Photocatalytic coatings to improve indoor air quality.
Indoor air pollutants impact human health, comfort and efficiency. The main contributing sources of VOC are motor vehicle exhaust, household products, paints, solvents and volatile additives in adhesives used in furniture, carpets and other floor covers.
One technology to remove VOC is the use of heterogeneous photocatalytic oxidation (PCO). Operating at room temperature, PCO can degrade a broad range of contaminants without significant energy input. Inactivation of microorganisms is the most important mechanism to avoid microbial growth on surfaces, which is normally connected to biofilm development in nature as well as on technical or construction materials. Thus, anti-microbial strategies mean to inactivate bacteria, fungi and algae cells to prevent contamination which may influence the optical as well as functional properties and can be, in serious cases, the origin of illnesses.
The available commercial products to remove VOCs are mainly for outdoor applications and most require UV light irradiation to be effective. One of the main innovations of the OSIRYS project will be the development of a photocatalytic system able to be active under visible light.
Coatings for indoor applications are typically applied onto base materials like paper, textiles, wood or metal. The biocomposites developed in the OSIRYS project will have a polymeric surface which is in general more hydrophobic than typical indoor surfaces.
VOCs in rooms, and biofilms on indoor-façades, impact human health and comfort. The biocomposites developed will be furnished with a multifunctional coating which decomposes the VOC and prevents the formation of biofilm. These functions will be achieved by preparing formulations with photocatalytic active additives. The formulations prepared by the project partner SICC will be applied to the selected materials and characterised with regard to their activity to decompose selected VOCs and to inactivate relevant microorganisms.
To evaluate the activity of the different commercial and new synthesized materials, the first objective for project partner Fraunhofer IGB was to build up and establish suitable methods for paints as well as powder materials. One task was to develop suitable test-setups to analyse VOC degradation capacity of photo catalytically active surfaces and powders.