Influence of the exchangeable cation on the adsorption of 2-nitro-1-propanol on smectite surface models

B3LYP/6-31+G∗∗ calculations and AIM analysis have been performed for studying the 2-nitro-1-propanol (NP) adsorption on smectite cluster models, employing Li+, Na+ and K+ as surface cations, and a fourth model with no cation. The adsorption is energetically more favored in the order K+>Na+>Li+. Adsorption takes place mainly by NP-NO2…cation and NP-OH…O interactions. The adsorption process weakens the interactions cation–surface, especially the interaction between the cation and the hydroxyl group in the ditrigonal cavity, which is believed to be particularly responsible for the differences observed in the adsorption energy among the different models.