Grand canonical Monte Carlo simulation on adsorption of aniline on the ice surface

Abstract

Aniline has been found to have frequent environmental occurrence and high toxicity. However, little study has been performed on its environmental fate. Here, we employed Grand Canonical Monte Carlo simulations (GCMC) to investigate the adsorption behavior of aniline on hexagonal ice surface at 200 K using our modified force field of aniline and TIP5P force field of water. The results indicate that the adsorption isotherm of aniline exhibits a “monolayer saturation plateau”, starting with a rapid increase, then a plateau, and finally a condensed phase. Under very low surface coverage, the adsorption isotherm apparently follows Langmuir type adsorption isotherm although anilines can be adsorbed to various sites. Within the range of the apparent Langmuir-type adsorption isotherm, adsorbed anilines are independent from each other and most anilines are almost parallel to the ice surface and form two N−H•••O hydrogen bonds. With the increase of coverage, the adsorbed anilines can interact with each other, resulting in the deviation from the apparent Langmuir-type adsorption isotherm. In addition, the adsorption energy from GCMC simulation (−65.91 kJ mol−1) is well consistent that from our validating quantum chemistry calculation (−69.34 kJ mol−1), further confirming the reliability of our GCMC simulation results.