Photocatalytic paint for fungi growth control under different environmental conditions and irradiation sources

Abstract

The fungicide effect employing Aspergillus niger as a representative microorganism was tested applying a Photocatalytic paint formulated with an anatase carbon doped TiO2 and compared with a homemade non-active paint (rutile TiO2), a commercial normal indoor latex paint and a commercial “antifungal” latex paint. For this purpose Aspergillus niger conidia inactivation on the paints coatings was performed under visible and UV radiation applying different experimental conditions (relative humidity, radiation flux and absence of light). Under visible light no significant difference in conidia inactivation was found for all studied paints. Nevertheless, the Photocatalytic paint under UV radiation presented around 1.4 times higher fungus inactivation than the blank control paints. In order to evaluate the damage produced by visible or UV radiation over the conidia and to analyze the ability of repairing it, incubation at optimal germination conditions of Photocatalytic and normal paints after irradiation treatment was performed. For conidia irradiated on Photocatalytic paint, not only conidia could not germinate but also the inactivation continued even after the end of the irradiation assay. Finally, A. niger conidia was exposed over a culture medium with or without the paints pigments (Carbon doped TiO2 or Rutile) under different types of radiation (visible and UV). Much greater growth control of vegetative forms was obtained by applying photocatalytic TiO2 under both types of light. It can be concluded that the developed Photocatalytic paint presents a higher ability to control fungal growth compared to the other paints studied and could be applied for indoor air decontamination. Also, it was possible to control the dissemination agent that can generate more mold growth on surfaces and affect the people health.