Adsorption behaviour and mechanism of benzene, toluene and m-xylene (BTX) solution onto kaolinite: Experimental and molecular dynamics simulation studies

• The optimal adsorption configuration, adsorption energy and forming bonds involved in adsorption is visualized and quantified. • BTX adsorption was driven by hydrophobic interaction and weak hydrogen bond. • Adsorption process was well described by the Langmuir-Freundlich isotherm model and pseudo-first order kinetic. • Benzene had an advantage over m-xylene during the competition adsorption process. Benzene, toluene and m-xylene (BTX) pollution due to industrial development has been a serious problem in recent years. The environmental mobility and fate of BTX in soils are mainly controlled by interactions with soil minerals such as kaolinite. Therefore, it is crucial to characterise the molecular-scale interactions that occur between BTX and kaolinite. In this study, molecular dynamics (MD) simulations, isothermal titration calorimetry (ITC) and batch adsorption experiments were performed to investigate the molecular interactions between BTX and kaolinite. Results revealed that the adsorption capacity of the kaolinite 00 1 ¯ surface was stronger than that of the kaolinite 001 surface due to the weaker hydrophilicity. BTX molecules were adsorbed on kaolinite surfaces by forming weak hydrogen bonds with the oxygen basal surface. The adsorption energy and adsorption isotherm obtained by the MD simulations were similar to those from the ITC and batch experiments, which validated the reliability of the MD simulations. The adsorption of BTX onto kaolinite was well described by the pseudo first-order kinetic and Langmuir-Freundlich isotherm model. Overall, performing MD simulations combined with experiments revealed the BTX adsorption mechanisms from a molecular interaction perspective.