典型PPCPs污染物在水体中氧化降解的实验与理论研究

发布时间：2018-04-04 03:46

本文选题：PPCPs　切入点：高级氧化技术　出处：《山东大学》2017年博士论文

【摘要】：药品和个人护理用品(PPCPs)是一种公认的新兴污染物,近年来在环境中不断被检出,成为污水处理系统的一大挑战。因此,本论文选取布洛芬、酮洛芬和阿司匹林作为PPCPs的典型代表物,通过量子化学中的密度泛函理论(DFT)方法,系统地研究了水环境中PPCPs的降解及迁移转化问题,为水环境中PPCPs的有效降解提供技术和理论依据,主要研究内容及结果如下:1.本文基于高精度量子化学计算方法和密度泛函数理论,揭示了布洛芬降解转化的微观机制,在M06-2x/6-311++G(2dp)//M06-2x/6-31+G(d,p)水平上研究了由OH自由基引发的布洛芬在高级氧化过程中降解机理。首先,对前线电子密度和键离解能进行计算和分析,指出最可能反应的位置。此外,构造了反应势能剖面,并在此基础上对所有可能的反应途径进行探讨和研究,从而发现氢抽提是最重要的反应机理。反应的主要产物为对异丁基苯乙酮(IBPA), 2-[4-(1-羟基异丁基)苯基]丙酸和1-(4-异丁基苯基)-1-乙醇。计算结果与实验数据进行了比较,两者具有很高的一致性。2.结合密度泛函理论计算和实验方法探究了 OH自由基引发的酮洛芬的转化降解机理。在密度泛函计算反面,分析了前线电子密度和键离解,构建了所有可能反应途径的反应势能剖面。此外,采用过渡态理论计算了每条反应途径的速率常数。同时讨论了次级反应中的脱羧基反应和双苯环结构解离反应。实验方面,进行了酮洛芬的Fenton降解实验并采用UPLC-MSn方法鉴定了主要的转化降解产物。3.采用密度泛函理论方法和实验探究了阿司匹林在高级氧化技术体系中氧化转化和水解的机理。在计算层面上分析了前线电子密度和键离解,构建了所有可能反应途径的反应势能剖面并计算了每条反应途径的速率常数。进行了UV/H2O2降解实验并采用UPLC-MS-MS方法鉴定了反应中的中间体和降解产物。得到了与之前报道不同的结论:甲基官能团上的氢抽提反应和苯环结构上的氢抽提反应在高级氧化技术降级阿司匹林时是最容易发生的。实验检测到羟基化阿司匹林为最主要的中间产物。更重要的是,这是首次采用密度泛函方法来探究芳香族酯类有机物的水解机理。
[Abstract]:Drugs and personal care products (PPCPs) are recognized as emerging pollutants, which have been continuously detected in the environment in recent years, and have become a major challenge in sewage treatment systems.Therefore, ibuprofen, ketoprofen and aspirin were selected as the typical representative of PPCPs, and the degradation and migration of PPCPs in water environment were systematically studied by using density functional theory (DFT) method in quantum chemistry.To provide technical and theoretical basis for the effective degradation of PPCPs in water environment, the main research contents and results are as follows: 1.Based on the high precision quantum chemistry calculation method and density universal function theory, the microcosmic mechanism of ibuprofen degradation and transformation was revealed. The degradation mechanism of ibuprofen initiated by OH radical during the advanced oxidation process was studied at the M06-2x/6-311 G(2dp)//M06-2x/6-31 Gudp level.First, the electron density and bond dissociation energy in the front line are calculated and analyzed, and the position of the most likely reaction is pointed out.In addition, the reaction potential energy profile was constructed, and all possible reaction pathways were discussed and studied on the basis of which, it was found that hydrogen extraction is the most important reaction mechanism.The main products of the reaction are p-isobutylacetophenone, 2-[ 4-butane-1-hydroxyisobutyl) phenyl] propionic acid and 1-mono-4-isobutyl phenyl -1-ethanol. the main products of the reaction are p-isobutyl acetophenone (p-isobutyl acetophenone), 2- [4-hydroxyisobutyl) phenyl] propionic acid.The calculated results are compared with the experimental data.The conversion and degradation mechanism of ketoprofen initiated by OH radical was investigated by density functional theory (DFT) and experimental method.On the contrary of density functional calculation, the forward electron density and bond dissociation are analyzed, and the potential energy profiles of all possible reaction pathways are constructed.In addition, the transition state theory is used to calculate the rate constants of each reaction pathway.At the same time, the decarboxylation reaction and the structure dissociation reaction of diphenyl ring in the secondary reaction were discussed.In addition, the Fenton degradation of ketoprofen was carried out and the main transformation degradation product. 3. 3 was identified by UPLC-MSn method.The mechanism of oxidation conversion and hydrolysis of aspirin in advanced oxidation system was investigated by density functional theory (DFT) and experiments.The electron density and bond dissociation at the front line were analyzed at the computational level. The potential energy profiles of all possible reaction pathways were constructed and the rate constants of each reaction pathway were calculated.UV/H2O2 degradation experiments were carried out and the intermediates and degradation products were identified by UPLC-MS-MS method.Different from previous reports, hydrogen extraction reaction on methyl functional group and hydrogen extraction reaction on benzene ring structure are most likely to occur when aspirin is degraded by advanced oxidation technology.Hydroxylated aspirin was identified as the most important intermediate product.More importantly, it is the first time that the density functional method is used to study the hydrolysis mechanism of aromatic esters.
【学位授予单位】：山东大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：X703

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