Surfaces and Interfaces of Clay Minerals

This Special Issue is a collection of five original articles devoted to both experimental and theoretical studies of phenomena and processes occurring at surfaces of clay minerals and related materials. The contributions cover the physical and chemical aspects of clay-water interactions and clay-organic interactions that are relevant to various environmental and engineering applications.

Molecular dynamics (MD) study of illite-montmorillonite mixed-layer clays (MLCs) with increasing hydration is presented in Yang et al. [1]. This work analyses interaction energy, basal spacing, and distribution of hydrogen bonds in the interlayer of MLCs containing K⁺ and Na⁺ with Na-montmorillonite of different water contents in order to better understand the swelling mechanisms of such clays. Ab initio Hartree—Fock’s theoretical study of the interaction of water molecules with the basal surfaces of kaolinite was performed by Yavna et al. [2]. The authors investigate the electronic structure and infrared spectra of kaolinite in the range of 2500–4500 cm⁻¹ to explain the surface hydration of 1:1 clay minerals. The works of Jiang et al. [3] and Shi et al. [4] are devoted to investigations of color dyes sorption on different types of clay minerals and zeolites. A combined theoretical and experimental study by Jiang et al. [3] aimed at determining the sorption sites and sorption mechanisms of acridine orange on non-swelling clay minerals (kaolinite, halloysite, and illite), as well as swelling clay minerals (Ca-montmorillonite and rectorite) with the evaluation of the prospects for their use as sorbents for removal of cationic dyes from solution. Shi et al. [4] consider clinoptilolite zeolite as a candidate for removal of cationic dyes safranin O and toluidine blue from single and binary solutions. Finally, Olukotun et al. [5] report the preparation and characteristics of a clay-based composite material containing waste low-density polyethylene.

We hope that the Special Issue on “Surfaces and Interfaces of Clay Minerals” will contribute to a better understanding of the surface properties of clay minerals and their interactions with other substances and will be useful to readers from academia and industry to enrich their perspectives of fundamentals and applications of clay minerals.