和產(chǎn)物的生成速率不隨初始濃度比的變化而變化。夏季模擬實(shí)驗(yàn)中二次有機(jī)氣溶膠數(shù)濃度和體積濃度隨紫外輻射的延長(zhǎng)表現(xiàn)出上升趨勢(shì),并在達(dá)到模擬實(shí)驗(yàn)中的最高值后出現(xiàn)小幅度下降,隨后在結(jié)束模擬實(shí)驗(yàn)前一直呈上升趨勢(shì);冬季模擬實(shí)驗(yàn)中二次有機(jī)氣溶膠體積濃度隨紫外輻射強(qiáng)度的變化而變化,而二次有機(jī)氣溶膠數(shù)濃度則隨紫外輻射的延長(zhǎng)而逐漸上升,當(dāng)達(dá)到實(shí)驗(yàn)中的最高值后出現(xiàn)小幅度的下降,隨后在關(guān)箱前一直呈上升趨勢(shì),并且冬季模擬實(shí)驗(yàn)的二次有機(jī)氣溶膠產(chǎn)率高于夏季。模擬實(shí)驗(yàn)中的醛酮化合物產(chǎn)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(chǎn)物濃度冬季低于夏季。夏季模擬實(shí)驗(yàn)的二次有機(jī)氣溶膠產(chǎn)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(shí)驗(yàn)二次有機(jī)氣溶膠產(chǎn)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(jù)對(duì)1,3,5-三甲苯大氣光化學(xué)氧化過(guò)程產(chǎn)物的情況可以判斷1,3,5-三甲苯存在分子重排現(xiàn)象,部分1,3,5-三甲苯發(fā)生了開(kāi)環(huán)反應(yīng);產(chǎn)物中分子量較大的物質(zhì)可能會(huì)轉(zhuǎn)變?yōu)榉菗]發(fā)性有機(jī)物分配到有機(jī)氣溶膠中;而分子量較低的物種由于具有更多官能團(tuán)或不飽和鍵,易與OH自由基、O3和NO3發(fā)生進(jìn)一步的氧化反應(yīng);另外一些高極性和低揮發(fā)性的小分子量物質(zhì)也容易分配到有機(jī)氣溶膠中。1,3,5-三甲苯光化學(xué)反應(yīng)實(shí)驗(yàn)結(jié)果表明,影響1,3,5-三甲苯光化學(xué)反應(yīng)過(guò)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(xué)反應(yīng)歷程;較高的溫度有利于提高二次有機(jī)氣溶膠產(chǎn)率,但較低的溫度有利于顆粒物粒徑和數(shù)濃度的增長(zhǎng);較強(qiáng)的紫外輻射可以提高1,3,5-三甲苯的光化學(xué)反應(yīng)速率,促進(jìn)二次有機(jī)氣溶膠濃度的生成。以上研究結(jié)果說(shuō)明在制定環(huán)境空氣中大氣顆粒物控制政策時(shí),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(xué)位授予單位】：山東大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類(lèi)號(hào)】：X513;O648.18

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