Anatase as an alternative application for preventing biodeterioration of mortars: Evaluation and comparison with other biocides

Abstract

a b s t r a c tThe aim of this study is the comparison between different treatments (anatase and two conventional biocides: Biotin T and Anios) for preventing biodeterioration of mortars. The treatments were applied both in the laboratory on mortar slabs and in situ on walls of Palácio Nacional da Pena (Sintra, Portugal). Mortar slabs treated with anatase (pure and Fe 3þ doped) applied as a coating or by mixing within the mortar were prepared, and their surfaces characterized by different methodologies. The mortars were inoculated with cyanobacteria and chlorophyta species, incubated for a period of 4 months and the chlorophyll content quantified by extraction method and fluorescence emission. For comparison purposes untreated mortar slabs were inoculated, incubated and finally treated with the biocides. After two weeks the respective chlorophyll contents was quantified.In situ studies in two external walls of Palácio Nacional da Pena covered by organisms were also performed by direct application of aqueous solutions of the three products, and the efficiency of the treatment monitored by spectrophotometry using the CIELAB method. Lichens and other phototrophic microorganisms were identified by direct observation with a microscope and cyanobacteria, green microalgae, bacteria and fungi by DNA-based molecular analysis targeting the 16S and 18S ribosomal RNA genes.The results show that anatase is a better agent for preventing biodeterioration than the two tested conventional biocides, both in mortars slabs and in situ studies. In fact, photographic and colorimetric records made in two external walls of Palácio Nacional da Pena after two weeks of treatments application showed that lichens and other phototrophic microorganisms disappear from the places where anatase was applied.

Conservation of the Exterior of the National Museum of the American Indian Building

“…Although there have been successful applications of this methodology (Fonseca et al, 2010;Quagliarini et al, 2013a), it may not always be effective because photocatalytic materials require a specific quality and quantity of light in order to be activated (Quagliarini et al, 2013b). Further complicating matters, they might overwhiten surfaces and/or change the rate of biofilm formation and/or secretion of organic materials (Maurer-Jones et al, 2013).…”

On the Modelling of Algal Biofouling Growth on Nano-TiO2 Coated and Uncoated Limestones and Sandstones

“…At the same time, many research papers have investigated on the most effective and cheaper solutions to limit (or solve) this problem and some recent articles have found a good candidate in TiO 2 nano-coatings, because of their biocide power under UV irradiation, their durability and affordable costs [12][13][14][15][16][17] as well as because they have self-cleaning and depolluting effects [18][19][20][21], too. They seemed to be able to slow down algal biofouling when applied on low porous materials with smooth surfaces [22], even if algal growth is not inhibit on the substrate [13,[23][24][25] and to facilitate its removal on some substrates through the formation of a superficial water film [5].…”

Combined Use of NMR, LC-ESI-MS and Antifungal Tests for Rapid Detection of Bioactive Lipopeptides Produced by <i>Bacillus</i>

“…The procedure of controlling biodegradation/biodeterioration of artworks with minimal environmental impact it is a major challenge for the professionals responsible for the conservation and preservation of built heritage [5]. The biocides commonly used in a restoration/conservation intervention are chemical biocides like inorganic compounds (Na and Ca hypochlorite) and very complex organic ones such as the Quaternary Ammonium Compounds (Preventol R50, Neo-Desogen) that constitute a serious environmental and human health issue that is urgent to solve [6].…”