Development and Application of Space- and Time-Resolved Hyperspectral Raman Imaging to in situ Study Mineral- and Glass-Water Reactions

空间和时间分辨高光谱拉曼成像的开发和应用，用于原位研究矿物和玻璃水反应

• 批准号: 389799517
• 负责人: Professor Dr. Thorsten Geisler-Wierwille
• 金额: --
• 依托单位: Institut für Geowissenschaften
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/389799517?language=en
• 关键词: Development; Application; Space; Time; Resolved

Solid-water reactions are often characterized by the formation of surface alteration layers that complexly affect the dissolution behaviour of the solid. Despite numerous sophisticated experimental studies, there is still an intensive debate about how these alteration layers form and about the rate-limiting reaction step. New insights into the mesoscopic partial reactions underlying their formation can be gained from confocal hyperspectral Raman spectroscopy (CHRS). This technique allows real-time imaging of moving reaction interfaces during fluid-mediated replacement reactions at the micrometer-scale and under elevated temperatures with the use of fluid cells (FC), omitting the imperative to interrupt the replacement reaction. FC CHRS thereby can provide a wealth of information such as, e.g., phase composition, crystallinity, interfacial strain, and, at the same time, the concentration of aqueous species in the solution, from which, in some cases, even the local pH could be determined. Moreover, due to the isotope shift of vibrational modes FC CHRS additionally facilitates to follow the exchange of oxygen and hydrogen isotopes among solids and aqueous molecular species, if isotopically enriched precursors are used. Intriguing proofs of concepts for such in situ FC CHRS studies are given by the results of first experiments which were performed to study the aqueous corrosion of borosilicate glass at 70°C and the replacement of celestine by strontianite in a sodium carbonate solution at 21°C. The experiments were carried out in home-made fluid cells with a sample arrangement that allows measuring the solution and the formation of the reaction product with a micrometer resolution. The results of these experiments are very encouraging. They revealed, in both cases, unpredicted, short-term changes in the mechanism and the overall reaction kinetics. They further demonstrate that dynamic phenomena such as re-equilibration reactions and potentially the diffusion of molecular water through the product layer can be studied and quantified when using 18-O and 2-H as tracers. FC CHRS thus potentially opens up the possibility to gain deeper insights into solid-water reactions. The main objectives of the here proposed project are (A) to develop/advance and eventually establish the experimental method, (B) to in situ study the mesoscopic mechanism(s), and (C) to identify and quantify the rate-limiting steps controlling the corrosion of borosilicate glasses and the replacement of celestine by strontianite at elevated temperatures. The planned experiments will deliver unique insights into the mechanism(s) and kinetics of replacement reactions in aqueous solutions, providing the basis to develop and test numerical models.

固体-水反应的特征通常在于形成复杂地影响固体的溶解行为的表面改变层。尽管有许多复杂的实验研究，仍然有一个激烈的争论，这些蚀变层如何形成和限速反应步骤。通过共焦高光谱拉曼光谱（CHRS）可以获得对其形成背后的介观部分反应的新见解。该技术允许在流体介导的置换反应期间在微米级和在升高的温度下使用流体池（FC）对移动的反应界面进行实时成像，省略了中断置换反应的必要性。因此，FC CHRS可以提供丰富的信息，例如，相组成、结晶度、界面应变，以及同时溶液中水性物质的浓度，在某些情况下，甚至可以由此确定局部pH。此外，由于振动模式的同位素位移，如果使用同位素富集的前体，FC CHRS还有助于跟踪固体和水性分子物质之间的氧和氢同位素的交换。这些原位FC CHRS研究的概念的有趣证据由第一个实验的结果给出，这些实验是为了研究硼硅酸盐玻璃在70 ° C下的水腐蚀和在21 ° C下在碳酸钠溶液中用菱锶矿代替塞莱斯廷而进行的。实验在自制的流体池中进行，该流体池具有允许以微米分辨率测量溶液和反应产物的形成的样品布置。这些实验的结果非常令人鼓舞。在这两种情况下，他们揭示了机制和整体反应动力学的不可预测的短期变化。他们进一步证明，动态现象，如再平衡反应和潜在的分子水通过产品层的扩散，可以研究和量化时，使用18-O和2-H作为示踪剂。因此，FC CHRS有可能为更深入地了解固体-水反应提供可能性。本文提出的项目的主要目标是（A）开发/推进并最终建立实验方法，（B）原位研究介观机制，以及（C）确定和量化控制硼硅酸盐玻璃腐蚀和高温下菱锶矿替代塞莱斯廷的限速步骤。计划中的实验将为水溶液中置换反应的机制和动力学提供独特的见解，为开发和测试数值模型提供基础。