张娜, 寇珏, 孙春宝. 固液界面水化膜结构研究进展[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.12.04.001
引用本文: 张娜, 寇珏, 孙春宝. 固液界面水化膜结构研究进展[J]. 工程科学学报. DOI: 10.13374/j.issn2095-9389.2023.12.04.001
ZHANG Na, KOU Jue, SUN Chunbao. Research progress on the structure of hydration films at solid–liquid interfaces[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.12.04.001
Citation: ZHANG Na, KOU Jue, SUN Chunbao. Research progress on the structure of hydration films at solid–liquid interfaces[J]. Chinese Journal of Engineering. DOI: 10.13374/j.issn2095-9389.2023.12.04.001

固液界面水化膜结构研究进展

Research progress on the structure of hydration films at solid–liquid interfaces

  • 摘要: 固液界面广泛存在于物质世界中,界面性质的变化在矿物浮选、石油开采以及土壤改良等领域具有重要作用,水化膜作为固液界面上的微纳米结构,对固液界面性质起到决定性的作用,水化膜的结构与厚度受固体表面性质与溶液性质的影响. 本文以云母和方解石两种常见矿物为例,总结了利用X射线反射率测量和原子力显微镜观察两种方法探索矿物‒水界面水化膜结构的研究进展,探讨了不同矿物表面水化膜的结构特点,讨论了溶液中金属阳离子及矿物表面解离离子对水化膜结构的影响,对比了两种方法所测水化膜结构的异同点. 旨在深化对固液界面水合结构的理解,推动水化膜动力学行为的深入研究.

     

    Abstract: Solid–liquid interfaces are pervasive across the material world, playing a crucial role in various fields such as mineral flotation, oil mining and processing, and soil improvement. At these interfaces, the hydration film, a nanostructure, significantly influences their properties. The structure and thickness of the hydrated film are affected by the properties of the solid surface and the solution. This review takes mica and calcite as examples and summarizes advances in understanding the structure of hydration films at solid–liquid interfaces through X-ray reflectivity (XR) and atomic force microscopy (AFM). It discusses the structures of hydration films on different mineral surfaces. It discusses how metal cations in solution, as well as ion dissociation, affect the mineral surface on these structures. The mica surface participates in ion exchange with H3O+ or other cations in the solution, resulting in a hydration film consisting of an adsorbed layer followed by the first and second hydration layers. Ca2+ and \mathrmCO_3^2- dissociate and interact with the hydration film, creating a checkerboard-like pattern. The hydration film encompasses four layers, with Ca2+ and \mathrmCO_3^2- sites alternating within. The thickness of the hydration film varies with ion concentration and type in the solution. For example, as the K+ concentration increases, the thickness of the hydration film on the mica surface increases. However, when K+ is replaced by Cs+ in the solution, the thickness of the hydration film on the mica surface reduces or even disrupts this film. The hydration film structures obtained by XR and AFM are also compared. XR measurements provide the electron density distribution on the crystal surface, allowing for analysis of the hydration film’s structure. By contrast, AFM measures the force–distance curve between the probe and the water on the sample surface, along with corresponding imaging. Both XR and AFM provide information on the thickness and structure of the hydration film on the mineral surface. However, the boundary between the mineral surface’s hydration film and bulk water is not defined owing to the dynamic nature of hydration films, leading to variations in measured thickness across different instruments, generally in the range of several nanometers. The objective of this review is to deepen understanding of the hydration structure at the solid–liquid interface, promoting further research into the dynamic behavior of hydration films.

     

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