东太湖水源水臭氧化过程中羰基化合物的生成与转化机制

发布时间：2018-04-14 16:16

本文选题：微污染水源 + 富里酸　；参考：《哈尔滨工业大学》2017年博士论文

【摘要】：羰基化合物是臭氧化主要的中间产物,但由于缺少相应的检测方法及相关标准的规定,同时与阈值较低的土溴素、2-甲基异莰醇相比,嗅味并不显著。基于与此,羰基化合物未能引起相关部门以及人们的广泛关注。此外,羰基化合物还能够引发输配水系统中微生物再生,且本身具有一定的致癌、致突变性。为了明确羰基化合物的主要来源、转化机制及其控制途径,本文以东太湖地区水源采用臭氧化处理工艺为依托,考察臭氧化处理工艺羰基化合物的种类、含量及其季节变化等分布特征。通过溶解性有机物表征分析间接确定羰基化合物前体物质。在此基础上,不但可以明确羰基化合物的生成与转化机制,还对饮用水处理厂控制和去除羰基化合物具有一定的参考价值。由于羰基化合物中芳香类有机酸没有规定的检测方法,但芳香类有机酸是染料厂、药剂厂、食品厂、化妆品厂和造纸厂等的原材料或作为排放物广泛存在于地表水体环境中。在河流中均检测出苯甲酸、1,2-邻苯二甲酸、3-羟基苯甲酸、硝基苯甲酸等的存在。利用双层固相萃取-超高效液相色谱法测定水中芳香类有机酸,具体包括富马酸、原儿茶酸、3-羟基苯甲酸、1,2-邻苯二甲酸、o-硝基苯甲酸、m-硝基苯甲酸、p-硝基苯甲酸、苯甲酸和间甲基苯甲酸。该方法对原儿茶酸回收率较低为79%,在可接受范围内,对其他有机酸回收率为85.7%~102.8%。该检测方法精密度,RSD为0.26~5.1%。在固相萃取-超高效液相色谱检测方法基础上,考察同水源地两个平行水处理厂(常规处理和臭氧化处理)羰基化合物的分布特征。由于季节变化,东太湖地区水源检出7~10种羰基化合物。其中,甲醛2.98~43.66μg/l、乙醛1.33~16.87μg/l、乙二醛1.08~217.18μg/l和甲基乙二醛15.6~168.79μg/l为主要醛类化合物。乙酸、富马酸、苯甲酸、3-羟基苯甲酸、原儿茶酸和1,2-邻苯二甲酸,有机羧酸总浓度为243.79~744.14μg/l。源水中羰基化合物含量随季节变化而变化。通常,在温暖的季节羰基化合物浓度应较低,但检测结果显示浓度较高。因此,除与温度有关外,其他环境和气象因素,如干旱、降雨的频率及强度、光照的时长及强度都可能影响着地表水中羰基化合物的浓度。与源水中含有的羰基化合物相比,臭氧化处理工艺单元出水中羰基化合物种类较多(15种),且原本源水中含有的羰基化合物浓度有一定地提高。臭氧化对羰基化合物具有相似地氧化作用,这一作用与季节变化无关。此外,经臭氧化处理导致了甲酸、草酸、乙二醛、丁烯醛和3-羟基苯甲酸等含氧官能团有机物的生成。混凝沉淀-砂滤和炭滤过程能够有效地去除羰基化合物。在最后氯消毒过程中,小分子醛酸的浓度有一定地提高,而芳香类有机酸浓度基本保持不变。通过三维荧光表征分析水溶解性有机物,发现在砂滤后出水中仍存在一定量的富里酸。表明小分子天然有机物,经常规的混凝沉淀-砂滤工艺难以完全去除。在后续处理工艺中,富里酸与氧化剂作用生成羰基化合物,或在消毒过程中成为消毒副产物前驱物。由此确定,在实际生产过程中,富里酸是羰基化合物生成的主要来源。富里酸经臭氧氧化生成芳香类有机酸和小分羰基化合物,主要有原儿茶酸、3-羟基苯甲酸、苯甲酸、1,2-邻苯二甲酸、富马酸、丙二酸、甲酸、乙酸、甲醛、乙二醛、甲基乙二醛等,且生成量随臭氧接触时间、投加量、溶液pH的变化,生成趋势发生一定量的变化。芳香类有机酸可以进一步被氧化开环生成小分羰基化合物。芳香类有机酸与臭氧的反应速率主要由化学结构所决定。若苯环上连有供电子基团,则反应速率较快;若含有吸电子基团,则反应速率较慢。因此,原儿茶酸和3-羟基苯甲酸含量较低,甚至不易检测到。此外,丁烯醛可能是苯氧化开环的直接产物,但由于醛化学性质活泼,易被氧化成相应的羧酸—富马酸,所以丁烯醛不易被检测到,而检测到大量的富马酸生成。此外,与臭氧单独作用富里酸相比,O_3/UV、O_3/H_2O_2联合作用富里酸生成羰基化合物的种类及生成量较少。O_3/UV、O_3/H_2O_2提高了溶液中·OH的浓度,使得反应系统选择性降低、矿化能力提高,加快反应速率,能够从根本上控制羰基化合物浓度。因此,在实际水处理过程应采用高级氧化技术控制去除羰基化合物。羰基化合物生成与转化的机制:富里酸在臭氧和羟基自由基共同氧化作用下,发生亲电反应、Criegee机制、去氢反应、脱羧基等一系列反应,脱落生成芳香类有机酸。臭氧氧化芳香类有机酸反应过程可能包含三个阶段。第一阶段,芳香类有机酸羟基化;第二阶段,氧化开环羟基化产物,伴有不饱和羰基化合物生成;第三阶段,小分子醛、羧酸生成。至于矿化过程,是小分子醛、羧酸进一步被氧化成水和二氧化碳。臭氧与芳香类有机酸反应过程,主要取决于苯环上的官能团是给电子基团/吸电子基团的作用。随后在次氯酸钠的作用下,发生水解、烯醇化、取代、氧化、脱羧等一系列反应,小分羰基化合物转化生成消毒副产物。
[Abstract]:Carbonyl compounds are the main intermediate products of ozonation, but due to lack of provisions of the corresponding detection method and related standards, at the same time and soil bromine threshold is low, compared with 2- methyl isobutyl camphol, smell is not significant. Based on this, to carbonyl compounds attracted wide attention of relevant departments and people. In addition, carbonyl compounds can lead to lost regeneration microbial in water distribution system, which itself has a certain degree of carcinogenicity, mutagenicity. In order to clear main sources of carbonyl compounds, and its control mechanism transformation way, in the East Taihu area water by ozonation process based on the investigation of ozonation process kinds of carbonyl compounds, the content and seasonal change the distribution of the precursor. Determination of carbonyl compounds indirectly through the analysis of the dissolved organic matter characterization. On this basis, not only can generate clear carbonyl compounds And the transformation mechanism of drinking water treatment plant control has a certain reference value and the removal of carbonyl compounds. The detection method of aromatic organic acid carbonyl compounds are not required, but aromatic organic acid dye factory, pharmaceutical factory, food factory, cosmetics factory and paper mills and other raw materials or as wide emissions in the environment of surface water. In the river were detected in two 1,2- benzoic acid, phthalic acid, 3- hydroxy benzoic acid, such as the existence of Nitrobenzoic Acid. Using double solid-phase extraction and ultra performance liquid chromatography determination of aromatic organic acids, including fumaric acid, protocatechuic acid, 3- hydroxy benzoic acid. 1,2- two o- phthalic acid, benzoic acid, m- Nitrobenzoic Acid, p- Nitrobenzoic Acid, benzoic acid and methyl benzoic acid. The method of protocatechuic acid has low recovery rate is 79%, within an acceptable range of other organic acid recovery rate For the 85.7%~102.8%. detection precision, RSD 0.26~5.1%. in solid phase extraction and ultra performance liquid chromatography detection method on the basis of investigation with two parallel water source water treatment plant (conventional treatment and ozonation) distribution of carbonyl compounds. Due to seasonal changes in water in eastern Taihu were 7~10 carbonyl compounds. 2.98~43.66 g/l, formaldehyde, acetaldehyde, 1.33~16.87 g/l, 1.08~217.18 g/l and B two aldehydes two methyl ethyl aldehyde 15.6~168.79 g/l as the main aldehydes. Acetic acid, fumaric acid, benzoic acid, 3- hydroxy benzoic acid, protocatechuic acid and 1,2- two phthalic acid, total organic carboxylic acid concentration is 243.79~744.14 g/l. the source water of carbonyl compounds the content of the seasonal changes in the warm season. Usually, carbonyl compounds concentrations should be lower, but test results showed higher concentrations. Therefore, in addition to related with temperature, the environment and meteorological factors , such as drought, frequency and intensity of rainfall, light duration and intensity may affect the surface water concentrations of carbonyl compounds. Compared with carbonyl compounds containing the source water, the ozone oxidation of carbonyl compounds effluent in many species (15 species), and the original concentration of carbonyl compounds in water containing a certain origin to improve the ozonation. With similar oxidation of carbonyl compounds, regardless of changes in this role and season. In addition, the ozonation resulted in formic acid, oxalic acid, acetic aldehyde two, generating Ding Xiquan and 3- hydroxybenzoic acid oxygen-containing functional groups of organic compounds. Coagulation sedimentation, sand filtration and carbon filter the process can effectively remove carbonyl compounds. At the end of the chlorine disinfection process, the concentration of small molecule acid were increased, while the aromatic organic acid concentration remained unchanged. The three-dimensional fluorescence characterization of dissolved organic matter in water, Found in the sand filter after the water there is still a certain amount of fulvic acid. That natural organic small molecules, coagulation sedimentation and sand filtration process is difficult to completely remove the routine. In the subsequent process, fulvic acid and oxidant effect formation of carbonyl compounds, or become the disinfection by-products precursors in disinfection in the process. Therefore, in the actual production process, fulvic acid is the main source of carbonyl compounds generated. Fulvic acid by ozone oxidation of aromatic organic acid and small carbonyl compounds are mainly protocatechuic acid, 3- hydroxy benzoic acid, benzoic acid, phthalic acid two 1,2-, fumaric acid, malonic acid formic acid, acetic acid, formaldehyde, methyl aldehyde, B two, B two aldehyde, and the formation with the ozone contact time, dosage, pH value of the solution, change the generation trend to produce a certain amount of aromatic organic acids. Can be further oxidized open loop generated small aromatic carbonyl compounds. The reaction rate of aroma of organic acid and ozone is mainly determined by the chemical structure. If the benzene ring is connected with electron donating group, the reaction rate is fast; if containing electron withdrawing groups, the reaction rate is slow. Therefore, protocatechuic acid and 3- hydroxy benzoic acid content is low, and not easily detected. In addition, butene may is a direct result of aldehyde oxidation of benzene ring opening, but due to aldehyde active chemical properties and is easy to be oxidized to the corresponding carboxylic acid, fumaric acid, so crotonaldehyde is not easy to be detected, and the detection to generate a large number of fumaric acid. In addition, compared with ozone alone fulvic acid O_3/UV, the combined effect of O_3/H_2O_2 fulvic acid formation of carbonyl compounds less species and amount of.O_3/UV, O_3/H_2O_2 increased in the concentration of OH, the reaction system reduces the selectivity of mineralization ability, accelerate the reaction rate, can control the concentration of carbonyl compounds by fundamentally. This, in the actual water treatment process should be controlled to remove carbonyl compounds using advanced oxidation technology. The mechanism of formation and transformation of carbonyl compounds: fulvic acid by ozone and hydroxyl radical CO oxidation, electrophilic reaction, Criegee reaction mechanism, hydrogen, and a series of decarboxylation reaction, generate aromatic organic acids. Off the ozone oxidation of aromatic organic acid reaction process may include three stages. The first stage of aromatic organic acid hydroxylation; second stage oxidation ring hydroxylated products, with unsaturated carbonyl compounds; the third stage, aldehydes, carboxylic acid generation. As for the mineralization process, small molecular aldehydes, carboxylic acid is further oxidized into water and carbon dioxide. Ozone and aromatic organic acid reaction process mainly depends on the functional groups on the benzene ring is electron donating / electron withdrawing groups. Then in the sodium hypochlorite under the action of hair A series of reactions such as hydrolysis, enolylation, substitution, oxidation, decarboxylation, and the conversion of small carbonyl compounds to the by-products of disinfection.

【学位授予单位】：哈尔滨工业大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TU991.2

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