【作者】 徐敏；

【导师】 季峻峰；

【作者基本信息】 南京大学 ， 地球化学， 2013， 硕士

【摘要】 粘土矿物对有机质的吸附是在沉积物和烃源岩中普遍存在的重要过程。在沉积物沉积、埋藏和成岩的过程中,粘土矿物和有机质相互依存,密不可分。研究粘土矿物对有机质的保存对于土壤和海洋沉积物的研究以及有机质生烃理论的深化和油气资源量的评价有着非常重要的作用。但是对于有机质与粘土矿物的相互作用以及演化过程的研究仍处于一个较为薄弱的阶段。为此,本文选用烷基铵盐类人工表面活性剂以及两种典型的天然有机质赖氨酸(左旋)、壳聚糖分别与蒙脱石进行复合与表征,对复合体在常温常压流体以及水热环境中的稳定性作了系统研究,并对蒙脱石、伊／蒙混层矿物、伊利石以及几种复合体对柴油的吸附展开研究。主要得到以下结果：1、蒙脱石对几种有机质的吸附主要存在两种机制：阳离子交换和有机分子间的相互吸引。有机质会优先选择阳离子交换的形式进入蒙脱石的层间。但随着浓度的增加,蒙脱石层间阳离子含量达到饱和,此时有机质会以有机分子间的吸引和分配作用,通过范德华力和氢键结合的形式进入蒙脱石层间。2、十六烷基三甲基铵盐主要以阳离子交换的形式进入蒙脱石层间,低浓度时以单层平躺的形式排布,高浓度时可能在蒙脱石层间倾斜,并可能形成双层或假三层的结构。赖氨酸在蒙脱石层间的排布有三种构型,随着赖氨酸浓度的增加分别以倾斜、垂直层面呈“之”字形排列,最后形成第二层并可能生成简单肽；蒙脱石对赖氨酸的吸附过程和赖氨酸的净电荷密切相关,而赖氨酸的净电荷是由溶液的pH和蒙脱石的层间微环境决定的。壳聚糖在低浓度下会以阳离子交换的形式在蒙脱石层间形成单层,高浓度下壳聚糖会通过范德华力和氢键作用进入蒙脱石层间,形成分层结构,多余的正电荷将与溶液中的阴离子结合以达到平衡。溶液的pH和无机盐的存在都会影响吸附过程。3、有机-粘土复合体的稳定性与有机质本身的性质以及有机质和蒙脱石的结合方式密切相关。常温常压流体中,十八烷基铵盐-蒙脱石、壳聚糖-蒙脱石复合体较为稳定,而赖氨酸-蒙脱石复合体在吸附量较大时不能稳定存在。水热条件下,赖氨酸和壳聚糖能够促进蒙脱石的伊利石化,而烷基铵盐存在时,蒙脱石的伊利石化程度有所降低。4、粘土矿物能有效的吸附柴油,从蒙脱石-伊/蒙混层-伊利石序列对柴油的吸附量呈缓慢的上升趋势。壳聚糖-蒙脱石复合体对柴油的吸附量与蒙脱石相近,而十八烷基铵盐-蒙脱石复合体对柴油的吸附量远高于其他样品。粘土矿物以及复合体对柴油的吸附大部分发生在颗粒间和外表面,只有少量柴油能进入粘土矿物层间。更多还原

【Abstract】 The adsorption of organic matter on clay minerals is an important process in sediments and sedimentary rocks. In the sediment deposition, burial and diagenesis process, clay minerals and organic matter are interdependent, interwovenness and intergration. Clay minerals preservation of organic matter has a very important role in studies of soil and marine sediment. It is also of great significance for deepening the hydrocarbon-generating theory and the evaluation of oil and gas resources. But the study on the interaction of organic matter and clay minerals as well as the evolution process is still in a relatively weak phase.For this purpose, alkyl ammonium salt and two typical kinds of natural organic matter, lysine(L) and chitosan, are intercalated in montmorillonite and under detail characterization. The stability of the complexes are studied in different solutions at room temperature and pressure as well as in hydrothermal conditions. The adsorption of diesel on montmorillonite, smectite-illite minerals, illite and organoclay complexes was studied afterwards. The main results are given bellow:1. The adsorption of the organic matter on montmorillonite is dominated by cation exchange and then by adsorption of electrically neutral forms. The organic matter first enters in the interlayer of the montmorillonite by cation exchange. But with the increasing of concentration, the organic matter is adsorbed in electrically neutral forms by van der Waals force and hydrogen bond into the interlayer of montmorillonite when the cationic exchange capacity of the clay is balanced. 2. The adsorption of hexadecyltrimethylammonium bromide (HDTMA) montmorillonite is mainly dominated by cation exchange. At low concentration, alkylammonium ions form a monolayer; when the amount of modifier is high, alkylammonium ions may tilt in the interlayer of montmorillonite, and it is possible to form a double-layer or pseudotrimolecular layer structure. Lysine has three kinds of configuration arrangement in the interlayer of montmorillonite. With increasing concentration of lysine, the molecules are first inclined in the interlayer, and then orientate perpendicular to the montmorillonite layers, maybe a zig-zag arrangement, finally form second rows and may generate simple peptide by lysine polymerization. The net charge of amino acids, which depends on the pH in both the bulk solution and in the proximity of the clay layer or the interlayer space, is an important factor affecting the adsorption process. For chitosan, a layered structure can form in the interlayer of montmorillonite. The first chitosan layer is adsorbed through a cationic exchange procedure, while the second layer is adsorbed in the acetate salt form. The pH of the solution and the presence of the inorganic salt will affect the adsorption process.3. The stability of the complex is related to the nature of the organic matter itself and its form combined with montmorillonite. At room temperature and pressure,18HD-montmorillonite and chitosan-montmorillonite complexes in different solutions are stable, but lysine-montmorillonite complexes are unstable under the same condition. Under hydrothermal conditions, lysine and chitosan can promote the illitization of smectite, but when alkyl ammonium salt is intercalated into montmorillonite, the conversion rate seems to be reduced.4. Clay minerals can adsorb diesel effectively, smectite-illite mixed-layer sequence seems to have a higher adsorption capacity with the increase of illitization. Adsorption capacity of chitosan-montmorillonite complex is close to smectite, but the adsorption capacity of18HD-montmorillonite complex is far higher than the other samples. The majority of adsorption amount of diesel on clay minerals and complexes are in the micropores and on the external surface. Only a small amount of diesel can enter into interlayer of the clay minerals and complexes.更多还原