Search Results (2,728)

Growing environmental concern over plastic pollution has increased the need to address the persistence of PET-derived monomers, such as bis(2-hydroxyethyl) terephthalate (BHET) and terephthalic acid (TPA). This work examines the use of excimer radiation lamps combined with hydrogen peroxide (H₂O₂) to enhance advanced oxidation processes (AOPs) for their degradation. This approach stands out for its high selectivity, absence of mercury, and lower production of toxic byproducts. Experimental tests assessed how different operational factors affect pollutant degradation, such as the initial pollutant concentration (50–200 mg/L), the reaction volume (125–500 mL), and the H₂O₂:monomer mass ratio (0:1–6:1 for BHET and 0:1–4:1 for TPA). For BHET, the best results occurred with a 5:1 mass ratio, while TPA degraded optimally with a 3:1 ratio, with a 250 mL reaction volume and a 100 mg/L initial concentration for both compounds. Under these conditions, total degradation of the initial monomers was achieved in around 30 and 80 min for BHET and TPA, respectively, and at the end of the reaction, COD decreased by 46% and 32% relative to their initial values. In both cases, hydrogen peroxide was crucial since UV radiation alone led to much lower degradation efficiency. These results emphasize the need to optimize operational conditions for greater efficiency and establish a starting point for future use of excimer technology in the treatment of wastewater contaminated with PET and its derivatives. Additionally, the degradation data closely matched a pseudo-first-order kinetic model (R² ≈ 1), confirming its reliability for predictive analysis, which is of high importance for the simulation and optimization of the process. Full article

High-energy Ni-rich layered cathodes are critical for next-generation lithium-ion batteries yet remain limited by severe interfacial degradation and thermal vulnerability under high-voltage operation. In this work, a robust spinel-layered heterostructure is constructed by encapsulating LiNi₀.₈Co₀.₁Mn₀.₁O₂ (NCM811) with a LiNi₀.₅Mn₁.₅O₄ (LNMO) spinel shell via a scalable sol–gel route. Structural characterizations confirm that the coating maintains the secondary-particle architecture, while X-ray photoelectron spectroscopy reveals a chemically reconditioned interface, achieved by the scavenging residual lithium species and suppressing of rock-salt-like surface reconstruction. Consequently, the optimized 4 wt% LNMO@NCM811 electrode demonstrates significantly enhanced high-voltage (2.8–4.4 V) stability, maintaining 41.84% of its initial capacity after 200 cycles compared to only 15.75% for the pristine sample. Crucially, thermogravimetric-differential scanning calorimetry (TG-DSC) uncovers the kinetic origin of this safety improvement: the spinel shell alters the thermal decomposition pathway, delaying the 10% mass loss temperature (T_10%) from 515.2 °C to 716.6 °C and suppressing the total exothermic heat release from 208.3 J g⁻¹ to 81.5 J g⁻¹. Collectively, these results demonstrate that the co-free spinel encapsulation is a dual-functional strategy to simultaneously stabilize surficial chemistry and intrinsically enhance the thermal safety of Ni-rich cathodes for carbon-neutral energy storage applications. Full article

The long-term interfacial reliability of Cu/Al brazed joints is critical for power equipment but is often compromised by severe intermetallic compound (IMC) degradation during thermal aging. This study investigates the evolution mechanism and mechanical stability of Cu/Al joints brazed with 0.5 wt.% Ga-modified Zn-15Al filler metal, aged at 200 °C for up to 1000 h. Microstructural evolution, diffusion kinetics, and mechanical properties were systematically characterized using SEM, EDS, nanoindentation, and shear testing. Results indicate that the unmodified control interface degrades via Zn-diffusion-driven “in situ Cu depletion” of the Cu₉Al₄ layer, leading to severe embrittlement. In contrast, the addition of Ga induces a “sacrificial reconstruction” mechanism, where the outer CuAl₂ layer transforms into a dense lamellar ternary structure via cellular decomposition. This reconstructed layer acts as an effective diffusion barrier and “Zn sink,” trapping infiltrating atoms and preserving the structural integrity of the underlying Cu₉Al₄ phase. Consequently, the Ga-modified joints demonstrate superior shear strength retention and an optimized H/E ratio throughout the aging process, shifting the failure mode from brittle cleavage to a toughened lamellar peeling mechanism. This work elucidates how Ga-modulated phase reconstruction fundamentally enhances interfacial stability, offering a theoretical basis for high-reliability interconnects. Full article

Scanning Electrochemical Microscopy represents one of the most advanced high-resolution techniques that enables detailed monitoring of electrochemical processes, with a particular focus on corrosion phenomena. Scanning Electrochemical Microscopy has become an indispensable tool in studying the behavior and degradation of protective coatings exposed to aggressive environmental conditions. This technique allows researchers to precisely track local electrochemical reactions on material surfaces, providing valuable information about the stability and effectiveness of coatings. Scanning Electrochemical Microscopy enables the detection of localized current variations in the pA–nA range, allowing the identification of microdefects with nanometric width. In this paper, the basic principles of Scanning Electrochemical Microscopy operation are first presented, including a description of the device. The method of scanning the electrode is discussed through the modes and their interpretation of the obtained data for systems with protective anticorrosive coatings. Furthermore, Scanning Electrochemical Microscopy techniques enable a detailed study of the mechanisms and kinetics of new, modified coatings, which is especially significant in the case of nanoparticle-enriched coatings. Such modifications often enhance the protective properties of materials, and Scanning Electrochemical Microscopy allows monitoring of their performance under real conditions, providing insight into local electrochemical changes that are otherwise difficult to detect with standard methods. Special attention is given to the challenges researchers may encounter during experiments, such as calibration prior to measurement, interpretation of input parameters, and signal analysis. This paper aims to provide a comprehensive overview of the capabilities and limitations of Scanning Electrochemical Microscopy (SECM), emphasizing its importance as a tool for the development and optimization of new, high-performance coatings for industrial applications and scientific research. Full article

The aim of this study is to investigate the impact of layered nanomodifiers with distinct chemical structure and morphology, namely graphene nanoplates (GnP) and sodium montmorillonite (Na-MMT), on thermal degradation of polylactic acid (PLA). The exploration was performed with thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and pyrolytic gas chromatography–mass spectrometry (PyGCMS). The findings revealed a catalytic effect of Na-MMT on PLA thermal destabilization, manifested in accelerated degradation and the notable change in the composition of pyrolysis products. In contrast, the incorporation of graphene nanoplates into the PLA matrix induced a “barrier effect”: it imposed diffusion limitations on the emission of volatile degradation products during pyrolysis, which enhanced the thermal stability of the PLA/GnP composite and led to quantitative alterations in the distribution of major pyrolysis products. To elucidate the underlying degradation pathways, authors proposed a model kinetic analysis of thermal degradation for both PLA/GnP and PLA/Na-MMT composites. The analysis clearly distinguished the mechanistic differences between the two systems: while Na-MMT promotes catalytic decomposition, GnP primarily acts as the physical barrier retarding mass transport and delaying the thermal degradation development. Good alignment of theoretical model–kinetic predictions with Pyrolysis–GC/MS observations confirms the robustness of the suggested kinetic modeling method. Full article

The growing interest in using edible flowers as functional ingredients has increased the demand for reliable and sustainable strategies to recover and characterize their bioactive compounds. Torch ginger is a tropical species rich in anthocyanins. In this study, an ultrasound-assisted extraction (UAE) method was developed, optimized, and validated for the efficient recovery of anthocyanins from torch ginger flowers, with a clear focus on food-related applications. A Box–Behnken experimental design was applied to evaluate the influence of solvent composition, temperature, solvent-to-sample ratio, and pH on anthocyanin yield, using chromatographic responses. Solvent composition and solvent-to-sample ratio were identified as the most influential parameters, and effective extraction was achieved under mild temperature and pH conditions. The optimized conditions consisted of 84% methanol in water as the extraction solvent, a temperature of 30 °C, a solvent-to-sample ratio of 20:1 (mL g⁻¹), and a pH of 5.6. Kinetic studies revealed that a 5 min extraction time maximized recovery while preventing compound degradation. The method was successfully applied to different torch ginger varieties, revealing a strong correlation between flower color and anthocyanin concentration. This research provides a fast, reliable, and environmentally friendly approach for assessing anthocyanin content in torch ginger flowers. The results support the valorization of this edible flower as a potential source of natural colorants and bioactive ingredients, contributing to ingredient selection, quality control, and the future development of functional foods and clean-label products. Full article

TiO₂ nanoparticles were synthesized by a simple sol–gel route followed by high-temperature calcination at 800 °C, aiming to obtain an anatase-dominant reference photocatalyst with enhanced structural stability after severe thermal treatment. Raman spectroscopy and X-ray diffraction confirmed that anatase is the major crystalline phase, with only a minor rutile contribution after calcination at 800 °C. Nitrogen adsorption–desorption measurements revealed a narrow mesoporous contribution arising from interparticle voids and a relatively high specific surface area (108 m² g⁻¹) despite the severe thermal treatment, while electron microscopy showed nanometric primary particles assembled into compact agglomerates. Surface hydroxyl groups were identified by Fourier-transform infrared spectroscopy, consistent with sol–gel-derived TiO₂ systems. Diffuse reflectance UV–Vis spectroscopy combined with Kubelka–Munk and Tauc analysis yielded an optical band gap of 3.12 eV, typical of anatase TiO₂. Methylene blue (MB) was used as a probe molecule to evaluate photocatalytic activity under ultraviolet and visible light irradiation. Under UV illumination, degradation kinetics were governed by band-gap excitation and reactive oxygen species generation, whereas a slower but reproducible reference behavior under visible light was predominantly associated with surface-related effects and dye sensitization rather than intrinsic visible-light absorption. Overall, the results establish this anatase-dominant TiO₂ as a reliable high-temperature reference photocatalyst, retaining measurable activity after calcination at 800 °C and exhibiting UV-driven behavior as the dominant contribution. Full article

Large quantities of agricultural waste, particularly rice husk ash (RHA), are generated worldwide each year, and the lack of rational, value-added disposal pathways poses both environmental and resource-utilization challenges. To address this practical problem while improving the freeze–thaw (F–T) durability of cement-based materials in cold regions, this study investigates the effects of replacing silica fume (SF) with finely milled RHA on the hydration behavior, mechanical performance, and durability of cement mortar. From a scientific perspective, the freeze–thaw behavior of RHA-modified cementitious materials and the underlying relationships among hydration kinetics, microstructural evolution, and durability remain insufficiently understood. Mortars with different RHA–SF blending ratios were prepared at a constant water-to-binder ratio. Compressive strength was measured before and after F–T cycling, and the underlying mechanisms were investigated using isothermal calorimetry, water absorption tests, and scanning electron microscopy. Results show that SF significantly enhances pre-F–T compressive strength, with the SF-only mixture reaching 56.8 MPa at 28 d, approximately 28.7% higher than the control. With increasing RHA replacement, pre-F–T strength decreased with a non-monotonic variation (40.1–51.5 MPa). F–T cycling caused severe degradation in the reference mortar, with a strength loss rate of 31.75%, whereas RHA- or SF-modified mortars exhibited substantially lower loss rates (6.30–21.54%). Notably, high-RHA mixtures retained residual strengths of 36.0–38.3 MPa after F–T cycling. Although RHA delayed early hydration and increased water absorption, freeze–thaw resistance was not proportionally reduced. These results demonstrate that freeze–thaw durability is governed primarily by long-term microstructural stability rather than early-age strength, and they provide mechanistic evidence supporting the rational utilization of finely milled RHA as a low-carbon supplementary cementitious material for cold-region applications. Full article

Hermetia illucens can digest toxic castor meal and tolerate ricinine stress. However, the underlying mechanisms of ricinine degradation and detoxification within the larval gut microbiome remain largely unknown. Here, the enhanced degradation kinetic process, and the roles of the gut bacterial community and metabolomics were investigated. When the ricinine content was 1000 mg kg⁻¹ in feeding substrate, larval development was not significantly affected. The ricinine degradation kinetics, facilitated by larval digestion, were significantly enhanced, reducing the degradation half-life to 5.13 days. The gut bacterial community structure adjusted in response to ricinine stress, suggesting that genera such as Dysgonomonas, Actinomyces, Phascolarctobacterium, Lachnoclostridium and Sedimentibacter might play key roles in ricinine resistance and degradation. Furthermore, the gut microbial metabolism responded to toxin stress, reflected by variations in metabolite expression and the enrichment of key metabolic pathways involved in amino acid and vitamin metabolism. This emphasizes the potential role of microbial metabolism in ricinine degradation and detoxification. The close association between gut bacteria and metabolites suggests a cooperative metabolic network within the gut microbiota, where bacteria may participate in ricinine degradation and detoxification either directly or through metabolic cooperation. These findings provide insights into host–microbe interactions and ricinine resistance, highlighting the need for further exploration into the microbiota’s role in host metabolism and the development of new therapeutic strategies. Full article

Currently, the mainstream methods for dye removal internationally include advanced oxidation, catalytic degradation, and adsorption. Catalytic and oxidation methods are costly and unsuitable for large-scale application. While adsorption is straightforward, selecting and modifying raw materials poses significant challenges. Therefore, identifying readily available and inexpensive adsorbents is crucial for dye removal. This study utilized Type A coal as raw material to prepare a series of specialized activated carbon (JA) for adsorbing methyl orange from wastewater, followed by optimization. The optimized screening results indicated that JA-12 exhibited the highest methyl orange removal rate (90.54%). This performance is attributed to its larger micropore structure and increased pore volume. Further analysis revealed that the adsorption process follows pseudo-second-order kinetics and the Langmuir adsorption isotherm model (R² ≈ 0.999). Compared to the theoretical adsorption capacity calculated based on specific surface area, the adsorption capacity calculated based on pore volume (270.66 mg/g) was closer to the actual adsorption capacity, indicating that the pore structure of JA-12 plays a dominant role in the adsorption process. Combined with the Langmuir adsorption model, it can be inferred that dye molecules in solution adsorb onto the inner surface of JA-12 in a monolayer form. Surface functional group analysis revealed that protonation enhances JA-12’s adsorption capacity for the azo dye methyl orange. Collectively, our findings elucidate the removal mechanism of methyl orange using readily available coal as raw material to prepare low-cost specialty activated carbon, providing a framework for cost-effective, large-scale dye removal. Full article

Nance fruit is considered an important source of antioxidants and is used as a raw material to produce various edible products including liqueur. This fruit is grown in various locations worldwide, and its use to prepare different products needs to be further developed. Nance pulp and liqueur were analyzed by evaluating their physicochemical characteristics, bioactive compounds, and antioxidant capacities during 90 days of storage. Ascorbic acid and antioxidant capacities decreased at higher rates than pulp as per their kinetic constants and half-life times (t_1/2 was shorter for liqueur than for pulp). Fourier Transform Infrared Spectroscopy (FTIR) allowed us to register the characteristic fingerprints from bonds from diverse functional groups and demonstrated that liqueur preserved, at a higher extent, the bioactive compounds of pulp. Phenolic compounds in both samples decayed over time, suggesting that, during storage, they release due to the breakage of cell walls. Infrared spectra showed considerable overlapping, presenting characteristic alcohol and functional group peaks distinctive of bioactive compounds and polysaccharides. At the end of their storage, both samples presented peaks of less intensity than those for the initial samples, which was in agreement with the bioactive compound content and antioxidant capacity kinetics. Bioactive profiles and kinetic parameters would be useful for establishing the processing and storage conditions of nance liqueur and could support the development of local communities. Full article

Developing efficient heterojunction photocatalysts is essential to address the challenge of degrading persistent organic pollutants. In this study, a multi-scale characterization strategy was employed to investigate the implications of interfacial connectivity between synthesized graphitic carbon nitride (g-C₃N₄) /bismuth oxychloride (BiOCl)e removal of Rhodamine B (RhB) and Methyl Orange (MO). Morpho-structural characterizations, including Scanning/Transmission Electron Microscopy (SEM/TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and N₂ physisorption (Brunauer–Emmett–Teller (BET)) analyses, confirmed the successful construction of an intimate interfacial contact between g-C₃N₄ and BiOCl. The optimized composite (15% g-C₃N₄/BiOCl), prepared via a one-step hydrothermal method, exhibited enhanced photocatalytic performance following pseudo-first-order kinetics described by the Langmuir–Hinshelwood model, with apparent rate constants of 0.166 min⁻¹ for MO and 0.519 min⁻¹ for RhB. Under visible-light irradiation, degradation efficiencies of 98% for MO (120 min) and 99% for RhB (35 min) were achieved, outperforming the pristine components. Complementary optical and electrochemical analyses indicate improved light absorption and charge-separation efficiency in the heterojunction system. In addition, the photocatalyst demonstrated good operational stability over four consecutive cycles, maintaining 91.70% activity for MO and 99.76% for RhB. Overall, this work highlights the synergistic photocatalytic g-C₃N₄/BiOCl heterojunction and provides a valuable insight to guide the design of advanced materials for pollutant remediation. Full article

The aim of this study was to investigate the biochemical properties of free and immobilized mushroom tyrosinase (EC 1.14.18.1) entrapped in calcium alginate beads for phenol oxidation in a batch system. Tyrosinase activity was determined spectrophotometrically at 400 nm under optimal conditions. The effects of key operational parameters on phenol oxidation kinetics were evaluated for both enzyme systems. The Michaelis–Menten constant (K_M) of the immobilized enzyme (0.94 ± 0.2 mM) was approximately twice that of the free enzyme (0.56 ± 0.04 mM), while its maximum reaction velocity (V_Max = 101.4 ± 2.2 µmol L⁻¹ min⁻¹) decreased by nearly 30-fold (V_Max(App) = 3.63 ± 0.3 µmol L⁻¹ min⁻¹). Immobilization also shifted the optimal pH of the enzyme to pH 6.0. The optimum temperature and activation energy for phenol oxidation were determined as 55 °C and 52.48 kJ/mol for immobilized tyrosinase, whereas they were 45 °C and 39.58 kJ/mol for the free enzyme. The highest level of activity was obtained with alginate beads of 2.6 mm diameter, and the immobilized preparation exhibited enhanced operational stability, completely retaining its initial activity after five reuse cycles. Overall, these findings suggest that mushroom tyrosinase immobilized in alginate beads is a promising system for phenol removal from wastewater. Full article

Dextrin-based nanosponges (D-NS) are promising candidates for oral drug delivery due to their biocompatibility, mucoadhesive properties, and tunable swelling behavior. In this study, pH-sensitive nanosponges were synthesized using β-cyclodextrin (β-CD), GluciDex^®2 (GLU2), and KLEPTOSE^® Linecaps (LC) as building blocks, crosslinked with pyromellitic dianhydride (PMDA) and citric acid (CA). The nanosponges were mechanically size-reduced via homogenization and ball milling, and characterized by FTIR, TGA, dynamic light scattering (DLS), and zeta potential measurements. Swelling kinetics, cross-linking density (determined using Flory–Rehner theory), rheological behavior, and mucoadhesion were evaluated under simulated gastric and intestinal conditions. The β-CD:PMDA 1:4 NS was selected for drug studies due to its optimal balance of structural stability, swelling capacity (~863% at pH 6.8), and highest apomorphine (APO) loading (8.23%) with 90.58% encapsulation efficiency. All nanosuspensions showed favorable polydispersity index values (0.11–0.30), homogeneous size distribution, and stable zeta potentials, confirming suspension stability. Storage at 4 °C for six months revealed no changes in physicochemical properties or apomorphine (APO) degradation, indicating protection by the nanosponge matrix. D-NS exhibited tunable swelling, pH-responsive behavior, and mucoadhesive properties, with nanoparticle–mucin interactions quantified by the rheological synergism parameter (∆G′ = 53.45, ∆G″ = −36.26 at pH 6.8). In vitro release studies demonstrated slow, sustained release of APO from D-NS in simulated intestinal fluid compared to free drug diffusion, highlighting the potential of D-NS as pH-responsive, mucoadhesive carriers with controlled drug release and defined nanoparticle–mucin interactions. Full article

The increasing atmospheric concentration of carbon dioxide (CO₂) poses a critical threat to global climate stability, highlighting the need for efficient carbon capture technologies. While amine-based solvents such as monoethanolamine (MEA) are widely used for industrial CO₂ capture, they are subject to limitations such as high energy requirements for regeneration, solvent degradation, and environmental concerns. This study investigates potassium carbonate/bicarbonate system as an alternative solution for CO₂ absorption. The absorption mechanism and reaction kinetics of potassium carbonate in the presence of bicarbonates were reviewed. A rate-based model was developed in Aspen Plus, using literature kinetics, to simulate CO₂ absorption using 20 wt% potassium carbonate (K₂CO₃) solution with 10% carbonate-to-bicarbonate conversion under different industrial conditions. Three flue gas compositions were evaluated: cement industry, biomass combustion, and anaerobic digestion, each at 3000 m³/h flow rate. The simulation was conducted to determine minimum column height and solvent loading requirements with a target output of 90% CO₂ removal from the gas streams. Results demonstrated that potassium carbonate systems successfully achieved the target removal efficiency across all scenarios. Column heights ranged from 18 to 25 m, with molar K₂CO₃/CO₂ ratios between 1.41 and 4.00. The biomass combustion scenario proved most favorable due to lower CO₂ concentration and effective heat integration. While requiring higher column heights (18–25 m) compared to MEA systems (6–12 m) and greater solvent mass flow rates, potassium carbonate demonstrated technical feasibility for CO₂ capture. The findings of this study provide a foundation for technoeconomic evaluation of potassium carbonate systems versus amine-based technologies for industrial carbon capture applications. Full article