Key parameters influencing the uptake of m-xylene on photocatalytic paints

Given the toxic nature of many volatile organic compounds (VOCs) present within indoor environments, it is necessary to develop new materials to eliminate them. Photocatalytic paints represent a promising technology to remove the indoor pollutants but they are not optimised yet. Here we evaluate the capacities of one conventional white-wall paint, three photocatalytic paints containing 3.5, 5.25 and 7% of nano-TiO2 PC 500, and two photocatalytic paints with a hybrid cellulose nanocrystals-nano-TiO2 (CNC-nano-TiO2) to eliminate m-xylene from the indoor environment. In particular, we assess the impact of nano-TiO2 content, light intensity, relative humidity (RH), surface temperature (288–320 K) and pigment volume concentration (PVC) on uptake of m-xylene. Uptake coefficients of m-xylene increase by a factor 3, 5 and 3, respectively, as a function of nano-TiO2 content, irradiance and PVC. In contrast, uptakes of m-xylene decrease for a factor of 2 and 3, as a function of RH, and surface, suppressing the photocatalytic activity. The addition of CNC-nano-TiO2 in the binder induces limited binder degradation. These are very promising results which may help to improve the performances of indoor photocatalytic paints aimed to eliminate indoor airborne pollutants.