Study on ionic liquid modified montmorillonite and molecular dynamics simulation

Abstract

In this study, the montmorillonite was modified by the ionic liquid 1-hexadecyl-3-methylimidazolium chloride (C16mimCl) and then characterized by the XRD, FTIR, BET, SEM and TGA. The loading characteristics and mechanisms of ionic liquids on montmorillonite were studied. The results show that C16mimCl was successfully intercalated in the montmorillonite interlayer or adsorbed on its surface. With the increase of the dosage of C16mimCl, the amount of C16mimCl loaded on montmorillonite also increased. After the dosage exceeds 3.0 CEC, the loading amount reached a stable value. The loading increased firstly and then decreased with the increase of pH. Ca2+ has different effects on the loading process at different dosage of C16mimCl. The modification process conforms to the Langmuir model and the pseudo-second-order kinetic model, and the adsorption capacity decreases with increasing temperature. Thermodynamic studies have shown that the modification is a spontaneous entropy increase and exothermic process. Molecular dynamics simulation (MDS) was used to construct modified montmorillonite models with C16mimCl loadings of 0.5, 1.0 and 3.0 CEC. Based on the simulation results, the arrangement of C16mimCl in montmorillonite and the modification mechanism are revealed. This study can provide new ideas for the synthesis of organic montmorillonite and its application in pollutant removal.