This study evaluated the influence of nanoalumina and nanosilica incorporation on the technological and colorimetric behavior of ceramic glazes fired between 1030 and 1080 °C. At lower temperatures (1030–1050 °C), formulations containing nanoparticles exhibited higher water absorption, indicating slower densification, particularly when the additives were combined. From 1060 °C onward, all formulations reached near-zero water absorption, with linear shrinkage stabilized between 10

Porcelain tiles are low-porosity ceramic coatings, formed by a mixture of clay minerals, quartz, and feldspars, and fired at temperatures close to 1200 degrees C with formation of a liquid phase that can result in unwanted pyroplastic deformations. In addition, the rectangular formats, large dimensions, reduced thicknesses, and fast thermal cycles worsen the deformations. Therefore, in this study, silica and boehmite-based nanoparticles were used to reduce the incidence of pyroplastic deformation in porcelain tile. Ten compositions were studied using mixture design, where the raw materials, nano-silica and nano-boehmite were the factors, independent variables. The response, dependent variable, was the pyroplastic deformation. The chemical composition of the raw materials and the size and specific surface area of the nanoparticles were determined. The mixture design results were evaluated by ANOVA and response surfaces, showing the effect of nanoparticles on the pyroplastic deformation of porcelain tiles. The composition with the lowest pyroplasticity index compared to the standard was selected, simulating an industrial process. In sequence, the pyroplasticity index was determined and evaluated by Tukey's test. The phase composition was analyzed by XRD after firing and was quantified by the Rietveld method. In addition, rational analysis was performed to estimate the glassy phase and finally the activation energy. There was 23.8% reduction in pyroplastic deformation of the porcelain tiles at 1210 degrees C when 5% nano-boehmite was added to the paste. The chemical composition of the glassy phase was a key role for the pyroplastic of the samples. The activation energy prior to the maximum densification of the samples increased by 43.8%, therefore forming a higher energy barrier against the deleterious effects of pyroplastic deformation.

Mineral coal is a primary energy source in many countries, and to enhance its quality, a beneficiation process is used to remove impurities like pyrite. Given its properties and potential applications such as photovoltaic cells and effluent treatment, this study focused on producing pyrite nanoparticles from coal mining waste through a high-energy wet milling process. The waste underwent three milling stages with varying sizes of milling elements in a high-energy mill. The influence of parameters such as mill rotation speed and milling time on the final particle size was analyzed. A rotation speed of 2,500 rpm reduced the particle size without significantly affecting the crystallinity of the pyrite phase, achieving nanometric dimensions after 390 min of processing and with greater size uniformity among the particles. The reduction in particle size led to a change in the material's composition. The process resulted in crystalline particles with a specific surface area of 29.5 m2/g, an increase of 26.0 m2/g. Due to their high specific surface area, nanoparticles exhibit much higher efficiency in reducing the color of a real textile effluent compared to microparticles.

The intercalation process, which involves the incorporation of organic molecules to increase the basal spacing between the structural layers of clay, also known as organophilization, has been extensively studied over several decades, particularly in clays with higher reactivity, such as montmorillonite, a mineral in the smectite group. In contrast, kaolinite, characterized by lower reactivity, presents significant challenges to the intercalation process due to its inherent mineralogical structure. Despite these challenges, the widespread abundance of kaolinite in the Earth’s crust continues to drive interest in its potential novel applications. The main objective of this study was to investigate the organophilization of kaolin using diaminomethanal (urea) and dimethyl sulfoxide (DMSO), alternating the variables that were studied in isolation previously. Initially, the kaolinite was characterized to determine its physicochemical, mineralogical, thermal, and morphological properties using various analytical techniques, including X-ray fluorescence, X-ray diffraction (XRD), thermogravimetric analysis, Brunauer–Emmett–Teller surface area analysis, Fourier-transform infrared spectroscopy, and scanning electron microscopy. A 2k factorial experimental design was then employed to evaluate several intercalation parameters, including the type of molecule (urea and DMSO), agitation time (ranging from 12 to 24 h), and powder mass (10–50 g) in a 100 mL solution maintained at 60 °C. The experimental results, as determined by XRD analysis, showed that DMSO was more effective in increasing the basal spacing (from 7.2 to 11.3 Å), with an intercalation efficiency of up to 80

The environmental impact of steel production is closely linked to the large amount of waste generated by this industrial process. Mill scale, a byproduct of the hot rolling process, is typically disposed of in landfills. In this context, aiming for technological enhancement and exploring potential applications, mill scale nanoparticles were produced through high-energy wet milling. After cleaning, the waste was first dry-milled in an eccentric mill and then subjected to three sequential stages of high-energy milling with spheres of varying diameters at each stage. Variations in mill rotational speed and milling time were evaluated to achieve smaller particle sizes with minimal oxidation of the waste. Steel rolling scale predominantly contains iron, which is present as wustite, magnetite, and hematite. Particles with an average diameter of 6.26 mu m, resulting from dry comminution, achieved nanometric sizes after the three stages of high-energy milling, as confirmed by transmission electron microscopy, with a specific surface area of 50.4 m2/g. The lowest tested rotational speed of 2500 rpm and a total processing time of 13 h were used for this. X-ray diffractograms and Mossbauer spectroscopy indicated oxidation of the material to more stable phases, such as magnetite and hematite, reducing the percentage of the wustite phase from 51.6 % to 7.3 %. The produced nanoparticles could serve as a promising alternative to iron-based materials, particularly in magnetic applications, such as in the biomedical field. Additionally, they may function as catalysts for wastewater treatment and have potential applications in solar energy.

The production of ferrous sulfate from alternative sources, such as industrial waste, has recently been explored. In this study, we used mill scale as the precursor for the synthesis of FeSO4 center dot H2O utilizing previously described chemical methods. Mill scale, which is a waste product of steel hot rolling in the metallurgical industry, was characterized physically and chemically. Mill scale, which consisted of 97 % wustite, magnetite, and hematite was reacted with sulfuric acid followed by filtration, concentration, cooling, and crystallization. The X-ray diffraction (XRD) profile of the obtained product confirmed the presence of FeSO4 center dot H2O; however, the XRD profile also included an indefinite peak. To investigate the occurrence of this peak, which was attributed to the presence of water in the reaction product, we subjected the synthesized ferrous sulfate sample to thermal analysis. The differential scanning calorimetry-thermogravimetry analysis results, revealed the relationship between the presence of the indefinite XRD peak and excess water in the molecular structure of the product. Moreover, we analyzed the dehydration, dehydroxylation, and decomposition of FeSO4 center dot H2O.

Stable aqueous dispersions of poly(styrene-co-butyl acrylate) (PSBA) and polyaniline doped with dodecyl benzene sulfonic acid (PANI.DBSA) were prepared with varying PANI content through in situ chemical oxidative polymerization of aniline (Ani) in PSBA latex. For comparison, an additional dispersion was prepared by physically mixing PANI.DBSA with PSBA latex. The stability of the PSBA/PANI dispersions and their ability to form electrically conductive films on glass substrates or carbon steel surfaces were investigated. The PSBA/PANI dispersions exhibited a narrow particle size distribution, with zeta potential (zeta) values lower than -25 mV, indicating stable dispersion due to strong electrostatic repulsion between particles caused by their high surface charge. As expected, the electrical conductivity of PSBA/PANI films increased with higher PANI content, reaching a maximum of 5.9 x 10-3 S cm- 1 at 3 wt% PANI. The blends prepared via in situ oxidative polymerization of Ani in aqueous PSBA emulsion demonstrated higher electrical conductivity than those produced by physically mixing PANI and PSBA dispersions. This was attributed to the superior dispersion of PANI particles in the PSBA matrix, as observed in SEM and AFM micrographs. Both types of PSBA/PANI.DBSA dispersions were cast onto carbon steel to evaluate adhesion and anti-corrosion performance. The adhesion between the carbon steel and PSBA/PANI coatings, as well as the electrochemical properties of the coatings, were not significantly affected by the preparation method. Impedance measurements revealed that coatings with 1 wt% PANI exhibited the best anticorrosive properties, likely due to fewer defects in the barrier effect compared to those with 2 and 3 wt% PANI. Overall, the findings of this study highlight the potential technological applications of PSBA/PANI dispersions, particularly for use as anticorrosion coatings on carbon steel surfaces. Furthermore, the results suggest that PSBA/PANI latex prepared via in situ polymerization is preferable for such applications.

Waste utilized for material development is increasingly under scrutiny in the pursuit of sustainability. Particularly, steel mill scale, a solid waste generated in the metallurgical industry through the oxidation of steel dowels, is a focus of study. In this investigation, X-ray diffraction (XRD) analysis identified wustite, magnetite, and hematite as crystalline phases, while X-ray fluorescence analysis revealed that iron oxides comprised 97

The escalating demand for drinking water, coupled with the contamination of surface water sources, has intensified interest in harnessing groundwater for water supply. Elevated fluoride levels in groundwater, surpassing recommended limits (1.5 mgL-1), pose a significant challenge, prohibiting the supply of water to the public. Various techniques exist for fluoride removal, with adsorption standing out for its versatility, simplicity, cost-effectiveness, and efficiency. This study assessed the kinetics and adsorption capacity of residues from the ceramic and cement industries, specifically process residues (PR) from red roof tiles, bricks, and cellular concrete. These materials, derived from the construction industry’s waste, were chosen for their accessibility and low-cost preparation. Characterization through X-ray diffractometry, X-ray fluorescence spectroscopy, and isothermal nitrogen adsorption revealed cellular concrete PR as the most promising adsorbent due to its larger specific surface area (28.2 m2 g-1) compared to brick PR (12.6 m2 g-1), and roof tile PR (2.366 m2 g-1). Adsorption capacity followed the order: cellular concrete PR > brick PR > roof tile PR. Kinetics adhered to pseudo-first-order and pseudo-second-order models, while equilibrium studies aligned with Langmuir, Freundlich, and Sips models. Langmuir’s Qmax values were 1.04, 0.709, and 1.66 (mg g-1) for cellular concrete PR, brick PR, and roof tile PR, respectively, illustrating the correlation between adsorption capacity and specific surface area.

Carbon dioxide levels in the atmosphere are related to global warming and climate change. Materials to be used for CO2 capture are an important factor in assisting humanity in overcoming this challenge. The goals of this study are to look into the synthesis of adsorbents from red mud (RM), fly ash (FA), and metakaolin (MK). The initial composition was chosen to induce in situ crystallization of zeolites dispersed together with a geopolymer matrix. Two aging steps were used, which combined temperature (25; 95 °C) and atmosphere (air; water). The MK + FA system crystallized zeolite sites dispersed throughout the geopolymer matrix. These crystals were identified as faujasite-Na. They were responsible for the surface area ranging from 23.2 to 238.4 m2.g−1, and CO2 adsorption from 0.83 to 2.32 mmol.g−1 at 35 °C and 1 atm. The best results were obtained by first aging at 95 °C for 120 h, followed by water aging at 25 °C for 120 h.

The increasing contamination of water resources is a severe environmental problem. Manganese is highly soluble in water, has adverse effects on the environment and human health during excessive exposure, and is difficult to remove. Biosorbents have been suggested to remove metals from aqueous solutions, therefore, apple pomace was utilized to prepare activated biochar (activated charcoal from apple pomace, ACAP). The biochar sample was characterized by X-ray fluorescence spectrometry, scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and Brunauer-Emmett-Teller analysis. The aim of this study was to use ACAP as an adsorbent to remove Mn2+ ions from aqueous solutions. Adsorption experiments were performed in the pH range 3.2-6.5, with various masses of ACAP biochar and Mn2+ ion concentrations. The results were evaluated using the pseudo-first order, pseudo-second order, general order, Elovich, and Webber and Morris kinetics models. All the models fitted the experimental results, the equilibrium time was 15 min, and the pseudo-second order model presented the highest constant (k2), indicating that chemosorption is an important mechanism in adsorption. The adsorption isotherm results were adjusted using different models, wherein the Langmuir and Temkin models exhibited the best fit to the experimental results. Adsorption experiments yielded a 97.5% removal rate of Mn2+ ions at pH 6.5 and <5% at pH 3.2, and the desorption of manganese in nitric acid (0.1 M) was 97.5%. Overall, apple pomace biochar is an efficient adsorbent for removing Mn2+ ions in aqueous media, and is applicable for treating water for human consumption.

The investigation aims to analyze the technical viability of addition the waste from the filter-press from the mineral coal treatment process (TFP) and bottom ash from a thermoelectric (CP), in ceramic paste on the laboratory scale. Physical-chemical characterization and waste classification tests were carried out. Subsequently, ten formulations were developed through the mixture design (DoE), incorporating these residues into a standard clay ceramic paste (STD). The samples were formed by extrusion without vacuum and subjected to heat treatment in an oven and fired in a muffle at 900 degrees C. The evaluated technological properties were: shrinkage of drying and firing, water absorption and mechanical resistance and, finally, efflorescence tests and phytotoxicological analysis were performed. The results of solid waste classification, indicated these as not being dangerous (Class II-B -inert). The technical analysis of the samples show that compared to the clay ceramic standard formulation (STD), the other mixtures obtained results within the technical parameters, which can later be carried out in an industrial scale test. Although the mechanical tests with waste incorporation were below the standard formulation (STD), a test on an industrial scale is not discarded. In the efflorescence test, it was observed that there was no presence of soluble salts. And finally, in the phyto-toxicological test, with Allium cepa L. of a formulation with aggregation of all raw materials, it presented a result marginally similar to the standard, proving itself capable of reproduction on an industrial scale.

Currently, the overheating detection of electric system components is performed using thermal imaging devices, which depend on on-site regulation parameters, require skilled operators and suitable weather conditions. The development and application of innovative technologies to monitor hotspots has highlighted the use of sensors based on thermosensitive materials. In this study, a temperature sensor with thermochromic coating was developed. Thermochromic sensors covered with a varnish layer and nano-titanium oxide, in addition to thermochromic paint, were produced. A 23 experimental design was established to assess the performance of thermochromic sensors under artificial weathering conditions. Color measurements of the coatings were performed using the CIELAB method. Fourier-transform infrared (FTIR), UV-Vis (Ultraviolet-Visible), (thermogravimetric TGA, and Differential Scanning Calorimetry (DSC) analyses were performed on the sensors exposed to photodegradation to detect changes in the thermochromic coatings. The sensors exposed to thermodegradation, and salt spray weathering showed ΔE (total color difference) values below 1.50 points in the presence of TiO2. In comparison, the sensors exposed to photodegradation showed ΔE values above 10 points, and UV-Vis analysis revealed changes in the chemical structure of the coatings. These results demonstrate that the varnish layer and TiO2 can help minimize the degradation effects of temperature, light, and salinity.

In this study, chemically bound phosphate ceramics (CBPCs), a type of geopolymer, were synthesized by reacting metakaolin (MK) with acidic solutions of phosphoric acid (PA), potassium dihydrogen phosphate (KDP), calcium dihydrogen phosphate (CDP), and aluminum dihydrogen phosphate (ADP). The obtained CBPCs were characterized using thermal analysis (DTA-TG), X-ray diffraction, dilatometry, and scanning electron microscopy and by their real density, porosity, water absorption, and compressive strength. The analyses revealed that the used acid phosphate type strongly influenced the properties of the resulting CBPCs. The best compressive strength results were found in CBPCs obtained using ADP, with an average value of 34.50 MPa and average porosity of 23.21%. For CBPCs obtained from PA, CDP, and KDP, the average compressive strength values were 14.18, 8.17, and 2.84 MPa, respectively; their average porosities were 18.79%, 36.23%, and 37.90%, respectively. The results demonstrate that CBPCs produced with MK can be cured at room temperature and that CBPCs obtained with ADP have higher compressive strength values than these of the other acids.

Magnetic nanoparticles (MNPs) have been widely studied for their properties and applications in the fields of electronics and medicine. Hydrothermal synthesis, in which the reaction parameters are extremely important because they influence the product characteristics, properties, and final applications, is an existing method for producing nanomaterials. Therefore, in this study, hydrothermal syntheses were performed to obtain nanomagnetite by varying the temperature, reaction time, and molar ratio, and their influences on the product particle size were analyzed using statistical analysis. The products were characterized in terms of composition and purity.Tthe purest samples were obtained at a reaction temperature of 214 celcius and the longest reaction time of 6 h, with 96 % purity for the tests with a higher magnetite content. All syntheses produced products with particles on the nanometer scale. The purest magnetite samples exhibited an average hydrodynamic diameter of 220 nm and ferromagnetic behavior. Statistical analysis revealed that the reaction time was the only statistically significant parameter influencing magnetite particle size, with smaller sizes at longer reaction times. The cytotoxicity of MNPs was evaluated in non-tumor cells (NIH3T3 and RAW 264.7). Human erythrocytes did not exert any cytotoxic effects on non-tumor cells, indicating that MNPs are promising drug delivery systems.

RESUMO A investigação teve por objetivo analisar a viabilidade técnica de incorporação do resíduo proveniente do filtro prensa do processo de beneficiamento do carvão mineral (TFP) e de cinzas pesadas (CP) advindos de uma termoelétrica, em massa cerâmica na escala laboratorial. Foram realizados ensaios de caracterização físico-química e de classificação dos resíduos. Posteriormente foram desenvolvidas dez formulações através de planejamento experimental por delineamento de misturas simplex centroide, incorporando esses resíduos a uma massa padrão de cerâmica vermelha. Os corpos-de-prova foram conformados por extrusão sem vácuo e submetidos a tratamento térmico em estufa e queima em forno mufla a 900 °C. As propriedades tecnológicas avaliadas foram: retração térmica linear de secagem e de queima, absorção de água e resistência mecânica à compressão e por fim, foram realizados testes de eflorescência e análise fitotoxicológica. Os resultados de classificação dos resíduos, indicaram esses como não sendo perigoso – Classe II-B – inerte. Os testes físicos dos corpos-de-prova mostram que comparados a formulação base de cerâmica vermelha (STD), as demais formulações obtiveram resultados dentro dos parâmetros técnicos, que podem ser posteriormente realizados em um ensaio de escala industrial. Embora os ensaios mecânicos das provas com incorporação de resíduo ficaram abaixo da formulação base (STD), não se descarta uma prova em escala similar a industrial. No ensaio de eflorescência, observou-se que não houve presença de sais solúveis. E por fim, no ensaio fitotoxicológico, com Allium cepa L. de uma formulação com agregação de todas matérias-primas juntas, apresentou um resultado próximos ao padrão, se mostrando apto a reprodução em escala industrial.

In this study, a modified fluidized bed reactor was used to roast pyrite concentrate (PC). To analyze the pyrite conversion and fluid flow in the bed, a 2D model incorporating the Euler-Euler method and the conservation equation of chemical species was employed. In addition, the reactant and product samples were characterized through X-ray diffraction (XRD), X-ray fluorescence (XRF), particle size distribution, and thermogravimetric analyses (TGA). The kinetic parameters of the pyrite decomposition were also determined. The isoconversional method was used to determine the activation energy, pre-exponential factor of the specific reaction-rate equation, and reaction mechanism from thermogravimetry results. This rate law was then applied in the model to account for the depletion of pyrite in the modified fluidized bed. The main crystallographic phase in the formed product was hematite. XRF and TGA result indicate that the PC had high purity and roasting occurred at a conversion of 80 %. The pyrite decomposition kinetics showed activation energy varies from 33.2 to 281.4 kJ.mol(-1) depending on the stage. The kinetic analysis of roasting and its implementation in the model demonstrated that the simulation achieved 72 % PC conversion into the products. These results validate the experimental conversion, illustrating the compatibility of the model with the experimental data. Specifically, the coupling of the rate law from TGA with the dispersed-phase velocity vector encourages to new research possibilities in this field of chemical engineering. (C) 2022 Elsevier Ltd. All rights reserved.

Civil construction has been seeking sustainable practices with the insertion of waste in their products. The objective of this work is to study for the first time the use of shavings generated in the production of disposable straws, without reprocessing by extrusion, in paver blocks as an alternative to commercial polypropylene fiber, because the production and use of disposable straws generate a significant portion of plastic waste worldwide. The concrete was produced with a ratio (by weight) of 1:1.5:1.5:2.5 for cement, fine sand, coarse sand, and gravel. Straw shavings were submitted to surface treatment using a 0.25 M sodium hydroxide solution and added to concrete at a volumetric content of 0.5%. The physical and mechanical properties of the mixture were analyzed and compared to those of reference samples and those produced by adding commercial fibers. The compressive strength at 28 days of the samples with the addition of drinking straw shavings (36.47 ± 1.63 MPa) was lower than the reference samples (43.61 ± 2.16 MPa) and those with commercial polypropylene fibers (44.23 ± 1.79 MPa), but respected the 35 MPa limit required by the technical standard. The water absorption of paver blocks containing commercial fibers (5.6 ± 0.1%) exceeded that of paver blocks containing shavings (4.9 ± 0.3%). The lower water absorption reduces the entrance of corrosive ions which directly collaborate with the material deterioration process. There is no statistical evidence that the incorporation of waste reduces the abrasion resistance and flexural tensile strength of the concrete parts.

The properties of waterborne epoxy coatings applied to 1020 carbon-steel plates were evaluated based on two factors: stoichiometry and the amount of coalescing aid used. The effects of the interactions between these two factors on coating properties were evaluated at three levels using a 32 factorial design and the Statistica 13.3Trial software. The coatings were subjected to accelerated weathering and salt-spray tests and evaluated based on gloss, yellowing, Fourier-transform infrared spectroscopy, atomic force microscopy, and differential scanning calorimetry. The evaluation of gloss showed that stoichiometry (F = 334.45) was a more important factor than the amount of coalescent (F = 62.81). An excess amount of curing agent produced glossier coatings. Yellowing was strongly influenced by both factors, with lower amounts of curing agent and higher amounts of coalescent resulting in coatings with higher resistance to yellowing. A salt-spray test was conducted to evaluate the corrosion resistance of the coatings. The coatings produced with an excessive amount of coalescent and curing agents exhibited the lowest corrosion resistance. The best results were obtained with 7% coalescent agent and reduced amounts of curing agent.