Modification of Clay Minerals by Surfactant Agents: Structure, Properties, and New Applications

Abstract

Organically surfactant-modified clays (OC) have attracted a great deal of interest because of their wide applications in industry and environmental protection. The OC are organic–inorganic complexes synthesized through the intercalation of organic cations mainly into the interlayer space of expandable clays. Different surfactants have been used to prepare OC. These include single and dual-cationic surfactants, anionic–cationic surfactants, and nonionic surfactants. The intercalation of the surfactant cations was governed by different processes: cationic exchange and Van der Waals ‘interactions of the alkyl chains with clay surface. The structure and properties of the resultant organoclays are affected by the type of surfactant, the clay used, and the preparation method such as the conventional technique, the solid-state intercalation, and the microwave irradiation. As the result, the organoclays are characterized by hydrophobic surfaces and have attracted great interest because of their potential use in several applications, such as sorbents for organic pollutants (dyes, pharmaceutic compounds…), heavy metals and inorganic oxy-anions, clay-based nanocomposites, and in several other industries.