Durable self-cleaning coatings for architectural surfaces by incorporation of TiO2 nano-particles into hydroxyapatite films

Sassoni, Enrico ; D'Amen, Eros ; Roveri, Norberto ; Scherer, George ; Franzoni, Elisa (2018) Durable self-cleaning coatings for architectural surfaces by incorporation of TiO2 nano-particles into hydroxyapatite films. Materials, 11 (2). ISSN 1996-1944
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To prevent soiling of marble exposed outdoors, the use of TiO2 nano-particles has been proposed in the literature by two main routes, both raising durability issues: (i) direct application to marble surface, with the risk of particle leaching by rainfall; (ii) particle incorporation into inorganic or organic coatings, with the risk of organic coating degradation catalyzed by TiO2 photoactivity. Here, we investigated the combination of nano-TiO2 and hydroxyapatite (HAP), previously developed for marble protection against dissolution in rain and mechanical consolidation. HAP-TiO2 combination was investigated by two routes: (i) in series application of HAP followed by nano-TiO2 (“H+T”); (ii) simultaneous application by introducing nano-TiO2 into the phosphate solution used to form HAP (“HT”). The self-cleaning ability was evaluated before and after prolonged exposure to simulated rain. “H+T” and “HT” coatings exhibited much better resistance to nano-TiO2 leaching by rain, compared to TiO2 alone. In “H+T” samples, TiO2 nano-particles adhere better to HAP (having flower-like morphology and high specific surface area) than to marble. In “HT” samples, thanks to chemical bonds between nano-TiO2 and HAP, the particles are firmly incorporated in the HAP coating, which protects them from leaching by rain, without diminishing their photoactivity and without being degraded by them.

Document type
Sassoni, EnricoUniversity of Bologna, Italyorcid.org/0000-0003-0716-510X
D'Amen, ErosChemical Center S.r.l., Italy
Roveri, NorbertoChemical Center R.r.l., Italy
Scherer, GeorgePrinceton University, USA
Franzoni, ElisaUniversity of Bologna, Italy
Soiling; Photocatalytic activity; Anatase; Marble; Calcium phosphates; Cultural Heritage; Protection; Rain; Leaching; Consolidation
Deposit date
05 Mar 2018 11:08
Last modified
23 May 2019 08:34
Project name
HAP4MARBLE - Multi-functionalization of hydroxyapatite for restoration and preventive conservation of marble artworks
Funding program
EC - H2020

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