P h o t o c a t a l y t i c S u p e r f i c i a l T r e a t m e n t s
183
Photocatalytic products can be applied in environments to high content of indoor
pollution, as those hospital, make part of the category of the layers of finish realized with
plaster and paintings. More precisely, these products are named photocatalytic paints
and photocatalytic microfilms.
These products effect the phenomenon of the photocatalysis through the combination of
two factors: the presence of the photocatalyst dioxide of titanium and the irradiation of
the surface treated with dioxide of titanium with a source of opportune light. The
application in external environment of these products in coverings of façades or floorings
has brought to very positive results: "1 m² of surface treated with photocatalyst dioxide
of titanium cleans 200 m³ of air with 10 hours of irradiation" (rif. conclusions of the project
PICADA). Products containing the photocatalyst dioxide of titanium, applied in inside
environments, possess some characteristics coming from the ability to use the bright
energy (solar or suitable artificial) to activate chemical reactions that bring to the
destruction of polluting mixtures absorbed on the surface, allowing to remove in this way
the polluting substances from the air. Besides they have other characteristics like:
•
Purification of the air;
•
Antimicrobial action;
•
Deodorant action;
•
Self-cleaning Action.
The normative references for the performance photocatalytic evaluation
Even if in Italy the phenomenon of the photocatalysis is by now known above all for the
effects that spring, it exists only a regulation that draws this phenomenon: the Decree of
the Ministry of the environment and the safeguard of the Territory, April 1
st
, 2004
(published on the Official Journal April 9
th
, 2004, n°84), containing guidelines for the use
of innovative systems in the evaluation of environmental impact. The principal objective
of this decree is the individualization of the guidelines for innovative systems able to
demolish or to mitigate the environmental pollution. Inside all typologies of environmental
pollution it is also possible to find the atmospheric pollution, not precisely specifying if it
deals with indoor or outdoor air pollution. Guidelines are defined in the enclosure I
entitled "Methodologies and Recommendations for the mitigation and demolition of the
environmental pollution." Inside this enclosure, are present guidelines for innovative
systems to oppose the atmospheric pollution. The technical card that analyzes this
thematic is the N.St-001 having a date of revision 28/02/2004. In these guidelines are
described all products that can be realized and used for reducing the atmospheric
pollution, focus on just on photocatalytic products as mortars, floorings, paints and
coverings, that have as common denominator the dioxide of titanium as photocatalyst.
Besides the description of products and materials, there is the definition of a the check of
technical-scientific validity, where is listed the documentation of technical tests and the
validations and the certifications of these products. The effectiveness of these innovative
photocatalytic systems is finally defined. From these guidelines stand out the variability
of the effectiveness of this phenomenon according to the power of the light that radiates
the surface of the processed material. Besides are brought data on the photocatalytic
effectiveness taken by documents and certificates, as for instance, the reduction of the
nitrogen oxides equal to around 30 tons/year for Km² of treated surface; the reduction
from 2% to 37% of the concentrations of nitrogen dioxide inside apartments with walls
treated with photocatalytic plasters; the 14% reduction of concentrations of nitrogen
dioxide and finally the ascertained photodegradation of tetrachlorophenol (TCP),
benzaldehyde, bisphenol.
In the last point of the file of this regulation, the field of application of such innovative
systems is defined, as for instance, with regard to finishes for walls, floorings, external
panels, etc.
