Fausto Langerame

A temporal monitoring of monumental buildings in calcarenite, exposed outdoors in the considered Mediterranean environment of Southern Italy, was performed using XPS, the surface-specific technique. The methodology adopted to monitor the surfaces interacting with atmospheric agents and biotic/abiotic pollutants involved progressive sampling, extended to about five years, from the walls of a new building, specifically installed in the immediate vicinity of an ancient farmhouse in an advanced state of degradation. Taking the ancient building as the final temporal reference, the aim was to obtain adequate information on the degradation processes of calcarenitic stones, from the initial and evolving phases of the new building towards those representative of the old reference. A large set of XPS data was obtained by resolving, through curve-fitting, the acquired spectra into component peaks, identified as ‘indicator’ chemical groups, which trend as a function of time, supported by PCA, demonstrates a close compositional similarity between the samples of the new building analyzed after 52 months from its installation and those of the ancient building dating back to over a century ago. The results obtained can be considered in the diagnostic strategy of the ongoing PNRR programs dedicated to the care of historical monuments and ecosystem sustainability.

A temporal monitoring of monumental buildings in calcarenite, exposed outdoors in the considered Mediterranean environment of Southern Italy, was performed using XPS the surface-specific technique. The methodology adopted to monitor the surfaces interacting with atmospheric agents and biotic/abiotic pollutants has involved the progressive sampling, extended to about five years, from the walls of a new building, specifically installed in the immediate vicinity of an ancient farmhouse in an advanced state of degradation. Taking the ancient building as the final temporal reference, the aim was to obtain adequate information on the degradation processes of calcarenitic stones, from the initial and evolving phases of the new building towards those representative of the old reference. A large set of XPS data was obtained by resolving, through curve fitting, the acquired spectra into component peaks, identified as ‘indicator’ chemical groups, whose trend as a function of time, supported by PCA analysis, demonstrates a close compositional similarity between the samples of the new building analyzed after 52 months from its installation and those of the ancient building dating back to over a century ago. The results obtained can be considered in the diagnostic strategy of the ongoing PNRR programs dedicated to the care of historical monuments and ecosystem sustainability.

The reaction of pyridinium chlorochromate with furan to give enedione derivatives cannot be performed by using commercial PCC. Homemade and commercial PCC had different color and showed some differences in the XRD spectrum. XPS showed the presence of relevant amount of Cr(III) in the homemade reagent. DFT calculations showed that Cr(III) impurities in the reagent can catalyze the reaction with furan derivatives, if oxygen atom in the Cr(III) derivative attacks the furan ring, while it is reoxidized by PCC, through a migration of a chlorine atom.

The aim of this research was to evaluate the multiple effects of both thermal modification and alkyl ketene dimer (AKD) on the deodar cedar (Cedrus deodara Roxb.) wood surface, before and after an irradiation test. The physical and chemical changes that occurred on the cedar wood samples due to the combined effect of these modifications were evaluated by measuring their wettability and colour and using attenuated total reflection Fourier-transform infrared spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The surface analysis by XPS showed the expected variability among the sampled layers for unmodified and thermally modified cedar wood samples and a uniform composition after the AKD coverage, regardless of their pre-treatments. The FTIR spectra before the irradiation test showed that the hydrophobicity of the samples was ensured by the formation of carbonyl groups originating from the reaction between the AKD and hydroxyl groups of cellulose, which is related to the presence of the absorption band between 1700 cm⁻¹ and 1750 cm⁻¹. Markedly, after the irradiation test, a degradation of the amorphous cellulose component occurred, showing that photoisomerisation to the enolic form took place. Overall, although uniform AKD coverage was derived from the surface analysis and wetting test, the combined ATR-FTIR results and colour measurements showed that it could not provide permanent protection to the underlying wood structure due to its own tendency to degrade mainly in colour over time, under the action of UV rays and atmospheric agents.

Limestone basements holding bronzes or other copper alloys artefacts such as sculptures, decorations and dedicatory inscriptions are frequently met both in modern and ancient monuments. In outdoor conditions, such a combination implies the corrosion products of the copper based alloy, directly exposed to rainwater, will be drained off and migrate through the porous surfaces, forming stains of different colours and intensities, finally causing the limestone structures to deteriorate.