Photocatalytic effect of addition of TiO₂ to acrylic-based paint for passive toluene degradation

Volatile organic compounds (VOCs) are known to be hazardous and associated with several human health problems. Thus, many technologies have been developed in recent years for their removal, such as thermal catalysis, photocatalysis and ozonization. In this study, the main objective was to evaluate the effects of incorporating titanium dioxide into an acrylic-based paint for gaseous toluene abatement. Paints with photocatalytic properties were prepared by adding TiO₂ P25 powder to an acrylic-based paint, using the following proportions: 0, 10, 15, 20 and 50 wt% (dry basis). Toluene and CO₂ concentrations at the reactor input and output were determined using GC/MS, and GC/FID, respectively, and the toluene conversion and CO₂ formation were assessed. The compounds adsorbed onto photocatalytic paints were extracted and then identified by GC/MS. The results indicated that the addition of 50 wt% of TiO₂ P25 results in a paint of reduced quality. The addition of 20 wt% of TiO₂ P25 to the paint led to higher values for the photocatalytic conversion of toluene to CO₂. The occurrence of two simultaneous processes was observed: the photocatalytic oxidation of toluene to CO₂ and the self-degradation of the organic compounds, such as polymeric acrylic, in the paint. The adsorption of different compounds onto the photocatalytic paints was identified by GC/MS analysis. The use of photocatalytic paints is a promising technique for toluene abatement, but it requires further study and improvement particularly with regard to the effects of the self-degradation of the paint.