Adsorption behavior of Cs+ ions to vermiculite demonstrated by molecular dynamics simulations

Abstract

The present paper discusses the simulation results, performed by classical molecular dynamics (MD), for vermiculite. The kinetic process of the [Formula: see text] ions in water that are adsorbed into vermiculite [Formula: see text] was investigated with classical MD simulations utilizing Coulomb and Born–Mayer–Huggins potentials. A monoclinic vermiculite crystal with a [Formula: see text] supercell was placed into 8461 molecules of water to form a rectangular supercell of [Formula: see text]. The water was placed into contact with both sides of the [Formula: see text]–[Formula: see text] planes of the vermiculite crystal, along the [Formula: see text]-axis only. The rectangular supercells, which were prepared with the vermiculite in water with and without an additional 200 [Formula: see text] ions, were simulated. The MD conditions included a constant pressure ensemble for 1 ps at a constant step of 0.1 fs. The results revealed an increase in the distances of the [Formula: see text] layers at the interface between the vermiculite and water. This increase in the separation of the [Formula: see text] layers was suitable for the uptake of [Formula: see text] ions by the vermiculite. The accelerated MD simulation which replaced the interfacial [Formula: see text] ions with [Formula: see text] ions tended to include the [Formula: see text] ions into the vermiculite by excluding the [Formula: see text] ions.