【作者】 肖翔；

【导师】 张勇；

【作者基本信息】 厦门大学 ， 环境科学， 2009， 硕士

【摘要】 多环芳烃（Polycyclic aromatic hydrocarbons,PAHs）是环境中常见的持久性有机污染物,主要由人类活动产生,可通过生物链积累,最终对人类健康造成危害。本文首先介绍了PAHs的性质、危害、来源以及天然水环境中PAHs的主要环境行为,综述了PAHs在液相介质中的光降解研究进展;然后介绍了表面活性剂的结构、性质及其应用,其中着重综述了表面活性剂在环境科学中的应用;随后介绍了荧光分析法在PAHs相关研究中的应用。在上述讨论的基础上提出了本论文的设想及研究内容,即选择葸（An）和芘（Py）作为模型分子,利用荧光分析法考察溶解态混合组分An和Py在水、人工海水（Simulated seawater,SSW）和经过滤和杀菌处理的天然海水（Pretreated natural seawater,PNSW）三种介质中的光降解过程以及表面活性剂对溶解态单组分An或Py光降解的影响。主要研究结果如下:首先,研究了溶解态混合组分An和Py的光降解过程。设计合适的光降解装置,利用同步荧光法直接研究溶解态混合组分An和Py在水、SSW和PNSW中的光降解过程,并分别考察了环境因子HCO₃^-、光敏剂腐殖酸（Humic acid,HA）和丙酮、H₂O₂、NO₃^-和重金属离子(Cu²⁺、Cd²⁺、Hg²⁺和Zn²⁺)对溶解态An和Py在水、SSW和PNSW中光降解的影响。结果表明:随着盐度的增加,溶解态混合组分An和Py的光降解速率都逐渐增大。溶解态混合组分An和Py在上述三种介质中的光降解速率大小顺序均为SSW＞PNSW＞水。在水、SSW和PNSW中分别加入HCO₃^-、丙酮、H₂O₂和NO₃^-后,溶解态混合组分An和Py的光降解速率提高;而HA的加入则抑制二者的光降解;重金属离子Cu²⁺、Cd²⁺、Hg²⁺和Zn²⁺对溶解态混合组分An和Py的光降解存在或抑制或促进的作用,并无统一的规律可循。溶解态An和Py在上述各种条件下的光降解过程都遵循一级反应动力学模式。溶解态单组分An在水中光降解的半衰期在0.3-18.6 min之间,而溶解态混合组分中An在水、SSW和PNSW中的光降解半衰期分别为0.5-18.9min之间、0.2-5.1 min之间以及1.5-10.7 min之间;溶解态单组分Py在水中的光降解半衰期在1.3-30.9 min之间,溶解态混合组分中Py在水、SSW和PNSW中的光降解半衰期分别为1.7-34.7 min之间、1.2-29.1 min之间以及2.3-31.7 min之间。其次,研究了溶解态An或Py在表面活性剂溶液中的光降解过程。利用表面活性剂能够增加PAHs表观溶解度的性质,用荧光法考察了三种表面活性剂（Brij35、SDS和DTAB）溶液中溶解态An或Py的光降解过程。结果表明在SDS和DTAB溶液中,溶解态An和Py都增溶于表面活性剂胶团的内核处,光降解受到抑制;而在Brij35溶液中An和Py增溶于Brij35胶团的聚氧乙烯外壳处,其光降解速率提高。动力学分析表明,溶解态An在水和Brij35溶液中的光降解均遵循一级反应动力学模式,反应半衰期分别为16.3 min^-1和8.9 min^-1。溶解态Py在水中的光降解也遵循一级反应动力学模式;但在Brij35溶液中的光降解却遵循二级反应动力学模式,反应半衰期分别为24.8 min^-1和1.3 min^-1。我们对有无表面活性剂存在下光降解反应动力学过程均遵循一级反应动力学模式的An在Brij35溶液中的光降解过程进行初步的机理探讨。结果表明在Brij35溶液中自由基抑制剂HCO₃^-对溶解态An的光降解无影响,且磁场效应能略微促进溶解态An的光降解,由此初步判断溶解态An在Brij35溶液中的光降解是一个由激发三重态发生且无自由基产生的过程,与其在水中的光降解机理（单重态氧氧化机理）一致。更多还原

【Abstract】 Polycyclic aromatic hydrocarbons（PAHs） are common persistent organic pollutants that are mainly produced by human activities in environment.They pose a potential threat to human health through bioaccumulation via food chains.In this dissertation the properties,hazards,sources and dominant environmental behaviors of PAHs in aquatic environment were presented firstly.Secondly,photodegradation of PAHs in liquid phase were reviewed.Thirdly,the structures,properties and applications of surfactants were introduced and their applications in environmental scientific were emphasized.Finally,the applications of fluorimetry in related studies of PAHs were summarized.On the basis of the discussions above,the proposals of this dissertation were illuminated.Anthracene（An） and pyrene（Py） were selected as the model molecules.Photodegradation of dissolved An and Py in a mixture in water, simulated seawater（SSW） and pretreated natural seawter（PNSW） which was filtered and sterilized before use was investigated,and the effect of surfactant on the photodegradation of dissolved An or Py was also studied.The mainly results were as follows:Firstly,photodegradation of dissolved An and Py in a mixture was investigated. Proper photodegradation apparatus was set up,then the photodegradation of dissolved An and Py in a mixture in water,SSW and PNSW was directly studied by synchronous fluorimetry.Several environmental factors such as radical inhibitor （HCO₃^-）,humic acid（HA）,acetone,hydrogen peroxide（H₂O₂）,nitrate（NO₃^-） and heavy metal ions(Cu²⁺,Cd²⁺,Hg²⁺ and Zn²⁺) were selected,and the effects of these environmental factors on the photodegradation of dissolved An and Py in a mixture in water,SSW and PNSW were investigated,respectively.Some important results were as follows:The photodegradation rates of dissolved An and Py in a mixture increased with the increment of salinity of aqueous solution.The photodegradation rates of dissolved An and Py in water,SSW and PNSW decreased as this order:SSW＞PNSW＞water.The processes of photodegradation of dissolved An and Py in a mixture were enhanced when HCO₃^-,acetone,H₂O₂ or NO₃^- was introduced to water,SSW and PNSW,respectively.Whereas,the contrary results were obtained when HA was introduced to water,SSW and PNSW.The effects of different heavy metal ions on the photodegradation of dissolved An and Py in a mixture varied a lot in water,SSW and PNSW.Experimental results show that all the processes of photodegradation of dissolved An and Py investigated followed first-order reaction kinetics.The half-lives of photodegradation of dissolved An in water varied from 0.3 to 18.6 min,and the half-lives of dissolved An in a mixture in water,SSW and PNSW varied from 0.5 to 18.9 min,0.2 to 5.1 min and 1.5 to 10.7 min,respectively.Moreover,the half-lives of photodegradation of dissolved Py in water varied from 1.3 to 30.9 min.The half-lives of dissolved Py in a mixture in water,SSW and PNSW varied from 1.7 to 34.7 min, 1.2 to 29.1 min and 2.3 to 31.7 min,respectively.Secondly,photodegradation of dissolved An or Py in three kinds of surfactant （Brij35,SDS and DTAB） solutions were investigated by fluorimetry,according to the characteristic of water solubility enhancement of PAHs.These three kinds of surfactants contain different charges.It was found that the processes of photodegradation of dissolved An or Py were retarded in SDS and DTAB solutions, because An and Py resided in the micelles within the core of surfactants in these solutions.While in Brij35 solution the processes of photodegradation of dissolved An or Py were enhanced,and the reason is that An and Py resided in the micelles among the polyoxyethylene portion of Brij35.The processes of photodegradation of dissolved An in water and Brij35 solution followed first-order reaction kinetics,and their half-lives were 16.3 min^-1 and 8.9 min^-1,respectively.Experimental results show that the process of photodegradation of dissolved Py in water also followed first-order reaction kinetics,but the process of photodegradation of dissolved Py in Brij35 followed second-order reaction kinetic.The half-lives of photodegradation of dissolved Py in water and Brij35 solution were 24.8 min^-1 and 1.3 min^-1.In addition, the mechanism of photodegradation of dissolved An in Brij35 solution was explored preliminarily.The experimental results showed that HCO₃^- had no effect on the photodegradation of dissolved An in Brij35 solution,and the photodegradation rate of dissolved An in Brij35 solution increased a little with the present of magnetic field.In conclusion,in Brij35 solution An decomposed according to the mechanism with the excited triple state of An but without a radical cation,and this mechanism was homologous with the mechanism of photodegradation of dissolved An in water.更多还原