Preface

This book presents state-of-the-art findings on the characterization and uses of nanoclay or nano-layered silicate, which are optimized clay minerals with a number of improved features. Many geological, technological, and biological processes are supported by adsorption, wetting, dispersion, coagulation, sedimentation, structure formation, capillary, electrokinetic, ion exchange, mechanical response, and other nanoclay phenomena.

This work's primary goal is to contribute to a complete knowledge of these processes, taking into account the rapid growth of nanotechnologies. Additionally, the book gives a thorough overview of how nanoclay is used as reinforcing filler among different nanoparticles, with a special emphasis on polymer and biopolymer-clay nanocomposites. Improvements in mechanical, thermal, electrical, flame-retardant, and gas barrier properties are also seen when clay nanoparticles are added to polymers. Students, academics, and researchers who want to learn more about nanoclay and its uses in the areas of nanotechnology, biotechnology, environmental science, and industrial remediation will find this book helpful.

> **Walid Oueslati** Faculty of Sciences of Bizerte, Physics Department, University of Carthage, Bizerte, Tunisia

**Chapter 1**

**Abstract**

X-ray Diffraction Profiles Modeling

*Walid Oueslati, Chadha Mejri and Abdesslem Ben Haj Amara*

The nanoclay properties find a large environmental application domain as depolluant, ion exchanger, natural geological barrier for industrial and radioactive waste confinement, clay-based nanocomposite for drug delivery, and more. Layered materials, such as nanoclay, present rather complex structures whose classical characterization requires a complementarity between several analysis methods to decipher the effects of interstratification (and its cause) on the intrinsic functional properties. The appearance of defects related to the layers stacking mode, which differ in their thickness and/or their internal structure are directly related to the reactivity of the mineral's surface. During the last decades, and with the development of computer codes, the modeling of X-ray diffraction profiles has proven to be an important tool that allows detailed structural reconstruction. The quantitative XRD analysis, which consists of the comparison of experimental (00l) reflections with the calculated ones deduced from structural models, allowed us to determine the optimal structural parameters describing interlamellar space (IS) configuration, hydration state, cation exchange capacity (CEC), layer stacking mode, and theoretical mixed-layer structure (MLS) distribution. This chapter will review the state of the art of this theoretical approach as a basic technique for the study of nanoclays. The basic mathematical formalism, the parameters affecting the theoretical models, and the modeling strategy

**Keywords:** nanoclay, layered materials, modeling of X-ray diffraction profiles, layer

Hydration properties of nanoclays are controlled by several factors such as the type

of the interlayer cation and the amount and the layer charge location (created by isomorphic substitutions in octahedral or tetrahedral sites). The nanoclay swelling process is controlled by the balance between the repulsive force owing to the layer interactions and the attractive forces between exchangeable cations and the negatively

Method for Layered Structures

Reconstruction: Nanoclay

Structural Verification

steps will be detailed in concrete examples.

**1. Introduction**

**1**

thickness, layer stacking mod, modeling strategy
