Air pollution effect of SO2 and/or aliphatic hydrocarbons on marble statues in Archaeological Museums.

This study allowed the identification of the main physicochemical characteristics of deterioration of the materials used in the construction of Greek ancient statues in order to plan a correct methodology of restoration. The method of Reversed-Flow Inverse Gas Chromatography is appropriate to investigate the influence of air pollutants on authentic pieces from the Greek Archaeological Museum of Kavala, near Salonica. Six local physicochemical quantities which refer to the influence of one or two pollutants (synergistic effect) were determined for each system. These quantities answer the question "when, why and how materials of cultural heritage are attacked".

Gas chromatographic study of degradation phenomena concerning building and cultural heritage materials.

Air pollution influences all aspects of social and economical life nowadays. In order to investigate the impact of air pollution on materials of works of art, the method of Reversed Flow-Inverse Gas Chromatography has been selected. The presence of various atmospheric pollutants is studied on marbles, oxides--building materials and samples of authentic statues from the Greek Archaeological Museums of Kavala and of Philippi. The method leads to the determination of several physicochemical quantities and the characterization of the heterogeneous surfaces of these solids. Moreover, the influence of a second pollutant (synergistic effect) is examined. The structure, the properties and the behavior of the materials are examined by X-Ray Diffraction, Scanning Electron Microscopy and Raman Spectroscopy. Therefore, the precise measurement of the above mentioned quantities form the scientific basis for elucidation of the mechanism of the whole phenomenon of the degradation, thus providing a scientific platform to conservation procedures.

Hydrogenation of 1-butene on nanosized Pd/ZnO catalysts.

The reaction concerning the hydrogenation of 1-butene has occupied the researchers conducting research based on the method of reversed-flow inverse gas chromatography (RF-IGC), for extended time periods. This work aims to define and record, with the utmost accuracy, the phenomena and their possible parallel reactions. It was a challenge for the RF-IGC, which was met. The venture consisted of many parts. Answers had to be provided to the following questions: (a) Can RF-IGC deal with issues of catalysis? (b) Can RF-IGC be applied to thin films? (c) Can RF-IGC identify peaks? (d) Can RF-IGC define the gnostic regions of adsorption, desorption, surface diffusion, surface reaction, the existence of more than one reaction? (e) Can it kinetically follow the above? The answer is certainly yes. The effort made is presented in this work and aims to answer all the above questions.

Development and characterization of ZnO, Au/ZnO and Pd/ZnO thin films through their adsorptive and catalytic properties.

In this paper, we report (a) the development of ZnO thin films prepared by pulsed laser deposition and partially covered with nano-particles Pd or Au and (b) their physicochemical study, in order to investigate their catalytic and/or adsorptive properties. It is the first time where two different and popular methods, namely pulsed laser deposition and reversed flow-inverse gas chromatography, are combined. The inverse gas chromatographic technique with the corresponding time-resolved analysis is used for the first time in order to characterise compounds in the nano-scale domain. We focus on the determination of physicochemical quantities mainly concerning the adsorption in thin films, with (Pd/ZnO) or without (Au/ZnO) catalytic behaviour. Thus, entropy and other important physicochemical quantities are calculated which reveal the mechanism of adsorption as well as of isomerization-hydrogenation of 1-butene and contribute to the study of heterogeneity of thin film surfaces. The programs used have been written in Fortran. An important achievement is also the determination of the standard deviations of the kinetic constants.

Physicochemical characterization of interfaces.

Reversed-flow inverse gas chromatography (RF-IGC) was used to measure, directly from experimental data, adsorption energies, local adsorption isotherms, the probability density function for the adsorption energies, and lateral interaction parameters, as distributed over experimental time. Local isotherms and the distribution energy function were correlated with adsorption energy. The results obtained are comparable to those calculated on the basis of the well-known integral equation. The RF-IGC method was used with the two most common hydrocarbons, acetylene and 1-butene, as probe gases, in the presence and absence of ozone, and with magnesium oxide and silicon oxide as solid adsorbents.

Experimental determination of adsorption energies, adsorption isotherms, probability density functions, and lateral molecular interactions on CXHY/CaO systems.

Reversed-flow gas chromatography (RF-GC) is extended to the measurements of the probability density function for the adsorption energies as well as the differential energies of adsorption due to lateral interactions of molecules adsorbed on different heterogeneous solid surfaces. All these calculations are based on a non-linear adsorption isotherm model as it is well accepted that the linear one is inadequate for substances such as these used in this work. Thus, some new important physicochemical parameters have been obtained for the characterization of the heterogeneous systems studied. The adsorbent used in this study was calcium oxide. The adsorption of many significant hydrocarbons was investigated. With these systematic experiments under conditions which are similar to the atmospheric ones, an extrapolation of the results obtained to "real" atmospheres with a high degree of confidence is possible.

Experimental adsorption isotherms based on inverse gas chromatography.

A new chromatographic perturbation method is used for studying the adsorption-desorption equilibrium in various gas-solid heterogeneous systems. It is the reversed-flow method giving accurate and precise values of many physicochemical constants including the basic and necessary adsorption isotherm values. For four inorganic oxides, namely, Cr2O3, Fe2O3, TiO2 and PbO, and two aromatic hydrocarbons (benzene, toluene) these adsorption isotherms have been determined through a non-linear model.

Corrosive effects from the deposition of gaseous pollutants on surfaces of cultural and artistic value inside museums.

The objectives of the project were to assess the critical relationships between environmental factors and damage of the artifacts and other cultural property exposed inside museums, by studying: (a) the outdoor/indoor pollutant concentration and their transfer inside the museum; (b) the distribution and circulation of pollutants inside the museum influenced by various factors; (c) chemical interactions between pollutants in the gas phase leading to removal and/or formation of secondary pollutants; (d) the final deposition of the indoor pollutants on surfaces of artistic interest and the damage on them, governed by strictly defined physicochemical parameters. All the above information, together with the main factors influencing each stage, were obtained by applying the methodology developed and described in detail here. Measurements of rate constants of reactions in the gas phase, of physicochemical deposition parameters on artefacts, and the synergistic effects of pollutants on the deposition parameters, were conducted. Seven PC programmes for analysing the experimental data were written and used. The pollutants, the solid materials and the museums chosen in this programme are only examples needed to develop the necessary methodology. The numerical results obtained serve the purpose of exemplifying the procedures and not enriching the world's bibliography with useless empirical information. Two commercially available protectives for marble were investigated from the point of view of their reactivity towards SO2 by using a diffusional technique. From measurements of SO2 concentration carried out on three types of marble, the deposition velocities have been calculated. Indoor monitoring of the church of San Luigi dei Francesi and of the Museo della Civiltá Romana in Rome has shown that indoor production of nitrous acid most likely results from heterogeneous reactions indoors, on the walls and the exposed surfaces.