The adsorption isotherm of various small, PAHs on ice are determined by using computer simulation methods. The results are compared in detail with available experimental data. In contrast with other PAHs, the isotherm of formaldehyde shows no particular stability of the saturated monolayer. Further, in contrast with that of methanol and formic acid, the obtained adsorption isotherm of formaldehyde is well described with the functional form of the Langmuir isotherm. The main thermodynamic driving force of the adsorption is the possibility of formation of water-adsorbate hydrogen bonds in every case. MD simulations of the adsorption and thermal desorption of oxalic acid at ice are also reported. It is found that the oxalic acid molecules have a strong tendency to form aggregates, while water molecules are located around them, in accordance with the fact that oxalic acid is an aerosol forming component and these aerosol particles act as cloud condensation nuclei.
ASJC Scopus subject areas
- Chemical Engineering(all)