Arianna Gambirasi - Academia.edu (original) (raw)
Papers by Arianna Gambirasi
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
NaCuO 2 has been prepared via electrodeposition from a sodium hydroxide/potassium hydroxide melt ... more NaCuO 2 has been prepared via electrodeposition from a sodium hydroxide/potassium hydroxide melt and characterized by single crystal and powder X-ray diffraction, magnetic susceptibility, and resistivity. Clusters of blue-black plate-like and needle crystals are grown at positive potentials on a platinum anode with a platinum or a zirconium crucible serving as the cathode and a platinum reference electrode. Details of the electrochemical procedure are described, along with a cyclic voltammogram. NaCuO2 exhibits temperature independent paramagnetism over the temperature range 30-300 K. Its room temperature resistivity is greater than 106 fl-cm.
Electrochimica Acta, Oct 1, 2011
A method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and ... more A method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and Ni nanowires with diameters from 1.0 m to 0.2 m are directly deposited on the electrode surface using a polycarbonate membrane filter template maintained in contact with the metal substrate by the soft homogeneous pressure of a sponge soaked with electrolyte. The morphologic and structural properties of the deposit are characterized by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The latter shows that the head of nanowires with diameter of 0.4 m is ordinarily polycrystalline, and that of nanowires with diameter of 0.2 m is almost always monocrystalline for Cu and frequently also for Ni. Cyclic voltammetries and impedance investigations recorded in alkaline solutions at representative Ni electrodes decorated with nanowires provide consistent values of roughness factor, in the range 20-25.
Electrochimica Acta, Sep 1, 2012
This study presents an electrosynthetic methodology to obtain hierarchically structured ZnO elect... more This study presents an electrosynthetic methodology to obtain hierarchically structured ZnO electrodes with improved surface area, by exploiting gold nanowires ensembles (3D-NEEs) as the growing substrate. By this way, semiconductor electrodes organized in the shape of fir-like branches are obtained. Branched nanofibres are characterized by electron microscopy and electron backscatter diffraction (EBSD), the latter technique allowing the determination of the crystalline habit of individual nanostructures. The hierarchical branched nanowires show enhanced performances with respect to water photooxidation in comparison with already known nanostructured materials such as 1D-ZnO nanowires.
Chemical Engineering Journal, 2016
Abstract The catalytic combustion of methanol in air under lean dry conditions has been studied u... more Abstract The catalytic combustion of methanol in air under lean dry conditions has been studied using Pt–Fecralloy catalysts. These catalysts were prepared by cathodic electrodeposition of Pt onto commercial 50 ppi Fecralloy foams, controlling the noble metal loading through the Pt deposition charge. The catalysts were characterized by SEM and XRD at three different stages (as-prepared, after 2 h pretreatment at 600 °C in air and after use in methanol combustion) and their Pt surface area was estimated by cyclic voltammetry. In combustion tests, methanol oxidation started at temperatures as low as 80 °C, and reached 100% conversion to CO 2 at temperatures that decreased progressively for Pt loadings increasing from 0.8 to 13 mg cm −3 . The apparent activation energy of methanol combustion was estimated to be 68–70 kJ mol −1 , independent of the Pt loading of the samples. Repeated combustion cycles converged with SEM, XRD characterization of used catalysts to prove the stability of Pt–Fecralloy, under the conditions employed in the tests.
Progress in Organic Coatings, 2017
Because stone surfaces in outdoor environments are exposed to natural and human-induced physico-c... more Because stone surfaces in outdoor environments are exposed to natural and human-induced physico-chemical agents, they are often treated with synthetic coatings to prevent their deterioration. To enable the best possible preservation of stone materials, it is crucial to examine the performances of those protective treatments. Many studies have been conducted to inspect the water-repellence properties of a variety of coatings, while their effects on airborne particle deposition are poorly established. In this work, the effects of the application of different protective treatments to marble surfaces exposed to an urban environment were investigated in relation to particle deposition and colour variation. Five commercial products for the preservation of stone buildings, including siloxanic, fluorinated and TiO 2-based coatings, were selected and applied to Carrara marble samples, which were exposed outdoors in the historic centre of Florence (Italy). The morphology and the chemical composition of particles deposited on the samples surfaces after one year were investigated by combining scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX). Cluster analysis and principal component analysis were then applied to SEM-EDX data, to identify the main sources of the deposited particles and to assess the performance of the applied products. Moreover, changes in surface colour due to both the application of the products and the outdoor exposure were evaluated using spectrocolorimetry. Based on the experimental results, all the treated surfaces showed a lower proneness to particle deposition and colour alteration in comparison to an untreated surface. In particular, among the tested products, organosilicon-based and fluorinated acrylic polymers were identified as the best performing protective coatings. Additionally, the experimental and statistical methodology used for this study proved a suitable approach for the investigation of deposition phenomena on stone surfaces.
Applied Physics A, 2016
Many historical 'silver' objects are composed of sterling silver, a silver alloy containing small... more Many historical 'silver' objects are composed of sterling silver, a silver alloy containing small amounts of copper. Besides the dramatic impact of copper on the corrosion process, the chemical composition of the corrosion layer evolves continuously. The evolution of the surface during the exposure to a Na2S solution was monitored by means of visual observation at macroscopic level, chemical analysis at microscopic level and analysis at the nanoscopic level. The corrosion process starts with the preferential oxidation of copper, forming mixtures of oxides and sulphides while voids are being created beneath the corrosion layer. Only at a later stage, the silver below the corrosion layer is consumed. This results in the formation of jalpaite and at a later stage of acanthite. The acanthite is found inside the corrosion layer at the boundaries of jalpaite grains and as individual grains between the jalpaite grains but also as a thin film on top of the corrosion layer. The corrosion process could be described as a sequence of 5 subsequent surface states with transitions between these states.
Journal of Cultural Heritage, 2016
Abstract Cleaning of historical stone surfaces has always been a challenging task, moreover in th... more Abstract Cleaning of historical stone surfaces has always been a challenging task, moreover in the last decades arose new restorations issues such as the need to remove aged conservation polymeric materials to avoid further damage. Different cleaning methodologies flourished in the past, mostly based on chemical, mechanical methods and on laser technology too. Nevertheless, these methodologies could not be so efficient in the removal of epoxy resins, acrylic polymers and hydrophobic siloxanes, because of their low solubility in solvents when aged or their high adhesion with the substrate. More recently, atmospheric plasma has been tested for such application even if it is not yet widely applied due to the lack of knowledge about possible side-effects on the artefacts. In the present work, assessment of three commercial atmospheric plasma devices (plasma torches) illustrated the potentialities and drawbacks of polymers’ removal from stone surface. Commercial epoxy resins, acrylic polymers and hydrophobic siloxanes were chosen for the removal test by plasma devices. Physical and chemical effects on the stone surface and the process efficiency were investigated by means of macro- and microscopic observations, preferring, when possible, non-invasive techniques and consolidated methodologies in the field of Stone Conservation Science. An introductory experimentation on coated Si specimen has allowed to find the proper working parameters, i.e. working distance, exposure time, to have an effective removal. The experimentation conducted on different lithic substrate, coated with the commercial protective, has showed that commercial devices are effective in the removal of epoxy and acrylic coatings via chemical and physical interactions. On the contrary, the removal of siloxane products is incomplete, because of the high stability of the bond Si–O in the back bone, which is not affected by the plasma. In general, the present trials highlighted that DBD apparatus used does not promote any macroscopic effects on the polymeric coating, while arc discharge ones guarantee satisfactory results. According to these preliminary trials, it was clearly evidenced that plasma is a potential cleaning tool, despite DBD systems need higher power or arc discharge needs treatment temperature mitigation and to avoid the deposition of metallic drops on the surface of the object due to electrode deterioration.
Since ancient times, several products have been used to prevent the deterioration of building sur... more Since ancient times, several products have been used to prevent the deterioration of building surfaces due to the adverse environmental factors in Venice. Natural products, mainly oxalate bearing solutions, waxes and other mixtures of vegetal and animal derivatives, were primarily used in the past to strengthen the stone surface and to prevent the effect of marine aerosols. In XIX century new products were introduced in the field thanks to the strong improvement of chemistry, which brought to several recipes for stone treatment. Most employed in Venice at that time were the silicate and fluosilicate treatments according to the Fuchs (1818), Kulmann (1854), Ransome (185660) and Kessler (1883) patents. Notwithstanding the innovations, the use of natural products was not abandoned until the middle of XX century, when polymers were introduced in the market and suddenly took the place of most traditional products, also in the occasion of the deleterious flood in 1966, that made clear the...
The impact of climate change on built heritage and the development of new preventive conservation... more The impact of climate change on built heritage and the development of new preventive conservation methods are nowadays topics seen as priorities by the scientifi c community involved in cultural heritage preservation. However, damage processes due to the environment-materials interaction are irreversible and often inevitable for outdoor built heritage. Research has therefore recently been focusing on the development of new materials specifi cally geared towards conservation use, such as consolidating and protective treatments, which meet the criteria of compatibility and durability. The ongoing European Project NANOMATCH has as one of the main objectives the development of an innovative nanostructured material for the consolidation of carbonate stones. An alkaline earth alkoxide as precursor of calcium carbonate has been synthesized to overcome the limits that traditional consolidating agents exhibit. As part of the research work, fi eld exposure tests are planned for the evaluation...
ECS Meeting Abstracts
Bipolar electrochemistry occurs when faradaic reactions are driven on electronic conductor not di... more Bipolar electrochemistry occurs when faradaic reactions are driven on electronic conductor not directly connected to an electrical power source, but in contact with a dielectric (typically a solution) which is polarized under the influence of an applied electric field. Bipolar electrochemical cells can be designed according to two configurations: open bipolar electrochemical cells (OBPECs) 1-3 and closed bipolar electrochemical cells (CBPECs) 4,5. In OBPEC, the bipolar electrode (BPE) is a conductor immersed in an electrolyte solution. When a voltage is applied between two driving electrodes (not in direct contact with the BPE), a potential difference between the two poles of the BPE and the electrolyte solution is generated by the polarization of the latter. The extent of polarization at the two ends of the BPE is directly proportional to the intensity of the electric field and inversely proportional to the critical dimension (e.g. length) of the BPE. As a consequence, for perfo...
An entry from the Cambridge Structural Database, the world's repository for small molecule cr... more An entry from the Cambridge Structural Database, the world's repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
NaCuO 2 has been prepared via electrodeposition from a sodium hydroxide/potassium hydroxide melt ... more NaCuO 2 has been prepared via electrodeposition from a sodium hydroxide/potassium hydroxide melt and characterized by single crystal and powder X-ray diffraction, magnetic susceptibility, and resistivity. Clusters of blue-black plate-like and needle crystals are grown at positive potentials on a platinum anode with a platinum or a zirconium crucible serving as the cathode and a platinum reference electrode. Details of the electrochemical procedure are described, along with a cyclic voltammogram. NaCuO2 exhibits temperature independent paramagnetism over the temperature range 30-300 K. Its room temperature resistivity is greater than 106 fl-cm.
Electrochimica Acta, Oct 1, 2011
A method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and ... more A method for decorating the surface of disk electrodes with metal nanowires is presented. Cu and Ni nanowires with diameters from 1.0 m to 0.2 m are directly deposited on the electrode surface using a polycarbonate membrane filter template maintained in contact with the metal substrate by the soft homogeneous pressure of a sponge soaked with electrolyte. The morphologic and structural properties of the deposit are characterized by scanning electron microscopy (SEM) and electron backscatter diffraction (EBSD). The latter shows that the head of nanowires with diameter of 0.4 m is ordinarily polycrystalline, and that of nanowires with diameter of 0.2 m is almost always monocrystalline for Cu and frequently also for Ni. Cyclic voltammetries and impedance investigations recorded in alkaline solutions at representative Ni electrodes decorated with nanowires provide consistent values of roughness factor, in the range 20-25.
Electrochimica Acta, Sep 1, 2012
This study presents an electrosynthetic methodology to obtain hierarchically structured ZnO elect... more This study presents an electrosynthetic methodology to obtain hierarchically structured ZnO electrodes with improved surface area, by exploiting gold nanowires ensembles (3D-NEEs) as the growing substrate. By this way, semiconductor electrodes organized in the shape of fir-like branches are obtained. Branched nanofibres are characterized by electron microscopy and electron backscatter diffraction (EBSD), the latter technique allowing the determination of the crystalline habit of individual nanostructures. The hierarchical branched nanowires show enhanced performances with respect to water photooxidation in comparison with already known nanostructured materials such as 1D-ZnO nanowires.
Chemical Engineering Journal, 2016
Abstract The catalytic combustion of methanol in air under lean dry conditions has been studied u... more Abstract The catalytic combustion of methanol in air under lean dry conditions has been studied using Pt–Fecralloy catalysts. These catalysts were prepared by cathodic electrodeposition of Pt onto commercial 50 ppi Fecralloy foams, controlling the noble metal loading through the Pt deposition charge. The catalysts were characterized by SEM and XRD at three different stages (as-prepared, after 2 h pretreatment at 600 °C in air and after use in methanol combustion) and their Pt surface area was estimated by cyclic voltammetry. In combustion tests, methanol oxidation started at temperatures as low as 80 °C, and reached 100% conversion to CO 2 at temperatures that decreased progressively for Pt loadings increasing from 0.8 to 13 mg cm −3 . The apparent activation energy of methanol combustion was estimated to be 68–70 kJ mol −1 , independent of the Pt loading of the samples. Repeated combustion cycles converged with SEM, XRD characterization of used catalysts to prove the stability of Pt–Fecralloy, under the conditions employed in the tests.
Progress in Organic Coatings, 2017
Because stone surfaces in outdoor environments are exposed to natural and human-induced physico-c... more Because stone surfaces in outdoor environments are exposed to natural and human-induced physico-chemical agents, they are often treated with synthetic coatings to prevent their deterioration. To enable the best possible preservation of stone materials, it is crucial to examine the performances of those protective treatments. Many studies have been conducted to inspect the water-repellence properties of a variety of coatings, while their effects on airborne particle deposition are poorly established. In this work, the effects of the application of different protective treatments to marble surfaces exposed to an urban environment were investigated in relation to particle deposition and colour variation. Five commercial products for the preservation of stone buildings, including siloxanic, fluorinated and TiO 2-based coatings, were selected and applied to Carrara marble samples, which were exposed outdoors in the historic centre of Florence (Italy). The morphology and the chemical composition of particles deposited on the samples surfaces after one year were investigated by combining scanning electron microscopy and energy dispersive X-ray microanalysis (SEM-EDX). Cluster analysis and principal component analysis were then applied to SEM-EDX data, to identify the main sources of the deposited particles and to assess the performance of the applied products. Moreover, changes in surface colour due to both the application of the products and the outdoor exposure were evaluated using spectrocolorimetry. Based on the experimental results, all the treated surfaces showed a lower proneness to particle deposition and colour alteration in comparison to an untreated surface. In particular, among the tested products, organosilicon-based and fluorinated acrylic polymers were identified as the best performing protective coatings. Additionally, the experimental and statistical methodology used for this study proved a suitable approach for the investigation of deposition phenomena on stone surfaces.
Applied Physics A, 2016
Many historical 'silver' objects are composed of sterling silver, a silver alloy containing small... more Many historical 'silver' objects are composed of sterling silver, a silver alloy containing small amounts of copper. Besides the dramatic impact of copper on the corrosion process, the chemical composition of the corrosion layer evolves continuously. The evolution of the surface during the exposure to a Na2S solution was monitored by means of visual observation at macroscopic level, chemical analysis at microscopic level and analysis at the nanoscopic level. The corrosion process starts with the preferential oxidation of copper, forming mixtures of oxides and sulphides while voids are being created beneath the corrosion layer. Only at a later stage, the silver below the corrosion layer is consumed. This results in the formation of jalpaite and at a later stage of acanthite. The acanthite is found inside the corrosion layer at the boundaries of jalpaite grains and as individual grains between the jalpaite grains but also as a thin film on top of the corrosion layer. The corrosion process could be described as a sequence of 5 subsequent surface states with transitions between these states.
Journal of Cultural Heritage, 2016
Abstract Cleaning of historical stone surfaces has always been a challenging task, moreover in th... more Abstract Cleaning of historical stone surfaces has always been a challenging task, moreover in the last decades arose new restorations issues such as the need to remove aged conservation polymeric materials to avoid further damage. Different cleaning methodologies flourished in the past, mostly based on chemical, mechanical methods and on laser technology too. Nevertheless, these methodologies could not be so efficient in the removal of epoxy resins, acrylic polymers and hydrophobic siloxanes, because of their low solubility in solvents when aged or their high adhesion with the substrate. More recently, atmospheric plasma has been tested for such application even if it is not yet widely applied due to the lack of knowledge about possible side-effects on the artefacts. In the present work, assessment of three commercial atmospheric plasma devices (plasma torches) illustrated the potentialities and drawbacks of polymers’ removal from stone surface. Commercial epoxy resins, acrylic polymers and hydrophobic siloxanes were chosen for the removal test by plasma devices. Physical and chemical effects on the stone surface and the process efficiency were investigated by means of macro- and microscopic observations, preferring, when possible, non-invasive techniques and consolidated methodologies in the field of Stone Conservation Science. An introductory experimentation on coated Si specimen has allowed to find the proper working parameters, i.e. working distance, exposure time, to have an effective removal. The experimentation conducted on different lithic substrate, coated with the commercial protective, has showed that commercial devices are effective in the removal of epoxy and acrylic coatings via chemical and physical interactions. On the contrary, the removal of siloxane products is incomplete, because of the high stability of the bond Si–O in the back bone, which is not affected by the plasma. In general, the present trials highlighted that DBD apparatus used does not promote any macroscopic effects on the polymeric coating, while arc discharge ones guarantee satisfactory results. According to these preliminary trials, it was clearly evidenced that plasma is a potential cleaning tool, despite DBD systems need higher power or arc discharge needs treatment temperature mitigation and to avoid the deposition of metallic drops on the surface of the object due to electrode deterioration.
Since ancient times, several products have been used to prevent the deterioration of building sur... more Since ancient times, several products have been used to prevent the deterioration of building surfaces due to the adverse environmental factors in Venice. Natural products, mainly oxalate bearing solutions, waxes and other mixtures of vegetal and animal derivatives, were primarily used in the past to strengthen the stone surface and to prevent the effect of marine aerosols. In XIX century new products were introduced in the field thanks to the strong improvement of chemistry, which brought to several recipes for stone treatment. Most employed in Venice at that time were the silicate and fluosilicate treatments according to the Fuchs (1818), Kulmann (1854), Ransome (185660) and Kessler (1883) patents. Notwithstanding the innovations, the use of natural products was not abandoned until the middle of XX century, when polymers were introduced in the market and suddenly took the place of most traditional products, also in the occasion of the deleterious flood in 1966, that made clear the...
The impact of climate change on built heritage and the development of new preventive conservation... more The impact of climate change on built heritage and the development of new preventive conservation methods are nowadays topics seen as priorities by the scientifi c community involved in cultural heritage preservation. However, damage processes due to the environment-materials interaction are irreversible and often inevitable for outdoor built heritage. Research has therefore recently been focusing on the development of new materials specifi cally geared towards conservation use, such as consolidating and protective treatments, which meet the criteria of compatibility and durability. The ongoing European Project NANOMATCH has as one of the main objectives the development of an innovative nanostructured material for the consolidation of carbonate stones. An alkaline earth alkoxide as precursor of calcium carbonate has been synthesized to overcome the limits that traditional consolidating agents exhibit. As part of the research work, fi eld exposure tests are planned for the evaluation...
ECS Meeting Abstracts
Bipolar electrochemistry occurs when faradaic reactions are driven on electronic conductor not di... more Bipolar electrochemistry occurs when faradaic reactions are driven on electronic conductor not directly connected to an electrical power source, but in contact with a dielectric (typically a solution) which is polarized under the influence of an applied electric field. Bipolar electrochemical cells can be designed according to two configurations: open bipolar electrochemical cells (OBPECs) 1-3 and closed bipolar electrochemical cells (CBPECs) 4,5. In OBPEC, the bipolar electrode (BPE) is a conductor immersed in an electrolyte solution. When a voltage is applied between two driving electrodes (not in direct contact with the BPE), a potential difference between the two poles of the BPE and the electrolyte solution is generated by the polarization of the latter. The extent of polarization at the two ends of the BPE is directly proportional to the intensity of the electric field and inversely proportional to the critical dimension (e.g. length) of the BPE. As a consequence, for perfo...