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This work is part of a research project aimed at producing ceramic-like materials, without the need for an initial sintering, for potential applications in catalysis or filtration at temperatures up to 1000 °C. In that context, cordierite-derived materials were prepared from recycled cordierite powder (automotive industry waste) bonded with metakaolin-potassium silicate geopolymer. The principle is that these materials, prepared at temperatures below 100 °C, acquire their final properties during the high-temperature commissioning. The focus is on the influence of the K/Al ratio and cordierite fraction on the stability of the dimensions and porosity during heating at 1000 °C, and on the final Young's modulus and coefficient of thermal expansion. Conventional and high-temperature XRD evidenced the absence of crystallization of the geopolymer binder and interaction with the cordierite filler during the heating stage when K/Al = 1 or 0.75. By contrast, crystallization of kalsilite and leucite, and diffusion of potassium ions in the structure of cordierite is evidenced for K/Al = 1.5 and 2.3. These differences strongly influence the shrinkage due to sintering and the final properties. It is shown that a K/Al ratio of 0.75 or 1 is favorable to the stability of the porosity, around 25 to 30%. Moreover, a low coefficient of thermal expansion of 4 to 4.5 × 10−6 K−1 and a Young's modulus of 40 to 45 GPa is obtained. [ABSTRACT FROM AUTHOR]

In civil engineering, both rapid setting and delayed setting are needed for various application scenarios. In order to regulate the setting time of concrete, the iron ore tailings-blast furnace slag (IOT-BFS)-based geopolymers were synthesized with a broad range of setting time and a high compressive strength in this study. The factors of iron ore tailings content, alkali content, liquid–solid ratio, and modulus of alkali activator on setting time of the geopolymers were analyzed. The setting times of geopolymers are tested by a manual Vicat apparatus, and their microstructure is characterized by scanning electron microscopy (SEM), as well as that the hydration heat flow is characterized by an isothermal heat conduction calorimeter (TAM Air). It is found that setting time of the geopolymers was mostly affected by the modulus of alkaline activators due to the reasons that changes in modulus lead to the accelerated hydration reaction, formation of low-polymeric silicates, generation of gels, and encapsulation of precursor particles caused by high viscosity. Adjusting the modulus of the alkaline activator to 0.8 can control the initial setting time of the geopolymers to around 3 min. When the modulus ranges from 1–1.8, the initial setting time fell in the range of 15–45 min. For an alkaline activator modulus of 2, the initial setting time increased to 108 min. This study gives a clue for the preparation of geopolymers with adjustable setting times for multi-scenario applications in construction materials. [ABSTRACT FROM AUTHOR]

Foaming or porous geopolymers can be utilized in various engineering applications, including heat and acoustic insulations, as well as passive fire protection in building materials. They are ecofriendly materials, as no significant production power is required. In this study, geopolymers possessing foaming features involving lightweight and porous materials were successfully created through the reaction of sodium hydroxide solution 6 M with powder of waste glass MG without/with rice husk (RH) 20 wt.% of heat treated (212, 420, and 600 μm) utilized as the foaming agent. The effect of rice husk ash (RHA) and various sizes of RH additives on the thermal treatment (volume and weight changes, percentage), compressive strength, and microstructure (pore content) was assessed. The results show swelling (foaming behavior) for MG‐N6, MGB‐N6, MGR212‐N6, and MGR600‐N6 at 550°C, unlike the MGR420‐N6 formula. Also, a high‐volume change (percentage) for MGR420‐N6 paste at 650°C was noticed. Additionally, foaming behavior (high volume expansion) appeared for all thoughtful pastes after treatment at 750°C. The weight loss for all specimens in the range of 10%–27% and a high percentage of weight changes for MGR400‐N6 and MGR600‐N6 were noticed. Low values of compressive strength (2.74–14.5 MPa) were recorded for all formulas studied. These synthesized materials, geopolymers containing glass waste and RH powder, resulting from this study, are highly recommended, mostly for thermal and acoustic insulation materials demanding lightweight, porosity, and low mechanical properties. [ABSTRACT FROM AUTHOR]

Non-alcoholic beer is becoming more and more popular every year. Due to the high demand for such drinks, numerous breweries decided to produce non-alcoholic beer. There are various methods to create a beer with a reduced alcohol content. Among them are biological methods influencing the biochemistry of the brewing process and physical methods focused on removing ethanol from ready beer. Thus far, the most popular methods are vacuum rectification and reverse osmosis. This work evaluated another method called pervaporation for non-alcoholic beer production. During the study, low-alcohol beer (0.58 vol.%) was achieved from standard beer (3.62 vol.%) using pervaporation. The colour of the product remained unchanged at level 7 EBC. The concentration of ferulic acid decreased from 11.5 to 9.1 mg/dm3, and maltol was concentrated, reaching a concentration of 38 mg/dm3 in the final retentate during a 5 h process. [ABSTRACT FROM AUTHOR]

Porous geopolymers have been the promising subject over the last decade owing to the functional domains from high surface area, structural stability upon heat and chemists, as well as eco-friendly and economy. Especially, the nano-sized geopolymers are playing a significant role in extensive applications. Here, we summarize recent progress in the development of nanoporous geopolymers in the applications of adsorption as well as catalyst supporter. Generally, microporous geopolymers were synthesized through gas bubbling or combination of zeolite to form partial porous structure, while mesoporous geopolymers were produced by the using of various structure directing agent. However, it remains a challenge to obtain functional materials with narrow porous distribution. Our recent work show that the uses of well-defined template method give rise to finely designed nanoporous geopolymers, which exhibited extremely excellent adsorptivity, solid acidic capacity as well as effective carbon-replication. We discussed well the relationship between nanoporosity regulation and corresponding performances to conclude that just using the bubbling, the compositing of zeolite, or traditional rough template method is difficult to form homogeneous pore structures. By analyzing the connection between the uniform porous structure and its related properties, the well-defined template-method would be recommended to generate emerging nanoporous structures with superior functions. [ABSTRACT FROM AUTHOR]

A study has been carried out to produce environmentally friendly lightweight concrete by substituting cement with alternative geopolymer binders. Fly ash and silica fume (waste materials) were used as source materials and their effect on pore structure and properties of aerated geopolymer concrete was evaluated. Autoclaved aerated concrete, locally known as thermostone, was supplied from the market and tested as a reference mix. Three aerated geopolymer concrete mixes (around 550 kg/m3 density) were produced by mixing source materials (fly ash and silica fume), activator solution (sodium silicate and sodium hydroxide), and aeration agent (aluminum powder). It was found that by not only enhancing the pore structure but also improving the binder medium, the aerated geopolymer mixes were stronger and less absorbed than the autoclaved aerated concrete mix. However, the thermal insulation of the aerated concrete mix was better than those of aerated geopolymer concrete mixes. In terms of the source material, it was found that usage of fly ash helped in enhancing the strength by about 100% of autoclaved aerated concrete. In addition, unless its lowest density, aerated geopolymer mix made with fly ash and silica fume in combination absorbed less water than the other investigated mixes. Adding superplasticizer to the geopolymer mix helped in enhancing its pore structure by making the pores smaller, their irregularity lesser, and their number higher. In general, an environmentally friendly lightweight material with strength and absorption better than those of autoclaved aerated concrete was produced by adopting a geopolymerization process. [ABSTRACT FROM AUTHOR]

Tyre waste is a common form of non-degradable polymer-based solid waste. This solid waste can be effectively managed by converting it into char through the pyrolysis process and then further converting the char into activated carbon (AC) through physical and chemical activation processes. Tyre-derived activated carbon (TDAC) has versatile applications, such as its use as an absorber, catalyst, and electrode material, among others. This study aims to review the electrochemical properties of TDAC. This study employed the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta analysis) bibliographic search methodology, with a specific focus on the application of TDAC in a wide variety of energy storage devices, including lithium-ion batteries, sodium-ion batteries, potassium-ion batteries, and supercapacitors. In several experimental studies, TDAC was utilised as an electrode in numerous energy devices due to its high specific capacitance properties. The study found that both activation processes can produce AC with a surface area ranging from 400 to 900 m2/g. However, the study also discovered that the surface morphology of TDAC influenced the electrochemical behaviours of the synthesised electrodes. [ABSTRACT FROM AUTHOR]

The interest on porous ceramics has increased in the last years with the developments in additive manufacturing methods, enabling design of components with complex geometries for membranes, filters, catalytic converters, or biostructures. In this study, porous alumina samples were produced by using different concentrations of poly(methyl methacrylate) (PMMA) as pore‐forming agent (PFA) in a photocurable slurry via vat photopolymerization (VPP). The effect of layer thickness, PMMA particle size, and sintering temperature on the mechanical properties and microstructural features of the samples was investigated as a function of PMMA concentration. It is shown that the mechanical properties of 3D‐printed porous alumina are comparable with those fabricated by conventional processes. The Young modulus, fracture toughness as well as the biaxial strength decreased with increasing weight concentration of PFA (resulting in an increased total porosity). Specially using smaller PMMA particles has a positive effect, resulting in higher Young's modulus as well as fracture toughness. The feasibility of VPP for fabricating novel parts with more complex porosity regions is explored by printing multi‐material samples and porosity‐graded architectures. The counterbalance effect between porosity and mechanical properties may be optimized by tailoring material composition and processing parameters. [ABSTRACT FROM AUTHOR]

The development of cement‐free refractories has gained attention in recent years. Geopolymers (GP) are cold‐setting binders that may be applied in the manufacturing of such ceramics. However, a systemic comparison between calcium aluminate cement (CAC) and GP‐bonded formulations is still necessary to understand the strengths and limitations of these novel binders. In this study, three GP were designed and characterized, and the most promising composition was incorporated into an alumina refractory. A corresponding CAC‐containing formulation was also evaluated as a reference material. The physico‐mechanical properties of the prepared ceramics were analyzed after heat treatments ranging from 40–1250°C. Among the designed GP, the sodium‐containing binder showed the best performance, although its addition to alumina refractory resulted in cured samples with low mechanical strength. However, with the progression of liquid formation, sintering, and densification during firing at 1100–1250°C, the GP‐bonded refractory displayed enhanced flexural strength, surpassing the performance of the CAC‐containing composition. [ABSTRACT FROM AUTHOR]

In this study, municipal solid waste incineration (MSWI) fly ash was subjected to mineral carbonation with the aim of investigating CO2 sequestration in waste material. The conducted study follows the trend of searching for alternatives to natural mineral materials with the ability to sequestrate CO2. The mineral carbonation of MSWI fly ash allowed for the storage of up to 0.25 mmol CO2 g−1. Next, both carbonated and uncarbonated MSWI fly ashes were activated using an alkaline activation method by means of two different activation agents, namely potassium hydroxide and potassium silicate or sodium hydroxide and sodium silicate. Mineral carbonation caused a drop in the compressive strength of alkali-activated materials, probably due to the formation of sodium and/or potassium carbonates. The maximum compressive strength obtained was 3.93 MPa after 28 days for uncarbonated fly ash activated using 8 mol dm−3 KOH and potassium hydroxide (ratio 3:1). The relative ratio of hydroxide:silicate also influenced the mechanical properties of the materials. Both carbonated and uncarbonated fly ashes, as well as their alkali-activated derivatives, were characterized in detail by means of XRD, XRF, and FTIR. Both uncarbonated and carbonated fly ashes were subjected to TG analysis. The obtained results have proved the importance of further research in terms of high-calcium fly ash (HCFA) utilization. [ABSTRACT FROM AUTHOR]

The application of large amounts of red mud in the field of building materials is one of the main ways to reuse this material, but the high alkali content of red mud limits its application. In this paper, the washable alkali, removable alkali, and lattice alkali contents of Bayer red mud were studied, and the occurrence states of potassium and sodium in red mud were studied using XRD, IR, XPS, and NMR. On this basis, the removal mechanism for potassium and sodium in red mud was analyzed. The results showed that the Na in the red mud was mainly deposited in the shelf silicon voids of hydroxy sodalite (Na8(AlSiO4)6(OH)2(H2O)2) in the form of Si-O-Na or Al-O-Na. K is deposited in the shelf silico-oxygen void of potassium feldspar (KAlSi3O8) in the form of Si-O-K or Al-O-K. The washable Na and K contents of the mud were 13.7% and 4.47%; the alkali removal agent CaO removed 83.1% and 50.8% of Na and K in the red mud; and the lattice alkali Na and K contents were 3.20% and 44.8%, respectively. In the process of red mud dealkalization, Ca2+ ions can enter the internal voids of the hydroxyl sodalite and potassium feldspar silica skeleton and then replace Al3+ in the Si-O skeleton and Na+ and K+ in the skeleton voids. The replacement reaction changes the silica tetrahedron network structure, resulting in the disintegration of the frame-like silica tetrahedron in the hydroxyl sodalite and potassium feldspar, forming an isolated, island-like silica tetrahedron in hydrated garnet. [ABSTRACT FROM AUTHOR]

Mullite and mullite–alumina ceramics materials with dominance of the mullite phase are used in different areas of technology and materials science. Porous mullite ceramics materials can be used simultaneously as refractory heat insulators and also as materials for constructional elements. The purpose of this work was to investigate the WO3 nanoparticle influence on the evolution of the aluminum tungstate and zircon crystalline phases in mullite ceramics due to stabilization effects caused by different microsize ZrO2 and WO3. The use of nano-WO3 prevented the dissociation of zircon in the ceramic samples with magnesia-stabilized zirconia (MSZ), increased porosity by approximately 60 ± 1%, increased the intensity of the aluminum tungstate phase, decreased bulk density by approximately 1.32 ± 0.01 g/cm3, and increased thermal shock resistance by ensuring a loss of less than 5% of the elastic modulus after 10 cycles of thermal shock. [ABSTRACT FROM AUTHOR]

Overall, 100% hypergolic coal gangue (HCG)‐based geopolymer foams were produced by a novel saponification‐microwave foaming combined route. Microwave foaming with and without expired vegetable oil was first used to produce CG‐based geopolymer foams. Macropores were mainly generated by microwave foaming, and mesopores were mainly obtained by the addition of expired soybean oil that underwent a saponification reaction. The effects of the oil content on the density, porosity, pore morphology, compression strength, and methylene blue adsorption properties were studied. High total porosity (85.9–89.0 vol%) and acceptable compression strength (0.46–1.1 MPa) HCG‐based geopolymer foams were produced. Foams with 12.59 wt% oil exhibited the best adsorption properties, with an adsorption capacity up to 9.4 mg/g and high removal efficiency of about 95.3%. These solid‐waste‐based porous components are promising monolithic adsorbents for wastewater treatment. [ABSTRACT FROM AUTHOR]

Mullite--zirconia composites were prepared using lanthanum oxide (La2O3) additive at three different molar ratios via reaction sintering (RS) of alumina, kaolinite and zircon. Starting materials were planetary milled, shaped into pellets and bars and sintered at a temperature range of 1450-1550 °C with 5 h soaking at peak temperature. Mullite-zirconia composites were characterized in this study by thermal expansion coefficient, physical, microstructural, and mechanical properties. The X-ray diffraction (XRD) method was employed for determining the crystalline phase composition of these composites. Samples with 8 mol% La2O3 exhibited a flexural strength of ~197 MPa and elastic modulus of 143 GPa. Significant improvements in thermal expansion coefficient were observed in samples with 5 mol % La2O3. Composite microstructures were examined via scanning electron microscopy (SEM). ZrO2 takes part in both the intergranular as well as intragranular positions. However, intragranular zirconia particles are much smaller compared to intergranular zirconia particles. [ABSTRACT FROM AUTHOR]

Dyeing industry is one of the fast-growing industries but at the same time has also brought us a big issue on environment pollution. Adsorption processes is the most effective method in dye removal compared to other methods of wastewater treatment. In recent years, there is an increasing interest in utilizing clay material such as kaolinite as an adsorbent to remove not only inorganic but also organic molecules. In this study, composite of kaolin-sodium alginate (SA) beads was synthesized by varying the weight of kaolin from 0.5 g to 2 g. XRD, FTIR, and surface area analyses were used to characterize the kaolin; while FTIR was used to characterize the composite where the functional groups of kaolin and SA are existing. The amount of 1 g kaolin in SA could improve the adsorption of methylene blue up to 78% of removal after 8 hours. The adsorption model fits pseudo second order kinetic and Langmuir isotherm. [ABSTRACT FROM AUTHOR]

This paper evaluated mechanical and thermal stability of alkali‐activated materials obtained from metakaolin and alternative silica sources, such as rice husk ash (RHA) and silica fume (SF), and were reinforced with recycled ceramic particles (RP) obtained by grinding bricks. Specimens were produced, and after 7 days of curing, they were exposed to temperatures between 300 and 1200°C to determine the influence that different percentages of RP had on the mechanical behavior and microstructure of the produced composites. The results showed a reduction in the linear contraction by 10.22% with 20 wt% RP and that the reinforcing materials improved the mechanical performance of the geopolymers after exposure to high temperatures; the compressive strengths reached 137.7 (±11.4)  MPa after being exposed to 1200°C for the matrix based on RHA and 180.6 (±19.15) MPa after being reinforced with 20 wt% RP. The improvement was mainly due to densification and the formation of crystalline products such as leucite, kalsilite, and mullite. [ABSTRACT FROM AUTHOR]

Nowadays, the interest in manufacturing non-alcoholic or low alcoholic content beverages from alcoholic beverages is a current challenge for food technologists; this is due to the fact that huge consumption of alcoholic beverages may produce health problems in the costumers. In principle, the post-fermentation ethanol removal from alcoholic beverages is carried out by means of evaporation or distillation. Such current dealcoholization methodologies are efficiently removing the ethanol, however, some organoleptic compounds can also be lost during the process. This makes the dealcoholization process highly sensitive in order to preserve the quality properties of the beverages. Thereby, membrane-based technologies, which use perm-selective barriers for the separation, have been highly promoted for such purpose. Pervaporation (PV) technology is indeed one of these technologies aimed for ethanol removal. Herein, the goal of this review is to provide a compelling overview of the most relevant findings for the production of non-alcoholic beverages (such as beer and wine) by means of PV. Particular attention is paid to experimental results which provide compelling feedback about the accurate ethanol removal and minimal changes on physicochemical properties of the beverages. Moreover, some theoretical basis of such technology, as well as key criteria for a more efficient dealcoholization, are also given. [ABSTRACT FROM AUTHOR]

Activated carbons prepared from rice husk by chemical activation with dual activation agents, KOH and NaOH, have been studied and characterized by BET, SEM, EDX, FTIR, Boehm titration, Raman, and TGA. It was found that the KOH/NaOH impregnation ratio plays an important role on textural properties of AC. At the same amount of total alkali hydroxide, the KOH/NaOH ratio higher than 1.33 resulted in larger specific surface area (2990∼3043 m2·g−1), microporous surface area (2747∼2831 m2·g−1), and higher micropore volume (1.4250∼1.4316 cm3·g−1). The as-prepared samples exist in the form of spherical-shaped particles with the size ranging from 20 to 60 nm and contain numerous surface functional groups. The as-prepared activated carbons were then assessed as an electrode material of supercapacitor operating in the 0.5 M K2SO4 electrolyte in potential windows of −1.0∼0.0 V. The highest capacitance obtained was 205 F·g−1 at the scan rate of 2 mV·s−1 and 225 F·g−1 at a current density of 0.2 A·g−1. At the scan rate as high as 50 mV·s−1, all the as-prepared activated carbons in this study have the specific capacitance greater than 100 F·g−1. [ABSTRACT FROM AUTHOR]

Ceramic Ultrafiltration membranes are considered as an alternative for the treatment of both stable water-in-oil and oil-in-water emulsions proved to be more effective in comparison with other conventional techniques. In this study, symmetric macro-porous ceramic membranes are prepared through dry pressing of α-alumina powder and the addition of various binders including Poly (vinyl alcohol). The disk is sintered after the organic material is burned away and the porosity can also be adjusted by the variation of sintering temperature. The results show that the fabrication of compact membrane supports can be done by increasing the sintering temperature which leads to grain size reduction. Moreover, application of different binders and additives result in various supports possessing different pore size and size distributions. Scanning electron Microscope (SEM) micrographs illustrate the surface and grain size distributions caused by various binders. These membranes can be used for microfiltration at elevated temperatures and extreme environmental conditions and also as porous supports for the fabrication of composite-asymmetric nanofiltration membranes. [ABSTRACT FROM AUTHOR]

Recycling geopolymer waste, by reusing it as a raw material for manufacturing new geopolymer binding matrices, is an interesting asset that can add to the many technical, technological and environmental advantages of this family of materials in the construction field. This can promote them as promising alternatives to traditional materials, such as Portland cements, which are not so environmentally friendly. Recent studies have shown that the partial replacement of reactive aluminosilicates (metakaolin and fly ash) up to a mass rate of 50% by geopolymer waste does not significantly affect the compressive strength of the new product. In line with these findings, this paper investigates the effects of aggressive environments, i.e., high temperatures (up to 1000 °C) and acid attacks (pH = 2), on the characteristics of these new matrices. Different techniques were used to understand these evolutions: mineralogical analysis by X-ray diffraction (XRD), thermogravimetry-differential thermal analysis (TGA-DTA), mechanical characterization and scanning electron Microscopy (SEM) observations. The results are very satisfactory: in the exposure temperature range explored, the new matrices containing geopolymer waste suffered losses in compressive strength similar to those of the matrices without waste (considered as materials reference). On the other hand, the new matrices exhibited good chemical stability in acid media. These results confirm that the reuse of geopolymer waste is a promising recycling solution in the construction sector. [ABSTRACT FROM AUTHOR]

The main aim of the presented article is to describe the behavior of class C fly ash—kaolin plastic doughs during the ageing process. Class C fly ash (CCFA) from the fluidized technology of fuel combustion in a thermal power plant was used as a non-plastic admixture to modify the plasticity in a kaolin–quartz sand mixture (for example, the base of a porcelain mixture). The ageing of plastic ceramic dough determined the effect of the CCFA admixture (0–10–20 wt. %) on the initial water content, plasticity (according to the Pfefferkorn test) and bulk density of a dried green body. The main feature of the CCFA admixture in the kaolin–quartz sand mixture is a solidifying effect. Fly ash increases the initial (mixing) water for the preparation of ceramic dough with constant plasticity (30 mm height of deformed cone Hf, according to the Pfefferkorn test), and Hf increases as the dough ages (the dough solidifies faster and loses its plasticity) with the addition of class C fly ash. The effect of CCFA addition on the plasticity and ageing of kaolin–quartz sand dough is documented on Bigot curves: higher content of fly ash decreases the drying shrinkage of the plastic dough, especially when drying samples that have been aged for 24 h in a plastic wrap (without the possibility of drying). The plastic dough's ageing increases the porosity of the dried green body with increased content of CCFA in the raw materials mixture and increased ageing time. [ABSTRACT FROM AUTHOR]

Hexagonal tungsten oxide (h-WO3) membrane is a novel candidate for dehydration of acetic acid (CH3COOH)/water mixtures owing to its molecular sieving property and acidic resistance. Meanwhile, c-plane orientation is an important factor for h-WO3 membranes because the pores of h-WO3 run along its c-axis. However, so far, high c-plane orientation has not been successful on tubular substrates. Here, the effect of synthesis conditions of h-WO3 membranes on tubular substrates against c-plane orientation and CH3COOH/water separation performance are investigated. The h-WO3 membranes were prepared by hydrothermal synthesis from a precursor sol containing various amounts of sodium tungstate (Na2WO4) in the presence of tubular substrates with seeds embedded on their outside surface. The seeding method and the amount of Na2WO4 in the precursor sol significantly affected both crystal orientation and densification of the membrane. A precursor sol with appropriate amounts of Na2WO4 was essential to simultaneously satisfy high c-plane orientation and densification of the membrane while excess Na2WO4 drastically decreased the degree of c-plane orientation. A highly c-plane oriented h-WO3 membrane was successfully obtained under the optimized condition, which exhibited a maximum separation factor of 40.0 and a water permeance of 1.53 × 10−7 mol·m−2·s−1·Pa−1 in a 90:10 wt % CH3COOH/water mixture. The water permeance approximately doubled compared to the previous report, possibly owing to the significantly higher degree of c-plane orientation. Furthermore, it was found that its separation ability can be maintained while stored in 90:10 wt % CH3COOH/water mixture with pH < 0 for more than 500 h. [ABSTRACT FROM AUTHOR]

This research focuses on an evaluation of mineral phase and structure transformations in Class F fly ash-based geopolymer systems. The research also studies the strength response of geopolymers when exposed to temperatures between 25 and 800 °C. The purpose of this research is to understand the processes that occur in alkali-activated systems within a wide range of high-working temperatures. The XRD, SEM, and DTA/TG analyses performed for the alkali-activated compositions after exposure to different temperatures confirmed a direct correlation of structural transformations with strength performance. The detrimental effect of sodium hydrocarbonate Na3(HCO3)(CO3) 2H2O or trona contained in one of the fly ash products was observed for the corresponding alkali-activated composite under high-temperature exposure between 600 and 800 °C. It was also detected that a high-temperature interval of 400–800 °C created favorable conditions that helped to form nanosized nepheline crystals and an additional vitreous substance that also contributed to a denser alkali-activated matrix. [ABSTRACT FROM AUTHOR]

Innovation in food packaging is mainly represented by the development of active and intelligent packing technologies, which offer to deliver safer and high-quality food products. Active packaging refers to the incorporation of active component into the package with the aim of maintaining or extending the product quality and shelf-life. The intelligent systems are able to monitor the condition of packaged food in order to provide information about the quality of the product during transportation and storage. These packaging technologies can also work synergistically to yield a multipurpose food packaging system. This review is a critical and up-dated analysis of the results reported in the literature about this fascinating and growing field of research. Several aspects are considered and organized going from the definitions and the regulations, to the specific functions and the technological aspects regarding the manufacturing technologies, in order to have a complete overlook on the overall topic. [ABSTRACT FROM AUTHOR]

It can be stated that in the fine chemical industries, especially in the pharmaceutical industry, large amounts of liquid waste and industrial waste solvents are generated during the production technology. Addressing these is a key issue because their disposal often accounts for the largest proportion of the cost of the entire technology. There is need to develop regeneration processes that are financially beneficial to the plant and, if possible, reuse the liquid waste in the spirit of a circular economy, in a particular technology, or possibly elsewhere. The distillation technique proves to be a good solution in many cases, but in the case of mixtures with high water content and few volatile components, this process is often not cost-effective due to its high steam consumption, and in the case of azeotropic mixtures there are separation constraints. In the present work, the membrane process considered as an alternative; pervaporation is demonstrated through the treatment of low alcohol (methanol and ethanol) aqueous mixtures. Alcohol-containing process wastewaters were investigated in professional process simulator environment with user-added pervaporation modules. Eight different methods were built up in ChemCAD flowsheet simulator: organophilic pervaporation (OPV), hydrophilic pervaporation (HPV), hydrophilic pervaporation with recirculation (R-HPV), dynamic organophilic pervaporation (Dyn-OPV), dynamic hydronophilic pervaporation (Dyn-HPV), hybrid distillation-organophilic pervaporation (D + OPV), hybrid distillation-hydrophilic pervaporation (D + HPV), and finally hybrid distillation-hydrophilic pervaporation with recirculation (R-D + HPV). It can be stated the last solution in line was the most suitable in the terms of composition, however distillation of mixture with high water content has significant heat consumption. Furthermore, the pervaporation supplemented with dynamic tanks is not favourable due to the high recirculation rate in the case of tested mixtures and compositions. [ABSTRACT FROM AUTHOR]

Metakaolinite-based geopolymer binder was prepared at room temperature by mixing calcined claystone and potassium alkaline activator. Various granular inorganic fillers were added, amounting to 65 vol % to form geopolymer composites. The effect of four types of fillers (sand quartz, chamotte, cordierite, and corundum) on the thermo-mechanical properties of metakaolinite-based geopolymer composites were investigated. The samples were also examined by an X-ray diffraction method to determine their phase composition. The pore size distributions were determined by a mercury intrusion porosimeter. The XRD revealed the crystallization of new phase (leucite) after thermal exposure at 1000 °C and higher. Geopolymer binders had low mechanical properties (flexural strength 2.5 MPa and compressive strength 45 MPa) and poor thermo-mechanical properties (especially high shrinkage—total shrinkage 9%) compared to geopolymer composites (flexural strength up to 13.8 MPa, compressive strength up to 95 MPa and total shrinkage up to 1%). The addition of fillers reduced the shrinkage of geopolymers and improved their mechanical properties. The results have shown that the compressive strength tested in situ and after exposure to high temperature are in conflict. Geopolymer composites with the addition of chamotte had the best mechanical properties before and after thermal exposure (compressive strength up to 95 MPa). The average pore size diameters increased with the increasing temperature (from 10 nm to approx. 700 nm). The fillers addition decreased the pore volume (from 250 mm3/g to approx. 100 mm3/g). [ABSTRACT FROM AUTHOR]

This review aims to provide a comprehensive assessment concerning alkali activation of natural stone wastes and minerals. In particular, the structure of the review is divided into two main sections in which the works dealing with alumino-silicate and carbonatic stones are discussed, respectively. Alumino-silicate stones are generally composed of quartz and feldspars, while carbonatic stones are mainly made of calcite and dolomite. The role of these minerals in the alkali activation process is discussed, attesting their influence in the development of the final product properties. In most of the works, authors use mineral additions only as fillers or aggregates and, in some cases, as a partial substitution of more traditional raw powders, such as metakaolin, fly ash, and granulated blast furnace slag. However, a few works in which alumino-silicate and carbonatic stone wastes are used as the main active components are discussed as well. Not only the raw materials, but also the entire alkali activation process and the curing conditions adopted in the literature studies here reviewed are systematically analyzed to improve the understanding of their effect on the physical, mechanical, and durability properties of the final products and to eventually foster the reuse of natural stone wastes for the purposes of sustainability in different applications. [ABSTRACT FROM AUTHOR]

This study aims at reviewing the alternative techniques for bioethanol recovery, highlighting its advantages and disadvantages, and to investigate the technical challenges facing these alternatives to be widely used. The findings showed that the integration of these techniques with the fermentation process did not meet a large acceptance in the industrial sector. The majority of conducted studies were mainly focusing on ethanol recovery from aqueous standard solution rather than the investigation of these techniques performance in fermentation-separation coupled system. In this context, pervaporation has received more attention as a promising alternative to distillation. However, some challenges are facing the integration of these techniques in the industrial scale as the fouling problem in pervaporation, the toxicity of solvent in liquid extraction, energy consumption in vacuum fermentation. It was also found that there is a lack of the technical economic analysis for these techniques which may limit the spread of its application in the large scale. Currently, hybrid systems integrating distillation with other alternative techniques are considered as an innovative solution to reduce the high cost of the distillation process and the low separation efficiency of the alternatives techniques. [ABSTRACT FROM AUTHOR]

In this study, mullite zirconia composites are synthesized via reaction sintering method by using zircon, kaolinite and alumina mixtures including colemanite (Ca2B6O115H2O) (7 wt.%). In mullite zirconia composites, the effect of colemanite additive on mineralogical, thermal, microstructure and mechanical properties and also on formation are studied. Mixtures are sintered at 1,450, 1,500 and 1,550°C for 5 h. in air. The resulting sintered materials are characterized in terms of bulk density, DTA, X-ray diffraction (XRD), SEM and mechanical properties such as flexural strength and elastic modulus. Various effects of colemanite addition on the composites are observed with regard to thermal, mineralogical and mechanical properties. Both DTA and XRD analyses show that colemanite addition in mullite zirconia composite reduces the reaction temperature. Zircon alone in the mixture resulted in a 1,550°C reaction temperature, whereas the compositions including colemanite is attenuated to 1,450°C. While zircon exists up to 1,550°C in the mixtures free of colemanite, it decays at 1,450°C due to 7 wt.% colemanite addition. Composites comprising of 7 wt.% colemanite exhibit a higher density, flexural strength (σ) and elastic modulus (E). Microstructural characterization of the sintered samples through scanning electron microscope indicate mullite and zirconia are the two main phases. Homogenously distributed round-shaped ZrO2 grains and irregularly shaped mullite grains are observed, which fundemantally constitute the microstructure. [ABSTRACT FROM AUTHOR]