Formation of Kaolinite in Inorganic and Organic Low-Temperature Systems

9909561PI：Kathryn L.Nagy，科罗拉多大学项目：在无机和有机低温体系中高岭石的形成高岭石是一种粘土矿物，形成于热带或温带风化环境或砂岩和页岩的埋藏成岩过程中。高岭石因其颜色和光反射率等特性而被开采，这些特性是陶瓷和纸张涂料等工业产品的重要特征。它是一种关键矿物，用于同位素追踪流体流动路径和过去的气候变化，改变地下砂岩的孔隙度和渗透率，并主导某些土壤。尽管利用表面和微观分析技术对天然高岭石进行了广泛的研究，但缺乏对低温下高岭石形成的基本控制和速率的定量知识。在这个项目中，将研究溶解有机分子、天然有机材料、矿物基质、溶液组成和温度在控制高岭石形成中的作用。该方法结合了控制良好的动力学实验、溶液和固体的全面表征以及溶解离子和有机分子与矿物表面相互作用的经验分子模拟。有机分子将代表可溶的腐殖质和植物和细菌的有机分泌物。研究结果将提供高岭石成核和生长的速率规律，可用于模拟土壤、沉积物和沉积岩中的自然过程，也可应用于土壤学、石油勘探和工业矿物学等相关领域。

9909561PI: Kathryn L. Nagy, University of ColoradoProject: Formation of Kaolinite in Inorganic and Organic Low-Temperature SystemsKaolinite is a clay mineral that forms in tropical or temperate weathering environments or during the burial diagenesis of sandstones and shales. Kaolinite is mined for its properties such as color and light reflectivity, which are important characteristics of industrial products such as ceramics and paper coatings. It is a key mineral used to isotopically trace fluid flow pathways and past climate change, that alters porosity and permeability in subsurface sandstones, and that dominates certain soils. Although natural kaolinite has been extensively investigated using surface and microscopic analytical techniques, quantitative knowledge of fundamental controls on and rates of kaolinite formation at low temperatures is lacking. In this project, the roles of dissolved organic molecules, natural organic materials, mineral substrates, solution composition, and temperature in controlling the formation of kaolinite will be investigated. The approach combines well-controlled kinetics experiments, full characterization of solutions and solids, and empirical molecular modeling of interactions between dissolved ions and organic molecules with the mineral surfaces. Organic molecules will represent soluble humic substances and organic exudates from plants and bacteria. Results will provide a rate law for kaolinite nucleation and growth that can be used to model natural processes in soils, sediments, and sedimentary rocks and may also be applied in the related fields of soils science, petroleum exploration, and industrial mineralogy.