【作者】 韩辉；

【导师】 曹晓燕；

【作者基本信息】 中国海洋大学 ， 海洋化学， 2011， 硕士

【摘要】 石油烃类化合物是海洋环境中常见的有机污染物,已成为近岸海域最主要的有机污染物之一。这些石油类污染物通过发生一系列的物理、化学和生物作用,对海洋生态环境造成了严重的破坏,危害人类健康。油类污染物进入水体后,随着风化过程的进行,其中的轻组分容易通过蒸发、溶解、乳化等作用其含量不断降低,而重组分有很大一部分会在悬浮颗粒物上吸附而随之沉降到海底沉积物,在沉积物有机质和粘土矿物中发生吸附分配等作用。一定条件下吸附在沉积物上的油类污染物又会向上覆水体中释放,成为一种内源污染,造成水体二次污染。油类污染物在沉积物-水界面处的吸附解吸是影响其在海洋环境中迁移、转化、和生物利用等的重要途径,因而研究其在近岸海洋环境中的吸附解吸具有重要的意义。本论文运用实验室模拟的方法,在尽可能保持颗粒原结构的基础上,采用湿筛法处理的胶州湾沉积物为吸附剂,研究在人工海水介质中,重油的吸附解吸行为,并讨论了相关的影响因素,重点考察了阴离子表面活性剂十二烷基苯磺酸钠（sodium dodecylbenzene sulfonate,SDBS）和非离子表面活性剂失水山梨醇聚氧乙烯（20）醚月桂酸酯（Polyoxyethylene （20） sorbitan Monolaurate,Tween20）存在时重油在胶州湾沉积物上的吸附解吸行为,得到的主要结论如下:1.吸附过程（1）动力学研究发现沉积物对重油的吸附速率较快,吸附动力学曲线符合伪二级非线性速率方程,SDBS的加入能够加快重油在沉积物上的吸附,且吸附速率常数k2随SDBS初始浓度的增大而增大,而Tween20存在下,重油在沉积物上的吸附速率随Tween20初始浓度的增大而减小。（2）热力学研究发现,沉积物对重油的吸附等温线较好地符合Freundlich等温线,吸附系数KF随SDBS浓度的增大而增大,SDBS能够显著提高沉积物对重油的吸附量;而Tween20不利于重油在沉积物上的吸附,KF随Tween20浓度的增大而减小,说明Tween20与重油的竞争吸附作用大于增强吸附作用。（3）重油在HCl、H₂O、H₂O₂处理沉积物上的吸附行为均可用Freundlich等温线描述,吸附等温线的线性程度随沉积物有机碳含量的升高而升高,表明沉积物对重油的吸附是通过分配作用和表面吸附作用来完成的,有机质的分配作用占主导。沉积物粒径的增大导致其吸附能力的降低,原因主要是不同粒径的沉积物具有的比表面积、有机碳、粘土矿物含量不同。（4）环境因素研究表明,三种体系下重油在沉积物上的吸附量均随盐度的增加而增大,其中SDBS存在下盐度的影响较显著,而Tween20影响下不明显。温度对重油吸附的影响表现为温度的升高吸附量降低,因为温度会影响重油在溶液中的溶解度和沉积物中有机组分向溶液中释放的程度,最终影响了沉积物有机碳的分配作用。（5）沉积物对重油吸附过程的热力学函数ΔG^φ<0,ΔH^φ<0,即该过程是一个自发、放热的物理吸附过程。在20mg·L^-1 SDBS影响下,重油在沉积物上的吸附有较大的标准吸附自由能变（|ΔG^φ|）和标准吸附焓变（|ΔH^φ|）,更大的标准吸附熵变（|ΔS^φ|）。而在20 mg·L^-1 Tween20存在下,重油在沉积物上吸附过程的|ΔG^φ|、|ΔH^φ|,较单一体系的小,且ΔS^φ>0。2.解吸过程（1）重油在沉积物上的解吸较慢,分两个阶段,第一阶段的快解吸阶段,第二阶段是从沉积物内部微孔扩散到溶液中的过程,解吸动力学符合二室一级动力学模型。（2）SDBS和Tween20均有利于重油在沉积物上的解吸,且解吸速率常数随表面活性剂浓度的增加而加快,但在相同的表面活性剂浓度下,Tween20的影响较显著。（3）环境因素研究表明,随着介质盐度的减小和温度的升高,沉积物对重油的解吸量和解吸速率常数均增加;重油在较大粒径的沉积物上的解吸较为明显,可能与粒径大的沉积物的比表面积较小,重油不易在其上面吸附有关。更多还原

【Abstract】 Petroleum hydrocarbon is a common organic pollutant in ocean environment, which has become one of the main organic pollutants in the offshore areas. These petroleum contaminants cause serious damage to the marine eco-environment and are harmful to human being through a series of physical, chemical, and biological processes. When oil pollutants enter into water system, the light components will disappear through evaporation, dissolution, emulsification, and so on. However, the heavy contents will be adsorbed onto suspension particle, and then set down to the bottom. Oil pollutants on sediments will release to seawater under certain conditions, and will cause secondary pollution to seawater. The adsorption and desorption of heavy oil in sediment/water interface is an important way to affect their migration, transformation, and biological utilization in marine environment. Therefore, it is very important to study the sorption and desorption behaviour of oil on marine sediments.In this paper, the sorption and desorption behaviors of heavy oil on Jiaozhou bay sediments were comprehensively studied through laboratory experiments. The sediment sample was wet sieved in order to keep the original nature of the particulate. Some related factors were also discussed to study the mechanisms of the sorption and desorption, such as treated method, particle size, salinity, temperature and surfactant. The main conclusions are as follows:1. Sorption process1)The sorption rate of heavy oil on sediment was rapid and the kinetic process was proven to follow the pesudo-second-order kinetic rate equation. The sorption was accelerated remarkably with the addition of anionic surfactant sodium dodecyl benzene sulfonate（SDBS）, while was retarded with the presence of nonionic surfactant polyoxyethylene（20）sorbitan Monolaurate （Tween20）.2)The sorption isotherms of heavy oil on sediment could be described by the Freundlich equation. The sorption capacity could be enhanced by SDBS obviously, while decreased with the presence of Tween20. 3)The equilibrium experiments of heavy oil sorption on HCl, H₂O and H₂O₂ treated sediments revealed that the isotherms became more linear for sediment with higher organic carbon, which indicated that heavy oil sorption onto sediments was through partition function and surface sorption effect, while the former was dominant. The sorption ability of sediment decreased with increasing particle sizes. The reason may be that sediments with different sizes had different specific surface areas, TOC values, and mineral compositions.4)The sorption capability was increased under higher salinity and lower temperature circumstances. In the presence of SDBS the effect of salinity was significant, while the influence of Tween20 was not clear. The temperature influenced the solubility of heavy oil and the organic matters in sediments, thus affacted the partition effect of sediment.5)Calculation of thermodynamic parameters indicated that the sorption process of heavy oil was spontaneous （ΔG^φ<0）, exothermic （ΔH^φ<0） and was a physical process. In the presence of 20 mg·L^-1 SDBS, the│ΔG^φ│and│ΔH^φ│values became higher, while in the presence of 20mg·L^-1 Tween20, the effect was reverse.2. Desorption process1)The desorption rate of heavy oil on Jiaozhou bay sediment was slow, and the kinetic process could be divided into two stages: The first stage was rapid which took place on sediment surface, while the second one was slow and due to the diffusion from the internal micropores of sediment. The desorption process of heavy oil according well with a two-compartment first order kinetic rate equation.2)SDBS and Tween20 could remarkably enhance the desorption of heavy oil from sediment. The desorption rate constant increased with the increasing concentration of surfactants. Under the same circumstances, the influence of Tween20 was more obvious.3)Larger particle size was favourable for the desorption of heavy oil from sediment. Environmental factors research indicated that the desorption capacity and rate constant of heavy oil was significantly increased at lower salinity and higher temperature.更多还原