On the adsorption affinity of graphene and white graphene sheets by dioxin-like pollutants

摘要

The affinity of graphene and white graphene sheets by dioxin-like pollutants was compared by means of high-level quantum chemical calculations. 2,3,7,8-tetrachloro-p-dibenzodioxin (TCDD) and 2,3,7,8-tetrachlorodibenzofuran (TCDF) were chosen as prototypes of dioxin-like pollutants with high toxicological activity. Large interaction energies were obtained both in graphene and white graphene surfaces, contrary to other previous works using the graphene surface only. The interactions clearly differed in the relative weight of inductive and dispersion forces, being the former more important in white graphene. Leaving thermal effects out, the stacking adsorption was energetically favored over the perpendicular in graphene whereas no difference was found in white graphene. Due to the low water solubility of dioxin-like pollutants very small differences were obtained between gas phase and solution adsorption enthalpies. Including thermal effects, perpendicular adsorption was found to be both energetically and entropically favored over stacking at 298 K. The adsorption free energies reflected a larger affinity by white graphene than graphene by around 2-5 kcal center dot mol(-1). Therefore, boron nitride 2D surfaces are expected to perform better than carbon 2D surfaces as adsorbents for dioxin-like pollutants in line with recent experimental works on water contaminants.