饱和多孔介质内多组分非水相有机物溶解传递机制研究

发布时间：2018-06-11 20:30

本文选题：NAPL + 一维土柱　；参考：《天津大学》2015年硕士论文

【摘要】：随着工业化进程的加快,有机物对地下环境的污染已经成为一个全球性的问题。进入地下环境的有机物会通过不断溶解过程形成大范围的、持久的污染源。而在有机污染物修复方面,很多技术如表面活性剂冲洗等依靠溶解过程实现有机物的稀释去除,因而溶解过程往往是非水相流体(NAPL)地下环境污染迁移的关键。到目前为止,关于NAPL在地下环境中溶解传质机制的研究尚不完全,因此本文主要研究NAPL在饱和多孔介质内溶解传质过程,为污染防治提供理论指导。本文首先测定了与NAPL溶解过程相关的参数:介质渗透率和吸附性。结果表明,介质尺寸越小渗透系数越小;石英砂对甲基叔丁基醚(MTBE)吸附类型符合线性平衡吸附与Freundlich平衡吸附,并且介质尺寸越小,吸附能力越强。本文利用自制的一维土柱研究MTBE溶解动力学,结果表明,水相流速提高可以促进MTBE溶解;初始饱和度越大,MTBE初始溶出浓度越低,完全溶出时间越长;介质尺寸减小可以形成较多小尺寸NAPL,从而促进MTBE溶解。进一步通过关联的溶解动力学表达式可以看出,当饱和度小于0.3000时,介质尺寸和NAPL饱和度明显影响MTBE溶解,而饱和度为0.30000.5482时,水相流速对溶解过程起到主要作用。对于多组分NAPL溶解实验,溶解度较低的对二甲苯与三氯乙烯共存时对MTBE的溶解有促进作用,而共存的溶解度很大的乙醇与MTBE为竞争溶解。最后利用自制的实验室小型二维砂箱探索了各参数对MTBE溶解的影响。结果表明,二维砂箱中流出口溶解规律与一维实验结果近似,而作为表征污染源区内瞬时动态的取样口溶出浓度,溶解过程与流出口有差异,其中显著差别为初始饱和度越大,溶出浓度越大。不同溶液对MTBE溶解过程表明:非离子型表面活性剂Tween 80和助溶剂乙醇可以促进MTBE溶解;阴离子表面活性剂SDBS没有增强MTBE迁移反而延缓了MTBE溶解;MTBE去除率80%以前,增溶效果的顺序依次为:非离子型表面活性剂Tween 80助溶剂乙醇水阴离子表面活性剂SDBS。
[Abstract]:With the acceleration of industrialization, organic pollution to underground environment has become a global problem. Organic matter entering the underground environment forms a large, persistent source of pollution through continuous dissolution. In the remediation of organic pollutants, many technologies, such as surfactant washing and so on, depend on the dissolution process to realize the dilution and removal of organic matter. Therefore, the dissolution process is often the key to the underground environmental pollution migration of non-aqueous phase fluid (NAPL). Up to now, the mechanism of mass transfer of NAPL in underground environment has not been fully studied, so this paper mainly studies the dissolution and mass transfer process of NAPL in saturated porous media, which provides theoretical guidance for pollution prevention and control. In this paper, the parameters related to the dissolution process of NAPL are measured: medium permeability and adsorbability. The results show that the smaller the medium size, the smaller the permeability coefficient, and the more linear equilibrium adsorption and Freundlich equilibrium adsorption, the stronger the adsorption capacity of quartz sand is. In this paper, the dissolution kinetics of MTBE is studied by using a self-made one-dimensional soil column. The results show that the increase of water flow rate can promote MTBE dissolution, the higher the initial saturation is, the lower the initial dissolution concentration is, and the longer the complete dissolution time is. Smaller size NAPL can be formed by decreasing the size of the medium, thus promoting the dissolution of MTBE. Further more, it can be seen that when the saturation is less than 0.3000, the medium size and NAPL saturation obviously affect the dissolution of MTBE, and when the saturation is 0.30000.5482, the water flow rate plays a major role in the dissolution process. For the multicomponent NAPL dissolution experiment, p-xylene and trichloroethylene with low solubility can promote the dissolution of MTBE, while ethanol with high solubility is competitive dissolution. Finally, the effects of various parameters on the dissolution of MTBE were investigated by using a small laboratory two-dimensional sandbox made by ourselves. The results show that the dissolution law of the outlet of the two-dimensional sand box is similar to that of the one-dimensional experimental results. However, the dissolution process of the sampling outlet, which is used as a representation of the instantaneous dynamic of the source area, is different from the flow exit, and the significant difference is that the greater the initial saturation is, the more the initial saturation is. The higher the concentration of dissolution is. The dissolution process of MTBE in different solutions showed that Nonionic surfactant Tween80 and co-solvent ethanol could promote MTBE dissolution, and anionic surfactant SDBS did not enhance MTBE migration but delayed MTBE removal rate before 80%. The order of solubilization effect is as follows: Nonionic surfactant Tween80 cosolvent ethanol water anionic surfactant SDBS.
【学位授予单位】：天津大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X132;TQ021.4

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