The DFT study of adsorption of 2,4-dinitrotoluene on kaolinite surfaces

Volatile organic compounds can be adsorbed on the surfaces of clay minerals, but the mechanisms and interactions between adsorbate and clay surface are still not well understood. In this paper, the adsorption of 2,4-Dinitrotoluene (2,4-DNT) molecule on the kaolinite surface has been studied at the B3LYP/6-31G(d) level. The cluster models of Si13O37H22 and Al6O24H30 for tetrahedral (Si–O) and octahedral (Al–O) surfaces of kaolinite were constructed, and various gas state properties (including electron density, adsorption energies (AE), hydrogen bonds (both primary hydrogen bonds and secondary hydrogen bonds), vibration frequencies, electrostatic potential, and so on) were explored. The results suggest that the adsorption of 2,4-DNT on kaolinite is due to the formation of hydrogen bonds. Simultaneously, 2,4-DNT molecule is preferentially adsorbed on the Al–O surface. The structures and energies of the absorption of 2,4-DNT molecule on the kaolinite surfaces present an intuitive view for future experimental studies on these atmospheric pollutants.