Search Results (88)

This study evaluated the effects of replacing 25% of wheat straw with dried carob (Ceratonia siliqua) leaves and twigs, either untreated or treated with 5% sodium hydroxide (NaOH), on growth performance, nutrient digestibility, carcass traits, meat quality, blood metabolites, and rumen microbial populations in Assaf lambs. Twenty-four male lambs (2.5 months old; 29 ± 0.5 kg) were randomly assigned to three dietary treatments (n = 8): a control diet containing wheat straw as the sole roughage source, supplemented with a concentrate feed, a diet with 25% untreated carob leaves and twigs (UCL), and a diet with 25% NaOH-treated carob leaves and twigs (TCL). Following a 14-day adaptation period, lambs were fed the corresponding experimental diet for 14 weeks. Carob inclusion improved growth performance, with UCL lambs showing the highest average daily gain (214 g/d) compared with TCL (201 g/d) and control (160 g/d), resulting in improved feed conversion ratio (9.02 vs. 5.68 and 5.63, respectively) (p < 0.001). Blood urea nitrogen was reduced (p < 0.001) in UCL lambs (26.8 vs. 38.5 mg/dL in control), suggesting improved nitrogen retention. Digestibility responses differed between treatments (p < 0.001), as TCL increased dry matter digestibility to 72.6% compared with 65.4% (UCL) and 63.6% (control), indicating enhanced nutrient utilization following NaOH treatment. Both UCL and TCL increased (p < 0.001) carcass weights (up to 24.7 vs. 21.0 kg in control), while TCL achieved the highest dressing percentage (46.6% vs. 43.4%). Meat quality traits were generally unaffected in terms of color (lightness, redness, and yellowness) and water-holding capacity; however, shear force decreased from 33.6 N (control) to 30.0 N (TCL), indicating improved tenderness. Carob inclusion modified meat composition by increasing (p < 0.001) lipid content (12.0–12.2 vs. 9.6%) and improving fatty acid profile, with reduced saturated fatty acids (53.4–56.5 vs. 61.4%) and increased α-linolenic acid (2.04 vs. 1.58%), leading to a lower n-6/n-3 ratio (5.54–5.61 vs. 6.45). Rumen fermentation was also affected (p < 0.001), as carob diets increased total bacterial populations and reduced protozoal counts, suggesting shifts toward more efficient microbial activity. In conclusion, replacing 25% of wheat straw with carob leaves improved growth performance and feed efficiency, with untreated carob primarily enhancing nitrogen utilization and treated carob improving fiber digestibility and carcass yield. These findings support the use of carob by-products as a viable alternative feed resource, although responses depend on processing method and targeted production outcomes. Full article

In recent years, oil spill accidents and oily wastewater discharge have posed severe threats to aquatic ecosystems and human health. Developing green, low-cost, efficient, and recyclable oil–water separation materials is therefore important for environmental remediation. In this work, kaolin/cellulose composite aerogels were fabricated through a low-temperature NaOH/urea dissolution system using N,N′-Methylenebisacrylamide (MBA) as the cross-linking agent, followed by freeze-drying and hydrophobic modification with Methyltrimethoxysilane (MTMS). The structure, morphology, thermal stability, wettability, mechanical behavior, oil adsorption capacity, and reusability of the aerogels were systematically investigated. The composite aerogels exhibited a honeycomb-like interconnected porous structure with low density and high porosity. Kaolin acted as an inorganic reinforcing and roughness-regulating component, which promoted the formation and anchoring of an MTMS-derived siloxane/SiO₂-like hydrophobic layer on the aerogel surface. The modified aerogels showed superhydrophobicity with a water contact angle above 152° and excellent oleophilicity. The optimized SC3K0.5 aerogel delivered adsorption capacities of 13.5 g/g for pump oil and 12.5 g/g for diesel. After 10 adsorption–desorption cycles, the adsorption capacity remained above 90% of the initial value, indicating good recyclability and mechanical stability. This recyclable kaolin/cellulose aerogel provides a feasible strategy for practical oil–water separation and oily wastewater treatment. Full article

Rapid and accurate urea detection is of considerable importance in environmental monitoring and biomedical analysis, as abnormal urea levels are associated with water contamination and various health conditions. In this study, a silver nanoparticle-decorated graphene oxide (Ag/GO) composite was synthesized via a simple chemical reduction method. The characterization results confirmed the successful formation of well-crystalline Ag nanoparticles (7.44 ± 1.46 nm) with uniform dispersion on GO, with a Ag loading of 39.1 wt%. The electrochemical performance for urea detection was evaluated in an alkaline medium (0.1 M NaOH) using cyclic voltammetry and chronoamperometry in a three-electrode system. The Ag/GO-modified glassy carbon electrode exhibited a strong electrocatalytic response toward urea oxidation, with a linear detection range of 1–10 mM. The sensitivity and limit of detection (LOD) were 36.8 μA mM⁻¹ and 0.11 mM, respectively. The sensor also demonstrated excellent selectivity in the presence of common interfering species, including uric acid, ascorbic acid, and glucose, along with good reproducibility, repeatability, and stability. Furthermore, the practical applicability of the sensor was assessed in real samples, where satisfactory recovery was achieved in tap water, while reduced performance was observed in milk due to matrix effects. These findings indicate that the Ag/GO composite can serve as an effective alternative electrode material for non-enzymatic electrochemical detection of urea, particularly in wastewater and biological systems. Full article

Photocatalytic degradation is a highly efficient, stable and promising technology for water treatment. Developing high-performance photocatalysts is crucial for removing aquatic contaminants. However, traditional zinc oxide (ZnO) photocatalysts are severely restricted by intrinsic drawbacks, such as a wide band gap, fast recombination of photogenerated carriers, and high photocorrosion tendency. Conventional powder catalysts also suffer from difficult recovery and serious secondary pollution. Therefore, developing simple strategies to fabricate high-performance, reusable, and stable ZnO-based photocatalysts is of great scientific and practical importance. In this work, silver-loaded nitrogen-doped ZnO nanoarrays (Ag_Y@N_X-ZnO NAs, where X and Y represent the urea and AgNO₃ concentrations, respectively) were synthesized on 304 stainless steel sheets (SSS) using a two-step hydrothermal method combined with photoreduction at room temperature. The samples were characterized by XRD, FESEM, XPS, and UV-Vis DRS, and the catalytic mechanism was studied through active species trapping and EPR. Nitrogen doping and Ag loading exhibited a strong synergistic effect, narrowing the band gap, enhancing visible-light absorption, and promoting the separation of photogenerated carriers. The optimal sample (Ag_1.5@N₄-ZnO NAs) degraded 93.2% of Rhodamine B (RhB) within 180 min, with a reaction rate constant 2.65 times higher than pure ZnO. The main active species were ·O₂⁻ and ·OH. This work provides a feasible route to fabricate recyclable and stable stainless steel-based ZnO nanoarray photocatalysts for efficient water purification. Full article

Cellulose dissolution solvents have been developed for the fabrication of regenerated cellulose (RC) films, which are known for their high optical transparency, excellent barrier properties, and biodegradability. In this study, three types of aqueous dissolution systems, including glycol ether/sodium hydroxide (NaOH), poly(ethylene glycol) (PEG)/NaOH, and urea/NaOH aqueous systems, were investigated to compare their effects on lignocellulosic microfine (LCMF) solutions and the resulting regenerated cellulose films. The dissolution yields of LCMFs in these solvents ranged from 77.0% to 85.0%. The incorporation of glycol-based co-solvents in NaOH significantly influenced the transparency (over 70% of transparency) of the regenerated LCMF films. The use of a high molecular weight of co-solvent (PEG) especially resulted in enhanced stability of the LCMF solutions, as evidenced by higher inherent viscosities and the minimal viscosity change over 30 days compared to glycol ether/NaOH and urea/NaOH systems. Furthermore, the films regenerated from the PEG/NaOH solvent showed the lowest shrinkage (19.4%) and the highest mechanical strength (47.8 MPa), followed by the glycol ether/NaOH and urea/NaOH systems. These results confirm that the type of co-solvent in cellulose dissolution systems influences the composition, coagulation behavior, and drying characteristics of regenerated LCMF films, affecting their mechanical performance. This study provides insights into the effective utilization of lignocellulosic materials for the efficient fabrication of regenerated cellulose. Full article

Currently, only a limited number of Mark–Houwink–Sakurada (MHS) equations are available for chitin, and their applicability is constrained by the narrow range of suitable solvent systems. The Mark–Houwink–Sakurada (MHS) equation is a widely used and practical approach for estimating polymer molecular weight from intrinsic viscosity measurements, particularly when chromatographic techniques are not readily accessible. This study aimed to establish new MHS equations for chitin to facilitate reliable molecular weight determination across different solvents and temperatures. Chitin samples with varying molecular weights were prepared via H₂O₂ degradation, and their weight-average molecular weights (Mw) were determined by high-performance size-exclusion chromatography (HPSEC). Intrinsic viscosity ([η]) was measured using a capillary viscometer at 25 and 30 °C in three solvent systems: 5% LiCl/N,N-dimethylacetamide (LiCl/DMAc), 8% NaOH/4% urea, and 10% NaOH/0.3% tannic acid (w/w). Double-logarithmic plots of Mw versus [η] were constructed to derive the corresponding MHS equations. At identical molecular weights and temperatures, intrinsic viscosity followed the order: LiCl/DMAc > NaOH/urea > NaOH/tannic acid. Increasing temperature led to higher intrinsic viscosity and conformation parameter (a) values. Chitin dissolved in LiCl/DMAc and NaOH/urea exhibited rod-like conformations, with a values ranging from 0.79 to 0.97, whereas chitin in NaOH/tannic acid displayed random coil behavior (a = 0.56–0.69). These established MHS equations expand the solvent applicability for chitin molecular weight determination and provide insights into its solution conformation under different chemical environments. Full article

The sustainable valorization of lignocellulosic biomass offers a promising route for developing low-cost photothermal materials for solar water purification. This study investigates natural fibers from Opuntia ficus-indica, Agave sisalana, and cellulose sponge, which were chemically purified through alkaline–peroxide pretreatment and subsequently functionalized with biochar via immersion and crosslinking-assisted deposition. Structural analyses (SEM, FTIR, XRD, CHNS/O) confirmed the transition from heterogeneous lignocellulosic matrices to cellulose-rich scaffolds and finally to hierarchical composites in which crystalline cellulose cores are coated with amorphous carbon structures containing aromatic domains typically formed during biomass carbonization. The NaOH/urea/citric acid crosslinking system significantly improved biochar adhesion, producing uniform and mechanically stable photothermal layers. Under 500 W m⁻² illumination, the biochar-modified fibers exhibited rapid thermal response and enhanced surface heating, resulting in increased water evaporation rates, with cellulose sponge achieving the highest performance (1.12–1.25 kg m⁻² h⁻¹). Water-quality analysis of the condensate showed >97% TDS removal, complete rejection of hardness, fluoride, nitrates, arsenic, and barium, and turbidity <0.2 NTU, meeting NOM-127-SSA1-2021 standards. Overall, the findings demonstrate that biochar-functionalized natural fibers constitute a scalable, environmentally benign strategy for efficient solar-driven purification, supporting their potential for sustainable clean-water technologies in resource-limited settings. Full article

Chitin–glucan complex (CGC) is a naturally occurring heteropolysaccharide in which chitin chains are covalently integrated with β-glucans, forming a rigid structural framework in fungal and yeast cell walls. CGC exhibits a broad spectrum of functional properties, including antimicrobial, antioxidant, adsorption, and tissue-regenerative activities; however, its technological exploitation has been severely constrained by its intrinsic insolubility in water and most common solvents. In this work, CGC was isolated from Aspergillus niger mycelial biomass and, for the first time, completely dissolved in a precooled aqueous NaOH/urea solvent system (12 wt.% NaOH, 8 wt.% urea) within 5 min at ambient temperature, yielding a clear and stable solution. The influence of alkali concentration on dissolution efficiency and solution stability was systematically examined. Structural integrity and covalent linkage between chitin/chitosan and glucan segments were confirmed using FTIR spectroscopy, two-dimensional NMR, and electron microscopy. The degree of deacetylation determined by NMR was approximately 25%. Rheological analysis revealed concentration- and temperature-dependent sol–gel transitions, with well-defined storage and loss moduli during gelation. Crosslinking with epichlorohydrin enabled the fabrication of lightweight, highly porous three-dimensional CGC aerogels. In vitro cytocompatibility studies using NIH 3T3 fibroblasts demonstrated no detectable cytotoxicity over 72 h. These results establish a green, efficient route for CGC dissolution and processing and highlight the promise of CGC aerogels as sustainable biomaterials for biomedical and environmental applications. Full article

The selective hydrocracking of polycyclic aromatic hydrocarbons to BTX requires precise control over catalyst porosity and metal–acid balance. Hierarchical porosity, integrating microporous and mesoporous networks, is pivotal for enhancing mass transport and regulating reaction pathways. USY zeolites were engineered to create distinct hierarchical architectures via HCl, urea, and NaOH–surfactant treatments. HCl treatment constructed a gradient pore acidity system, urea treatment enhanced acidity while preserving microporosity, and NaOH–surfactant fabricated ordered mesopores with reduced acidity. The catalyst with the HCl-engineered gradient pore (NiMo/YH-1) achieved a 91% BTX yield at 425 °C in naphthalene hydrocracking, outperforming others. This performance is attributed to its gradient structure that enforces an optimal “hydrogenation-then-cracking” pathway, highlighting the critical role of tailored hierarchical porosity. Full article

This work reports the electrochemical behavior of a nickel hydroxide electrode, electrodeposited in a deep eutectic solvent (DES), in alkaline solutions of varying composition, aiming to elucidate the influence of the cation (Na⁺ vs. K⁺), urea, and carbonate ions on the mechanism and kinetics of anodic processes. Cyclic voltammetry and electrochemical impedance spectroscopy were employed to analyze the electrochemical responses of electrode processes in alkaline water electrolysis systems. For the urea oxidation reaction (UOR), the frequency-dependent characteristics were thoroughly characterized, and the impedance response was simulated according to the Armstrong–Henderson equivalent circuit. It was found that the addition of urea significantly transforms the impedance structure, sharply reducing the polarization resistance and increasing the pseudo-capacitive component of the constant phase element at low frequencies, indicating activation of the slow steps of urea oxidation via a direct mechanism and the formation of an extended adsorptive surface. It was demonstrated that, unlike conventional alkaline electrolysis where KOH-based systems are generally more effective, urea-assisted systems exhibit superior performance in NaOH-based electrolytes, which provides more favorable kinetics for the electrocatalytic urea oxidation process. Furthermore, the accumulation of carbonate ions was shown to negatively affect UOR kinetics by increasing polarization resistance and partially blocking surface sites, highlighting the necessity of controlling electrolyte composition in practical systems. These findings open new opportunities for the rational design of efficient urea-assisted electrolyzers for green hydrogen generation. Full article

Porous Ni, Ni–Ir, and Ni–Pt electrodes were prepared on Ni substrates by molten-salt Al co-deposition followed by dealloying. SEM/EDS and XRD confirmed a Raney-type porous network with Ir or Pt present across the layer. A urea oxidation reaction (UOR) was tested in 1 M NaOH + 0.33 M urea by cyclic voltammetry and chronoamperometry at +0.40 V vs. SCE (60 min). Smooth Ni showed near-zero current. Porous Ni resulted in ~11 mA cm⁻² initially and ~9 mA cm⁻² after 60 min. Porous Ni–Ir started at ~7 mA cm⁻² and fell to ~2 mA cm⁻² within 5 min, indicating fast deactivation, likely due to Ir-oxide formation that suppresses the Ni²⁺/Ni³⁺ redox couple. Porous Ni–Pt remained at ~11 mA cm⁻² over 60 min, consistent with a stable Ni–Pt effect in which Pt aids urea adsorption/activation while Ni provides the redox path for oxidation. Overall, Pt improves UOR performance, whereas Ir lowers it under these conditions. Full article

This study aims to develop high-performance biocomposites for structural applications using kenaf, bagasse, hemp, and softwood fibers bonded with phenol-formaldehyde (PF) and phenol-urea-formaldehyde (PUF) adhesives, commonly used in particleboard manufacturing. A simple, low-cost fiber treatment was applied by adjusting the fiber pH to 11 and 13 using a 33% NaOH solution, following standard protocols to enhance fiber–adhesive interaction. The effects of alkaline treatment on the chemical structure of bagasse, kenaf, and hemp fibers were investigated using Fourier Transform Infrared Spectroscopy (FTIR) and correlated with composite mechanical performance. PF and PUF were applied at 13% (w/w), while polymeric diphenylmethane diisocyanate (pMDI) at 5% (w/w) served as a control for untreated fibers. The fabricated panels were evaluated for mechanical properties; modulus of elasticity (MOE), modulus of rupture (MOR), and internal bond strength (IB), and physical properties such as thickness swelling (TS) and water absorption (WA) after 24 h of immersion. FTIR analysis revealed that treatment at pH 11 increased the intensity of O–H, C–O–C, and C–O bands and led to the disappearance of the C=O band (~1700 cm⁻¹) in all fibers. Bagasse treated at pH 11 showed the most significant spectral changes and the highest IB values with both PF and PUF adhesives, followed by kenaf at pH 13, exceeding EN 312:6 (2010) standards for heavy-duty load-bearing panels in dry conditions. The highest MOE and MOR values were achieved with kenaf at pH 11, meeting EN 312:4 (2010) requirements, followed by bagasse, while softwood and hemp performed less favorably. In terms of thickness swelling, bagasse consistently outperformed all other fibers across pH levels and adhesives, followed by Kenaf and Hemp, surpassing even pMDI-based composites. These results suggest that high-pH treatment enhances the reactivity of PF and PUF adhesives by increasing the nucleophilic character of phenolic rings during polymerization. The performance differences among fibers are also attributed to variations in the aspect ratio and intrinsic structural properties influencing fiber–adhesive interactions under alkaline conditions. Overall, kenaf and bagasse fibers emerge as promising, sustainable alternatives to industrial softwood particles for structural particleboard production. PF and PUF adhesives offer cost-effective and less toxic options compared to pMDI, supporting their use in eco-friendly panel manufacturing. FTIR spectroscopy proved to be a powerful method for identifying structural changes caused by alkaline treatment and provided valuable insights into the resulting mechanical and physical performance of the biocomposites. Full article

Recently, the development of nanoparticle pigments has attracted interest in chemical preparation due to their potential functional properties, such as phosphate-based pigments. The present research focuses on the feasibility of synthesising the BaCr₂(P₂O₇)₂ pigment under hydrothermal conditions. The effect of the microstructural features of ceramic pigments (the crystalline structure, morphology, and particle size) on their optical properties (colour and reflectance) was also studied. The BaCr₂(P₂O₇)₂ compound was prepared in different fluid media, including water and NaOH solutions (0.5–1.0 M), at several reaction temperatures (170–240 °C) and intervals (6–48 h). The single-phase BaCr₂(P₂O₇)₂ did not crystallise without by-products (BaCr₂O₁₀, BaCr₂(PO₇)₂) in water and the alkaline solutions, even at 240 °C for 48 h; in these fluids, the ionic Cr³⁺ species oxidised to Cr⁶⁺. In contrast, the BaCr₂(P₂O₇)₂ single-phase crystallisation was favoured by adding urea as a reductant agent (25.0–300.0 mmol). Monodispersed BaCr₂(P₂O₇)₂ fine particles with a mean size of 44.0 nm were synthesised at a low temperature of 170 °C for 6 h with 0.5 M NaOH solution in the presence of 50.0 mmol urea. The phosphate pigment particle grew to approximately 62.0 nm by increasing the treatment temperature to 240 °C. A secondary dissolution–recrystallisation achieved after 24 h triggered a change in the particle morphology coupled with the incrementation of the concentration of NaOH in the solution. The pyrophosphate BaCr₂(P₂O₇)₂ pigments prepared in this study belong to the green colour spectral space according to the CIELab coordinates measurement, and exhibit 67.5% high near-infrared (NIR) solar reflectance. Full article

Chitosan (CS)-based films have demonstrated significant potential as biodegradable packaging materials, but their suboptimal barrier and mechanical properties limit practical applications. In this study, CS/carboxymethyl cellulose (CMC) composite films were prepared using a NaOH/urea-based alkaline system. Optimal ratios (1.5% CS, 2% CMC, 2.5% NaOH, and 4% urea) were determined through an L₁₆(4⁴) orthogonal array design. Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD) analyses confirmed the formation of stable physical crosslinks between CS and CMC via hydrogen bonding. These interactions significantly enhanced mechanical properties (tensile strength: 46.08 MPa; elongation at break: 68%), improved thermal stability (maximum decomposition temperature: 304 °C), and superior barrier properties (water vapor transmission rate: 0.26 × 10⁻⁵ g/(m²·h·Pa); oxygen transmission rate: 1.12 × 10⁻⁴ g/(m²·s)). NaOH concentration exhibited the most pronounced influence on film performance. The composite film combines inherent biodegradability with excellent functional properties, offering a sustainable alternative to conventional petroleum-based packaging materials. Full article

Developing scaffolds with a three-dimensional porous structure and adequate mechanical properties remains a key challenge in tissue engineering of bone. These scaffolds must be biocompatible and biodegradable to effectively support osteoblastic cell attachment, metabolic activity, and differentiation. This study successfully fabricated a chitosan–bacterial cellulose (CS–BC) composite scaffold using the solvent casting/particle leaching (SCPL) technique, with NaOH/urea solution and sodium chloride crystals as the porogen. The scaffold exhibited a well-distributed porous network with pore sizes ranging from 300 to 500 µm. Biodegradation tests in PBS containing lysozyme revealed a continuous degradation process, while in vitro studies with MC3T3-E1 cells (pre-osteoblastic mouse cell line) demonstrated excellent cell attachment, as observed through SEM imaging. The scaffold also promoted increased metabolic activity (OD values) in the MTT assay, and enhanced alkaline phosphatase (ALP) activity and upregulated expression of osteogenic-related genes. These findings suggest that the CS–BC composite scaffold, fabricated using the SCPL method, holds great potential as a candidate for bone tissue engineering applications. Full article