Search Results (58)

This study investigates the hydrogen permeability of injection-molded polyamide 6 (PA6) nanocomposites reinforced with organo-modified montmorillonite (OMMT) at varying concentrations (1, 2.5, 5, and 10 wt. %) for potential use as Type IV composite-overwrapped pressure vessel (COPV) liners. While previous work examined their mechanical properties, this study focuses on their crystallinity, morphology, and gas barrier performance. The precise inorganic content was determined using thermal gravimetry analysis (TGA), while differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and scanning electron microscopy (SEM) were used to characterize the structural and morphological changes induced by varying filler content. The results showed that generally higher OMMT concentrations promoted γ-phase formation but also led to increased agglomeration and reduced crystallinity. The PA6/OMMT-1 wt. % sample stood out with higher crystallinity, well-dispersed clay, and low hydrogen permeability. In contrast, the PA6/OMMT-2.5 and -5 wt. % samples showed increased permeability, which corresponded to WAXD and SEM evidence of agglomeration and DSC results indicating a lower degree of crystallinity. PA6/OMMT-10 wt. % showed the most-reduced hydrogen permeability compared to all other samples. This improvement, however, is attributed to a tortuous path effect created by the high filler loading rather than optimal crystallinity or dispersion. SEM images revealed significant OMMT agglomeration, and DSC analysis confirmed reduced crystallinity, indicating that despite the excellent barrier performance, the compromised microstructure may negatively impact mechanical reliability, showing PA6/OMMT-1 wt. % to be the most balanced candidate combining both mechanical integrity and hydrogen impermeability for Type IV COPV liners. Full article

Solid oxide fuel cell (SOFC) systems often employ metallic cathode air pre-heaters (CAPHs), frequently made from alloys with high chromium (Cr) content, to recover thermal energy from exhaust gases and pre-heat incoming air and fuel. Cr evaporation from metallic CAPHs can poison SOFC cathodes, reducing their durability. To mitigate this, we investigated controlled pre-oxidation of a FeCrAl alloy (alloy 318) to form a protective alumina scale by self-growing, assessing its impact on and oxidation resistance and Cr retention capability for CAPH applications. The effects of pre-oxidation were investigated across a temperature range of 800 to 1100 °C and dwelling times of 0.5 to 4 h. The formed oxide scales were characterised using gravimetry in combination with advanced analytic techniques, such as SEM/EDX, STEM/EDX, TEM, and XRD. Subsequently, the pre-oxidised FeCrAl alloys were characterised with respect to the oxidation rate and Cr₂O₃ evaporation in a tubular furnace at 850 °C, with 6.0 L/min air flow and 3 vol% H₂O to simulate the SOFC cathode environment. TEM analysis confirmed that the FeCrAl alloys formed alumina scales with 10 nm and 34 nm thickness after 1 h of pre-oxidation at 900 and 1100 °C, respectively. The corrosion and Cr₂O₃ evaporation rates of the FeCrAl alloy at 850 °C in humidified air were shown to be dramatically decreased by pre-oxidation. It was found that the mechanisms of oxidation and Cr₂O₃ evaporation were found to be controlled by the formation of different alumina phases during the pre-oxidation. Measurements of Cr₂O₃ evaporation and weight gain revealed that the alloy 318 pre-treated at 1100 °C for 1 h will form an α-Al₂O₃ scale, leading to a 98% reduction of the oxidation rate and 90% reduction of Cr₂O₃ evaporation compared to the non-oxidised alloy 318 under simulated SOFC cathode conditions. Full article

Very large quantities of stone waste sludge are disposed in exhausted quarries and have a very low reuse rate to date. The paper considers the possibility of using these types of industrial waste in partial substitution of natural aggregates for the production of lime-based plasters. Traditional materials based on lime, the only material with a carbon neutrality life cycle, have considerable potential for use as components of green materials for plastering and finishing building surfaces in both new construction and historic heritage conservation. The paper presents the preliminary results of a research activity aimed at developing pre-packaged products based on Traditional Lime Putty (TLP) by partially replacing natural aggregates with Stone Waste Sludge (SWS), with a low rate of recovery from the Apricena limestone production district in Apulia. The mineralogical and chemical analysis carried out using XRD (X-Ray Diffraction), TG-DTA (Thermo Gravimetry-Differential Thermal Analysis), and hydrochloric acid attack test showed that the SWS consisted of 98.4 % CaCO₃ by mass. The particle sizes measured by laser diffraction technique are below 22.5 μm for the 92% mass of the sample. The high fineness of the stone waste was confirmed by the Blaine-specific surface method, which equals to 9273.79 cm²/gr. The behavior of three fresh mixtures for prepacked coarse plaster, fine plaster, and finishing plaster with 12.90%, 17.94%, and 18.90 by mass of SWS, respectively, was evaluated by spreading test and applicability tests on a perforated ceramic slab. The finishing plaster has the highest consistency value of 235 mm, while the fine plaster and the coarse plaster have values of 205 mm and 155 mm, respectively. The coarse plaster is suitable for use as base plaster (arriccio) or second layer rendering (tonachino) up to a thickness of approximately 1 cm. Both the fine plaster and finishing plasters can be used for the surfaces finishing with the application of layers of a few millimeters thick. Full article

Polycaprolactone (PCL) is a biodegradable polyester that might be used in tissue engineering to obtain scaffolds for bone reconstruction using 3D-printing technologies. New material compositions based on PCL, with improved physicochemical properties and excellent biocompatibility, would improve its applicability in bone regeneration. The aim of this study was to assess the potential toxic effects of PCL-based composite materials containing 5% hydroxyapatite (PCL/SHAP), 5% bioglass (PCL/BIO), or 5% chitosan (PCL/CH) on MG-63 human fibroblast-like cells in vitro. Material tests were carried out using X-ray diffraction, differential thermal analysis/thermal gravimetry, BET specific surface analysis, and scanning electron microscopy. The effect of the biomaterials on the MG-63 cells was then assessed based on toxicity tests using indirect and direct contact methods. The analysis showed that the tested biomaterials did not significantly affect cell morphology, viability, proliferation, or migration. We concluded that biodegradable PCL-based scaffolds may be suitable for tissue scaffold production, and the addition of bioglass improves the growth of cultured cells. Full article

In this study, nanostructured cerium-doped TiO₂ (Ce-TiO₂) films with the addition of different amounts of cerium (0.00, 0.08, 0.40, 0.80, 2.40, and 4.10 wt.%) were deposited on a borosilicate glass substrate by the flow coating sol-gel process. After flow coating, the deposited films were dried at a temperature of 100 °C for 1 h, followed by calcination at a temperature of 450 °C for 2 h. For the characterization of sol-gel TiO₂ films, the following analytic techniques were used: X-ray diffraction (XRD), differential thermal analysis (DTA), thermal gravimetry (TG), differential scanning calorimetry (DSC), diffuse reflectance spectroscopy (DRS), and energy dispersive X-ray spectroscopy (EDS). Sol-gel-derived Ce-TiO₂ films were used for photocatalytic degradation of ciprofloxacin (CIP). The influence of the amount of Ce in TiO₂ films, the duration of the photocatalytic decomposition, and the irradiation type (UV-A and simulated solar light) on the CIP degradation were monitored. Kinetics parameters (reaction kinetics constants and the half-life) of the CIP degradation, as well as photocatalytic degradation efficiency, were determined. The best photocatalytic activity was achieved by the TiO₂ film doped with 0.08 wt.% Ce, under both UV-A and solar irradiation. The immobilized catalyst was successfully reused for three cycles under solar light simulator radiation, with changes in photocatalytic efficiency below 3%. Full article

The modification method of aluminosilicate clays and the modifier content have a decisive influence on the structure and properties of the obtained nanocomposites. Therefore, the development and research of new techniques of nanoclays modification are of great importance for polymer nano-chemistry. The work studied the modification of montmorillonite (MMT) using polyvinylpyrrolidone (PVP) in an aqueous colloidal solution with the subsequent separation of three separate fractions of the solution according to the previously developed method. The influence of the initial mass ratio of components (MMT/PVP) on the structure and thermal properties of the modified MMT in each solution layer was determined. Scanning electron microscopy (SEM), X-ray diffraction (XRD), thermal gravimetry (TG), differential scanning calorimetry (DSC), and Fourier-transform infrared (FTIR) spectroscopy were used for research. It was established that the mass ratio of components in the initial solution has almost no effect on the structure of MMT in the top and middle solution layers, but significantly affects the yield of final products. Different structures can be obtained in the bottom layer of the solution. Still, intercalated MMT was obtained exclusively at the mass ratio of MMT/PVP = 1:2. In addition, the work investigated the structure and thermal properties of modified montmorillonites with the same PVP content, and it has been proven that such composites have dissimilar structures and properties when obtained by different methods. Full article

Reclamation of fluid fine tailing (FFT) storage facilities to their pre-disturbance equivalent landforms is hampered because micrometer size fines, whose surface-area-to-volume ratio is remarkably high, are occupied with siloxane and hydroxy groups, which bind water strongly. The purpose of this study is to differentiate the forms of water physically distributions in FFT and determine their propensities for dewaterability under compressive stresses. Two thermal and two mechanical methods were used to analyze water distributions in FFT. Dynamic and isothermal thermogravimetric analyses of FFT gave a transition from predominately bulk water to coevolution with water of higher enthalpy of vaporization at 81% (w/w) solids. Differential scanning calorimeter studies were used to determine the non-freezable water amount, with the premise that water that does not freeze by −30 °C is also unlikely to be removable by compressive stresses encountered in tailing treatment processes. The solid weight percent of FFTs with the non-freezable water was 79.6%. A 1D finite-strain model simulation using the constitutive relations of void ratio and effective stress, void ratio, and hydraulic conductivity show that deep-pits filled with such clayey-silt FFT will consolidate to a maximum solids content of 74% (w/w). For separation by centrifugation, the solids content plateaued to a mean of 74% (w/w) for total centrifugal force of ≥30 mega Newtons. These solid contents represent upper thresholds and demonstrate dewatering limit property of an FFT under compressive stresses. Full article

In this study, anti-leishmanial activities were performed on silver oxide nanoparticles green synthesized from hexane, ethereal, chloroform, and methanolic extracts of the Ericaria amentacea seaweed. The extracts were obtained using a soxhlet extraction system, and the silver oxide nanoparticles were synthesized through a simple and environmentally friendly method. Physicochemical characterizations, including UV spectrophotometry, transmission electron microscopy (TEM), X-ray diffraction (XRD), thermal gravimetry analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), and zeta potential analysis (ZPA), were conducted to confirm the formation of silver oxide particles. The anti-leishmanial activity was evaluated in vitro using the MTT assay against the Leishmania infantum, Leishmania tropica, and Leishmania major strains. Additionally, a brine shrimp cytotoxicity test was performed on Artemia salina larvae to assess the toxicity of the products. The results showed that the anti-leishmanial activity of the synthesized silver oxide nanoparticles was significant, with inhibitory concentration values ranging from 27.16 μg/mL to 38.18 μg/mL. The lethal doses in the cytotoxicity activities were higher than 17.08 μg/mL, indicating low toxicity. These findings suggest that silver oxide nanoparticles derived from Ericaria amentacea seaweed have potential applications in the treatment of leishmaniasis. Further research is needed to elucidate the mechanisms of action and assess the in vivo efficacy of these nanoparticles. Moreover, comprehensive toxicity studies are necessary before considering their clinical use in leishmaniasis treatment. Full article

Bovine serum albumin (BSA) has been used extensively as a suitable carrier system for alternative drug delivery routes, such as nasal administration. However, the optimization of BSA nanoparticles with respect to their nasal applicability has not been widely studied. The present study focuses on the characterization of BSA nanoparticles prepared using the desolvation method, followed by a gelation process to facilitate intranasal drug delivery. The results demonstrated that the ratio of BSA and the desolvating agent, ethanol, played a critical role in the nanoparticle characteristics of the BSA nanogel matrices (BSA-NGs). Based on the gelling properties, the formulations of BSA-NG 2, BSA-NG 4, and BSA-NG 6 were selected for further investigation. The Raman spectra confirmed that there were no specific changes to the secondary structures of the BSA. The mucoadhesion studies revealed moderately high mucoadhesive properties, with a mucin binding efficiency (MBE) value of around 67%, allowing the dose to avoid elimination due to rapid mucociliary clearance of the nasal passage. Via studying the nexus of the carrier system, BSA-NGs loaded with dexamethasone as a model drug were prepared and evaluated by differential scanning calorimetry (DSC) and thermal gravimetry (TG), ascertaining that no ethanol remained in the samples after the freeze-drying process. Furthermore, the viscosity measurements exhibited moderate viscosity, which is suitable for nasal liquid preparations. The in vitro release studies performed with a simulated nasal electrolyte solution (SNES) medium showed 88.15–95.47% drug release within 4 h. In conclusion, BSA nanoparticle gelling matrices can offer potential, value-added drug delivery carriers for improved nasal drug administration. Full article

Lignin isolated from agricultural residues is a promising alternative for petroleum-based polymers as feedstocks in development of antimicrobial materials. A polymer blend based on silver nanoparticles and lignin–toluene diisocyanate film (AgNPs–Lg–TDIs) was generated from organosolv lignin and silver nanoparticles (AgNPs). Lignin was isolated from Parthenium hysterophorus using acidified methanol and used to synthesize lignin capped silver nanoparticles. Lignin–toluene diisocyanate film (Lg–TDI) was prepared by treating lignin (Lg) with toluene diisocyanate (TDI) followed by solvent casting to form films. Functional groups present and thermal properties of the films were evaluated using Fourier-transform infrared spectrophotometry (FT–IR), thermal gravimetry (TGA), and differential scanning calorimetry (DSC). Scanning electron microscopy (SEM), UV–visible spectrophotometry (UV–Vis), and Powder X-ray diffractometry (XRD) were used to assess the morphology, optical properties, and crystallinity of the films. Embedding AgNPs in the Lg–TDI films increased the thermal stability and the residual ash during thermal analysis, and the presence of powder diffraction peaks at 2θ = 20, 38, 44, 55, and 58⁰ in the films correspond to lignin and silver crystal planes (111). SEM micrographs of the films revealed the presence of AgNPs in the TDI matrix with variable sizes of between 50 to 250 nm. The doped films had a UV radiation cut-off at 400 nm as compared to that of undoped films, but they did not exhibit significant antimicrobial activity against selected microorganisms. Full article

The use of copper anode slime (CAS) for the removal of lead, bismuth, and arsenic is the key to recovering precious metals. In this paper, vacuum differential gravimetry experiments combined with thermodynamic equilibrium calculations reveal the effects of the temperature, system pressure, and carbon concentration on the interactions among Pb, Bi, and As during reduction. The carbon content is a direct factor limiting the reduction reactions of sulfate and arsenate phases, and affects the presence of arsenate reduction products. When the carbon content of the system is insufficient, As mainly exists as oxides in the reduction products, and the form of arsenic gradually converts to monomers with increasing carbon content. The reduction product Bi₂S₃ gradually converts to Bi and BiS as the temperature increases. The effect of temperature on arsenate is mainly related to the phase of the Pb- and Bi-containing reduction products. Moreover, vacuum differential gravimetry experiments were performed to verify the phase transformation of As, Pb, and Bi in CAS during vacuum carbon thermal reduction. Full article

An agro-waste composite with a pelletized form was prepared and characterized via IR and ¹³C solids NMR spectroscopy. Thermal gravimetry analysis (TGA) was used to study the weight loss profiles, while SEM images provided insight on the biocomposite morphology, along with characterization of the sulfate adsorption properties under equilibrium and dynamic conditions. The sulfate monolayer adsorption capacity (q_e = 23 mg/g) of the prepared agro-waste pellets was estimated from the adsorption isotherm results by employing the Langmuir model, and comparable fitting results were obtained by the Freundlich model. The dynamic adsorption properties were investigated via adsorption studies with a fixed bed column at pH 5.2. The effects of various parameters, including flow rate, bed height and initial concentrations of sulfate, were evaluated to estimate the optimal conditions for the separation of sulfate. The experimental data of the breakthrough curves were analyzed using the Thomas and Yoon–Nelson models, which provided satisfactory best-fits for the fixed bed kinetic adsorption results. The predicted adsorption capacities for all samples according to the Thomas model concur with the experimental values. The optimum conditions reported herein afford the highest dynamic adsorption capacity (30 mg/g) as follows: 1100 mg/L initial sulfate concentration, 30 cm bed height and 5 mL/min flow rate. The breakthrough time was measured to be 550 min. This study contributes to a strategy for controlled separation of sulfate using a sustainable biocomposite material that is suitable for fixed-bed column point-of-use water treatment systems. Full article

Structured hydrotalcite NiAl-HT material with Ni/Al atomic ratio of 2.5 was prepared by co-precipitation of Ni and Al nitrate precursors and then modified by the addition of 1 wt% Ce and/or 3 wt% Au species. The obtained materials, after calcination at 600 °C, were characterized by XRD, XPS and TPR. Their catalytic performance was tested through dry reforming of methane (DRM) and by the temperature-programmed surface reaction of methane (TPSR-CH₄). Thermal gravimetry analysis (TGA) of the spent catalysts was performed to determine the amount of carbon accumulated during the reaction. The effects of the addition of cerium as a support promoter and gold as nickel promoter and the sequential addition of cerium and gold on the structural properties and on the catalytic efficiency were investigated. Under the severe condition of high space velocity (600,000 mL g⁻¹ h⁻¹), all the catalysts were quite active, with values of CH₄ conversion between 67% and 74% at 700 °C. In particular, the combination of cerium and gold enhanced the CH₄ conversion up to 74%. Both additives, individually and simultaneously, enhanced the nickel dispersion with respect to the unpromoted NiAl and favored the reducibility of the nickel. During DRM all the catalysts formed graphitic carbon, contributing to their deactivation. The lower carbon gasification temperature of the promoted catalysts confirmed a positive effect played by Ce and Au in assisting the formation of an easier-to-remove carbon. The positive effect was testified by the better stability of the Ce/NiAl with respect to the other catalysts. In the gold-containing samples, this effect was neutralized by Au diffusing towards the catalyst surface during DRM, masking the nickel active sites. TPSR-CH₄ test highlighted different CH₄ activation capability of the catalysts. Furthermore, the comparison of the deposited carbon features (amount and removal temperature) of the DRM and TPSR spent catalysts indicated a superior activation of CO₂ by the Au/Ce/NiAl, to be related to the close interaction of gold and ceria enhancing the oxygen mobility in the catalyst lattice. Full article

Lignin derived from black liquor has a lot of potentials, particularly in its thermal stability, for making value-added chemicals. The purpose of this study was to determine the effect of washing frequency during hydrochloric acid lignin isolation on the properties of eucalyptus kraft lignin. To improve its thermal characteristics and enable its usage as an additive flame retardant, the isolated lignin was synthesized into lignosulphonate. The lignin produced by 3× and 5× washing treatments had a purity of 85.88 and 92.85%, respectively. An FTIR analysis indicated that lignosulphonate was successfully synthesized from isolated lignin after 3× and 5× washing treatments, as the S=O bond was detected at around 627 cm⁻¹. The lignosulphonate exhibited a purity of 71.89 and 67.21%, respectively. Thermal gravimetry and differential scanning calorimetry analysis revealed that the lignin and lignosulphonate after 3× and 5× washing treatments had a char residue of 44, 42, 32, and 48%, respectively. Glass transition temperatures (Tg) of 141, 147, 129, and 174 °C were observed. According to the findings, washing frequency increases lignin purity and Tg, thereby improving the thermal properties of lignosulphonate. Furthermore, the flammability of rattan impregnated with lignosulphonate was V-0 in the UL-94 vertical burning test. Full article

In this study, a novel galloyl phytol antioxidant was developed by incorporating the branched phytol chain with gallic acid through mild Steglich esterification. The evaluation of the radical scavenging activity, lipid oxidation in a liposomal model, and glycerol trioleate revealed its superior antioxidant activities in both dispersed and bulk oils. Then, the antioxidant capacity enhancement of galloyl phytol was further explored using thermal gravimetry/differential thermal analysis (TG/DTA), transmission electron microscopy (TEM), and molecular modeling. The EC50 values of GP, GPa, and GE were 0.256, 0.262, and 0.263 mM, respectively, which exhibited comparable DPPH scavenging activities. These investigations unveiled that the branched aliphatic chain enforced the coiled molecular conformation and the unsaturated double bond in the phytol portion further fixed the coiled conformation, which contributed to a diminished aggregation tendency and enhanced antioxidant activities in dispersed and bulk oils. The remarkable antioxidant performance of galloyl phytol suggested intriguing and non-toxic natural antioxidant applications in the food industry, such as effectively inhibiting the oxidation of oil and improvement of the quality and shelf life of the oil, which would contribute to the use of tea resources and extending the tea industry chain. Full article