LAUSR

Heteroaromatic hydrocarbons (including thiophene [TH], benzothiophene [BT], and dibenzothiophene [DBT]) do not have apparent functional groups capable of interacting with the silica-oxide tetrahedral surface of kaolinite. Thus, question remains concerning what would be the driving forces for the adsorption. Here, the Si13O37H22 cluster model for the surface is constructed, and the interactions of the surface with three heteroaromatic compounds are studied at the MP2/6-31G(d,p)//B3LYP/6-31G(d) level. The computed properties characterizing the complexes include optimized structural parameters, electron density characteristics (the ρ and ∇2ρ values for CH…O bonds), adsorption energies, vibration frequencies and electrostatic potential maps. The results suggest that the CH…O hydrogen bonding interactions between the heteroaromatic compounds and tetrahedral surface are likely among the important interactions for the adsorption. The order of the stability of the cluster model of kaolinite complexed with the heteroaromatic compounds is found to be 3SiODBT > 3SiOBT > 3SiOTH based on the calculations.