Innovative Nano-TiO2 Particles for Self-cleaning Treatments of Historic Architecture and Sculptures

Abstract The study reports the results of a new treatment based on water and ethylene glycol nano-TiO2 dispersions showing photocatalytic properties that was tested on both Noto stone (calcarenite) and Carrara marble. To verify that the proposed treatments did not affect the intrinsic properties of the stone materials, colour measurement, static contact angle and water absorption by capillarity tests were carried out before and after the treatments. The efficacy of the photocatalytic activity of TiO2 nanoparticles applied to the stone substrates was evaluated by decomposition tests of organic colorants (Rhodamine B), both after indoor natural light exposition and after ageing in a Xenon lamp solar box. The specimens were also exposed to outdoors environment in order to verify their properties as self-cleaning agents to prevent soiling. The results showed that nano-TiO2 dispersions were effective and suitable for the use in the field of architectural heritage.