X-ray Photoelectron Spectroscopic Study of Some Organic and Inorganic Modified Clay Minerals.

J Theo Kloprogge,Danilo O Ortillo,Concepcion P Ponce

doi:10.3390/ma14237115

J Theo Kloprogge, Danilo O Ortillo + Show 1 more

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https://doi.org/10.3390/ma14237115

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Abstract

Layered clay systems intercalated with inorganic and organic compounds were analyzed to highlight how XPS can provide information on the different environments surrounding a particular atom as well as provide discernments on the size, coordination, and structural and oxidative transformations of the intercalating/pillaring compounds. XPS data on the intercalation of urea and K-acetate in low- and high-defect kaolinite revealed the interaction of the intercalating group NH2 with the siloxane functional groups in the interlayer surface. The intercalation of HDTMA in Mt demonstrated the use of XPS in monitoring the change in conformation assumed by alkylammonium intercalating compounds in Mt with increasing CEC. Studies on the pillaring of Mt by Al13 and Ga13 by XPS allowed determination of the coordination of the pillaring compound within the Mt layer. Lastly, the intercalation of hexacyanoferrate in hydrotalcite demonstrated the capability of XPS in following changes in the oxidation state of the iron compound. These were gleaned from interpretation of the shifts in binding energies and presence of multiplet splitting in the XPS of the component elements of the minerals or the intercalating compounds.

Highlights

IntroductionClay minerals can host a large number of functional organic and inorganic systems through a process called intercalation
Kaolinite has frequently been depicted as a clay mineral that has a low capacity to expand, contrary to the swellable 2:1 clay minerals—smectites, which include montmorillonite, saponite, etc
Thepreparation preparationofof these intercalated systems is dependent on the desired applications by optimizing and enhancing calated systems is dependent on the desired applications by optimizing and enhancing the properties properties of location, and structural the of the the resulting resultingproducts

Summary

Introduction

Clay minerals can host a large number of functional organic and inorganic systems through a process called intercalation. These intercalated systems can impart new and/or unique properties that afford wide ranging applications of these modified clay minerals in various fields such as in environmental remediation technologies [1]; cosmetics and pharmaceutical science [2]; material science [3]; carbon dioxide capture and storage [4]; and abiogenesis [5] to name a few. The driving forces of the intercalation process includes intermolecular forces of interactions between the clay mineral interlayer surfaces and the intercalating molecule (e.g., hydrogen-bonding, ion-dipole interactions, and van der Waals attractions) [6]. Understanding and control of the above-mentioned interactions of the clay minerals with the intercalating or with the pillaring compound relies on the researchers’ abilities to use innovative approaches in probing these interactions

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