Department of Chemical and Biomolecular Engineering, University of Notre Dame, 182 Fitzpatrick Hall, Notre Dame, Indiana 46556, United States.
J Phys Chem B. 2011 Sep 8;115(35):10488-99. doi: 10.1021/jp203838j. Epub 2011 Aug 15.
The ionic liquid-carbon dioxide system is of interest because ionic liquids (ILs) have potential to be used for carbon dioxide capture. Because water will be present in a real carbon dioxide capture operation, the interaction between water and the IL is also of interest. Classical molecular dynamics simulations have been used to study the IL 1-n-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (bmim-Tf(2)N) at the interface with vacuum as well as with carbon dioxide, water, or both present in the system. Density and orientational ordering of the ionic liquid molecules at the interface was not significantly altered by the presence of either carbon dioxide or water. The structure of the liquid solutions in the pseudobulk region in the center of the slab was studied using metrics of pairwise association such as radial distribution functions. At the interface, there is an increased density of cation-anion association. When carbon dioxide is present, it forms a dense layer on the surface, and the cation-anion associations at the interface are disrupted, with a corresponding decrease in surface tension. Water slows down the diffusion of the ions as well as carbon dioxide in the bulk. Water has little effect, however, on the interfacial transport dynamics of carbon dioxide.
离子液体-二氧化碳体系很有研究价值，因为离子液体（ILs）有可能用于二氧化碳捕获。由于在实际的二氧化碳捕获操作中会有水存在，因此水与 IL 的相互作用也很重要。经典的分子动力学模拟已被用于研究离子液体 1-丁基-3-甲基咪唑双（三氟甲基磺酰基）亚胺（bmim-Tf2N）与真空的界面以及系统中存在二氧化碳、水或两者的界面。界面处离子液体分子的密度和取向有序性不受二氧化碳或水的存在的显著影响。使用径向分布函数等对关联的度量标准研究了在板中心的伪体相区域中液体溶液的结构。在界面处，阳离子-阴离子的缔合密度增加。当二氧化碳存在时，它在表面形成一个密集层，界面处的阳离子-阴离子缔合被破坏，表面张力相应降低。水会减缓离子和二氧化碳在本体中的扩散速度。然而，水对二氧化碳的界面输运动力学几乎没有影响。
