Temperature Matters: An Infrared Spectroscopic Investigation on the Photocatalytic Efficiency of Titania Coatings

Titania is one of the most studied photocatalytic materials for self-cleaning applications. To maximize the photocatalytic efficiency, different strategies are currently under investigation, such as control of the nano- or microstructure, optimization of the crystalline phase and addition of doping agents. A parameter too often neglected is temperature, which dramatically affects the self-cleaning processes in thin titanium dioxide (TiO2) films. In this study, we prepared a titania coating using the sol–gel route. Stearic acid and a triblock copolymer (Pluronic F127) were used as model pollutants. A dedicated heating cell was used to precisely control the temperature. The infrared spectroscopy was used to follow the amount of residual pollutant agents within 60 minutes every 10 C. The photocatalytic reaction rate was calculated for the stearic acid in the 25–60 C range

Evaluating two nanosilica dimensional range for the consolidation of degraded silicate stones

The application of silica nanoparticles strengthening agents in conservation of monumental and architectural heritage field is currently a challenge of particular interest. Some commercial products are already on the market and several studies highlighted the related strength and weakness. In order to contribute to the knowledge of the interaction between nanoparticles and stone materials as well as to provide key elements to improve the approach to conservative treatments, two silica nanoparticles products for the consolidation of silicate stones were developed in the laboratory. Bianco Sardo granite, Firenzuola and Muggia sandstones were selected as substrates for the experimentation after a laboratory investigation of their open porosity. Silica nanoparticles having two different particles size, both compatible with the porosimetric features of the selected stones, were synthesized and dispersed in an ethanol-water solution. The carrier was specifically studied for avoiding the agglomeration of silica nanoparticles and facilitating the penetration of the products in the stone substrates. Sound and artificially aged specimens were impregnated by capillary absorption method and the effectiveness of the treatment was evaluated through morphological and physical analyses. Microscopic observations, colorimetric analyses, sponge tests, ultrasound velocity determinations and porosimetric measurements showed positive results, which encourage, on one hand, the use of silica nanoparticles for consolidating silicate stones, on the other hand, further researches aimed to improve the synthesized products by reaching a deeper penetration and the reduction of water absorption

Climate change and land subsidence in the frame of "Venezia 2021" project : the deterioration of architectural stone materials

The overflowing of the canals and the flooding of the pedestrian walkways are the consequences of the well-known periodic large water inflow into the Venetian lagoon (high water or acqua alta). These phenomena lead the strong degradation of the stone buildings over time. With the aim to better understand the effects of high water and support the best actions and practices for preserving the cultural heritage of Venice by Municipality and Superintendences, thirty samples of five varieties of carbonate lithotypes were exposed to natural weathering in different Venetian areas and on Torcello island. The specimens were periodically monitored and compared with samples made of the same lithologies subjected to accelerated artificial aging tests. The results concerning the main deterioration morphologies observed on all the samples after three years of exposure are here presented and commented

Formation and Controlled Growth of Bismuth Titanate Phases into Mesoporous Silica Nanoparticles: An Efficient Self-Sealing Nanosystem for UV Filtering in Cosmetic Formulation

The application of nanosized inorganic UV filters in cosmetic field is limited by their high photocatalytic properties that could induce the degradation or dangerous transformation of the organic molecules in sunscreen formulations. To overcome this problem and simultaneously enlarge the window of filter's absorption, we propose the growth of bismuth titanates BixTiyOz into mesoporous silica nanoparticles (MSN). We investigated the chemical-physical properties by means of XRPD, TEM, UV-vis spectroscopy, N2 physisorption, XPS, and SF-ICP-MS analysis, while the influence on the environment was evaluated through photocatalytic tests. The growing process of this new nanosystem is discussed underlining the key role of the Bi(3+) ion that, acting as a low-melting point agent for the silica framework, led to a self-sealing mechanism. The excellent UV shielding properties combined with a radical suppression of the photocatalytic activity make the proposed nanosystem a perfect candidate for the development of the next generation nanomaterials for sunscreen formulations

TiO2-Mesoporous Silica Nanocomposites: cooperative effect in the photocatalytic degradation of dyes and drugs

TiO2-SiO2 composites containing 10 wt.%, 20 wt.%, 30% and 40 wt.% of TiO2, obtained by using preformed mesoporous silica nanoparticles MSNs and titanium isopropoxide as titanium source, have been investigated in detail using a variety of techniques. All the samples were characterized by N2-physisorption, X-ray powder diffraction (XRPD), diffusive reflective UV–vis spectroscopy (DRUV-vis), X-ray photoelectron spectroscopy (XPS) and imaged using transmission electron microscopy (TEM). The TiO2-MSN composites, that exhibited a spherical morphology, high specific surface areas and titania in the anatase phase, owing to their specific chemical-physical properties were studied as catalysts in the photocatalytic degradation of Methylene Blue, Methyl Orange and Paracetamol, as examples of polluted wastewaters. The well-defined porous structures of MSNs may offer a special environment for titania nanoparticles, increasing the specific surface area and the thermal stability of the composite, thus modifying the photocatalytic behavior of the materials. The TiO2 loading, the particle size and the surface characteristics were related to the degree of UV absorption and the measured energy band gap of the nanocomposites. A cooperative effect between the two components (TiO2 and SiO2) could be the key factor at the basis of the good photocatalytic performances: nanostructured TiO2 in intimate contact with MSN provides the sites for generation of OH• radicals by oxidation of water and the SiO2 skeleton is able to adsorb the molecules of cationic dyes and prevent poisoning of the TiO2 surface

Genotoxicity and Immunotoxicity of Titanium Dioxide-Embedded Mesoporous Silica Nanoparticles (TiO2@MSN) in Primary Peripheral Human Blood Mononuclear Cells (PBMC)

Background: TiO2 nanoparticles (TiO2 NPs) are the nanomaterial most produced as an ultraviolet (UV) filter. However, TiO2 is a semiconductor and, in nanoparticle size, is a strong photocatalyst, raising concerns about photomutagenesis. Mesoporous silica nanoparticles (MSN) were synthetized incorporating TiO2 NPs (TiO2@MSN) to develop a cosmetic UV filter. The aim of this study was to assess the toxicity of TiO2@MSN, compared with bare MSN and commercial TiO2 NPs, based on several biomarkers. Materials and Methods: Human peripheral blood mononuclear cells (PBMC) were exposed to TiO2@MSN, bare MSN (network) or commercial TiO2 NPs for comparison. Exposed PBMC were characterized for cell viability/apoptosis, reactive oxygen species (ROS), nuclear morphology, and cytokines secretion. Results: All the nanoparticles induced apoptosis, but only TiO2 NPs (alone or assembled into MSN) led to ROS and micronuclei. However, TiO2@MSN showed lower ROS and cytotoxicity with respect to the P25. Exposure to TiO2@MSN induced Th2-skewed and pro-fibrotic responses. Conclusions: Geno-cytotoxicity data indicate that TiO2@MSN are safer than P25 and MSN. Cytokine responses induced by TiO2@MSN are imputable to both the TiO2 NPs and MSN, and, therefore, considered of low immunotoxicological relevance. This analytical assessment might provide hints for NPs modification and deep purification to reduce the risk of health effects in the settings of their large-scale manufacturing and everyday usage by consumers

Compatibilità, efficacia, sostenibilità come indicatori per l’intervento e la manutenzione tra tradizione e innovazione

The management of restoration interventions, in a complex context such as the case of Venice, requires specific methodologies for the monitoring of the pre- and postintervention conservative state. It is indeed necessary to take into account the current environmental conditions but also the environmental conditions that are expected to occur in the future, with specific regard to both climate change and the effects due to the activation of the system of mobile dams "MOSE". This paper presents some of the preliminary results of the interdisciplinary research programme called "Venezia 2021", relating to the development of a methodology based on a set of indicators and descriptors to assess the vulnerability of the elements of the built heritage and therefore useful for the design of the conservative intervention and its monitoring throughout time. The definition of the intervention and monitoring plan takes advantage of the formulated indicators, which best represent the case study and which best define its vulnerability. Indicators, which can be defined as quantitative or qualitative factors or variables, thus provide an instrument for measuring whether the desired result, value or criterion has been reached or met; they can therefore be useful to assess long-term trends and to provide essential information in the planning of interventions, including with the involvement of stakeholders

VENEZIA 2021 : indicatori condivisi per la costruzione del modello e del piano di monitoraggio e intervento : esiti di una ricerca interdisciplinare

La gestione degli interventi di restauro in un contesto complesso quale quello veneziano necessita di metodologie per il monitoraggio dello stato conservativo pre e post intervento che tengano in considerazione l’attuale situazione ambientale e quella che si prevede possa verificarsi in futuro, a seguito dei cambiamenti climatici e dell’entrata in funzione del sistema di dighe mobili “MOSE”. In questo contributo si presentano alcuni tra gli esiti preliminari del Programma di ricerca interdisciplinare “Venezia 2021”, relativi allo sviluppo di una metodologia basata su una serie di indicatori e descrittori atti a valutare la vulnerabilità degli elementi del patrimonio costruito e dunque utili per l’appropriata progettazione dell’intervento conservativo e del suo successivo monitoraggio negli anni

Venezia 2021. Piano di adattamento al cambiamento climatico e implementazione di strategie di intervento per la salvaguardia del patrimonio architettonico e ambientale. Primi esiti di una ricerca interdisciplinare

This research aims to provide a complete vision of the Venetian Lagoon system including both environmental and building aspects, with a specific focus on the interface between the mainland and the wetland of Venice. In particular, in perspective of climate change and MOSE infrastructure working and, consequently, in order to safeguard the city of Venice, all the peculiarities of the historical city, i.e. environment, economy, architecture, and cultural heritage, are being considered. Furthermore, the project will base all the proposals on the same set of data and analysis, designing comparative solutions and possible alternatives regarding the state of the urban environment, landscape, and state of conservation of historical heritage. The multidisciplinary approach, which combines architecture, urban planning, and disciplines applied to cultural heritage -chemistry, applied petrography, conservation science, technical physics, restoration, structural engineering- will set a foundation for an exhaustive vision, providing synergic, cost-effective and legitimized actions