Photocatalytic Glazed Tiles

A parent glass in the SiO2–CaO–ZnO–B2O3–K2O–Al2O3 system, deposited and processed by the monoporosa firing method (1085 °C), was coated using a sol–gel procedure and by serigraphy with silica, bismuth oxide, zirconia, and anatase with thermal treatment at 600 °C. The photocata- lytic activity of the samples determined by degradation in the Orange II dye test shows that a first-order reaction according to the Langmuir- Hinshelwood model is followed. From the UV-Vis-NIR results the band gap calculated is around 3.5 eV for the parent glass and that with a silica coating, and slightly lower for the other coatings. The needle-shaped microstructure of the parent glass shows the best photocatalytic results in agreement with the literature. The preserved zircon microstructure can explain the relatively high results for the silica coating, which unexpect- edly showed better results than both the anatase and tetragonal zirconia coatings. Finally, the interaction with the parent glass can explain the relatively high results of the bismuth oxide sampl

An integrated approach for assessing the bioreceptivity of glazed tiles to phototrophic microorganisms

18 páginas.-- 7 figuras.-- 5 tablas.-- 63 referenciasA laboratory-based methodology was designed to assess the bioreceptivity of glazed tiles. The experimental set-up consisted of multiple steps: manufacturing of pristine and artificially aged glazed tiles, enrichment of phototrophic microorganisms, inoculation of phototrophs on glazed tiles, incubation under optimal conditions and quantification of biomass. In addition, tile intrinsic properties were assessed to determine which material properties contributed to tile bioreceptivity. Biofilm growth and biomass were appraised by digital image analysis, colorimetry and chlorophyll a analysis. SEM, micro-Raman and micro-particle induced X-ray emission analyses were carried out to investigate the biodeteriorating potential of phototrophic microorganisms on the glazed tiles. This practical and multidisciplinary approach showed that the accelerated colonization conditions allowed different types of tile bioreceptivity to be distinguished and to be related to precise characteristics of the material. Aged tiles showed higher bioreceptivity than pristine tiles due to their higher capillarity and permeability. Moreover, biophysical deterioration caused by chasmoendolithic growth was observed on colonized tile surfaces.This work was supported by the Portuguese Foundation for Science and Technology (FCT) [grant SFRH/BD/46038/2008; project UID/EAT/00729/2013]. A.Z. Miller acknowledges support from a Marie Curie Intra-European Fellowship of the European Commission’s 7th Framework Programme [PIEF-GA-2012-328689]. J.P. Veiga and H. Águas acknowledge funding by FEDER funds through the COMPETE 2020 Programme and National Funds through FCT [project UID/ CTM/50025/2013]. This work was supported by the European Commission’s 7th Framework Programme, through the Marie Curie International Research Staff Exchange Scheme [NANO_GUARD (PIRSES-GA-2010-269138)].Peer reviewe

Testing the feasibility of titanium dioxide sol-gel coatings on portuguese glazed tiles to prevent biological colonization

Historical glazed wall tiles are a unique vehicle of artistic expression that can be found outdoors, integrating the buildings of many countries, therefore they are often subjected to biodeterioration. In this work, the applicability of protective coatings on glazed tiles to prevent biological colonization was evaluated. Thin films of titanium dioxide (TiO2) obtained by sol-gel were applied on glazed tiles to appraise its anti-biofouling properties and to evaluate their suitability for cultural heritage application. The TiO2 coating was tested on four different Portuguese glazed tiles and a modern tile. The chemical and mineralogical characterization of the glaze and ceramic body of the tiles was examined by wavelength dispersive X-ray fluorescence spectroscopy (WDXRF) and X-ray diffraction (XRD). The produced TiO2 coating was chemically and morphologically characterized by micro Raman spectroscopy (µ-Raman) and field emission scanning electron microscopy (FESEM). The anti-biofouling properties of the TiO2 treatment were evaluated by inoculating the fungus Cladosporium sp. on the glazed tiles. Potential chromatic and mineralogical alterations induced by the treatment were assessed by color measurements and XRD. The TiO2 coating did not prevent fungal growth and caused aesthetical alterations on the glazed tiles. A critical analysis evidenced that the tested coating was not suitable for cultural heritage application and highlighted the challenges of developing protective coatings for glazed tiles

Biodeterioration of glass-based historical building materials: An overview of the heritage literature from the 21st century

The main goal of this work was to review the 21st century literature (2000 to 2021) re-garding the biological colonisation and biodeterioration of glass-based historical building materials, particularly stained glass and glazed tiles. One of the main objectives of this work was to list and systematize the glass-colonising microorganisms identified on stained glass and glazed tiles. Biodiversity data indicate that fungi and bacteria are the main colonisers of stained-glass windows. Glazed tiles are mainly colonised by microalgae and cyanobacteria. Several studies have identified microorganisms on stained glass, but fewer studies have been published concerning glazed tiles. The analysis of colonised samples is a vital mechanism to understand biodeterioration, particularly for identifying the colonising organisms and deterioration patterns on real samples. However, the complexity of the analysis of materials with high biodiversity makes it very hard to determine which microorganism is responsible for the biodeteriogenic action. The authors compared deterioration patterns described in case studies with laboratory-based colonisation experiments, showing that many deterioration patterns and corrosion products are similar. A working group should develop guidelines or standards for laboratory experiments on fungi, bacteria, cyanobacteria, and algae on stained glass and glazed tiles

Recycling of construction and demolition waste generated by building infrastructure for the production of glassy materials

The use of waste materials generated by construction and demolition industry to yield valuable glassy materials, i.e. enamel for glazed ceramic tiles and cellular glasses is presented in this study. Both types of materials are produced by one-step treatment at moderate temperatures after simple waste chemical composition adjust. The enamels are manufactured directly from the initial waste powder by melting, while the expanded materials result from mixing of the vitreous material obtained after waste vitrification with an adequate foaming agent and posterior thermal treatment. Through the manuscript the feasibility of one step production of second generation profit materials is discussed in order to help achieving sustainable development and environmental protectio

A method of improving wettability and enamelling

There is described a method of enamelling a substrate, the method including the steps of: treating a thin surface layer of said substrate with a laser beam so as to promote a change in the surface energy thereof; allowing the surface to cool; and, applying enamel thereto to wet and coat said substrate

Grout or mortar removal by lasers

The method comprises the steps of directing the beam of a portable laser device (40) onto grout (14) at a power level to cause removal of the grout; causing mutual relative movement between said laser beam and said grout; and, providing removal means (30, 32) for debris resulting from said grout removal. The laser beam (16) is transmitted to the grout (14) via optical fibre. The laser is selected from the group comprising: Nd-YAG laser; semi-conductor laser; and, diode pumped fibre laser, and may also include a low-power visible aiming laser. An area of grout being treated is surrounded by an enclosure (22) to prevent escape of laser light. The enclosure is transparent to optical light and opaque to laser light of the wavelength, e.g. 0.4 to 10.6 $g(m)m, in use. The laser beam spot (18) size being commensurate with the grout width. Debris removal means, possibly assisted with a gas jet (42), comprises suction removal (44) at a position adjacent the grout laser treatment area. The method may include the step of applying additional water to the grout

Two examples of how to solve conservation problems in ceramic pieces from the museum of Murcia

Se estudia un proceso de alteración química de materiales arqueológicos en los museos, concretamente de unos azulejos vidriados de época moderna y de platos con decoración de cobre, proponiéndose las soluciones más adecuadas para su conservación.The process of chemical alterations of archaeological materials in the Museums is studied, particularly the process of damage of modern glazed tiles and of the plates with copper decoration. Appropriate methods of treatment are proposed

A multiproxy approach to evaluate biocidal treatm entson biodeteri orated majolica glazed tiles

23 páginas.-- 10 figuras.-- 6 tablas.-- 88 referencias.-- Supporting information Additional Supporting Information may be found in the online version of this article at the publisher’s web-site: http://dx.doi.org/10.1111/1462-2920.13380The Fishing House located on the grounds of the Marquis of Pombal Palace, Oeiras, Portugal, was built in the 18th century. During this epoch, Portuguese gardens, such as the one surrounding the Fishing House, were commonly ornamented with glazed wall tile claddings. Currently, some of these outdoor tile panels are covered with dark colored biofilms, contributing to undesirable aesthetic changes and eventually inducing chemical and physical damage to the tile surfaces. Phylogenetic analyses revealed that the investigated biofilms are mainly composed of green algae, cyanobacteria and dematiaceous fungi. With the aim of mitigating biodeterioration, four different biocides (TiO2 nanoparticles, Biotin® T, Preventol® RI 80 and Albilex Biostat®) were applied in situ to the glazed wall tiles. Their efficacy was monitored by visual examination, epifluorescence microscopy and DNA-based analysis. Significant changes in the microbial community composition were observed 4 months after treatment with Preventol® RI 80 and Biotin® T. Although the original community was inactivated after these treatments, an early stage of re-colonization was detected 6 months after the biocide application. TiO2 nanoparticles showed promising results due to their self-cleaning effect, causing the detachment of the biofilm from the tile surface, which remained clean 6 and even 24 months after biocide application.This work was supported by the Portuguese Foundation for Science and Technology (FCT-MCTES) under grant no. SFRH/BD/46038/2008 and project no. UID/EAT/00729/2013. A. Z. Miller acknowledges the support from a Marie Curie Intra-European Fellowship of the European Commission’s 7th Framework Programme (PIEF-GA-2012-328689). Authors acknowledge the Spanish Ministry of Science and Innovation Research Programme in Technologies for the Assessment and Conservation of Cultural Heritage (TCP CSD2007-00058),Peer reviewe

Export market integration in the European Union

This paper examines the degree and recent evolution (1988-2001) of export-price dispersion among European Union countries. It also explores the effect of exchange rates on exportprice dispersion by reviewing the experience of some European countries that participated in the exchange rate stability zone. The results indicate that export-price dispersion across European Union countries was usually lower than across OECD countries. Moreover, although there is little evidence of convergence, this is stronger across European Union countries. Finally, even though price dispersion was often lower across European Union countries where exchange rates have been relatively stable than across countries with relatively volatile exchange rates, exchange-rate stability has not significantly contributed to export-price convergence across participating countries over the sample period.export market integration, European Union, exchange rates