云母表面润湿性的分子动力学模拟

发布时间：2018-11-05 20:09

【摘要】：经济的飞速发展伴随着不可再生化石燃料的大量使用,产生的二氧化碳被排放到大气中,带来了诸如全球温室效应等环境问题,如何有效收集利用二氧化碳成为当今学术界的研究课题之一。将二氧化碳封存在化石能源开采后的废矿井中是解决二氧化碳过量排放进大气中的有效途径,即对二氧化碳进行地质封存,因此探究影响二氧化碳地质封存的因素成为研究课题的重点。本论文根据前人的研究得出,岩石表面的润湿性是影响二氧化碳地质封存的主要因素,因此进行岩石表面润湿性的研究对二氧化碳的地质封存具有重要意义。本论文利用分子动力学模拟方法探究了二氧化碳环境下压强对水在云母表面接触角的影响,模拟结果表明当压强为12-13.5兆帕范围内时水／二氧化碳／云母体系中水在云母表面的接触角随压强的增大而增大,而当压强为11兆帕左右时接触角出现峰值22度,说明水在云母表面的接触角与压强并不是线性的递增关系,不能只是将压强作为衡量接触角大小的唯一标准。采用的水分子势能模型是SPC/E、二氧化碳分子势能模型是EPM2、氧气为刚性双原子模型、氩气为单原子模型。流体采用CHARMM力场,而云母采用的是与CHARMM力场兼容的层状硅酸盐力场。本论文还探究了不同的气体环境下水在云母表面接触角的大小。为了验证气体对云母表面接触角的影响,本论文构建了摩尔浓度都是3：1的氩气／二氧化碳体系和氧气／二氧化碳体系,并分别进行了分子动力学模拟,探究在各个混合气体体系下水在云母表面的接触角。模拟结果说明,在二氧化碳中分别加入氧气和氩气后,由于气体各自不同的物理化学性质,氩气会减小水在云母表面的接触角,即增大了云母表面的润湿性,却并没有得出与氧气会增大水在云母表面的接触角这一预测相符的结果,这可能是由于氧气与二氧化碳之间的相互作用减小了水在云母表面的接触角。
[Abstract]:The rapid development of the economy has been accompanied by the massive use of non-renewable fossil fuels, and the resulting carbon dioxide has been emitted into the atmosphere, causing environmental problems such as Greenhouse Effect around the world. How to effectively collect and utilize carbon dioxide has become one of the research topics in academic circles. Sequestration of carbon dioxide in waste coal mines after fossil energy extraction is an effective way to solve the problem of excessive carbon dioxide emissions into the atmosphere, that is, geological storage of carbon dioxide. Therefore, to explore the factors affecting geological storage of carbon dioxide has become the focus of research. According to the previous studies, the wettability of rock surface is the main factor affecting the geological storage of carbon dioxide, so the study of the wettability of rock surface is of great significance to the geological storage of carbon dioxide. In this paper, the effect of pressure on the contact angle of water on the surface of mica was investigated by molecular dynamics simulation. The simulation results show that the contact angle of water in water / carbon dioxide / mica system increases with the increase of pressure when the pressure is in the range of 12-13.5 MPA, but the contact angle reaches a peak value of 22 degrees when the pressure is about 11 MPA. It is shown that the contact angle of water on the surface of mica is not linearly increasing, and the pressure cannot be taken as the only criterion to measure the contact angle. The water molecular potential energy model is a SPC/E, carbon dioxide molecular potential energy model. It is a rigid diatomic model for EPM2, oxygen and a monoatomic model for argon. The fluid uses CHARMM force field, while mica uses layered silicate force field compatible with CHARMM force field. The contact angle of water in different gas environment on the surface of mica is also studied in this paper. In order to verify the effect of gas on the surface contact angle of mica, the argon / carbon dioxide and oxygen / carbon dioxide systems with 3:1 molar concentrations were constructed and simulated by molecular dynamics, respectively. Explore the contact angle on the surface of mica in each gas mixture system. The simulation results show that after the addition of oxygen and argon into carbon dioxide, argon will decrease the contact angle of water on the surface of mica, that is, increase the wettability of the surface of mica, because of the different physical and chemical properties of the gas. The results are not consistent with the prediction that oxygen will increase the contact angle of water on the surface of mica, which may be due to the interaction between oxygen and carbon dioxide reducing the contact angle of water on the surface of mica.
【学位授予单位】：大连理工大学
【学位级别】：硕士
【学位授予年份】：2016
【分类号】：TB306;O647

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