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

由于坡缕石和海泡石的形成环境有限，它们在土壤和沉积物中的存在被广泛用作古环境指标。此外，它们的物理性质（特别是它们的吸附能力和催化行为）使它们作为吸附剂在工业和环境中得到了广泛的应用。在meigs - attapulga - quincy地区的样品中发现了坡缕石-海泡石向蒙脱石的物理化学转化，这是这些粘土的重要来源。由于这种转化可以显著影响坡面石-海泡石作为工业吸附剂的使用，因此本项目拟研究坡面石-海泡石向蒙脱石的转化及其对活性表面位点的类型和分布以及微织物变化的影响。利用透射电子显微镜（TEM）和原子力显微镜（AFM）研究了meigs - attapulgasquincy地区天然坡面石-海泡石-蒙脱石组合的微观结构、形态和表面微观形貌，并利用同步x射线衍射和透射电子显微镜（TEM）数据研究了坡面石-海泡石的整体结构。坡缕石、海泡石，特别是过渡形态的体积和表面结构的原子模型将从TEM、x射线和AFM数据中发展出来。本研究的目的是逐步了解这种转变，并对吸附行为的变化进行建模。该结果对于环境（例如重金属吸附）和商业应用（例如石油的漂白剂和澄清剂）以及利用蚀变岩相指示古环境信息的潜在能力具有重要意义。

RakovanEAR-0001251The 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.