Alberto Strini and Emanuela Mapelli
Titanium dioxide is a well-known catalyst able to degrade by oxidation several organic compounds. Recent studies have proposed to exploit this property to prepare additives for construction materials based on this compound. A particular interest arises from the possibility of obtaining coating materials that, being activated by sun light, are able to destroy the organic compounds which deposit on them. This property might potentially lead to the development of a new class of materials having self-cleaning and depolluting properties.
The self-cleaning property derives from the possibility to destroy by catalytic photooxidation the deposit of dark organic substance (soot) that normally covers the external surfaces of buildings, especially in densely populated urban areas. The possible depolluting properties derive instead from the oxidative degradation of gaseous pollutants adsorbed at the surface of the material itself. This class includes both inorganic pollutants (e.g. nitrogen oxides) and organic pollutants (among which benzene and other aromatic compounds).
A specific European research project has been launched for the study of the potentials of titanium dioxide in this field. The PICADA project (Photocatalytic Innovative Coverings Applications for Depollution Assessment) in the framework of the European research programme "Competitive and Sustainable Growth" involves the leading European research centres specialized in the field of building materials and several companies of this sector (for further information visit the project's website at the following address: www.picada-project.com).
This project envisages the laboratory study and full-scale investigation of self-cleaning and depolluting properties (NOx and basic aromatics) of different preparations of titanium dioxide, in order to assess their actual usability in formulas to be used in the building field as façade coating.
CNR is represented in the project by the Construction Technologies Institute (ITC). In particular, ITC contributed to the project by developing the experimental technology and by performing laboratory measurements aimed at investigating the photocatalytic abatement of aromatic organic substances (BTEX) in the concentrations that are normally found in the outdoor urban environment (from parts per billion to parts per million).
In this case, it was extremely important to rely on the long time experience of ITC laboratories in the field of measurements of organic volatile compounds (VOC) emissions from building materials, and in particular of the technologies set up over the last years to recreate and verify, in a controlled and reliable way, synthetic atmospheres with pre-established contents of VOC traces (up to concentrations of parts per billion).
At so low concentrations, it is essential to check both parasitic adsorptions of the experimental equipment, and volatiles traces that may be released by the systems generating the artificial atmosphere.
ITC participations demonstrates the ever increasing importance of developing state-of-the-art experimental technologies allowing to provide meaningful contributions to international projects requiring high level specialized know-how.