Titania–Graphene Hybrids for Photocatalytic Applications: Exploring Relations between Hansen Solubility Parameters and Liquid-Phase Pollutant Adsorption

Pollutant degradation via titania photocatalysts holds significant potential. For ‘smart’ or knowledge-based design of photocatalysts, it is, however, important to understand the adsorption and degradation dynamics and their relationship with the particulate surface. Hansen solubility parameters (HSPs) can provide relevant information about the particle surface characteristics in dispersions. Herein, HSPs of six different titania materials including their composites with graphene are determined and they are related to the adsorption capacities of Bisphenol A and chloroform. The effect of the underlying synthesis procedures and graphene addition on the pollutant adsorption in the liquid phase is examined. The results show that the Hansen sphere radii correlate with the specific equilibrium adsorption capacities of the titania-based substrates for both pollutants. The type of crystallographic structure and the addition of graphene increase the adsorption dynamics and are accurately correlated with the HSP sphere radii. HSPs can thus serve as a characterization method for understanding liquid pollutant adsorption or, set in a wider context, the interaction of ligands or surface groups with a specific particle surface.