Electronic Structure and Mechanical Properties of Solvated Montmorillonite Clay Using Large-Scale DFT Method

Abstract

Montmorillonite clay (MMT) has been widely used in engineering and environmental applications as a landfill barrier and toxic waste repository due to its unique property as an expandable clay mineral that can absorb water easily. This absorption process rendered MMT to be highly exothermic due to electrostatic interactions among molecules and hydrogen bonds between surface atoms. A detailed study of a large supercell model of structural clay enables us to predict long-term nuclear waste storage. Herein, a large solvent MMT model with 4071 atoms is studied using ab initio density functional theory. The DFT calculation and analysis clarify the important issues, such as bond strength, solvation effect, elasticity, and seismic wave velocities. These results are compared to our previous study on crystalline MMT (dry). The solvated MMT has reduced shear modulus (G), bulk modulus (K), and Young’s modulus (E). We observe that the conduction band (CB) in the density of states (DOS) of solvated MMT model has a single, conspicuous peak at −8.5 eV. Moreover, the atom-resolved partial density of states (PDOS) summarizes the roles played by each atom in the DOS. These findings illuminate numerous potential sophisticated applications of MMT clay.

Fabrication and Characterization of Montmorillonite Clay/Agar-Based Magnetic Composite and Its Biological and Electrical Conductivity Evaluation

“…Formation of MMT results from the weathering of eruptive rock materials. It is considered a valuable model for studying the properties of smectic clay minerals due to its high swelling capacity and ability to produce stable suspensions . According to their ionic or nonionic nature, the polymers in the MMT dispersions interact with the clay particles.…”

“…It is considered a valuable model for studying the properties of smectic clay minerals due to its high swelling capacity and ability to produce stable suspensions. 13 According to their ionic or nonionic nature, the polymers in the MMT dispersions interact with the clay particles. The nonionic polymers are adsorbed on the surface of clay minerals by the steric interactions, whereas the ionic polymers cause electrostatic interactions.…”