Search Results (1,288)

This study evaluates the technical feasibility, environmental sustainability, and economic viability of producing sulfoaluminate cement (SW-SAC) by co-utilizing bauxite and industrial solid wastes—phosphogypsum, calcium carbide residue (CCR), and red mud—with the solid wastes accounting for approximately 75% of the raw meal. CCR replaces limestone as the primary CaO source, releasing H₂O instead of CO₂, while phosphogypsum supplies SO₃; the raw meal is directly calcined in a single step at 1300–1350 °C, 100–150 °C below that of ordinary Portland cement (OPC). Calcination temperature and holding time were optimized through phase analysis, microstructural observation, free lime (f-CaO) determination, and strength testing. SW-SAC meeting the 42.5 strength class was then prepared using phosphogypsum as a setting regulator and phosphorus slag or limestone powder as Supplementary materials. X-ray diffraction (XRD), thermogravimetry (TG), and scanning electron microscopy (SEM) were used to examine hydration products and microstructural evolution. The optimized clinker was dominated by ye’elimite (C₄A₃S̄)  and belite (C₂S). Phosphorus slag favored the formation of gel-like products at later ages, whereas limestone powder promoted ettringite (AFt) stabilization and monocarboaluminate (Mc) formation. SW-SAC exhibited a lower carbon footprint than both Type P·I Portland cement and conventional SAC, and a lower production cost than conventional SAC. These results demonstrate a promising low-carbon route for high-value utilization of industrial solid wastes. Full article

The present research article deals with the thermal degradation study of epoxy resins filled with hybrid nanostructured forms of carbon under oxidative conditions. In particular, the formulated polymer composites (denoted as HYB_0.1%_CNTs:GNs and HYB_0.5%_CNTs:GNs, respectively) consist of two kinds of fillers, namely multi-walled carbon nanotubes (CNTs) and graphene nanosheets (GNs), mixed together with two different total mass amounts: 0.1 and 0.5%. In both kinds of nanocomposites, three different CNT:GN mixing ratios were considered (5:1, 1:1, and 1:5, respectively), thus providing a total of six hybrid samples. The thermal behavior of these samples was studied by simultaneous thermogravimetry and differential thermal analysis (TG/DTA) under flowing air, and two processes took place in distinct temperature ranges. In each step, about 50% of mass loss is detected with an exothermic effect in the corresponding DTA curve, with the second one accompanied by an intense heat release. The kinetic analysis of the two-stage oxidative thermal degradation was investigated using a model-free isoconversional approach. A non-Arrhenian behavior of the temperature function k(T) was assumed, and lifetime prediction was estimated at temperatures close to those of the possible applications. Isoconversional analysis shows nearly constant activation energies for all composites except HYB_0.1%_5:1 (from 142 to 96 kJ·mol⁻¹), while lifetime predictions indicate that thermal stability increases with graphene content at 0.1% loading (HYB_0.1%_1:5) and with CNT content at 0.5% loading (HYB_0.5%_5:1), with uncertainties below 7%. Finally, because of the π–π bond interactions between the CNTs and the GNs dispersed in the epoxy resin matrix, an effective and remarkable electrical performance was found and a correlation with both electrical and morphological properties was established. In this regard, Tunneling Atomic Force Microscopy (TUNA) proved to be particularly powerful in allowing the simultaneous mapping of topography and localized conductive networks with exceptional sensitivity to nanofiller dispersion, such as CNTs and GNs. DC conductivity increased by up to nine orders of magnitude at 0.1 wt% hybrid loading (up to 3.73 × 10⁻⁴ S/m vs. 1.06 × 10⁻¹³ S/m for CNT-only), with nanoscale TUNA currents (−1.9 to 4.5 pA) mirroring macroscopic trends, while at 0.5 wt% all hybrids reached 10⁻² S/m, indicating reduced synergy once a fully developed conductive network is established. Full article

This work presents the results of an archaeometric research study of the geomaterials used in the construction of the Late Antique wall of Emerita Augusta (currently Mérida, Spain). Dated to the 5th century C.E., this structure belongs to one of the best-preserved historical ensembles in Europe. In-depth knowledge of the geomaterials used in this ancient wall is essential for ensuring reliable restoration strategies and the successful long-term conservation of this monument. To this end, a rigorous sampling procedure was conducted in areas containing original archaeological remains. Samples were characterized using optical microscopy, X-ray diffraction (XRD), X-ray fluorescence (XRF), inductively coupled plasma–mass spectrometry (ICP-MS), thermogravimetry and differential thermal analyses (TGA-DTA), and scanning electron microscopy (SEM). This integrated multi-analytical approach is highly effective for the study of built heritage. The mineralogical, textural, and geochemical properties of the granites allowed for the identification of the granite types used in the wall, while the results obtained for the mortars indicated that lime, fully carbonated and transformed into calcite, was used as the binding agent. Furthermore, the binder/aggregate ratios were found to be consistent with traditional Roman mortar formulations. These findings provide a comprehensive understanding of the material provenance and construction techniques used in this landmark of late antiquity. Full article

The thermochemical properties of Norharmane, Harmane, and Harmine were investigated using DSC, combustion calorimetry, thermogravimetry, and G3B3 computational methods. DSC measurements enabled accurate determination of melting temperatures and fusion enthalpies. Complementary IR, NMR, and HPLC analyses performed for Harmine indicate that partial degradation occurs during the melting process, becoming more evident at higher temperatures (above ~330 °C). The standard enthalpies of formation in the solid state were 159.6 kJ·mol⁻¹ (Norharmane), 80.5 kJ·mol⁻¹ (Harmane), and −47.0 kJ·mol⁻¹ (Harmine). Using sublimation enthalpies derived from TGA, the gas-phase formation enthalpies were established as 282.7, 186.0, and 87.4 kJ·mol⁻¹, respectively. Homodesmotic G3B3 calculations showed excellent agreement with experimental data, with absolute deviations below 1.5 kJ·mol⁻¹. The combined results reveal a consistent thermodynamic stability trend in both phases: Harmine > Harmane > Norharmane. Full article

This study presents a definitive framework for Cocos nucifera (coconut) shell valorization, integrating high-resolution thermogravimetry with advanced machine learning. Physicochemical analysis confirms a high-energy feedstock (45.7% carbon, 71.5% volatiles), with SEM/XEDS and FTIR revealing heterogeneous, lignocellulosic, catalytic-rich structural matrix. TG/DTG analysis identified distinct degradation windows: hemicellulose (135–395 °C), cellulose (270–430 °C), and protracted lignin decomposition (275–675 °C). Kinetic modeling indicates that pyrolysis follows a third-order (F3) continuous degradation mechanism across the studied range, supported by high correlation coefficients ($R^2$ = 0.93–0.96). The mean kinetic and thermodynamic parameters—specifically an activation energy of 165 kJ·mol⁻¹ (calculated across the 10–60 wt% conversion range during hemicellulose and cellulose pyrolysis), a positive activation enthalpy (159 kJ·mol⁻¹), and a Gibbs free energy of activation (155 kJ·mol⁻¹)—suggest that the thermochemical conversion of coconut shell is an endothermic, non-spontaneous process with moderate energy requirements. Furthermore, the integration of kNN machine learning yielded near-perfect predictive metrics ($R^2\approx 1.000$) using optimized hyperparameters ($k=85$ for TG, $k=100$ for DTG, and $k=50$ for conversion). These findings suggest that coconut shells can be efficiently valorized as a high-energy feedstock, with data enabling reliable and optimized prediction of thermal degradation to minimize experimental waste. Full article

Organic light-emitting diode (OLED)-based devices continue to grow rapidly in popularity. This work presents a comprehensive thermodynamic study of four nitrogen-containing organic semiconductors: 1,3-bis(9H-carbazol-9-yl)benzene (mCP), 1,3,5-tri(9H-carbazol-9-yl)benzene (TCB), 1,3,5-tris(diphenylamino)benzene (TDAB), and 1,3,5-tris[(3-methylphenyl)phenylamino]benzene (m-MTDAB). A self-consistent set of phase-change thermodynamic parameters in a wide temperature range was obtained using several independent experimental and computational techniques. Vapor pressure measurements above the liquid and crystalline phases of the compounds under study were carried out using the thermogravimetry–fast scanning calorimetry method. Based on the temperature dependence of the measured vapor pressures, vaporization and sublimation enthalpies were derived. Differential scanning calorimetry was employed to determine the heat capacities of the condensed phases and the melting parameters of the studied compounds, as well as to investigate the polymorphism of TCB. Solution calorimetry was used to determine the fusion enthalpies of the compounds at 298.15 K. The obtained values were additionally compared with the literature data and calculated estimates. The results of this study may be used to predict properties for compounds with similar molecular structures. Full article

Garlic (Allium sativum) has antimicrobial and antioxidant properties. However, only the cloves are used from the bulb; the peels or husks are waste material with limited utility that nevertheless retain properties that can be exploited in other materials such as edible films or coatings. Chitosan is a widely used biopolymer, due its interesting properties. The same is true for alginate and pectin, which are polysaccharides that have interesting application areas; among the most common are film or coating materials in the food industry. Therefore, in this research, comprising the elaboration of films based on Chitosan-Pectin-Alginate (Q-P-A) reinforced with garlic husk (GH) particles, the films were characterized by Brookfield viscosity (the biopolymers solutions), Fourier Transform infrared Spectroscopy (FTIR), Dynamic mechanical analysis (DMA), and thermogravimetry (TGA). According to the results, the addition of GH caused a significant decrease in viscosity without altering the pseudoplasticity behavior and also generating physical interactions with the matrices; no chemical reaction byproducts were identified by FTIR. An increase in the reinforcing effect was identified in Q-GH films, whereas the opposite effect was observed in Q-P-A-GH films. In addition, no significant changes in the thermal stability were observed. Full article

The high mortality rate from microbial infections underscores the need to discover new antimicrobials. This work produced antibacterial Chitosan biofilms with and without the incorporation of the ethanolic extract of Libidibia ferrea stem bark and its ethyl acetate and aqueous fractions. The extract and fractions were subjected to FTIR and ¹H NMR analysis. The biofilms were characterized by FTIR, scanning electron microscopy, thermogravimetry, and differential scanning calorimetry analysis. The ¹H NMR and FTIR data, as well as the colorimetric quantification of total phenolics, demonstrated the presence of phenolic compounds. Staphylococcus aureus and Bacillus cereus were the most susceptible bacteria for Chitosan/L. ferrea biofilms and fractions (growth inhibition zones values in the range of 10.8 ± 0.1 to 14.0 ± 0.1 mm, and minimum inhibitory or bactericidal concentration, MIC or MBC values of the fractions were in the range of 125 to 250 µg mL⁻¹. Only the fractions inhibited Pseudomonas aeruginosa (MIC = 250 µg mL⁻¹). Chitosan/L. ferrea biofilms exhibited efficient interactions between chitosan functional groups and secondary metabolites, good thermal stability, and increased rigidity in mechanical tests. This study reinforces the pharmacological potential of biodegradable Chitosan/L. ferrea biofilms as antibacterial agents biofilms. Full article

Solid-state studies evaluating intermolecular geometries in methylated nucleobases are not extensively explored. In the course of the present study, we have solved the crystal structures of 1-, 3- and 7-methylated adenines and guanines, including the monohydrate and sesquihydrate forms of 3-methyladenine and 3-methylguanine, respectively, by means of single-crystal X-ray diffraction and synchrotron/laboratory X-ray powder diffraction (XRPD). In situ high temperature XRPD experiments, coupled with differential thermal analysis/thermogravimetry (DTA/TG) measurements, allowed for monitoring crystallographic changes after water removal of N3-methylated compounds, and the discovery of a high temperature polymorph in the case of 3-methyladenine. Our findings indicate that H-bonding schemes describe ribbon planar motifs of molecules in the majority of cases, or linear double-bonded strands of molecules in a few cases. π-π stacking interactions were compared with existing findings of theoretical calculations and existing crystallographic data, showing how N-methylated purine bases follow the trend predicted by Hunter and Sanders, 1990. The present study provides the first systematic experimental insights into the solid state of the presented compounds. Full article

Background: Beets are enriched in bioactive compounds with beneficial effects on cardiovascular function. Nitrate is a precursor for nitric oxide synthesis, exhibiting an effect on cardiomyocytes and myocardial ischemia/reperfusion, improving endothelial function and reducing arterial stiffness. Betanin, saponins and phenolic compounds, other beet compounds, can limit the generation of reactive oxygen species and modulate gene expression. However, it has been a challenge to develop beetroot formulations for the oral administration of these compounds while preserving pleasant sensory characteristics. Objective: The objective of this study was to develop an innovative dairy–beetroot powder drink, microencapsulated in polysaccharides, i.e., maltodextrin, cassava starch or a combination of both, that could be easily reconstituted. Key Results: The microencapsulated formulation following freeze-drying displayed low water activity (<0.30) and high solubility (>90%), with rapid dispersion in aqueous medium. Fourier transform infrared spectroscopy confirmed the preservation of functional groups from the dairy base and sugar beetroots. Thermogravimetry analyses pointed out a slight increase in thermal stability for the powder formulation. The microencapsulation efficiency of betalains reached 81% in the powder formulation that combined cassava starch and maltodextrin as encapsulation agents. The novel dairy–beetroot powder drink can be stored at room temperature, ensuring microbiological safety and preserving good sensory acceptance. Conclusions: Dairy–beetroot powder microcapsules emerge as an efficient food strategy to provide bioaccessible dietary nitrate and antioxidant compounds, overcoming flavor and stability limitations but still aiding in terms of its vascular and hemodynamic-protective effects. Full article

This study aimed to evaluate the impact of liquid–solid (LS) systems on the dissolution profiles of a poorly soluble drug—suvorexant (SUV). In the first stage of this study, LS systems were prepared by using two different non-volatile solvents: ethylene glycol diethyl ether and polyethylene glycol 400 (PEG 400). To compare the properties of different types of LS systems, formulations were prepared that differed in the content of SUV (10 and 20 mg) as well as in the ratio of excipients (microcrystalline cellulose and colloidal silica), which was 10:1 or 1:1. The physicochemical properties of the prepared formulations were characterized by X-ray diffractometry (XRD), thermogravimetry (TGA) and differential scanning calorimetry (DSC). This was followed by a dissolution study of SUV from prepared LS systems, using a 0.4% sodium lauryl sulfate solution as the medium to maintain sink conditions. Results showed that the LS systems change the crystalline structure of SUV to an amorphous one and improve the dissolution rate of SUV. The greatest improvement was achieved by using the microcrystalline cellulose and colloidal silica in a 10:1 ratio for the preparation of the system (CCA variant). It was observed that the type of solvent used and the order of combining excipients during the preparation of LS systems are also important for the properties. The main point was that physicochemical characterization of the prepared formulations lead to a loss of crystallinity of SUV associated with its introduction into liquid–solid systems. Full article

Activated carbons are usually prepared from natural precursors (e.g., fruit stones or nutshells) by carbonization and activation processes carried out at 400–1000 °C. They exhibit well-developed porosity, and chemical activation introduces hydrophilic functional groups on their surface, providing excellent sorption properties. However, the high temperatures required during thermal treatment increase production costs. In this work, cost-reducing methods for preparing carbon sorbents are proposed. Carbonization of H₃PO₄ activated waste pistachio nutshells was performed using classical pyrolysis (500 or 550 °C, 30 min, N₂ atmosphere) and microwave treatment (power 1000 W, 20 min). The properties of the synthesized carbons were characterized using thermogravimetry and spectroscopic techniques including infrared (ATR), Raman, photoelectron (XPS) spectroscopies, and scanning electron microscopy with energy-dispersive X-ray spectroscopy (SEM-EDS). Porous structure parameters were determined using nitrogen adsorption experiments. The efficiency of Pb²⁺ removal from spiked ultrapure, tap and river water was evaluated by batch sorption experiments and inductively coupled plasma–mass spectrometry. The most porous carbons were those prepared at 500 and 550 °C, with specific surface areas of 910 and 256 m²/g, respectively. Surface phosphates increased the Pb²⁺ sorption efficiency to 99% from ultrapure water, at an initial concentration of 300 µg Pb²⁺/L. The material obtained with the microwave method was not fully carbonized and remained nonporous, but it also exhibited 99% Pb²⁺ uptake from ultrapure water due to the presence of oxygen-containing surface groups. The Pb²⁺ removal from spiked tap and river water reached up to 84% and 94%, respectively, at the spiking level of 300 µg Pb²⁺/L. Full article

This study presents a source-specific experimental evaluation of particle board waste sludge (PBWS), a sludge-type industrial by-product from the wood-based panel industry, as a partial cement replacement in Portland cement paste systems. The hydration-related behavior of cement pastes containing 0%, 5%, 10%, and 20% PBWS at 7, 28, and 90 days was investigated using Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD), and Thermogravimetry/Derivative Thermogravimetry (TG/DTG). The results showed that PBWS affected phase development and thermal decomposition behavior depending on replacement level and curing age. In the TG/DTG analysis, mass losses in the 30–230 °C region were generally higher in the PBWS-containing mixtures than in the reference paste, particularly at 28 and 90 days, suggesting differences in dehydration-related phase development. FT-IR and XRD results further showed that PBWS modified the evolution of hydration-related phases in the blended systems. From an environmental perspective, increasing PBWS replacement reduced the calculated energy intensity, CO₂ emissions, and production cost; at 20% replacement, these values decreased from 3300 to 2654 MJ/t, from 830 to 706.77 kg/t, and from 3400 to 2867.16 TL/t, respectively. Overall, the results indicate that PBWS has the potential to improve the environmental profile of cement-based production while influencing hydration-related phase evolution in blended paste systems. Full article

The Amazonian açaí waste is promising for producing charcoal through pyrolysis and bioenergy through combustion, but the property losses from its poor disposal in the environment remain unknown. Therefore, this work aimed to analyze how different storage conditions of the açaí waste over time, which mimic the reality throughout the Amazon, modify its bioenergetic properties. The samples were stored in a covered greenhouse for nine months in the following conditions: immersed in water, on the soil, and in open plastic bags. The biomass was analyzed by Fourier-transformed near-infrared spectroscopy, physical properties, stereomicroscopy, proximate composition, and thermogravimetry. The degraded waste showed endocarp attack and fungi proliferation. The chemical groups of primary cell wall components were concentrated, unlike water-soluble materials, raising the fixed carbon from 22% to 25% after 30 days. Consequently, higher heating values were kept (≈19 MJ/kg). However, water immersion storage sharply decreased the waste basic density from 0.81 g/cm³ to 0.56 g/cm³, dropping the energy density from 12 GJ/m³ to 8 GJ/m³. Moreover, storage raised ash content from 1.1% up to 1.9%. The storage hindered the start of the main phases of combustion and pyrolysis, which were later intensified, especially for soil-stored waste. Therefore, more stable combustion and pyrolysis require fresh waste. Besides natural drying, plastic bag storage over time kept the waste quality closer to that of the fresh waste. Full article

Within a waste biorefinery framework, integrating agro-industrial by-products into the circular economy requires a detailed understanding of the thermochemical conversion behaviour of low-grade carbonaceous materials. This study evaluates the co-pyrolysis characteristics of Soma lignite (SL) and pectin-rich sugar beet pulp (SBP) as a sustainable route for upgrading these resources into clean energy carriers. Interactions between the two feedstocks were analysed by thermogravimetric measurements, triple-region kinetic modelling, and quantitative synergy indices at six mixing ratios, including the pure samples (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 wt% SL:SBP). The Reactivity Index ($R_{\mathrm{m}}$) increased from 0.97 × 10⁻⁴ s⁻¹K⁻¹ for pure SL to 8.65 × 10⁻⁴ s⁻¹K⁻¹ for the 20:80 blend, showing that SBP acts as a highly reactive biomass component that accelerates devolatilisation in the main pyrolysis region. Synergy analysis indicated a shift from inhibitory behaviour in coal-rich blends to slightly positive synergy in SBP-rich mixtures, with the onset of positive $\Delta TC$ around 60 wt% SBP under the present single-heating-rate, non-replicated TGA conditions. This tentative threshold-like behaviour suggests that a critical level of literature-supported, hypothesised hydrogen-donating biomass radicals may be required to overcome the structural resistance of the coal matrix. Within these experimental limitations, the apparent macro-kinetic deviations and first-order Arrhenius parameters suggest that SL/SBP co-pyrolysis follows a complex, non-additive pathway that should be further validated by multi-heating-rate and product characterisation studies in future work. The primary contribution of this work lies in proposing this distinct threshold-like biomass fraction at the macro-kinetic level that governs the transition from heat-transfer-limited antagonism to radical-influenced synergy in low-rank coal and pectin-rich biomass blends. Overall, the combined $\Delta TC$, $\Delta E$ and $R_{\mathrm{m}}$ descriptors provide useful macro-kinetic benchmarks for guiding the optimisation of thermochemical processes for low-grade carbonaceous resources. Full article