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Five porcelain and porcelain stoneware bodies were investigated to compare sintering mechanisms and kinetics, phase and microstructure evolution, and high temperature stability. All batches were designed with the same raw materials and processing conditions, and characterized by optical dilatometry, XRF, XRPD-Rietveld, FEG-SEM and technological properties. Porcelain and porcelain stoneware behave distinctly during sintering, with the convolution of completely different phase evolution and melt composition/structure. The firing behavior of porcelain is essentially controlled by microstructural features. Changes in mullitization create conditions for a relatively fast densification rate at lower temperature (depolymerized melt, lower solid load) then to contrast deformations at high temperature (enhanced effective viscosity by increasing solid load, mullite aspect ratio, and melt polymerization). In porcelain stoneware, the sintering behavior is basically governed by physical and chemical properties of the melt, which depend on the stability of quartz and mullite at high temperature. A buffering effect ensures adequate effective viscosity to counteract deformation, either by preserving a sufficient skeleton or by increasing melt viscosity if quartz is melted. When a large amount of soda–lime glass is used, no buffering effect occurs with melting of feldspars, as both solid load and melt viscosity decrease. In this batch, the persistence of a feldspathic skeleton plays a key role to control pyroplasticity.

The development of sustainable and efficient catalysts -namely Ru supported on activated biochars- is carried out for the selective hydrogenation of 5-hydroxymethylfurfural (HMF) to 1-hydroxy-2,5-hexanedione (HHD). Activated biochars obtained from pyrolysis and steam-based physical activation of two different biomasses from animal (leather tannery waste; A

Construction and demolition waste (CDW) from earthquake rubbles was used here as recycled aggregates (RA) in cementitious binders. The materials were sorted in six groups: concrete (CO), natural stone (NS), tile (TI), brick (BR), perforated brick (PF) and roof tile (RT). The abundance (wt.%) of crystalline phases in each RA type was determined by X-ray Powder Diffraction (XRPD). Each group of RAs was used alone (100 wt.% of RA) and mixed with quartz-rich virgin aggregates (VA) to prepare 13 types of mortars (12 specimens per type): one reference mortar (RM) with only VA, six recycled aggregate mortars (RAM) and six recycled-plus-virgin aggregate mortars (RVAM). The physical and mechanical properties of aggregates and mortars reflect the type and abundance of crystalline phases in each CDW group. Recycled mortars rich in concrete, natural stones and tiles have better mechanical performance than mortars prepared with recycled bricks, perforated bricks and roof tiles. For each RA, RVAMs have superior mechanical characteristics than the corresponding RAM. Since the type and amount of phases contained in recycled aggregates strongly control the mechanical performance of new construction materials, they should be routinely quantified as reported here, in addition to other physical features (water absorption, density, etc.). The separation of heterogeneous CDW into homogeneous RA groups is necessary for the production of new construction materials with stable and predictable performances to ensure CDW recycling, especially in areas hit by major adverse events, where large amounts of still valuable materials could be used for reconstruction processes.

Hydrogen is largely adopted in industrial processes and is one of the leading options for storing renewable energy. Due to its high explosivity, detection of H

The addition of wastes to silicate ceramics can considerably expand the compositional spectrum of raw materials with a possible inclusion of hazardous components. The present work quantitatively examines relevant literature to determine whether the benefits of incorporating hazardous elements (HEs) into silicate ceramics outweigh the pitfalls. The mobility of various HEs (Ba, Zn, Cu, Cr, Mo, As, Pb, Ni, and Cd) has been parameterised by three descriptors (immobilisation efficiency, mobilised fraction, and hazard quotient) using leaching data. HEs can be incorporated into both crystalline and glassy phases, depending on the ceramic body type. Moreover, silicate ceramics exhibit a remarkably high immobilisation efficiency (often exceeding 99.9%), as accomplished for Ba, Cd, Ni, and Zn elements. The pitfalls of the inertization process include an insufficient stabilisation of incorporated HEs, as indicated by the high hazard quotients (beyond the permissible limits established for inert materials) obtained in some cases for Mo, As, Cr, Pb, and Cu elements. Such behaviour is related to oxy-anionic complexes (Mo, As, Cr) that can form their own phases or are not linked to the tetrahedral framework of aluminosilicate glass. Pb and Cu elements are preferentially partitioned to glass with a low coordination number, while As and especially Mo are not always stabilised in silicate ceramics. These drawbacks necessitate conducting additional studies to develop appropriate inertisation strategies for these elements.

In the present work, the formulation and performance of the silica-aluminosilicate-based composites were studied for catalytic conversion of sugars to levulinic acid. Tailoring the acidity, surface area and the porosity of the catalysts were the main goal of the work. The acidities of the catalysts were provided by ZSM-5 zeolite and were modulated by microwave assisted solid state ion-exchange with copper. The high surface area and porosity of the catalysts were guaranteed by mesopores silica type HMS. The composites of HMS and CuZSM-5 with different contents of 30, 50, 60 and 70% were synthesized and the morphological and textural features and acidity of the materials were assessed using XRD, EDX, SEM, TEM, N2-physisorption, and FTIR, FTIR with pyridine and NH3-TPD. CuZ(60%)@H composite acted as the best catalyst with production of 45% yield and 30% yield of LA from glucose and cellulose conversion, respectively. High surface area, large pore size and volume of HMS in the best composite structure favored mass transfer of the substrates and products and higher performance of the catalyst especially in cellulose hydrolysis. In addition, tuned and balanced concentration, strength and type of CuZSM-5 acidity in the composite promoted the desired pathway, favored formation of levulinic acid and suppressed humins formation.

High-chromium cast irons are frequently used in high-demanding applications, where low production costs and wear performance are key factors. The excellent abrasive resistance of these alloys results from the overall microstructural features, i.e., type, morphology, and distribution of hard primary and secondary carbides, along with the matrix constituents. Such a microstructure is the result of the chemical composition and solidification process, even though it could be further tuned by heat treatments. These latter are usually performed to destabilize the austenite and to induce the precipitation of secondary carbides. The present study investigates the combined effect of destabilization heat treatment route and erodent powder type on the erosive wear behavior of two commercial hypereutectic white cast irons. The as-received and the heat-treated materials were analyzed through optical and scanning electron microscopy, hardness tests, and X-ray diffraction to determine the relationship between microstructural variations and applied heat treatment. The erosive resistance was evaluated per the ASTM G76 standard in a purpose-built air blast test rig. Experiments were performed considering a raw meal powder, commonly used in cement factories, and Al2O3 as erodent powders. The adopted heat treatments were effective in increasing the overall hardness of the material, but this was not directly related to the erosion resistance. By contrast, the relative hardness ratio, i.e., erodent/target hardness, affects the erosion rate and different behaviors in relation to the softer/harder erodent particles were found.

A low-cost NaP zeolite@TiO

Increasing the photocatalytic efficiency of earth-abundant wide-bandgap semiconductors is of high interest for the development of cheap but effective light-driven chemical conversion processes. In this study, the coupling of ZnO and TiO2 with low contents of the rare-earth Ce species aimed to assess the photo-catalytic performance of the two semiconductors (SC). Structural and optical characterizations were performed to estimate the effect of the different interactions between Zn2+, Ti4+ and Ce4+ ions, and how the photo-responsive behaviour of Ce-Ti and Ce-Zn composites was affected. Therefore, photo-catalytic tests were performed for all Ce-modified SC to assess both their photo-oxidative and photo-reductive properties. Amongst all the tested materials, only Zn-based samples resulted in being suitable for the photo-oxidation of the methylene blue (MB) organic pollutant in a synthetic-dependent fashion.

The Venetian marmorino is a traditional material used for wall coating in Venice city, composed of hydrated lime and marble powders, and is part of the cultural heritage of the city. Several surface damage processes can negatively affect its aesthetic properties, such as the formation of stain deposits of different origin (i.e. pollution, bio-deterioration, vandalism) which eventually change the colour of this material. An appealing way to avoid these deposits rely on inducing self-bleaching features by introducing a photocatalyts on this material. In the present work, TiO2-based and ZnO-based photocatalysts were introduced within the marmorino, then evaluating how the addition of these materials influenced the compositional, structural and morphological properties though X-ray diffraction (XRD), N2 physisorption and electron microscopy (SEM). ZnO-modified samples, which exhibited comparable morphological and structural properties, were further analyzed to get information concerning the surface compostion and the opto-electronic properties, through attenuated total reflectance (ATR) spectroscopy and photoluminescence (PL), respectively, in turn related to the presence of defects and heterojunctions. The self-bleaching activity was evaluated by irradiation in mild condition (room temperature) in air using a dye as model stain compound. Finally, the morphological, surface and opto-electronic properties of the photocatalyst-modified marmorino were correlated to the activity results, aiming to understand how they can influence the material performances, and thus how to design an active self-bleaching Venetian marmorino.

The present work is focused on the improvement of an effective approach to tailor the acidity of silica alumina composite. SBA-15 was selected based on high surface area, uniform porosity and large mesopores. Modification of SBA-15 was performed to improve both Lewis and Bronsted acidities and hence catalyst activity. Therefore, introduction of alumina as a co-catalyst was carried out to enhance Lewis acid sites through its incorporation into the silica network. Evaporation impregnation method was evaluated for incorporation of aluminium to SBA-15 and materials with different SiO2/Al2O3 ratios were prepared. Acidity and morphological features of the materials were assessed using XRD, EDX, SEM, TEM, N2-physisorption, 27Al MAS-NMR and FTIR with pyridine. Bronsted acidity was attained by the introduction of sulfonic acid groups in the final catalyst via the post-synthesis grafting method. Therefore, the balanced Lewis and Bronsted acidities and proper porosity of modified SBA-15 led to its efficient performance in the conversion of glucose as a biomass-based model component to levulinic acid.

The relative stability of CdS and CdO with respect of substrates has been widely studied up to 500 °C, the upper temperature in many applications. The physical-chemical properties of the deposited films are often revealed to be influenced by deposition substrates. In this paper, using XRD, SEM and EDX methods, we have studied the oxidation/desulphurization of CdS to CdO and the intermediate stabilized materials therein (i.e. 2CdO·CdSO4 and 2CdS·2CdO·CdSO4), by using CdS films deposited on different substrates (i.e. nickel, Si-polycrystalline, glaze porcelain and α-Al2O3) which were annealed in air up to 800 °C. At the annealing temperatures used in this study, different phases were found to be stabilized on different substrates. The relative stability of CdO and 2CdO·CdSO4 phases is greater on α-Al2O3 than on glazed porcelain substrate. A mixed phase of CdO and 2CdO·CdSO4 was obtained at the annealing temperature of 800 °C if films are deposited on Ni and polycrystalline silica. The amount of the oxidized CdS (i.e. CdO and 2CdO·CdSO4) obtained by mixing CdS and Al2O3 powders at different Al2O3/CdS ratios and annealed up to 800 °C, were also investigated. Decreasing the Al2O3/CdS ratio, the interactions between Al2O3 and CdS particles are reduced, consequently the CdO stabilization is strongly retarded in favour of 2CdO·CdSO4, while reverse results was proven for high values of Al2O3/CdS ratio. The results show the role of the interface area between Al2O3 and Cd-materials for stabilization of CdO. A low interface area was also obtained by filling an α-Al2O3 crucible with CdS powder. After annealing, the CdO stabilization was strongly reduced, in line with the low Al2O3/CdS ratio sample. Spreading the CdS powder on the α-Al2O3 substrate, instead of drop coating deposition method, showed a remarkable CdO stabilization in line with the results obtained with drop coating method. To account for the role of the interface area a model is proposed (Stabilization model), based on surface energy, as responsible to phase stabilization to explain the nucleation – stabilization of the CdO and 2CdS·2CdO·CdSO4. The morphologies of the CdO and 2CdS·2CdO·CdSO4 resemble hexagonal-prism shapes and compact chips, respectively, while 2CdO·CdSO4 phases has a sponge-like appearance.

CO2 photoreduction has claimed as appealing process to upgrade a waste gas into valuable fuels or chemicals. Titanium dioxide (TiO2) is one of the most popular material used as catalyst for this reaction, having however a poor activity. The utilization of transparent, insulating and highly porous scaffolds to support a photoactive phase has been reported as one of the possible strategies to improve the performances of this material. In this work, two silica-based materials with different porosity type and level, were involved as support for the TiO2 and assessed in the gas-phase CO2 photoreduction with H2O. The morphological, structural and surface properties were then evaluated by means of different characterization techniques, aiming to correlate them with the catalytic activity and selectivity. The TiO2-SiO2 composites revealed a comparable activity compared to pure TiO2, despite the low fraction of photoactive phase due to improved light harvesting and reagents adsorption on the composites. The CO2 capture/photoconverting ability was evaluated, to explore the potentiality as multifunctional material.

In this work, NaY zeolite/ZnO nanocomposites with different amounts of ZnO were prepared. The nanocomposites were characterized by different methods such as X-ray diffraction (XRD), Fourier transform infrared spectroscopy, scanning electron microscope, Energy-Dispersive X-ray analysis, Diffuse reflectance spectroscopy (DRS) surface area (BET), NH3-TPD, Fluorescence microscopy and thermal gravimetric analysis. The results of BET confirmed the micro-meso structure of NaY zeolite in which low angle XRD shows that mesophase is not completely ordered in the composite. DRS result shows the decreasing band gap in the ZnO. In addition, Si/Al ratio decreasing to lower than two which increasing in the acidity confirmed by NH3-TPD. Therefore, can be said, a good zeolitic photocatalyst with high acidity and micro-meso structure was prepared in the mild condition, which was useful for degradation of the pollution in out coming works.

International audience; Experimental results and simulation models show that crystals might play a relevant role for the development of new generations of high-energy and high-intensity particle accelerators and might disclose innovative possibilities at existing ones. In this paper we describe the most advanced manufacturing techniques of crystals suitable for operations at ultrahigh energy and ultrahigh intensity particle accelerators, reporting as an example of potential application the collimation of the particle beams circulating in the Large Hadron Collider at CERN, which will be upgraded through the addition of bent crystals in the frame of the High Luminosity Large Hadron Collider project.

The overburning test method was developed to simulate and predict lime densification, agglomeration, and sporadic melting at the highest potential temperature of lime kilns. These events, that belong to the so-called “sticking tendency” phenomenon, are associated to formation of crusts, occlusions, and blockages in vertical lime kilns. In this work, fifty carbonate rocks, their insoluble residues, and derived burnt products were investigated through a multianalytical approach. Four groups of rocks having different burnability were identified. In addition, three fundamental mechanisms were related to the above-mentioned phenomena: dehydration melting, solid-state, and liquid-phase sintering processes. Guidelines for raw materials suitability were outlined for designing new kilns and to check the quality control in already active plants.

A two component three degree simplex lattice experimental design was employed to evaluate the impact of different mixing fractions of TiO2 and ZnO on an ordered mesoporous SBA-15 support for CO2 photoreduction. It was anticipated that the combined advantages of TiO2 and ZnO: low cost, non-toxicity and combined electronic properties would facilitate CO2 photoreduction. The fraction of ZnO had a statistically dominant impact on maximum CO2 adsorption (β2 = 22.65, p-value = 1.39 × 10-4). The fraction of TiO2 used had a statistically significant positive impact on CO (β1 = 9.71, p-value = 2.93 × 10-4) and CH4 (β1 = 1.43, p-value = 1.35 × 10-3) cumulative production. A negative impact, from the interaction term between the fractions of TiO2 and ZnO, was found for CH4 cumulative production (β3 = -2.64, p-value = 2.30 × 10-2). The systematic study provided evidence for the possible loss in CO2 photoreduction activity from sulphate groups introduced during the synthesis of ZnO. The decrease in activity is attributed to the presence of sulphate species in the ZnO prepared, which may possibly act as charge carrier and/or radical intermediate scavengers.

This work investigates, for the first time, the hydrogen permeation of BaCeZrYO-CeGdO (BCZY-GDC) asymmetric membranes for 100 h, using wet 15% CO in Ar as sweep gas. In the same frame, ex-situ aging tests were performed for 100 h exposure at 750 °C in different atmospheres (H, CO, H + CO), to evaluate the phase, microstructure, and mechanical long-term stability of this system. The thermal aging in H-atmosphere leads to lower flexural strength caused by a microstructure embrittlement of the BCZY-GDC asymmetric membrane, due to chemical expansion/contraction of the GDC cell after the aging cycle. Indeed, micro-cracking of GDC grains, that decreases the composite hardness, is observed in symmetric (pressed pellet) membranes. The aging in CO causes a slightly increase in flexural strength values due to the formation of sub-micrometric Zr-doped ceria-BaCO phases at the expense of the perovskite. Higher hardness values related to the emerging of BaCO islands on the symmetric membrane surface were also recorded. In H + CO atmosphere (real testing condition), the membrane shows a slight decrease in flexural strength and hardness while no evident morphological or structural changes (except the BaCO formation in traces) were observed. This study highlights that promising and stable hydrogen permeation flux values can be recorded using the asymmetric configuration for 100 h, using wet 15% CO in Ar as sweep gas. Neither structural nor morphological modification of the membrane were detected after the testing., This work was financially supported by the agreement between the Italian Ministry of Economic Development and the Italian National Research Council ‘‘Ricerca di sistema elettrico nazionale’’ and by the Spanish Government (RTI2018-102161) and the Generalitat Valenciana (PROMETEO/2018/006).

This paper deals with thermal analyses, burning trials and reactivity tests on 15 carbonate rocks, i.e., pure and impure carbonates, mud-supported and grain-supported limestones, crystalline marbles, and dolomites, used for the production of different lime products in industrial vertical shaft kilns worldwide. In particular, thermogravimetric and differential thermogravimetric analysis (TG–DTG) on massive (80–120 g) fine-grained (

The physical–chemical properties of guest molecules confined within a zeolite framework host are known to be strongly affected by the confinement effects exerted through noncovalent host–guest interactions. On the basis of synchrotron time-resolved powder diffraction measurements and the Landau theory of ferroelastic phase transitions, we provide in this work evidence for the strong coupling existing between the thermodynamic properties of organic molecules (toluene, 1,2-dichloroethane, methyl-tert-butyl-ether) adsorbed within the ZSM-5 zeolite and the lattice strain driving the monoclinic-to-orthorhombic (ferroelastic-to-paraelastic) phase transition which controls connectivity and diffusivity in the zeolite framework.

The new nanocomposite of NaP-Hydroxyapatite (NaP:HAp) has been developed for removal of fluoride from aqueous solution. NaP:HAp nanocomposite has been characterized by using different method such as: X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), scanning electron microscope (SEM), Energy Dispersive X-ray analysis (EDAX), surface area (BET) and thermal gravimetric analysis (TGA). Box–Behnken design with three-level and four-factor has been employed for determination of effective process parameters such as solution pH (4–11), temperature (25–55° C), initial adsorbent dose (1–3 g) and initial fluoride concentration (5–25 mg/L) on removal of fluoride from aqueous solution. After 29 batch runs, Quadratic model was established by regression analysis of the experimental data obtained from 29 batch runs. Quantity uptake of fluoride was evaluated using the Langmuir, Freundlich and Dubinin–Radushkevich (DR) models. The rate of adsorption was rapid and followed pseudo-second-order kinetics for this adsorbent. Moreover, thermodynamic parameters (ΔΗ°, ΔG°, ΔS°) for fluoride sorption on NaP:HAp nanocomposite was also studied from the temperature dependence. The significant novelty of this work is the simple preparation of a new nanocomposite from Hydroxyapatite and zeolite that increased stability of HAp in different pH and temperature. Also, this nanocomposite shows high capacity for adsorption of fluoride related of other sorbent and reusable for several times that makes this method nearly green and friendly environmentally.

The advent of digital decoration has changed the technological requirements of colorants and the way they are applied onto ceramic substrates. This technological revolution has introduced additional steps in colorant production (ink micronization) and new constraints in application (ink-jet printing) that cannot be reproduced in a standard ceramic laboratory, so stretching the distance between academic and industrial research. The goal of this work is to provide an up-to-date picture of ceramic pigments, dyes and effects, with emphasis on their behavior in the current decoration technologies, which are shortly reviewed. Technological performance expected for ceramic colorants and new requirements imposed by digital decoration are discussed in detail. An extensive overview of both industrially used and candidate pigments, dyes and effects is focused on the suitability to different ceramic applications and firing conditions. Finally, lines of future research are outlined and commented.

Valorisation of lignocellulosic biomass for chemical production is one of the main challenges of the 21st century. Levulinic acid (LA) has been chosen as the target product due to its potential as an intermediate to produce a wide variety of other chemicals. The attention has been focused on the formulation of an active solid acid catalyst for the hydrolysis of glucose to LA. Therefore, a deep modification of SBA-15 with sulfonic groups was performed using post-synthesis grafting method. In particular, this work focuses on the role of different grafting solvents. Since the traditional solvents such as toluene or hexane, are flammable and toxic, a safer and more environmentally friendly solvent, a mixture of water and NaCl has been investigated. It was found that the nature of the solvent highly affects the morphological and chemical features of the materials. Thus, the best catalytic results were obtained with the catalyst prepared in water and NaCl; indeed 30 % and 16 % of LA yield were obtained from fructose and glucose hydrolysis at 180 °C respectively. Water and NaCl mixture guarantees the best distribution of sulfonic groups over the surface, leading to the most balanced acid catalyst.

Despite advantages highlighted by MOX-based gas sensors, these devices still show drawbacks in their performances (e.g. selectivity and stability), so further investigations are necessary. SnO2 is the most used semiconductor for chemoresistive gas sensors production due to its broad spectrum of physical-chemical properties, and then it represents the best candidate for the innovative work here proposed. Indeed, among the gaps in research on this material, it is placed the study of oxygen deficiency and its impact on the tin dioxide physicochemical properties. A series of first-principles study was carried out in order to study the impact of oxygen vacancies on the physical-chemical properties of SnO2. The results showed a high electrical conductivity for the samples with oxygen vacancies, which can give a decrease of the operating temperature that sensing material needs to be thermo-activated. The arrangement of the impurity states is one of the important parameters that involve the reactions on the material surface, making the excitation of weakly bound valence electrons into the unoccupied energy levels in the conduction bands.

Silicon carbide is a well-known material with high thermal, mechanical and chemical stability. These properties have allowed, over time, its wide use as an inert material to be employed as a substrate or support in different applications. In this work, we demonstrate that, under proper conditions, it is possible to activate the chemical reactivity of nanostructured SiC, which can be employed for chemoresistive purposes. With this aim, a commercial powder of SiC has been characterized from a morphological, structural and thermal point of view. Then, screen–printed thick films were obtained from SiC powder and thus tested as a functional material for chemoresistive gas sensors, in thermo-activation mode. The samples were exposed to 13 gases with important chemical differences. Analyses showed that SiC is an extremely selective functional material for the detection of sulphur dioxide (SO2) in concentrations within the ppm range. This interesting result was found at high working temperatures (600−800 °C), useful for harsh environments, and the measurements proved to be completely free from humidity negative interference. Thermo-gravimetric and X-ray photoelectron spectroscopy characterizations highlighted that the high selectivity of the SiC layer is promoted by the thermal formation of a SiC/SiOC core-shell, tunable by controlling temperature and humidity parameters. An interpretation of the gas sensing mechanism occurring between SO2 molecules and SiC/SiOC core-shell has been proposed. The unexpected chemical activity, identified for nanostructured SiC, can be exploited for the specific detection of SO2, since this gaseous compound plays an important role in air pollution, industrial processes and winemaking.