Papers by Author: Giovanni Baldi

Abstract: Nowadays the use of multifunctional nanomaterials has significantly increased with interesting applications for the cultural heritage conservation sector, leading to the definition and use of products with innovative properties. Therefore, a preliminary validation of the performances and behavior over time of these treatments becomes an unavoidable key point for a correct use of these products before being applied to historical materials, in order to avoid irreparable damage over time. In this direction, the aim of this study was to evaluate the effectiveness of the treatment with multifunctional nanostructured products on Apuan marble. The focus of the work was to test methods to accelerate aging, in order to simulate different environmental agents of degradation to which marble in historical buildings can be exposed. Stone samples were examined after exposition to high temperature cycles in a muffle furnace, treatments in saline solution, cycles of thermal shock and aging by SO₂ action in presence of humidity. After each artificial aging cycle, changes in appearance were noted and chemical-physical properties were measured in order to compare differences between fresh and treated samples. The protective qualities of the coatings were evaluated using the following tests: contact angle; photocatalytic properties by methylene blue degradation tests; photodegradation kinetics of pollutants under UVA irradiation. Before and after the treatments, scanning electron microscopy equipped by microanalysis detector (SEM-EDS) was also used to evaluate changes in the surface morphology of the samples. The results showed effects of degradation in the rock samples due to aging after each test and all the products applied to the sample surface seemed to be very efficient in relation to their functions.

Abstract: In the last years there was an increasing interest of the scientific and technological community in the field of healthy and ecological buildings. Nanotechnology gives a substantial contribution in the development of new advanced materials, environmentally sustainable and safe for the consumers. Due to their multi-functional behaviour, nano-materials are at the basis of a revolutionary technical improvement in buildings: titania nano-structured films are applied on ceramic and glass surfaces increasing drastically the self-cleaning and anti bacterial activity. Substrates with controlled porosity can be designed to obtain anti-pollution surfaces either for external and internal environments, a photo reactor has been developed in our laboratory: a device to assess the photo degradation kinetic of pollutants (NOx and VOC’s) and help customers in the certification of eco-buildings. Surfaces based on nano-silver have been also developed leading to an anti bacterial effect in absence of light meanwhile anti-scratch and zero porosity substrates can be obtained from nano-zirconia and nano-silica suspensions. CERICOL has developed and scaled-up a “green chemistry” synthesis in water or glycols allowing simple industrial applications on different substrates as tiles, glass, plastic, paint, wood and concrete.

Abstract: A formulation belonging to the CaO-MgO-SiO2-Al2O3 system was characterized in order to found a monophase system based on indialite (Mg2Al4Si5O18), known for its good mechanical characteristics. The classical kinetic studies performed in the muffle kiln show an initial surface crystallization followed from immediate bulk crystallization. The kinetic results obtained via differential scanning calorimetry (DSC) were treated with isothermal method, Kissinger, Ozawa and Matusita and Sakka approaches and compared. These results partially explain the macroscopic behavior, because the studies performed on sample of different grain size show a typical trend for a surface crystallization, while the value of Avrami parameter calculated from the kinetics is 2.3, demonstrating a bi-dimensional crystallization. The value of crystallization energy EC calculated with the isothermal method is 517.8 kJmol-1 and the comparison with nonisothermal studies suggests bulk crystallization to occur with an increasing number of nuclei and a two-dimensional growth of crystals.

Abstract: Ink-jet printing is becoming a leading technology for traditional ceramics, due to its capacity of reproducing highly resolved and customized images on tile surfaces. Nano-sized inks, produced by the polyol synthesis route, proved to fulfil the printing requirements, tailoring their chemico-physical properties (e.g. viscosity, surface tension) on industrial ink-jet devices, so representing a major breakthrough in the quadrichromy process.

Abstract: Nanocrystalline titania pigments were produced by a novel synthesis route consisting of a high temperature forced hydrolysis in a coordinating high-boiling solvent. The effect of synthesis conditions as well as doping with Cr, Sb and V on the particle size and on the anatase-to-rutile transformation was studied by temperature-resolved synchrotron powder diffraction. The experiments were performed directly on as-synthesized low concentration suspensions of titania nanoparticles (up to 230°C) and on dried titania nanoparticles (up to 950°C). Crystallite size of as-synthesized nanoparticles is in the 5 to 50 nm range, being affected by the synthesis conditions as well as by doping and exhibits a slow-rate coarsening trend with temperature. The anatase-to-rutile transformation is drastically influenced by both synthesis conditions and doping. In particular, doping affected the anatase-to-rutile transformation rate, while the synthesis conditions influenced the phase composition, causing the appearance of brookite.