Next Article in Journal
A Novel Ruthenium-Decorating Polyoxomolybdate Cs3Na6H[MoVI14RuIV2O50(OH)2]·24H2O: An Active Heterogeneous Oxidation Catalyst for Alcohols
Previous Article in Journal
On the Ageing of High Energy Lithium-Ion Batteries—Comprehensive Electrochemical Diffusivity Studies of Harvested Nickel Manganese Cobalt Electrodes
Article Menu
Issue 2 (February) cover image

Export Article

Open AccessArticle
Materials 2018, 11(2), 177; https://doi.org/10.3390/ma11020177

Durable Self-Cleaning Coatings for Architectural Surfaces by Incorporation of TiO2 Nano-Particles into Hydroxyapatite Films

1
Department of Civil, Chemical, Environmental and Materials Engineering (DICAM), University of Bologna, Via Terracini 28, 40131 Bologna, Italy
2
Chemical Center S.r.l., Via S. Donato 5, 40057 Granarolo dell’Emilia (BO), Italy
3
Department of Civil and Environmental Engineering (CEE), Princeton University, 69 Olden Street, Princeton, NJ 08540, USA
*
Author to whom correspondence should be addressed.
Received: 19 December 2017 / Revised: 11 January 2018 / Accepted: 19 January 2018 / Published: 23 January 2018
View Full-Text   |   Download PDF [4413 KB, uploaded 24 January 2018]   |  

Abstract

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) sequential 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. View Full-Text
Keywords: soiling; photocatalytic activity; anatase; marble; calcium phosphates; cultural heritage; protection; rain; leaching; consolidation soiling; photocatalytic activity; anatase; marble; calcium phosphates; cultural heritage; protection; rain; leaching; consolidation
Figures

Graphical abstract

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

Share & Cite This Article

MDPI and ACS Style

Sassoni, E.; D’Amen, E.; Roveri, N.; Scherer, G.W.; Franzoni, E. Durable Self-Cleaning Coatings for Architectural Surfaces by Incorporation of TiO2 Nano-Particles into Hydroxyapatite Films. Materials 2018, 11, 177.

Show more citation formats Show less citations formats

Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Related Articles

Article Metrics

Article Access Statistics

1

Comments

[Return to top]
Materials EISSN 1996-1944 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top