Search Results (536)

Citrus fruit processing, mainly for fresh juice production in the food industry, generates significant amounts of residues and by-products enriched with bioactive components. Peels are the primary waste fraction of citrus fruits, along with discarded pulp and seeds. This study aimed to identify the most fast and sustainable extraction process for flavonoids on a laboratory scale by varying the solvent and extraction methodology, and comparing the yields in order to evaluate their influence on total and individual flavonoid content. A chromatographic analysis was also performed using ultrahigh-performance liquid chromatography (UHPLC) with a 10 min run time. Our focus was on selecting the most user-friendly and cost-effective methodology. Ultrasound- and microwave-assisted extraction equipment were used with green solvents (water and ethanol) and compared for their efficiency in recovering flavonoid compounds from a mixture of peel and pulp. For this study, two widely cultivated Mediterranean citrus varieties were selected: ‘Marsh’ seedless grapefruits (Citrus paradisi Macf.) and ‘Comun’ mandarins (C. deliciosa Ten.). Lab-scale extraction results showed that ultrasound-assisted extraction with a simple ultrasonic bath, using an ethanol–water mixture provided the highest total flavonoid recovery and improved the extraction of key flavanones such as hesperidin, narirutin, and naringin. All ethanol–water mixtures tested (1:1, 7:3, and 3:7) yielded higher flavonoid levels in grapefruit (approximately 2500 mg/100 g DW) and mandarin (approximately 1200 mg/100 g DW) wastes compared with water or ethanol alone. This method offers a scalable and green strategy for valorizing citrus residues. Full article

The increasing food waste generated along the food chain should be considered as a source of high-value compounds, with the aim of improving the circularity of productions. In this study, carrot pomace, the major by-product of carrot juice processing, was used as a source of carotenoids. For the valorisation of this by-product, different non-conventional extraction methods of carotenoids such as Ultrasound-Assisted Extraction (UAE) and Pressurised Liquid Extraction (PLE) have been developed. For the latter, the main parameters influencing the extraction have been optimised using a multivariate response surface design. Compared with previous reports, this study advances the current knowledge by using only food-grade ethanol/water mixtures as solvents and by combining the optimisation of carotenoid recovery with the measurement of energy consumption to evaluate process efficiency. Moreover, the sustainability of the extraction was quantitatively assessed using the AGREEprep metric, providing a more integrated and environmentally sound strategy for the valorisation of Daucus carota L. pomace. Full article

The enzymatic production of fatty acid ethyl esters (FAEEs) and xylose fatty acid esters (XFAEs) from soybean oil deodorizer distillate (SODD) was investigated using a hydroesterification strategy. SODD was enzymatically hydrolyzed, and the glycerol-free fraction was esterified with either xylose or ethanol. Free lipase from Pseudomonas fluorescens (PFL) yielded 84 wt% of free fatty acids (FFAs) production (with approximately 15% FFAs remaining as glycerides) after 48 h, using a SODD-to-water mass ratio of 1:4 and an enzyme loading of 5 wt% (based on oil mass). In the synthesis of FAEEs, free Eversa Transform converted approximately 82% of the FFAs into FAEEs after 48 h, using an ethanol-to-FFA molar ratio of 3.64:1 and an enzyme loading of 8.36% (w/v). For the synthesis of XFAEs, commercially immobilized lipases from Thermomyces lanuginosus (TLL-T2-150) and Pseudomonas fluorescens (IMMAPF-T2-150) were employed. These commercial lipase preparations are available in their immobilized form on Immobead T2-150. TLL-T2-150 resulted in a lower degree of xylose ester formation (80.20%) compared to IMMAPF-T2-150 (89.20%) after 24 h, using an FFA-to-xylose molar ratio of 5 in ethyl-methyl-ketone (xylose concentration of 7 mmol L⁻¹) and an enzyme loading of 0.5% (w/v). However, TLL-T2-150 consumed more FFAs, suggesting a higher degree of xylose esterification. The final reaction mixture containing XFAEs obtained with this biocatalyst exhibited suitable emulsifying properties. A Life Cycle Assessment (LCA) revealed that the enzymatic hydroesterification process offers a sustainable route for FAEEs and XFAEs production, with configurations using free PFL in hydrolysis and IMMAPF-T2-150 in esterification showing the lowest environmental impacts due to higher catalytic efficiency. The findings point to a clear environmental edge in using SODD for ester production, offering a cleaner alternative to standard methods and making better use of a renewable resource. Full article

Chlorpyrifos (CHP) is a persistent organophosphate pesticide whose presence in water poses serious ecological and health risks. Here, we report a sustainable adsorbent obtained by high-temperature carbonization of immature walnuts (Juglans regia). The adsorbent’s structure, surface chemistry, and charge properties were comprehensively characterized using FTIR, SEM-EDX, zeta potential measurement, BET analysis, and XPS. The synthesis yielded a mesoporous carbon material with a BET surface area of 303 m² g⁻¹. Its performance in CHP removal was assessed under batch and dynamic conditions. Adsorption followed pseudo-second-order kinetics (k₂ = 0.122 mg min⁻¹ g⁻¹; contact time 0–120 min). Isotherm experiments performed at 20, 25, and 30 °C, with equilibrium data best described by the Langmuir and Sips models, reaching a maximum capacity of 43.2 mg g⁻¹. Thermodynamic analysis indicated a spontaneous and endothermic process. The adsorbent demonstrated selectivity for CHP over chlorpyrifos-oxon (CPO) in binary mixtures, retained its efficiency over at least ten regeneration cycles with ethanol, and removed up to 90% of CHP toxicity, as measured by acetylcholinesterase inhibition. Dynamic filtration confirmed its applicability under flow conditions. These findings demonstrate that the investigated adsorbent is an effective, reusable, and selective adsorbent, offering a low-cost and eco-friendly approach to pesticide removal from contaminated waters. Full article

In this study, hydrophilic covalent organic framework (COF) nanosheets with triazine structures and hydrophobic COF nanosheets with fluorinated imine skeletons were designed to enhance the membrane separation process for ethanol pervaporation. The mass transfer of ethanol–water mixtures within the confined structures of COF nanosheets was investigated through experimental characterization and computational simulations, establishing a quantitative relationship between mass transfer performance and the pore size/chemical properties of COF nanosheets. These COF nanosheets were employed to optimize the confined architecture of mixed matrix membranes (MMMs), effectively regulating the critical parameters of MMMs and improving their separation performance. Through systematic investigation of formation mechanisms and modulation principles, we revealed the correlation between confined structural parameters and membrane separation efficiency. This work develops methodologies and foundational theories to overcome the permeability-selectivity trade-off effect, providing theoretical guidance for designing novel membrane materials with ethanol-permelective COF-based MMMs. Full article

A polyamidoamine-based hydrogel (H-M-GLY) and its montmorillonite-based composite (H-M-GLY/MMT) were studied as selective cleaning materials for cultural heritage conservation. H-M-GLY was synthesized from a glycine-based polyamidoamine oligomer with acrylamide terminals (M-GLY) through radical polymerization at pH 7.3 and had a basic character. The M-GLY oligomer was in turn synthesized from N,N′-methylenebisacrylamide and glycine in a 1:0.85 molar ratio. H-M-GLY/MMT was obtained by cross-linking a 1:0.1—weight ratio—M-GLY/MMT mixture at pH 4.0, to promote polyamidoamine-MMT interaction. The composite hydrogel absorbed less water than the plain hydrogel and proved tougher, due to montmorillonite’s electrostatic interactions with the positively charged M-GLY units. Scanning electron microscopic analysis showed that MMT was uniformly dispersed throughout the hydrogel. Both hydrogels were subjected to ink bleeding tests on papers written with either iron gall or India ink. Microscopic observation revealed neither bleeding nor release of hydrogel fragments. Being basic, H-M-GLY successfully deacidified the surface of aged paper. H-M-GLY/MMT, swollen in a 1:9 ethanol/water solution, was found to be effective in removing wax, known to trap carbonaceous particles and form dark stains on artistic artifacts. This study demonstrates the great potential of polyamidoamine-based hydrogels as versatile selective cleaning systems for cellulosic and other cultural heritage materials. Full article

Columnar-structured thermal barrier coatings deposited via the suspension plasma spray process have attracted significant attention due to their long thermal cycling life and high cost-effectiveness. In this work, the effects of suspension properties, including solvent type, viscosity, and particle size, on the formation of different coating microstructures were investigated via a comparative study. Two different kinds of solvents (water and ethanol) and particles of different sizes (D50 = 0.45 μm and 1.2 μm) were used to prepare suspensions for coating deposition, respectively. When using suspensions containing small-sized particles as feedstock, coatings deposited from the ethanol-based suspension showed columnar microstructures with inter-column crevices, while the water-based suspension resulted in cracked–columnar microstructures, showing a mixture of columns and cracks. When the large-sized particles were used to prepare the suspension, both the ethanol-based suspension and the water-based suspension resulted in homogeneous coating microstructures. The formation mechanism of different microstructures was investigated by modelling the diverted plasma jet and the in-flight particle movement during the impingement period. Particles smaller than 2 μm were strongly affected by the diverted plasma gas, showing obvious oblique impinging trajectories, while particles larger than 3 μm kept their original trajectories and impinged on the substrate orthogonally. The formation mechanism of different microstructures was elaborated by analyzing the impinging trajectories of particles transitioning from different suspensions. Full article

Olive leaves, a significant source of agri-food waste, can be valorized as feedstock in biorefineries due to their high content of antioxidant compounds, mainly polyphenols. This study aims to valorize olive leaves through an efficient solid/liquid extraction of oleuropein, its main polyphenol, using green solvents and advanced technologies. Accordingly, three natural eutectic solvents formed with 1,2-butanediol and choline chloride, betaine, or proline, which incorporated water or ethanol as cosolvents, and ultrasound-assisted extraction to enhance the process were used in this work. Additionally, the effect of the cosolvent composition on the physical properties of the solvent mixtures (i.e., density and viscosity as a function of temperature) was evaluated. The extraction time was optimized for both conventional and intensified extractions, and the antioxidant activity of the extracts was assessed over time to determine their stability. Measurements through high-performance liquid chromatography and antioxidant activity assays concluded that ultrasound-assisted extraction using the solvent proline:1,2-butanediol prepared with ethanol at 25–75% composition yielded the best results at 37.00 mg of oleuropein per gram of dry sample (g/ds), obtained after just 1 min of intensified extraction, with a notable reduction in both time and energy consumption from conventional extraction, while providing significant antioxidant activity and stability. Full article

Fusel oil is a fermentation by-product composed of a complex mixture of alcohols (ethanol, isoamyl, propanol, and butanol isomers) and water. The primary challenges lie in water separation and the recovery of the valuable component, isoamyl alcohol. In this work, we demonstrate an efficient separation process using a non-polar, non-toxic, water-immiscible solvent, namely hexane, to reduce the water content of fusel oil from an initial 14 wt.% to 1.46 wt.% at a solvent to fusel oil ratio of 1:1 and to 0.55 wt.% at a 4:1 ratio. The proposed separation process was designed with a 1:1 ratio to minimize equipment size. In the first step, a decanter vessel enabled phase separation, followed by two distillation columns. The bottom product from the second column achieved a purity of 99.29 wt.% isoamyl alcohol (97.91 wt.% isomers and 1.38 wt.% hexanol) with a recovery rate of 97.33%. The distillate flows were directed to the second decanter vessel, recovering 99.665% of hexane. This study confirms the effectiveness of the proposed process in separation of highly valuable isoamyl alcohol from fusel oil via a hybrid decanter–distillation scheme. The proposed process attains a specific energy consumption in the reboilers of 0.65 kWh per kilogram of product (equivalent to 1.21 kg of steam per kilogram of product). This represents a notable improvement compared to the configuration reported by other authors for the separation of isoamyl alcohol using divided-wall columns (DWC), which requires 2785 kJ per kilogram of product (i.e., 0.774 kWh per kilogram of product). An economic analysis was performed to compare the process of separating isoamyl alcohol from fusel oil using the minimum hexane ratio (1:1) and the maximum ratio (4:1). All cost values increased significantly with higher solvent ratio. Remaining challenges include the purification of waste aqueous streams and future valorization of the hexane–alcoholic mixture. Full article

The rising demand for platinum-group metals, driven by their essential applications in catalysis, energy storage, and chemical conversion, underscores the need to identify new sources for their recovery. Waste solutions originating from industrial processes offer a promising alternative source of noble metals. However, due to their typically low concentrations, effective recovery requires a highly targeted approach. In this study, we present a synthetic waste solution containing trace amount of Rh(III) ions as both a medium for metal ion recovery and a direct precursor for catalyst synthesis. Using a bimodal water–ethanol solvent system, ultra-small rhodium nanoparticles were synthesized and subsequently immobilized onto activated carbon fibers (ACFs) within a microreactor system. The resulting Rh@ACF catalyst demonstrated high efficiency in the reduction of 4-nitrophenol (4-NP) to 4-aminophenol (4-AP), serving as a model catalytic reaction. The Rh@ACF catalyst, containing 4.24 µg Rh per milligram of sample, exhibited notable catalytic activity, achieving 75% conversion of 4-NP to 4-AP within 1 h. Full conversion to 4-AP was also reached within 5 min, but requires extra NaBH₄ addition to the catalytic mixture. Full article

The low water solubility of sulfamethazine (SMT) limits its clinical efficacy, making it crucial to study techniques such as cosolvency to optimize pharmaceutical formulations. This study aimed to thermodynamically evaluate the solubility of SMT in {acetonitrile (MeCN) + ethanol (EtOH)} cosolvent mixtures over a temperature range of 278.15 to 318.15 K in order to understand the molecular interactions that govern this process. SMT solubility in the mixtures was measured using a flask-shaking method. The solid phases were analyzed using differential scanning calorimetry (DSC) to rule out polymorphisms. Using the Gibbs–van’t Hoff–Krug model, we calculated the apparent thermodynamic functions of the solution and mixture from the obtained data. The results showed that solubility increased almost linearly with MeCN fraction and temperature, indicating that MeCN is a more efficient solvent and that the process is endothermic. Thermodynamic analysis revealed that dissolution is an endothermic process with favorable entropy for all compositions. The higher solubility in MeCN is attributed to the lower energetic cost required to form the solute cavity compared to the high energy needed to disrupt the hydrogen bond network of ethanol. This behavior can be explained by an enthalpy–entropy compensation phenomenon. This phenomenon provides an essential physicochemical basis for designing pharmaceutical processes. Full article

Corncobs, produced globally at over 200 million tons annually with 11–18% lignin content, represent an abundant and underexploited lignocellulosic resource for sustainable lignin valorization. In this study, two distinct extraction methodologies, alkaline treatment using sodium hydroxide and an organosolv process with a 50:50 ethanol/water mixture, were systematically compared for their efficiency in isolating lignin from corncobs. Both protocols achieved high yields, up to 82% for alkaline and 84% for organosolv extraction under optimized conditions. The resulting lignins displayed notable differences in chemical structure and physical properties, as revealed by spectroscopic and thermal analyses, highlighting their divergent potential for downstream applications. To evaluate the suitability of these lignins to biocatalytic upgrading, post-extraction enzymatic treatment was performed using Pycnoporus cinnabarinus laccase (EC 1.10.3.2). Significant structural modifications were observed in alkaline-extracted lignin, as determined by FTIR spectroscopy, while organosolv lignin remained largely unaltered, a difference attributed to its lower aqueous solubility at the enzyme’s optimal pH. These results demonstrate the critical impact of extraction conditions on lignin reactivity and suitability for enzymatic tailoring. This work underscores the potential for holistic corncob valorization within integrated biorefinery frameworks. Selective extraction and targeted enzymatic modification not only facilitate efficient by-product utilization but also expand the prospects for producing versatile bio-based materials, thereby advancing the transition toward a sustainable, circular bioeconomy. Full article

Due to the prevalence of plastic-packaged foods, as well as the need for real-time food monitoring by consumers, reducing plastic pollution is essential for a healthier environment and nutrition. For these reasons, in this work, biodegradable pH-responsive chitosan films enriched with wine lees-derived anthocyanins were produced, and their pH sensitivity was thoroughly evaluated. Optimization of ultrasound-assisted extraction using ethanol/water mixtures as conventional solvents was conducted and the optimal conditions (regarding total anthocyanin content, total phenolic content, and antioxidant activity) were used to perform a screening of extraction with 16 different Natural Deep Eutectic Solvents. Among them, choline chloride: butylene glycol (1:4), at a concentration of 50% v/v in water, demonstrated the highest anthocyanin recovery and was selected for the preparation of the films. The resulting films exhibited an excellent colorimetric response to pH changes, with a color difference (ΔE) exceeding 6.8 at all tested pH values, improved mechanical properties, nearly zero UV permeability, and their antioxidant activity increased by up to 6.1-fold compared to pure chitosan film. Finally, the film was applied in detecting the freshness of pork meat, exhibiting a ΔE of 15.3. The results demonstrate that the developed film is a promising alternative for intelligent, bioactive, and biodegradable food packaging for food applications. Full article

Fuel cells have become a fundamental technology in the development of clean energy systems, playing a vital role in the global shift toward a low-carbon future. With the growing need for sustainable hydrogen production, perfluoro sulfonic acid (PFSA) ionomer membranes play a critical role in optimizing green hydrogen technologies and fuel cells. This study aims to investigate the effects of different environmental and solvent treatments on the chemical and physical properties of Nafion N−115 membranes to evaluate their suitability for both hydrogen production in proton exchange membrane (PEM) electrolyzers and hydrogen utilization in fuel cells, supporting integrated applications in the local and global green hydrogen economy. To achieve this, Nafion N−115 membranes were partially dissolved in various solvent mixtures, including ethanol/isopropanol (EI), isopropanol/water (IW), dimethylformamide/N-methyl-2-pyrrolidone (DN), and ethanol/methanol/isopropanol (EMI), evaluated under water immersion and thermal stress, and characterized for chemical stability, mechanical strength, water uptake, and proton conductivity using advanced electrochemical and spectroscopic techniques. The results demonstrated that the EMI-treated membrane showed the highest proton conductivity and maintained its structural integrity, making it the most promising for hydrogen electrolysis applications. Conversely, the DN-treated membrane exhibited reduced stability and lower conductivity due to solvent-induced degradation. This study highlights the potential of EMI as an optimal solvent mixture for enhancing PFSA membranes performance in green hydrogen production, contributing to the advancement of sustainable energy solutions. Full article

Grape pomace is a major by-product of winemaking and a rich source of phenolic compounds with antioxidant potential. The Carménère variety, emblematic of Chilean viticulture, remains underutilized despite its high anthocyanin and flavanol content. This study aimed to develop a cost-effective method to recover and stabilize bioactive compounds from Carménère grape pomace. Five extracts were obtained using ethanol–water mixtures (0–100%) and characterized by HPLC-DAD and antioxidant assays (DPPH, FRAP, ORAC-FL). The 80% ethanol extract (EET-80) showed the highest antioxidant capacity (FRAP: 2909.3 ± 37.6; ORAC-FL: 1864.3 ± 157.8 µmol TE/g dw) and was selected for microencapsulation via spray drying using maltodextrin. This scalable technique protects thermosensitive compounds and enhances their applicability. The optimized 1:50 extract-to-carrier ratio achieved high encapsulation efficiency (85.7 ± 0.7%). In Caco-2 cells, the microencapsulated extract (5–250 µg/mL) showed no alteration in metabolic activity and significantly reduced intracellular ROS levels (65% inhibition at 250 µg/mL). Solvent polarity selectively influenced polyphenol recovery—50% ethanol favored catechin (581.1 µg/g) and epicatechin (1788.3 µg/g), while 80% ethanol enhanced malvidin-3-O-glucoside (118.0 µg/g). These findings support the valorization of Carménère grape pomace as a sustainable source of antioxidants and highlight the role of microencapsulation in improving extract stability and functionality. Full article