Microstructure and process of intercalation of imidazolium ionic liquids into montmorillonite

Abstract

Organically modified clays exhibit adsorption capacities for cations, anions, and nonpolar organic compounds, which make them valuable for various environmental technical applications. Research into organic molecule modified montmorillonite should place importance on studying the mechanism of the intercalation process. Herein a new kind of green and steady ionic liquid, 1-Hexadecyl-3-methylimidazolium chloride monohydrate (C16mimCl) has been chosen as the intercalant agent. We have investigated the process that C16mimCl is intercalated into Na-montmorillonite in aqueous solution under batch studies and molecular simulations. The C16mimCl intercalation has been found relatively fast with a large rate constant. The intercalation is driven by both cations exchange and negative charge on the layer surface. The process is affected by the initial concentration and pH value of the solution; the basal spacing is increased to 2.88nm after intercalation. Molecular dynamic simulation further reveals that the initial concentration of C16mimCl can influence its configuration in the interlayer, causing the change of interlayer spacing. Apart from the electrostatic interaction, the hydrophobicity of the organic molecule also plays an important role in the intercalation process. Overall, ionic liquid intercalated montmorillonite is a promising environmental composite material with broad application potentials such as chemical fiber and aviation.