Silvestro Antonio Ruffolo

Marine Antifouling for Underwater Archaeological Sites: TiO2 and Ag-Doped TiO2

Marine fouling plays a crucial role in the degradation of underwater archaeological sites. Limitation of fouling activity and its damages are one of the most critical issues for archaeologists and conservators. The common cleaning procedure, consisting in the manual removal of fouling, requires a continuous maintenance, while a proper inhibition of biological colonisation would provide a long-time protection against biofouling. On the other hand, the most used antifouling paints, especially for ship hulls, show considerable toxicity level. Since submerged archaeological sites are often included in environmental protected areas, more eco-friendly products must be used. We have explored the possibility to use titanium dioxide and Ag-doped titanium dioxide as antifouling agents. For this purpose, they have been synthetized by sol-gel method, and then XRD, XPS, and reflectance spectroscopy measurements have been carried out to gain structural information. The powders have been dispersed in a polymer and then applied to marble surface to evaluate the chromatic alteration induced by the treatments. By means of biological tests, it was possible to assess their behaviour as biofouling agents. Results show a decreasing of biofouling activity on treated stony surfaces.

Application of spectrometric analysis to the identification of pollution sources causing cultural heritage damage

Black crusts are recognized to have been, up to now, one of the major deterioration forms affecting the built heritage in urban areas. Their formation is demonstrated to occur mainly on carbonate building materials, whose interaction with an SO2-loaded atmosphere leads to the transformation of calcium carbonate (calcite) into calcium sulfate dihydrate (gypsum) which, together with embedded carbonaceous particles, consequently forms the black crusts on the stone surface. An analytical study was carried out on black crust samples collected from limestone monumental buildings and churches belonging to the European built Heritage, i.e., the Corner Palace in Venice (Italy), the Cathedral of St. Rombouts in Mechelen (Belgium), and the Church of St. Eustache in Paris (France). For a complete characterization of the black crusts, an approach integrating different and complementary techniques was used, including laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), Fourier transform infrared spectroscopy, optical and scanning electron microscopy. In particular, the application of LA-ICP-MS permitted to obtain a complete geochemical characterization in terms of trace elements of the black crusts from the inner parts to the external layers contributing to the identification of the major combustion sources responsible for the deterioration over time of the monuments under study. In addition, the obtained results revealed a relation between the height of sampling and the concentration of heavy metals and proved that the crust composition can be a marker to evaluate the variation of the fuels used over time.

An analysis of the black crusts from the Seville Cathedral: A challenge to deepen the understanding of the relationships among microstructure, microchemical features and pollution sources

The Cathedral of Seville is one of the most important buildings in the whole of southern Spain. It suffers, like most of the historical buildings located in urban environments, from several degradation phenomena related to the high pollution level. Undoubtedly, the formation of black crusts plays a crucial role in the decay of the stone materials belonging to the church. Their formation occurs mainly on carbonate building materials, whose interaction with a sulfur oxide-enriched atmosphere leads to the transformation of calcium carbonate (calcite) into calcium sulfate dihydrate (gypsum) which, together with embedded carbonaceous particles, forms the black crusts on the stone surface. To better understand the composition and the formation dynamics of this degradation product and to identify the pollutant sources and evaluate their impact on the stone material, an analytical study was carried out on the black crust samples collected from different areas of the building. For a complete characterization of the black crusts, several techniques were used, including laser ablation inductively coupled plasma mass spectrometry, Fourier transform infrared spectroscopy, micro infrared spectroscopy, optical and scanning electron microscopy. This battery of tests provided information about the nature and distribution of the mineralogical phases and the elements within the crusts and the crust-substrate interface, contributing to the identification of the major pollution sources responsible for the deterioration of the monument over time. In addition, the results revealed a relation among the height of sampling, the surface exposure and the concentration of heavy metals. Finally, information has been provided about the origin of the concentration gradients of some metals.

A new methodological approach for the chemical characterization of black crusts on building stones: a case study from the Catania city centre (Sicily, Italy)

Mineralogical, petrographic and chemical analyses were carried out on black crusts covering the stone surface of monuments and buildings of the historical city centre of Catania, one of the most beautiful Baroque places in eastern Sicily. Black crusts were studied through the careful and synergic employment of traditional techniques, including polarizing optical microscopy (POM), scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDS), and infrared spectroscopic techniques (FT-IR), in combination with an innovative technique, i.e.laser ablation inductively coupled mass spectrometry (LA-ICP-MS). The validity of such an integrated approach to study black crusts has been recently demonstrated by the authors. The main goal of this study was to develop and test the reliability of the LA-ICP-MS method on black crusts in order to evaluate the degree of chemical contamination of examined stones and to determine the role of the different sources of pollution in Catania, both anthropogenic (domestic heating, industrial combustion, vehicular traffic) and natural (emissions by Mt Etna) in the formation of crusts. Results obtained demonstrated that this innovative approach has a double potential in the study of black crusts, since it allows the analysis of alteration and degradation processes induced by migration of specific chemical elements from the crust to substrate, and, at the same time, it represents a reliable indicator of the environmental pollution.

The Use of FTIR and Micro-FTIR Spectroscopy: An Example of Application to Cultural Heritage

Micro-FTIR and FTIR spectroscopy is useful for the study of degradation forms of cultural heritage. In particular it permits to identify the degradation phases and to establish the structural relationship between them and the substratum. In this paper, we report the results obtained on marble from a Roman sarcophagus, located in the medieval cloister of St. Cosimato Convent (Rome), and on oolitic limestone from the facade of St. Giuseppe Church in Syracuse (Sicily). The main components found in the samples of both monuments are: gypsum, calcium oxalate, and organic matter due to probably conservation treatments. In particular, the qualitative distribution maps of degradation products, obtained by means of micro-FTIR operating in ATR mode, revealed that the degradation process is present deep inside the stones also if it is not visible macroscopically. This process represents the main cause of crumbling of the substrate. The results of this research highlight the benefits of the 𝜇-FTIR analysis providing useful insights on the polishing and consolidation processes of stone materials.

Application of laser ablation ICP-MS and traditional techniques to the study of black crusts on building stones: a new methodological approach

IntroductionIn this work, we propose an innovative application of laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) as a methodological approach for the chemical characterisation of black crusts on stone monuments, associated with traditional micro-morphological (optical and scanning electron microscopy) and infrared spectroscopic techniques (FTIR).MethodsThis new approach was tested on black crusts developing on two marble substrates, one, the columns of the San Cosimato cloister in Rome, and the other, a sculpture representing an angel, located in Pessano con Bornago, a small industrial town near Milan.DiscussionThe main aim of this study was to develop and test the reliability of the LA-ICP-MS analytical method on black crusts and to explore the idea that trace element concentrations in black crusts can be applied to investigate their origin and the relations between concentrations of polluting elements in black crusts and environmental conditions.ConclusionThe results obtained by applying traditional techniques find considerable support in the innovative method used here, which could determine the concentrations of a large number of trace elements (including heavy metals) in the black crusts examined, and thus could also be used as a reliable indicator of environmental pollution.

Advanced mortar coatings for cultural heritage protection. Durability towards prolonged UV and outdoor exposure

In the present work, two kinds of hybrid polymeric–inorganic coatings containing TiO2 or SiO2 particles and prepared starting from two commercial resins (Alpha®SI30 and Bluesil®BP9710) were developed and applied to two kinds of mortars (an air-hardening calcic lime mortar [ALM] and a natural hydraulic lime mortar [HLM]) to achieve better performances in terms of water repellence and consequently damage resistance. The two pure commercial resins were also applied for comparison purposes. Properties of the coated materials and their performance were studied using different techniques such as contact angle measurements, capillary absorption test, mercury intrusion porosimetry, surface free energy, colorimetric measurements and water vapour permeability tests. Tests were also performed to determine the weathering effects on both the commercial and the hybrid coatings in order to study their durability. Thus, exposures to UV radiation, to UV radiation/condensed water cycles and to a real polluted atmospheric environment have been performed. The effectiveness of the hybrid SiO2 based coating was demonstrated, especially in the case of the HLM mortar.

New insights on the consolidation of salt weathered limestone: the case study of Modica stone

The deterioration of a stone material is related to its pore structure, which affects the interaction between surface and environmental agents. Indeed, salt crystallization is one of the most dangerous weathering agents in porous building materials. The crystallization pressure of salt crystals, growing in confined pores, is found to be the main cause for damage. The consolidation of such degraded stone materials represents a crucial issue in the field of restoration of cultural heritage. This paper presents the results of a laboratory experimentation carried out on Modica stone, a limestone largely used in the Baroque architecture of eastern Sicily. Several specimens, collected from a historical quarry near the city of Modica, were artificially degraded by salt crystallization tests. Then, degraded samples were treated with three different consolidating products: a suspension of nanolime in alcohol, a suspension of nanosilica in water, and ethyl silicate dispersed in white spirit. A systematic approach, including mercury intrusion porosimetry, peeling tests and point load test, was used to evaluate the correlation between the salt crystallization and the micro-structural features of the limestone, as well as the efficacy of treatments. The consolidating behavior of the tested products was also appraised by repeating salt crystallization tests after consolidation, in order to assess the resistance of treated stone to further salt crystallization phenomena. Results showed that nanolime provides a good resistance to the stone; conversely, ethyl silicate, although inducing an enhancement of stone cohesion, leads to an increase of the crystallization pressure, which generates dangerous susceptibility to weathering.

Handheld XRF and Raman equipment for the in situ investigation of Roman finds in the Villa dei Quintili (Rome, Italy)

In the present work, a variety of fragments of frescoes coming from the Villa dei Quintili in Rome (Italy) and dating back to the II century A.D. were subjected to, first of all, an X-ray fluorescence (XRF) analysis by optimizing a portable spectrometer for non-destructive investigation in the field of cultural heritage. The innovative aspect is the ability to obtain coloured maps referring to the distribution and concentration of elements present in the sample. Other than characterization, the aim was to improve the technique for non-invasive and fast in situ analysis. It has been performed, in conjunction with portable Raman analysis, at the ruins of the Villa dei Quintili on samples of different typologies including pottery, statues and frescoes, dating back to the II/III century A.D., different in colour, support and shape. From the results, the identification of the main pigmenting agents is attempted, providing the group of archaeologists in the villa with extremely valuable information for their work too. In particular, by comparing the XRF results for frescoes analysed in the laboratory, taken from the warehouse of the villa, and XRF and Raman data of frescoes analysed in situ, for which the provenance area inside the villa was known, the context of excavation and the manufacture process for some of the former has been hypothesized.

Mosaic marble tesserae from the underwater archaeological site of Baia (Naples, Italy): determination of the provenance

This paper is focused on defining the geographic provenance of eight marble tesserae of archaeological interest used for the opus sectile floor slabs of the Villa con ingresso a protiro , located in the Roman underwater Archaeological Park of Baia (Naples, Italy). Geochemical, isotopic and petrographic data show that Carrara, Thasian and Docimium/Afyon marbles were used in manufacturing the mosaic constituting the floor slabs of the Roman Villa.