The development and application of self-cleaning treatments on historical and architectural stone surfaces could bring a significant improvement in conservation, protection and maintenance of Cultural Heritage. The aim of this investigation is the application of titanium dioxide based coating on historical and architectural surfaces to evaluate its possible use as a self-cleaning treatment.Titanium dioxide based coating was obtained by sol-gel and hydrothermal (134 °C) processes and then the TiO2 sol was applied on travertine (a limestone largely used in historical buildings of Mediterranean area) by spray coating in two different ways, obtaining a single-layer and a three-layer coating.In order to verify the potential use of TiO2 based coating in the field of Architectural Heritage, the maintenance of appearance properties of treated surfaces was monitored by colour and gloss analyses. Static contact angle and wettability were monitored to assess possible changes in surface properties of treated stones and to evaluate photo-induced hydrophilicity. Static contact angle analysis, water adsorption, de-pollution and soiling removal tests were carried out under UV-light exposure to evaluate photo-induced effects and self-cleaning efficiency.Obtained results show that analyzed TiO2 based treatments modify the aestethic aspect of the treated surfaces in a negligible way, while without UV-light exposure there are no evident changes in static contact angle, capillary rise and wettability of treated surfaces. The trasparency of the coatings and the absence of significant changes in the morphology of the limestones seem to allow the use of these coatings on historical and architectural surfaces made up by travertine.Photo-induced effects (hydrophilicity, nitrogen oxide and soiling degradation) are very evident. Treated surfaces show hydrophilic behaviour during UV-light exposure, but this increase in wettability does not seem to lead to higher values of water adsorption, since water creates a film on solid surface without being adsorbed. The analyzed TiO2 coatings are able to effectively photo-degrade NO under UV-light exposure and to accelerate the degradation process of deposited dye. The combination of these properties may lead to an actual self-cleaning effect.The deposited amount of TiO2 through spray coating does not seem to increase photo-induced properties, since just outer layer is in contact with UV-light and external materials to be degraded, like NO (as well as other polluting substances) and deposited soiling.

Self-cleaning materials for architectural heritage: application and characterization of TiO2-based coatings on stone surfaces / P., Munafo; Bondioli, Federica; Quagliarini, E.; Goffredo, G. B.; Licciulli, A.; Diso, D.; Franza, S.. - 2:(2011), pp. 322-331. (Intervento presentato al convegno 5° Congresso internazionale "Scienza e Tecnologia per la Salvaguardia dei Beni Culturali nel Bacino del Mediterraneo" tenutosi a Istanbul nel 25/12/2011).

Self-cleaning materials for architectural heritage: application and characterization of TiO2-based coatings on stone surfaces

BONDIOLI, Federica;
2011-01-01

Abstract

The development and application of self-cleaning treatments on historical and architectural stone surfaces could bring a significant improvement in conservation, protection and maintenance of Cultural Heritage. The aim of this investigation is the application of titanium dioxide based coating on historical and architectural surfaces to evaluate its possible use as a self-cleaning treatment.Titanium dioxide based coating was obtained by sol-gel and hydrothermal (134 °C) processes and then the TiO2 sol was applied on travertine (a limestone largely used in historical buildings of Mediterranean area) by spray coating in two different ways, obtaining a single-layer and a three-layer coating.In order to verify the potential use of TiO2 based coating in the field of Architectural Heritage, the maintenance of appearance properties of treated surfaces was monitored by colour and gloss analyses. Static contact angle and wettability were monitored to assess possible changes in surface properties of treated stones and to evaluate photo-induced hydrophilicity. Static contact angle analysis, water adsorption, de-pollution and soiling removal tests were carried out under UV-light exposure to evaluate photo-induced effects and self-cleaning efficiency.Obtained results show that analyzed TiO2 based treatments modify the aestethic aspect of the treated surfaces in a negligible way, while without UV-light exposure there are no evident changes in static contact angle, capillary rise and wettability of treated surfaces. The trasparency of the coatings and the absence of significant changes in the morphology of the limestones seem to allow the use of these coatings on historical and architectural surfaces made up by travertine.Photo-induced effects (hydrophilicity, nitrogen oxide and soiling degradation) are very evident. Treated surfaces show hydrophilic behaviour during UV-light exposure, but this increase in wettability does not seem to lead to higher values of water adsorption, since water creates a film on solid surface without being adsorbed. The analyzed TiO2 coatings are able to effectively photo-degrade NO under UV-light exposure and to accelerate the degradation process of deposited dye. The combination of these properties may lead to an actual self-cleaning effect.The deposited amount of TiO2 through spray coating does not seem to increase photo-induced properties, since just outer layer is in contact with UV-light and external materials to be degraded, like NO (as well as other polluting substances) and deposited soiling.
2011
Self-cleaning materials for architectural heritage: application and characterization of TiO2-based coatings on stone surfaces / P., Munafo; Bondioli, Federica; Quagliarini, E.; Goffredo, G. B.; Licciulli, A.; Diso, D.; Franza, S.. - 2:(2011), pp. 322-331. (Intervento presentato al convegno 5° Congresso internazionale "Scienza e Tecnologia per la Salvaguardia dei Beni Culturali nel Bacino del Mediterraneo" tenutosi a Istanbul nel 25/12/2011).
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11381/2672877
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