胡敏酸介导水中17α-乙炔基雌二醇光降解的机制及活性研究

发布时间：2018-01-31 14:41

  本文关键词： 17α-乙炔基雌二醇 光降解 胡敏酸 光化学活性 活性物质 雌激素　出处：《昆明理工大学》2017年博士论文　论文类型：学位论文

【摘要】：环境中的类固醇雌激素(SEs)是一类典型的内分泌干扰物,其可通过环境介质和食物链进入动物和人体内干扰天然激素的合成、分泌、运输和代谢等过程,进而影响生物体发育、生长和繁殖等生理过程。其中,17α-乙炔基雌二醇(EE2)是SEs中雌激素活性最强者,即使其环境浓度低于1.0 ng/L,也会对生态系统造成危害。近年来,许多国家的污水处理厂出水、环境地表水甚至自来水都被检测出了 EE2。因此,除对EE2生产和使用进行有效管理外,准确认识其环境行为,为其环境风险评估和污染控制措施建立提供理论依据也是刻不容缓的。EE2 一旦进入环境地表水体,便会经历各种迁移转化过程。其中,光化学降解是EE2环境行为的重要组成部分。由于天然有机质(NOM)是环境水体中广泛存在的一类光敏性和滤光性物质,因此探究NOM对EE2光化学转化的影响是认识EE2在环境水体中的光化学行为规律和生态风险的关键。然而,关于NOM介导下的EE2光化学行为、转化机制及雌激素活性变化等信息至今尚不清晰。再者,NOM的结构和性质极为复杂,其对有机污染物光化学转化的介导效应和机制常随污染物种类及NOM理化性质不同而异。这便意味着,NOM对EE2光化学转化的影响不能简单地参考现有研究结论。因此,本文以NOM的主要组分胡敏酸(HA)为代表物质,首先系统地研究了 EE2在HA介导下的光化学转化过程和机制,以及各水环境因子对HA介导EE2光化学转化机制的影响。然后,探究了光化学转化对EE2雌激素活性和植物生长毒性的影响。最后,在明确光漂白改变HA结构组成、理化性质和光化学活性的基础上,分析了不同来源和理化性质HA介导EE2光降解效力与自身结构组成、理化性质及光生活性物质(RS)间的相关性,并探讨了 HA介导EE2光降解的主要光活性组分和结构。主要研究结论如下:(1)EE2在纯水和HA溶液中的光化学转化过程均服从拟一级动力学规律。在纯水溶液中,EE2能发生直接光降解和自敏化降解两种过程,但整体光降解过程较缓慢,降解速率仅为0.0163h-1左右。在HA溶液中(5.0mgC/L),EE2主要以与HA相结合的形态存在,其主要结合机制为氢键、π-π作用力和疏水性分配。与EE2纯水溶液光降解相比,HA能有效提高EE2光降解速率4倍左右,并缩减EE2半衰期至10 h以内。(2)EE2在HA溶液中的快速光降解主要由光生HO·和~3HA*引起,二者对EE2光降解的贡献分别约为34%和30%。其中,HO·与EE2主要发生了亲电加成反应;而~3HA*与EE2间的主要反应机制为氢原子和电子抽取。尽管HA溶液中光生~1O2的量通常高出光生HO·量3个数量级,但其对EE2光降解的贡献始终小于17%。另外,光生H2O2和O2·-均不能直接导致EE2转化,但二者都能转化生成HO·,从而引起EE2降解。除RS外,HA结合作用也是EE2在HA溶液中发生快速光降解的原因之一,这是因为EE2与HA相结合时有利于EE2与HO·和~3HA*发生反应。(3)酚结构是EE2分子中的光敏感结构,EE2在纯水和HA溶液中的光降解产物均主要由酚环变化产生。在HA溶液中,尽管EE2能发生快速的光化学转化过程,但EE2不能被彻底矿化,只能被转化成其他有机化合物。经酵母菌和MCF-7细胞检测显示,光化学转化能彻底消除EE2雌激素活性。但值得注意的是,EE2对水稻、小麦和红豆种子发芽及其幼苗生长的刺激效应并不能被光化学转化彻底消除。(4)各水环境因子影响EE2光降解过程的规律如下:在纯水和HA溶液中,EE2光降解速率均随自身浓度增大呈现出先减小后趋于稳定的变化趋势;在pH = 6.5～8.5的溶液中,EE2光降解速率最小,当pH9.0时,EE2光降解速率显著增大;OO和Fe(111)均能促进EE2光化学转化。离子强度和C1-对EE2纯水溶液光降解没有影响,但二者分别能促进和抑制HA溶液中EE2的光降解过程。HC03-对EE2在纯水和HA溶液中的光降解过程均没有影响。NO3-能显著促进EE2光降解,但其促进作用会受到HA的滤光作用和HO·淬灭作用的影响。(5)光漂白能显著改变HA的组成、结构和理化性质。光漂白使HA优先失去长波光吸收能力并使其分解成脂肪性组分和小分子有机酸等,从而提高HA的生物可利用性。尽管HA光生HO·、~1O2和~3HA*的能力均随光漂白程度增大而减小,但光漂白70h后的HA仍能有效地介导EE2光降解,其降解速率约为纯水中EE2光降解速率的2.5倍。(6)HA的光化学活性与自身疏水性、极性和分子量大小密切相关。不同疏水性组分中,过渡性亲水组分具有最高的光化学活性,疏水性组分次之,亲水性组分最小;HA光生HO·、~1O2和~3HA*的能力随极性和分子量增大而减小。从结构上看,HA介导EE2光降解的能力是由含氧官能团、电子转移复合结构、芳香化程度和分子大小主导的。一定HA浓度下,光谱斜率比(S275-295/S350-400)能有效指示HA介导EE2光降解的能力,且这种指示作用不受低浓度H202和NaClO改变HA结构和性质的影响。以上研究结论一方面有利于我们更清晰地认识EE2光化学行为和HA光化学过程在污染物环境地球化学行为中的作用;另一方面,能为EE2的环境归趋预测、生态风险评价及污染控制措施建立等提供必要的理论依据。
[Abstract]:In the environment of steroid estrogens (SEs) is a kind of typical endocrine disruptors, which can be achieved by the environmental medium and food chain into the synthesis of natural hormones in animal and human disturbance secretion, transport and metabolism, thereby affecting the organism development, growth and reproduction and other physiological processes. Among them, 17 ethinyl estradiol glycol (EE2) is the strongest estrogenic activity in the SEs environment, even if its concentration is lower than 1 ng/L, will cause harm to the ecosystem. In recent years, sewage treatment plant effluent in many countries, the environment of surface water and even tap water were detected in the EE2. so, in addition to the effective management of EE2 production and use, accurate understanding the environmental behavior, provided theoretical basis for the establishment of the environmental risk assessment and pollution control measures are imperative for.EE2 once in the surface water, it will go through all kinds of migration and transformation process. Among them, actinic Study of degradation is an important part of the environmental behavior of EE2. Because the natural organic matter (NOM) is widely existed in aquatic environment a kind of photosensitive and filter material, thus exploring the impact of NOM on the transformation of EE2 is the key to understanding the photochemical photochemical behavior of EE2 in environmental water and ecological risk. However, EE2 on the photochemical behavior of NOM mediated transformation mechanism, and estrogenic activity changes of information is still not clear. Furthermore, the structure and properties of NOM is very complex, the organic pollutants in photochemical transformation mediated by the effect and mechanism of pollutants and NOM often vary in different physical and chemical properties vary. This means that the effect of NOM on the transformation of EE2 photochemistry can not simply refer to the existing research results. Therefore, this paper takes the main components of NOM acid (HA) as the representative of Hu Min, the first systematic study of EE2 in HA mediated photochemical conversion process And the mechanism and the influence factors of water environment by EE2 on HA mediated photochemical conversion mechanism. Then, explores the effects of transforming growth toxicity on EE2 photochemical activity and plant estrogen. Finally, in the clear light bleaching to change the structure of HA. The basic physicochemical properties and photochemical activity, analysis of different sources and physicochemical the properties of HA mediated EE2 degradation effect of composition and its structure, physicochemical properties and optical active substances (RS) and to explore the correlation between, HA mediated EE2 degradation of main light active components and structure. The main conclusions are as follows: (1) EE2 in water and HA solution in the photochemical transformation the process follows pseudo first-order kinetics. In aqueous solution, EE2 can direct photodegradation and self sensitized degradation of two kinds of process, but the overall degradation process is slow, the degradation rate is only about 0.0163h-1. In the solution of HA (5.0mgC /L), mainly in the EE2 涓嶩A鐩哥粨鍚堢殑褰㈡，

本文编号：1479299