Collaborative Research: The Palygorskite-Sepiolite to Smectite Transformation and the Influence on Reactive Surface Sites

凹凸棒石和海泡石在土壤和沉积物中的存在因其形成环境的限制而被广泛用作古环境指示剂。此外，它们的物理性质(特别是它们的吸附能力和催化性能)导致它们在工业和环境中被广泛用作吸附剂。在梅格斯-阿塔普尔加斯-昆西地区的样品中发现了坡缕石-海泡石向蒙皂石的物理化学转化，这是坡缕石-海泡石的重要来源。由于这种转化对坡缕石-海泡石作为工业吸附剂的使用有很大的影响，本项目研究了坡缕石-海泡石向蒙脱石的转化及其对活性表面位置的类型和分布以及微观结构变化的影响。利用透射电子显微镜和原子力显微镜对梅格斯-阿塔普尔加斯-昆西地区天然坡缕石-海泡石-蒙脱石组合的显微组构、形貌和表面微形貌进行了研究，并利用同步辐射X射线衍射仪和透射电子显微镜对坡缕石-海泡石的体相结构进行了研究。凹凸棒石、海泡石，特别是过渡形式的体相和表面结构的原子模型将从透射电子显微镜、X射线和原子力显微镜数据中开发出来。这项研究的目的是逐步了解这一转变，并对吸附行为的变化进行建模。这些结果对于环境(例如重金属吸附)和商业应用(例如石油的漂白和澄清剂)以及利用改变的岩相指示古环境信息的潜在能力都是重要的。

GuggenheimEAR-0001122The presence of palygorskite and sepiolite in soils and sediments is widely used as a paleoenvironmental indicator because of their restricted environments of formation. In addition, their physical properties (especially their sorption capacity and catalytic behavior) has lead to their extensive industrial and environmental use as sorbants. The physiochemical transformation of palygorskite-sepiolite to smectite has been identified in samples from the Meigs-Attapulgas-Quincy district, an important source of these clays. Because this transformation can considerably affect the use of the palygorskite-sepiolite as industrial sorbants, the proposed project investigates the palygorskite-sepiolite to smectite transformation and its influence on the type and distribution of reactive surface sites and changes in micro-fabrics. The micro-fabric, morphology, and surface micro-topography of a natural palygorskite-sepiolite-smectite assemblage from the Meigs-Attapulgas-Quincy district will be studied using transmission electron microscopy (TEM) and atomic force microscopy (AFM), and the bulk structure of palygorskite-sepiolite will be studied using synchrotron X-ray diffraction and TEM data. Atomic models of the bulk and surface structures of palygorskite, sepiolite, and especially transitional forms will be developed from the TEM, X-ray, and AFM data. The purpose of this study is to obtain a step-by-step understanding of the transformation and to model the variation in sorption behavior. The results are important for environmental (e.g., heavy-metal adsorption) and commercial applications (e.g., bleaching and clarifying agents of oils) as well as the potential ability to use altered lithofacies to indicate paleoenvironmental information.