【作者】 李涛；

【导师】 吴平霄；

【作者基本信息】 华南理工大学 ， 环境工程， 2010， 硕士

【摘要】 多环芳烃(PAHs)作为环境中广泛存在的一类有机污染物,因被证实具有“致癌、致畸、致突变”效应而被列为环境监测中的优先污染物。为了揭示水溶性有机物(DOM)对粘土矿物吸附PAHs的影响,选取蒙脱石和高岭土为粘土矿物的代表,以垃圾渗滤液为DOM提取原料,模拟制备了蒙脱石/高岭土-DOM有机无机复合体,并对原土和复合体表面微结构变化进行测试分析,然后通过批量静态吸附平衡法考察了复合体对菲、芘的吸附特征及吸附稳定性,最后探讨了粘土矿物/DOM复合体对PAHs的吸附机理,为多环芳烃类物质在环境中的环境化学行为和迁移转化规律提供理论依据。本研究得到的主要结论如下:首先,粘土矿物与DOM发生复合后微结构发生了一系列变化:XRD分析表明,与DOM复合后,粘土矿物的层间距只发生了微小的变化,没有发生明显的插层反应;IR分析表明,蒙脱石和高岭土与DOM发生了一定程度的化学键合,蒙脱石还增加了C-H振动的特征吸收;SEM分析表明,与DOM复合后粘土矿物表面则变得比较粗糙,结构也变得相对疏松;TG分析表明:在整个温度范围内空白粘土原土的失重量大于复合体的失重量,另外,与空白粘土失重曲线相比,复合体失重曲线向低温区偏移,表明这少量的DOM也影响了粘土原土脱去结构水和层间水的起始温度。其次,粘土矿物/DOM复合体吸附PAHs的实验研究发现:粘土矿物/DOM复合体对菲、芘的吸附速度都非常快,并很快达到吸附平衡,蒙脱石/DOM复合体对PAHs的吸附能力较原土有较大程度提高,而高岭土/DOM复合体对PAHs的吸附能力提高较小;pH值对吸附过程的影响很小;吸附过程为放热反应,随着吸附温度的升高,吸附量都有不同程度的减少,吸附能力降低;随着吸附剂投加量的增加,单位平均吸附量呈递减趋势,总吸附去除率增大;随着PAHs初始浓度的升高,吸附量都有明显的增加。最后,吸附等温线拟合结果表明:蒙脱石/DOM复合体对PAHs的吸附过程比较符合Henry线性方程和Freundlich经验方程,属于线性吸附;高岭土/DOM复合体对PAHs的吸附过程则比较符合Langmuir吸附等温方程描述,属于非线性吸附。吸附解吸动力学拟合结果表明:Pseudo-first order模型和Pseudo-second order模型都可以较好的描述PAHs在两种粘土矿物/DOM复合体上的吸附和解吸动力学过程,拟合结果与实验的实际吸附解吸量值比较接近,吸附过程以快速吸附为主。更多还原

【Abstract】 As a kind of organic pollutants which widely exist in the environment, polycyclic aromatic hydrocarbons (PAHs) were confirmed―carcinogenic, teratogenic, mutagenic effect‖, and have been classified as priority pollutants in environmental monitoring. In order to reveal the adsorption effect of the dissolved organic matter (DOM) on PAHs of clay minerals, we first select montmorillonite and kaolinite as clay mineral representation, taking landfill leachate as DOM material, and then prepared montmorillonite/kaolinite-DOM complexes simulation, and tests of the surface microstructure changes of the raw clays and the complexes was carried out. Then through the batch adsorption equilibrium method, we investigated adsorption characteristics and absorption stability of the complexes to phenanthrene and pyrene. Finally, we discussed the adsorption mechanism of clay mineral/DOM complexes to the PAHs, which provides the theoretical basis for environmental chemistry behavior and the migration transformation rules of the multi-link aromatic hydrocarbon materials in the environment. The main conclusions of the thesis will be shown as following:Firstly, after the compounding of clay mineral and DOM, the microstructure of the complexes takes a series of changes: the results of XRD showed that, after compounding with DOM, the distance between clay mineral change a little, without obvious intercalation phenomena; IR analysis shows that the montmorillonite and the kaolinite have certain extent chemistry linkage with DOM, and the montmorillonite also has an extra C-H vibration characteristic absorption; the SEM analysis indicated that, after compounding with DOM, clay mineral surface becomes quite rough, and the structure becomes relatively loose; the thermal analysis figure of clay minerals and complexes showed that the lost weight of clay minerals is obviously larger than that of complexes, and comparing to the lost weight curve of the clay minerals, the lost weight curve of complexes shift to the low temperature area, which indicates that DOM also cause some effects on the initial temperature of the clay minerals dewatering structure water and interlayer water.Secondly, we studied the adsorption of PAHs on clay mineral/DOM complexes. The result showed that: the adsorption rate of PAHs on clay mineral/DOM complexes is very fast and soon reached equilibrium. the adsorptive capacity of montmorillonite /DOM complexes to the PAHs has been largely improved, but that of the kaolinite/DOM complexes just improves a little.; the pH value has a little effects on the adsorption process; the adsorption is an exothermic process, along with the rising adsorption temperature, adsorption content had different reduction, and adsorption capacity decreases; along with the absorbent increasing, the unit average adsorptive content tends to decrease, and the total desorption rate increases; with the rising initial concentration of PAHs , the adsorption capacity increase significantly.Finally, the fitting results of adsorption isotherm curve showed that: the adsorption process of montmorillonite /DOM complexes to the PAHs fits to the Henry linear equation and the Freundlich empirical equation much better, which belongs to the linear adsorption; and, the adsorption process of kaolinite/DOM complexes to the PAHs is more consistent with the Langmuir adsorption uniform temperature equation, which belongs to the nonlinear adsorption. The fitting results of adsorption-desorption indicated that: both Pseudo first order model and Pseudo-second the order model can describe well the adsorption and desorption dynamics process of PAHs in the two kinds of clay mineral/DOM complexes, the fitting results are close to the experiment’s actual adsorption-desorption content, and the adsorption process is primarily a fast adsorption.更多还原