城市污水处理厂邻苯二甲酸酯类污染物控制技术研究

发布时间：2018-05-06 07:59

本文选题：邻苯二甲酸酯类物质 + 纳米催化剂　；参考：《山东建筑大学》2016年硕士论文

【摘要】：随着城市化和工业化的不断推进,经市政排水管道收集的污水中除了含有大量常规污染物,另外多种微量或者痕量的有毒有害污染物也不断增多,常规的水处理工艺并不能有效去除这些生物难降解的痕量污染物质,如内分泌干扰物质,这不但加重了城市污水处理厂处理废水的负担和难度,也对环境安全和人体健康构成了威胁。本研究选取六种常见的邻苯二甲酸酯类物质为目标污染物,应用高级催化氧化技术对此种典型环境激素类物质进行降解研究。采用水热法合成纳米a-Fe2O3作为催化剂,研究其联合光助Fenton氧化技术对污染物的降解效果及影响因素,针对邻苯二甲酸二甲酯(DMP)、邻苯二甲酸二乙酯(DEP)、邻苯二甲酸二丁酯(DBP)、邻苯二甲酸丁苄酯(BBP)、邻苯二甲酸(2-乙基己基)酯(DEHP)、邻苯二甲酸二正辛酯(DnOP)六种邻苯二甲酸酯类物质寻找最优降解条件；研究对实际城市污水处理厂高效沉淀池出水的应用效果,并分析降解机理；通过分析光催化氧化降解DEP过程中的中间产物,探讨了其降解历程。主要研究内容与结果如下：(1)建立了对实际水样中低浓度的PAEs进行净化和富集的固相萃取(SPE)预处理方法。应用液相色谱-串联质谱(LC-MS-MS)联用仪对水样中的PAEs进行定性定量分析。使用气相色谱-质谱(GC-MS)仪建立了针对DEP光催化氧化降解过程的中间产物的分析检测方法。(2)基于本课题组的前期的研究,本研究采用液相水热合成法制成纳米α-Fe2O3催化剂,尺寸均匀(约为70-80nm左右),呈球体和类球体状。反应时间9h以上,反应温度180%以上可得到纯相的α-Fe2O3纳米晶体。为了提高纳米催化剂粉体的实用性,应用活性炭为载体,通过烧结法得到α-Fe2O3-AC复合材料,活性炭负载催化剂避免了粉体催化剂在处理废水过程中的流失、在光降解时粉体互相遮蔽,使光利用效率低以及处理后的回收等问题。(3)纳米α-Fe2O3催化剂的应用大大提高了光Fenton反应的氧化效果。使用实验室自制光催化反应器,研究各种因素对非均相光助Fenton催化氧化降解含苯酚模拟废水的影响,并探索最优实验条件的主要结果为：H2O2、Fe2+或纳米催化剂α-Fe2O3投加量的适当增加,都会促进苯酚的降解,但过量的H2O2、Fe2+或α-Fe2O3,反而使降解效率降低或停滞。低浓度的苯酚废水并没有得到更高的降解率。α-Fe2O3-AC复合物投入量的适当增加,苯酚的降解率逐渐变大。随着初始pH值的增大,降解率逐渐变小。研究结果表明：最佳反应条件为：pH=3.0,H2O2初始浓度为20mM, Fe2+的初始浓度为0.5mM, α-Fe2O3投加量10mg·L-1,或者α-Fe2O3-AC复合物投加量为10g·L-1,对模拟苯酚废水的去除率达98%以上。(4)六种PAEs在不同催化体系中的光催化降解效果不同,且遵循不同的降解机理。单独UV光照、H202氧化、单独Fenton反应降解模拟PAEs水溶液的结果均不理想；使用UV/Fenton联用工艺的降解率已经大幅度提高；催化系统再增加活性炭后,六种PAEs的降解效率增加幅度并不大;而光催化系统将活性炭换成纳米α-Fe2O3催化剂后,降解效率有较大幅度的提高,去除率均超过94%；而UV/Fenton/α-Fe2O3-AC工艺对PAEs的降解效率却稍微有所降低。而与实验室模拟水样的降解实验结果对比,真实水样中六种PAEs的降解率均有所降低。不同PAEs的降解机理是有规律可循的,侧链较短且简单的,相对较容易去除,而侧链较长且复杂,分子量较大的,相对难降解。不同的降解体系中,在α-Fe2O3表面上的催化降解过程遵循光催化机理,光生空穴会与催化剂表面的羟基族相互作用产生羟基自由基(·OH)。导带上的光生电子可与溶解氧(O2)反应生成活性氧物种O2-,O2-和·OH均具有强氧化性；而UV、H2O2、Fe2+和α-Fe2O3催化剂同时存在时,PAEs的催化降解存在两种路径：光催化机理和光-Fenton机理；α-Fe2O3-AC复合材料光催化降解PAEs的过程中,载体AC与催化剂α-Fe2O3之间的协同耦合作用,同时促进了邻苯二甲酸酯的降解程度和速率。(5)在UV/Fenton/a-Fe203工艺的最优条件下,以DEP为目标污染物,间接证明了·OH为降解DEP的主要因子,应用GC-MS-MS检测方法测定其降解的中间产物,主要有苯甲酸乙酯和邻苯二甲酸二甲酯。分析DEP的降解历程,DEP的光催化氧化降解主要发生在侧链上,主要有两种途径：一是DEP的两个侧链末端的C原子被.OH进攻,使C-C键发生断裂,形成DMP：另一降解途径是-OH攻击DEP苯环和侧链酯基相连的a碳位,使C-C键发生断裂,生成苯甲酸乙酯及其他小分子物质。通过应用纳米α-Fe2O3催化剂及其与活性炭的复合物对六种典型邻苯二甲酸酯类物质的光催化氧化降解效果和机理的研究,为实际城市污水处理厂中邻苯二甲酸酯类污染物质的控制技术提供了理论指导,具有重要的实际应用价值。
[Abstract]:With the continuous advancement of urbanization and industrialization, the sewage collected by municipal drainage pipes contains a large number of conventional pollutants, and other trace or trace amounts of toxic and harmful pollutants are increasing. The conventional water treatment process can not effectively remove the trace contaminants, such as endocrine disrupting substances, which are difficult to reduce. This not only aggravates the burden and difficulty of wastewater treatment in urban sewage treatment plants, but also poses a threat to environmental safety and human health. In this study, six kinds of common phthalic acid esters were selected as the target pollutants, and advanced catalytic oxidation technology was used to study the degradation of the typical environmental irritable substances. As a catalyst, nano a-Fe2O3 was used as a catalyst to study the degradation effect and influence factors of the combined Fenton oxidation technology on pollutants, including two methyl phthalate (DMP), two ethyl ortho two formic acid (DEP), dibutyl phthalate (DBP), butyl benzyl ortho two formate (BBP), phthalic acid (2- ethyl hexyl) ester (DEHP), and phthalic acid two. Six ortho benzoate esters of ortho octyl (DnOP) were found to find the best degradation conditions. The application effect of the effluent from the high efficiency sedimentation tank of the actual municipal wastewater treatment plant was studied and the degradation mechanism was analyzed. The degradation process was discussed by analyzing the intermediate products in the process of photocatalytic oxidation degradation of DEP. The main contents and results were as follows: (1) A solid phase extraction (SPE) pretreatment method for the purification and enrichment of low concentration PAEs in the actual water samples was established. The qualitative and quantitative analysis of PAEs in water samples by liquid chromatography tandem mass spectrometry (LC-MS-MS) was applied to the analysis of the intermediate products of the photocatalytic oxidation degradation of DEP by gas chromatography-mass spectrometry (GC-MS). (2) (2) based on the previous study of this research group, this study uses liquid hydrothermal synthesis method to form a nano -Fe2O3 catalyst, with a uniform size (about 70-80nm), spherical and spheroid. The reaction time is above 9h and the reaction temperature is above 180%. The pure phase alpha -Fe2O3 nanocrystalline can be obtained. Using the active carbon as the carrier, a -Fe2O3-AC composite is obtained by sintering. The activated carbon supported catalyst avoids the loss of the powder catalyst in the process of wastewater treatment. In the light degradation, the powder is shielded from each other, and the use efficiency is low and the recovery after treatment. (3) the application of nano -Fe2O3 catalyst has been greatly improved. The effects of various factors on the degradation of simulated wastewater containing phenol by heterogeneous photoassisted Fenton catalytic oxidation were studied by a laboratory self-made photocatalytic reactor, and the main results of the optimal experimental conditions were the appropriate increase in the dosage of H2O2, Fe2+ or nano catalyst alpha -Fe2O3, which would promote the degradation of phenol. However, excessive H2O2, Fe2+ or alpha -Fe2O3 reduced the degradation efficiency or stagnated. The low concentration of phenol wastewater did not get a higher degradation rate. The degradation rate of phenol increased gradually with the appropriate increase of the input of alpha -Fe2O3-AC complex. The degradation rate gradually became smaller with the initial pH value increasing. The results showed that the optimum reaction condition was p The initial concentration of H=3.0, H2O2 is 20mM, the initial concentration of Fe2+ is 0.5mM, the dosage of alpha -Fe2O3 is 10mg. L-1, or the dosage of alpha -Fe2O3-AC complex is 10g L-1, and the removal rate of the simulated phenol wastewater is above 98%. (4) the photocatalytic degradation effect of six kinds of PAEs in different catalytic systems is different and follows different degradation mechanisms. The results of degradation of simulated PAEs aqueous solution by the single Fenton reaction were not ideal, and the degradation rate of the combined use of UV/Fenton was greatly improved, and the degradation efficiency of the six PAEs was not greatly increased after the catalytic system was added to the activated carbon, and the photocatalytic system changed the activated carbon to the nano - -Fe2O3 catalyst. The removal efficiency of the UV/Fenton/ alpha -Fe2O3-AC process is slightly lower than 94%, while the degradation efficiency of PAEs is slightly reduced. Compared with the experimental results of laboratory simulated water samples, the degradation rates of six kinds of PAEs in real water samples are reduced. The degradation mechanism of different PAEs is regular, and the side chain is shorter and simpler. It is relatively easy to remove, while the side chain is longer and complex, and the molecular weight is relatively difficult to degrade. In the different degradation systems, the catalytic degradation process on the surface of the alpha -Fe2O3 follows the photocatalytic mechanism, the photogenerated cavitation can produce hydroxyl radical (. OH) with the hydroxyl group on the catalyst surface. The photogenerated electrons on the guide band and the dissolved oxygen (O2) can be found. The reactive oxygen species O2-, O2- and OH have strong oxidation, while UV, H2O2, Fe2+ and alpha -Fe2O3 exist at the same time, there are two pathways in the catalytic degradation of PAEs: photocatalytic mechanism and optical -Fenton mechanism; in the process of photocatalytic degradation of alpha -Fe2O3-AC composite, the synergistic coupling between carrier AC and catalyst alpha At the same time, the degradation degree and rate of phthalate two formate were promoted. (5) under the optimal condition of UV/Fenton/a-Fe203 process, DEP was used as the target pollutant, and OH was indirectly proved to be the main factor of degradation of DEP. The intermediate products of degradation were determined by GC-MS-MS detection method, including ethyl benzoate and two methyl phthalic acid two formate. Analysis of the degradation process of DEP, the photocatalytic oxidation degradation of DEP mainly occurs on the side chain, and there are two main ways: one is that the C atom at the end of the two side chain of DEP is attacked by.OH, which causes the C-C bond to break up and form DMP. The other degradation pathway is -OH attacking the a carbon position connected by the DEP benzene ring and the side chain ester group, making the C-C bond broken and producing ethyl benzoate. The study on the photocatalytic oxidation degradation effect and mechanism of six typical phthalic acid esters by using nano -Fe2O3 catalyst and its complex with activated carbon has provided theoretical guidance for the control technology of phthalic acid esters in actual municipal wastewater treatment plant. Practical application value.

【学位授予单位】：山东建筑大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：X703

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