EAGER: Compressibility of Nanopore-Confined Liquids Probed by Ultrasonic Experiments

了解波如何在地质材料中传播非常重要，因为它是创建强大的角色化工具的基础。例如，地震波可以用来了解地质构造，超声波可以用来分析实验室里的岩石样品。波的传播速度由它通过的材料的可压缩性决定。由于许多地质材料是多孔的，并且充满液体(水、盐水、石油等)，波的传播取决于固体和液体部分的可压缩性。因此，通过了解单个的可压缩特性，可以利用波的传播来确定固体的气孔中含有多少液体。然而，当孔隙直径测量到几个纳米时，限制在这些孔隙中的液体可能具有与散体中非常不同的压缩特性。这项研究项目旨在量化纳米孔中的限制如何改变一系列液体的可压缩性。这一研究将有助于加深对含油气页岩等重要纳米孔隙介质中波传播的认识。从这项研究中获得的知识有助于更有效地勘探和开发能源、二氧化碳封存和大规模能源储存技术。这一研究项目将通过将与研究有关的主题纳入该大学教授的本科课程，为改善STEM教育做出贡献。在夏季的几个月里，NJIT针对经济困难的高中生的ACS-SEED项目的实习生将致力于与这项研究相关的项目。本研究项目的目的是通过吸附-超声波实验来探索限制对流体可压缩性的影响。当流体被限制在纳米孔中时，与块体相比，它们的许多物理化学性质都会发生变化。少数实验研究表明，限制在纳米孔中的流体的可压缩性也偏离了散体中相同流体的可压缩性。模拟研究预测，随着孔径的减小，可压缩性的偏差逐渐增大。因此，该研究项目的中心假设是，当孔隙大小与流体分子大小相当时，限制将改变所有流体的弹性性质，并且这种变化的程度由孔隙大小和固液相互作用的强度决定。这项研究项目将通过实验验证这一假设，并探索其他参数的影响，如孔表面的性质和流体分子结构。实验证实，纳米受限流体的压缩率明显偏离相应的体积值具有转化潜力，当介质为纳米多孔时，需要对多孔介质中的波传播理论进行修正。这项研究项目还将通过将受限流体的可压缩性研究(分子热力学)与多孔介质中的波传播研究(地球物理)联系起来，促进新的跨学科视角。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Understanding how waves propagate through geological material is important because it forms the basis for creating powerful characterization tools. For example, seismic waves can be used to learn about geological formations, and ultrasonic waves can be used to analyze rock samples in the laboratory. Wave propagation speed is determined by the compressibility of the material through which it passes. Because many geological materials are porous and filled with liquids (water, brine, petroleum, etc.), wave propagation depends on the compressibilities of both the solid and liquid parts. Therefore, by knowing the individual compressibility properties one can use wave propagation to determine how much liquid is contained within the pores of a solid. However, when the pore diameters measure a few nanometers across, the liquids confined in those pores may have very different compressibility properties than in bulk. This research project aims to quantify how confinement in nanopores changes the compressibility of a range of liquids. This research will advance the understanding of wave propagation in important nanoporous media, such as hydrocarbon-bearing shale. The knowledge gained from this research could contribute towards the more efficient exploration and development of energy resources, carbon dioxide sequestration, and large-scale energy storage technologies. This research project will contribute to improved STEM education through the inclusion of research-related topics in the undergraduate courses taught at the university. During the summer months high school interns from the NJIT ACS-SEED program for economically disadvantaged high-school students will work on projects related to this research.The objective of this research project is to explore the effects of confinement on the compressibility of fluids by means of adsorption-ultrasonic experiments. When fluids are confined in nanopores, many of their physico-chemical properties change as compared to bulk. A small number of experimental studies suggest that the compressibility of fluids confined in nanopores also deviates from the compressibility of the same fluids in bulk. Modeling studies predict that the departure of compressibility progressively increases with decreasing pore size. Thus, the central hypothesis of this research project is that confinement will change the elastic properties of all fluids when the pore size is comparable to the fluid molecule size and that the extent of this change is determined by the pore size and strength of the solid-fluid interactions. This research project will test this hypothesis experimentally and explore the effects of other parameters, such as the properties of the pore surface and the structure of the fluid molecules. Experimental confirmation of a significant departure of nano-confined fluid compressibility from the corresponding bulk values has transformative potential, requiring the revision of wave propagation theory in porous media when the media are nanoporous. This research project also will promote novel interdisciplinary perspectives by connecting the studies of compressibility of confined fluids (molecular thermodynamics) to studies of wave propagation in porous media (geophysics).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.