Search Results (642)

Urban leaf litter represents an underutilized biomass resource with potential applications in sustainable building materials. This study investigates the suitability of dried, comminuted leaves collected from municipal green areas as a loose-fill thermal insulation material. The material was characterized in terms of thermal conductivity, settlement behavior, fire reaction, resistance to mold growth, water vapor diffusion, hygroscopic sorption, and short-term water absorption. Tests were conducted following relevant DIN and ISO standards, with both untreated and flame-retardant-treated samples examined. Results indicate that the thermal conductivity of leaf-based insulation (λ = 0.041–0.046 W/m·K) is comparable to other bio-based loose-fill materials such as cellulose and wood fiber. Optimal performance was achieved for particles sized 2–16 mm, showing settlement below 1%. All variants, including untreated material, fulfilled the fire resistance requirements of class E, while selected treatments further improved fire resistance. The material exhibited moderate vapor permeability (μ ≈ 4–5), low water absorption, and moisture buffering behavior similar to that of other bio-based insulation materials. Resistance to mold growth was satisfactory under standardized conditions. Overall, the results demonstrate that leaf litter can serve as an effective and environmentally favorable loose-fill insulation material, offering an innovative recycling pathway for urban green waste. Full article

The article presents a comprehensive comparative performance evaluation and validation of composite adsorbents based on the Se-derivative of 4-amino-N′-hydroxy-1,2,5-oxadiazole-3-carboximidamide for U (VI) recovery from complex multicomponent aqueous media. Our results indicate the composite materials to be comparable to, and in some cases to surpass, existing adsorbents in recovery efficiency. Under static sorption conditions for trace U (VI) from real multicomponent solutions (tap, river, and sea water), the sorption efficiency reached 80–98%, while the distribution coefficients ranged from 10⁴ to 10⁶ cm³ g⁻¹. The sorption-selectivity properties of the materials were evaluated in the presence of competing ions (EDTA and oxalate ions), which possess a high chelating capacity and a strong tendency to form complexes with uranium. The dependence of sorption efficiency on the concentration of these ions and the solution pH was investigated. The possibility of reusing the materials over multiple sorption-desorption cycles was assessed. An optimal regenerating eluent agent was identified (NaHCO₃/NH₄NO₃), providing a desorption efficiency of >95% without degrading the material’s sorption properties over repeated cycles. Using a combination of physicochemical methods, including sorption techniques, the mechanism of uranium sorption and its dependence on the material structure were determined. The efficiency of uranium recovery from multicomponent natural waters was also investigated under dynamic conditions over repeated sorption-desorption cycles. The results demonstrate through comparative analysis that the developed composites exhibit a high sorption capacity and possess a high practical potential for the concentration and recovery of uranium from high-salinity solutions with complex composition. Full article

Developing sustainable and molecularly selective adsorbents for heavy-metal removal remains a critical challenge in water purification. Herein, we report a green molecular-engineering approach for fabricating aza-crown ether functionalized sodium alginate aerogels (ACSA) capable of highly selective Cu²⁺ capture. The aerogels were synthesized via saccharide-ring oxidation, Cu²⁺-templated self-assembly, and reductive amination, enabling the covalent integration of aza-crown ether motifs within a hierarchically porous biopolymer matrix. Structural analyses (FTIR, ¹³C NMR, XPS, SEM, TGA) confirmed the in situ formation of macrocyclic N/O coordination sites. Owing to their interconnected porosity and chemically stable framework, ACSA exhibited rapid sorption kinetics following a pseudo-second-order model (R² = 0.999) and a Langmuir maximum adsorption capacity of 150.82 mg·g⁻¹. The material displayed remarkable Cu²⁺ selectivity over Zn²⁺, Cd²⁺, and Ni²⁺, arising from the precise alignment between Cu²⁺ ionic radius (0.73 Å) and crown-cavity dimensions, synergistic N/O chelation, and Jahn-Teller stabilization. Over four regeneration cycles, ACSA retained more than 80% of its original adsorption capacity, confirming excellent durability and reusability. This saccharide-ring modification strategy eliminates crown-ether leaching and weak anchoring, offering a scalable and environmentally benign route to bio-based adsorbents that combine molecular recognition with structural stability for efficient Cu²⁺ remediation and beyond. Full article

Quercetin’s therapeutic potential is limited by its poor water solubility and rapid degradation. Natural clay minerals such as kaolinite present sustainable platforms for drug delivery, yet the molecular mechanisms of drug encapsulation are not fully understood. Specifically, the role of kaolinite’s structural polarity, its hydrophilic aluminol (001) and hydrophobic siloxane (00-1) basal surfaces, in selective drug adsorption remains unexplored. This study combines Monte Carlo sampling and Density Functional Theory (DFT) to provide the first quantitative, atomistic comparison of quercetin adsorption on both kaolinite surfaces. The results demonstrate a pronounced polarity-driven selectivity. Strong, exothermic adsorption (−206.65 kJ mol⁻¹) occurs on the hydrophilic (001) surface, stabilized by a network of five hydrogen bonds. In contrast, the hydrophobic (00-1) surface exhibits significantly weaker sorption (−147.16 kJ mol⁻¹), dominated by van der Waals interactions. Charge-transfer analysis shows that the hydrophilic (001) surface exhibits a net charge transfer of −0.198 e, approximately 2.4 times greater than that of the hydrophobic (00-1) surface (−0.083 e), consistent with differential electron density maps and partial density of states. By linking hydrogen bonding and charge transfer to adsorption energy, these results elucidate how surface polarity dictates drug encapsulation. This work establishes a predictive framework for designing kaolinite-based nanocarriers with optimized stability, bioavailability, and controlled release, guiding the development of sustainable drug delivery systems. It is noted that this DFT study models adsorption at 0 K using periodic slab models in a vacuum. Full article

Heavy metals are major toxic anthropogenic contaminants released into the environment mainly through wastewater discharges. Adsorption is one of the most effective and widely applied methods for their removal from aqueous systems. However, although activated carbon is commonly used, its high cost and limited regenerability motivate the search for cheaper and more environmentally friendly alternatives. In this study, selected natural and waste-derived materials were evaluated for Cu²⁺ removal from both model solutions and atypical textile wastewater. Coffee grounds, chestnut seeds, acorns, potato peels, eggshells, marine shells, and poultry bones were tested and compared with commercial activated carbon. Their structural and functional properties were characterised using specific surface area measurements, optical microscopy, SEM-EDS, and FTIR analyses. Two adsorption isotherm models (Langmuir and Freundlich) were used to analyse the experimental data for the selected adsorbents, and model parameters were determined by linear regression. Based on model solution tests, two materials showed the highest Cu²⁺ sorption potential: coarse poultry bones (97.0% at 24 h) and fine cockle shells (96.2% at 24 h). When applied to real textile wastewater, the bone-derived material achieved the highest Cu²⁺ removal efficiency (79.4%). Although this efficiency is lower than typical values obtained in laboratory solutions, it demonstrates the feasibility of waste-derived materials as low-cost adsorbents and suggests that further optimisation could further improve their performance. Full article

Ionic liquids (ILs) have attracted considerable attention for light olefin separation owing to their negligible vapor pressure, excellent thermal stability, and tunable molecular structures. However, their intrinsically high viscosity severely restricts gas diffusion, leading to poor mass-transfer efficiency and limited separation performance in bulk form. Herein, we report the develop a high-performance adsorbent by immobilizing a silver-functionalized ionic liquid within ordered mesoporous MCM-41 to overcome the diffusion limitations of bulk ILs. The IL@MCM-41 composites were prepared via an impregnation–evaporation strategy, and their mesostructural integrity and textural evolution were confirmed by XRD and N₂ sorption analyses. Their C₂H₄/C₂H₆ separation performance was subsequently evaluated. The composite with a 70 wt% IL loading achieves a high C₂H₄ uptake of 25.68 mg/g and a C₂H₄/C₂H₆ selectivity of 15.59 in breakthrough experiments (298 K, 100 kPa). X-ray photoelectron spectroscopy results are consistent with the presence of reversible Ag⁺–π interactions, which governs the selective adsorption of C₂H₄. Additionally, the composite exhibits excellent thermal stability (up to 570 K) and maintains stable separation performance over 10 adsorption–desorption cycles. These IL@MCM-41 composites have significant potential for designing sorbent materials for efficient olefin/paraffin separation applications. Full article

Magnesium hydride (MgH₂) is a promising solid-state hydrogen storage material owing to its high hydrogen capacity and low cost, yet its practical application is limited by sluggish kinetics, high operating temperatures, and poor cycling stability. Among various catalytic approaches, Fe-based catalysts have emerged as attractive candidates due to their abundance, compositional tunability, and effective promotion of hydrogen sorption reactions in MgH₂ systems. This review critically summarizes recent progress in Fe-based catalysts for MgH₂ hydrogen storage, encompassing elemental Fe, iron oxides, Fe-based alloys, and advanced composite catalysts with nanostructured and multicomponent architectures. Mechanistic insights into catalytic enhancement are discussed, with particular emphasis on interfacial electron transfer, catalytic phase evolution, hydrogen diffusion pathways, and synergistic effects between Fe-containing species and MgH₂, supported by experimental and theoretical studies. In addition to catalytic activity, key stability challenges—including catalyst agglomeration, phase segregation, interfacial degradation, and performance decay during cycling—are analyzed in relation to structural evolution and kinetic–thermodynamic trade-offs. Finally, a roadmap for the scalable design of Fe-based catalysts is proposed, highlighting rational catalyst selection, interface engineering, and compatibility with large-scale synthesis. This review aims to bridge fundamental mechanisms with practical design considerations for developing durable and high-performance MgH₂-based hydrogen storage materials. Full article

Hexakis(4-(4-carboxylphenyl)phenyl)benzene, H₆cbb, was used to prepare the rod-based metal–organic frameworks (rod-MOFs) [Mn₄(cbb)(dmf)₂(OAc)₂] CTH-50 and [Gd₃(cbb)(dmf)₂(H₂O)(OAc)₃] CTH-51 by solvothermal synthesis (dmf = N,N-dimethylformamide) with single crystal diffraction revealing that CTH-50 (by X-ray) and CTH-51 (by electron diffraction) can be described as 5- and 6-connected yav-nets. Gas sorption analysis gave a BET surface area of 787 m²/g for CTH-50 and 187 m²/g for CTH-51, with CTH-50 having an Ideal Adsorbed Solution Theory (IAST) selectivity for SF₆ of 35 at 10 kPa, and thermogravimetry indicated the possible stability of CTH-50 to 300 °C and CTH-51 to 400 °C. Full article

Acidic agricultural soils are frequently challenged by co-occurring heavy metal contamination and greenhouse gas (GHG) emissions. While biochar is widely used for integrated remediation, the specific role of silicon (Si) in modulating its effectiveness in cadmium (Cd) stabilization and nitrous oxide (N₂O) mitigation remains insufficiently understood. This study evaluated the co-remediation efficacy of two types of high-Si (bamboo leaves, ML; rice straw, RS) and two types of low-Si (Camellia oleifera leaves, CL; Camellia oleifera shells, CS) biochar, produced at 450 °C, within a Cd-contaminated and nitrogen-fertilized acidic soil. Results from a 90-day incubation showed that while all biochar effectively immobilized Cd, the low-Si CL biochar exhibited a superior stabilization efficiency of 66.2%. This enhanced performance was attributed to its higher soil organic carbon (SOC) and moderate dissolved organic carbon (DOC) release, which facilitated robust Cd²⁺ sorption and complexation. In contrast, high-Si biochar was more effective in mitigating cumulative N₂O emissions (up to 67.8%). This mitigation was strongly associated with an elevated abundance of the nosZ gene (up to 48.1%), which catalyzes the terminal step of denitrification. Soil pH and DOC were identified as pivotal drivers regulating both Cd bioavailability and N₂O dynamics. Collectively, low-Si biochar is preferable for Cd stabilization in acidic soils, whereas high-Si biochar is more effective at elevating pH and reducing N₂O emissions. These findings emphasize that optimizing co-remediation outcomes necessitates a targeted approach, selecting biochar based on the specific contamination profile and desired environmental benefits. Full article

Titania catalysts containing cerium, copper, or iron were obtained using the sol–gel method and tested in the selective reduction of nitrogen oxide. Samples with cerium and iron showed high activity at temperatures ranging from 200 to 400 °C, without the formation of N₂O. The materials crystallized in anatase structure, and only a small amount of ceria was detected by XRD. Their crystallites were nanometric in size. The solids were mesoporous, with a specific surface area between 74 and 160 m²/g, determined based on nitrogen sorption at low temperature. The optimum Ce/Ti and Fe/Ti atomic ratio was 0.1 to 0.9, and such catalysts were composed of small anatase crystallites, although the presence of ceria also resulted in high catalytic activity. This activity was due to the presence of Fe³⁺ or Ce³⁺ ions on the surface of the material. Full article

Strawberries and blueberries are globally recognized for their dense nutritional profile, bioactive compounds, and health-promoting properties. Yet, their perishability and seasonality limit their availability, stability, and functionality in food and nutraceutical formulations. Drying technologies, particularly spray drying and freeze drying, are effective preservation strategies that convert fresh berries into stable, shelf-ready powders. However, the high sugar content, low glass transition temperature (Tg), and hygroscopic nature of berry matrices pose significant challenges in maintaining powder flowability, preventing caking, and ensuring structural integrity during processing, storage, and transportation. This review examines the physicochemical and surface properties of strawberry and blueberry powders as influenced by the drying method, environmental conditions, and carrier selection (e.g., maltodextrin, gum arabic, and whey proteins). Emphasis is placed on glass transition phenomena, moisture sorption behavior, and surface composition as determinants of physical stability and shelf life. The roles of water activity (aw), particle morphology, and interparticle interactions are analyzed in the context of formulation design and powder performance. Analytical techniques in characterizing bulk properties for the amorphous structure and sorption kinetics and probing surface properties of powders are crucial for understanding interactions with water, assessing flow, caking, sintering, and dissolution. By integrating insights from food physical chemistry and materials surface properties, this review provides a framework for the rational design of berry-based powders with improved handling, stability, and bio-functionality. The findings have direct implications for scalable production, global distribution, and the development of functional ingredients aligned with health and wellness priorities worldwide. Full article

A comparative sorption dependence was carried out between the Dowex HCR-S/S″ industrial ion-exchange sorbent and the synthesized ion-exchange sorbent based on dibenzylamine, epichlorohydrin and polyethylenimine in relation to copper and silver ions. The sorption of copper and silver was studied by ionometry and the dependences of the sorption of copper and silver ions in the static mode were established depending on the concentration of metal ions and the duration of ionite contact with solutions of copper and silver nitrates. It was found that the maximum sorption capacity of the synthesized ion exchanger is 672.4 mg/g for copper ions and 721.0 mg/g for silver ions, and 626.3 mg/g and 679.7 mg/g for industrial Dowex HCR-S/S″ ionite, respectively. It is shown that the sorption of copper and silver is described by various kinetic models: for copper, the best correspondence is demonstrated by a pseudo second order kinetic model, whereas for silver, the Elovich kinetic model the different nature of the interaction of ions with active centers. It has been revealed that the synthesized ion exchanger is superior to an industrial sorbent in terms of sorption rate and degree of extraction of valuable metals, especially in concentrated solutions, which indicates the prospects of its use in the processes of selective extraction of copper and silver. Full article

Natural gas plays a pivotal role in the global energy landscape under the dual challenges of energy transition and climate change. However, the impurities present within natural gas pose several disadvantages, including corrosion of transportation pipelines, toxicity, hydrate formation, and a reduction in the fuel’s calorific value. Membrane separation technology has been recognized as an ideal approach for natural gas purification owing to its advantages of low energy consumption, operational simplicity, and excellent separation performance. This review summarizes recent progress in the development of advanced membrane materials, including polymer bulk membranes, two-dimensional (2D) nanosheet membranes, mixed-matrix membranes (MMMs), surface-modified membranes, and carbon molecular sieve membranes (CMSMs). The fundamental separation mechanisms—such as solution-diffusion, molecular sieving, adsorption-selectivity, and competitive sorption and surface diffusion—are analyzed in detail. Moreover, the critical scientific questions and technological challenges in this field are discussed in depth. Finally, future research perspectives are proposed to guide the rational design and practical application of high-performance membranes for natural gas separation. Full article

The sustainable operation of hydroponic systems depends on maintaining the chemical stability of circulating nutrient solutions and preventing the accumulation of toxic compounds. The accumulation of phytotoxic ammonium, heavy metals, and organic metabolites in recirculating nutrient solutions remains one of the key challenges limiting the efficiency, sustainability, and scalability of hydroponic cultivation. This review provides a comprehensive comparative analysis of zeolites, activated carbons (ACs), and their functionalized and composite forms as key sorbents for nutrient management, contaminant removal, and environmental safety in hydroponic cultivation. Natural zeolites, with their well-defined crystalline structure and high ion-exchange selectivity toward ammonium and heavy metal cations, enable effective NH₄⁺/K⁺ balance regulation and phytotoxicity mitigation. ACs, characterized by high specific surface area and tunable surface chemistry, complement zeolites by offering extensive adsorption capacity for organic compounds, root exudates, and pesticide residues, thereby extending the operational lifespan of nutrient solutions and improving overall system performance. Further advancements include the integration of zeolites and ACs with two-dimensional (graphene, g-C₃N₄) and three-dimensional (MOF, COF) frameworks, yielding multifunctional materials that combine adsorption, ion exchange, photocatalysis, and nutrient regulation. Transition-metal modification, particularly with Fe, Mn, Cu, Ni, and Co, introduces redox-active centers that enhance sorption, catalysis, and phosphate stabilization. The comparative synthesis reveals that the combined application of zeolite- and carbon-based composites offers a synergistic strategy for developing adaptive and low-waste hydroponic systems. From a techno-economic and environmental standpoint, the judicious application of these materials paves the way for more resilient, efficient, and circular hydroponic systems, reducing fertilizer and water consumption, lowering contaminant discharge, and enhancing food security. This systematic review was conducted according to the PRISMA 2020 guidelines. Relevant studies were identified through Scopus, Web of Science, and Google Scholar databases using specific inclusion and exclusion criteria. Full article

Cordycepin (3′-deoxyadenosine, 3′-dA), the flagship nucleoside antibiotic from Cordyceps militaris, exerts potent anti-inflammatory, antimicrobial, and antitumor activity but is rapidly inactivated by human adenosine deaminase (ADA). While prodrugs, ADA inhibitors, and nanocarriers have been pursued to prolong its half-life, the influence of solid form on delivery performance remains unexplored. Here, three polymorphs—anhydrate-I (flake-like), anhydrate-II (rod-like), and a previously unreported monohydrate (fibrillar)—were prepared, characterized (PXRD, TG-DSC, FTIR), and subjected to equilibrium solubility, slurry-conversion, and humidity-sorption mapping. The monohydrate dehydrates at 144 °C and sequentially transforms to anhydrate-I → anhydrate-II (ΔH = −127.5 J g⁻¹), establishing a monotropic relationship between the two anhydrous forms. Solubility displays a bell-shaped profile versus water activity: the monohydrate is stable above aw 0.8, whereas anhydrate-II predominates below aw 0.2. In model immediate-release tablets, anhydrate-II achieves complete dissolution within 10 min, whereas the monohydrate sustains release for 30 min. Hygroscopicity tests show the monohydrate absorbs <6% water up to 75% RH without structural change, whereas anhydrate-I converts to the monohydrate above 63% RH. The quantitative humidity–crystal form–performance correlations provide a rational platform for crystal form selection and the design of stable, efficacious cordycepin solid dosage forms. Full article