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Separations, Volume 12, Issue 2 (February 2025) – 24 articles

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19 pages, 2910 KiB  
Review
Techniques and Methods for Fatty Acid Analysis in Lipidomics: Exploring Pinus cembroides Kernels as a Sustainable Food Resource
by Luis Ricardo León-Herrera, Luis Miguel Contreras-Medina, Ana Angélica Feregrino-Pérez, Christopher Cedillo, Genaro Martín Soto-Zarazúa, Miguel Angel Ramos-López, Samuel Tejeda, Eduardo Amador-Enríquez and Enrique Montoya-Morado
Separations 2025, 12(2), 41; https://doi.org/10.3390/separations12020041 - 6 Feb 2025
Viewed by 255
Abstract
The large-scale conversion of forests to agriculture has caused biodiversity loss, climate change, and disrupted dietary fatty acid balances, with adverse public health effects. Wild edibles like pine nuts, especially Pinus cembroides, provide sustainable solutions by supporting ecosystems and offering economic value. [...] Read more.
The large-scale conversion of forests to agriculture has caused biodiversity loss, climate change, and disrupted dietary fatty acid balances, with adverse public health effects. Wild edibles like pine nuts, especially Pinus cembroides, provide sustainable solutions by supporting ecosystems and offering economic value. However, variability in seed quality limits market potential, and lipidomic studies on P. cembroides remain sparse. This paper underscores the ecological, social, and nutritional value of P. cembroides while advocating for advanced research to enhance its use as a non-timber forest resource in Mexico’s communal areas. It explores various analytical techniques, such as nuclear magnetic resonances (NMR), chromatography coupled with mass spectrometry (HPLC-MS, GC-MS) and GC coupled with flame ionization detector (GC-FID), highlighting extraction methods like derivatization, purification, and thin-layer chromatography. Likewise, some considerations are addressed for the treatment of data obtained in the detection of fatty acids from bioformatics and the evaluation of the data through statistical methods and artificial intelligence and deep learning. These approaches aim to improve fatty acid profiling and seed quality assessments, fostering the species economic viability and supporting sustainable livelihoods in rural communities, encouraging researchers across the country to explore the fatty acid composition of different P. cembroides populations can drive valuable insights into its nutritional and ecological significance. Such efforts can enhance understanding of regional variations, promote sustainable use, and elevate the specie’s economic and scientific value. Full article
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15 pages, 5808 KiB  
Article
Synthesis of Zeolitic Imidazolate Framework-8 from Waste Electrodes via Ball Milling for Efficient Uranium Removal
by Minhua Su, Jinyao Zhu, Ruoning Wu, Jiaqi Pan, Jingran Yang, Jiaxue Zhao, Diyun Chen, Changzhong Liao, Kaimin Shih and Shengshou Ma
Separations 2025, 12(2), 40; https://doi.org/10.3390/separations12020040 - 6 Feb 2025
Viewed by 224
Abstract
Developing a cost-effective approach for the remediation of wastewater containing uranyl [U(VI)] ions is essentially important to ecosystems and human health. In this study, a Zn-based ZIF-8 framework was fabricated from wasted batteries through an environmentally friendly ball milling process featuring a distinct [...] Read more.
Developing a cost-effective approach for the remediation of wastewater containing uranyl [U(VI)] ions is essentially important to ecosystems and human health. In this study, a Zn-based ZIF-8 framework was fabricated from wasted batteries through an environmentally friendly ball milling process featuring a distinct microstructure compared to those synthesized from commercial Zn(II) sources. The as-obtained Zn-based ZIF-8 framework can effectively remove U(VI) ions from water, and a high removal efficiency of up to 99% is achieved across different process parameters, including initial dosage, pH values, and the presence of interfering ions. The superior U(VI) removal performance is attributed to the synergistic effect of microstructural features (e.g., crystallite size, specific surface area and pore diameter) and chemical interaction within the framework of Zn-based ZIF-8, resulting in the formation of the U···N chelates. This study integrates waste upcycling and hazardous U(VI) removal in an environmentally sound way, thereby promoting a circular economy. Full article
(This article belongs to the Section Environmental Separations)
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11 pages, 1947 KiB  
Article
Exploring Chicken Feathers as a Cost-Effective Adsorbent for Aqueous Dye Removal
by Marcela Caovilla, Carolina E. Demaman Oro, Rúbia Mores, Luciana D. Venquiaruto, Marcelo L. Mignoni, Marco Di Luccio, Helen Treichel, Rogério Marcos Dallago and Marcus V. Tres
Separations 2025, 12(2), 39; https://doi.org/10.3390/separations12020039 - 6 Feb 2025
Viewed by 174
Abstract
This study explored the use of chicken feathers, a low-cost and abundant agricultural byproduct, as a sorbent for the removal of reactive yellow dye from aqueous solutions. The dual potential of feathers as both adsorbents and sorbents, attributed to their keratin-rich structure, was [...] Read more.
This study explored the use of chicken feathers, a low-cost and abundant agricultural byproduct, as a sorbent for the removal of reactive yellow dye from aqueous solutions. The dual potential of feathers as both adsorbents and sorbents, attributed to their keratin-rich structure, was utilized to investigate their effectiveness in dye removal. Feathers, activated with 1.0 mol/L HCl, exhibited a maximum adsorption capacity at 70 °C and pH 5.5, as determined from Langmuir isotherm modeling. A 22 central composite rotatable design revealed that temperature and pH significantly influence the adsorption efficiency, with higher temperatures favoring the process. Kinetic studies demonstrated pseudo-first-order behavior, with rapid initial adsorption reaching equilibrium within 120 min. Thermodynamic analysis confirmed the endothermic nature of the process (ΔH° = 28.04 kJ mol−1), a positive entropy change (ΔS° = 66.62 J/mol·K), and a reduction in Gibbs free energy (ΔG°) with increasing temperature, suggesting enhanced feasibility at elevated temperatures. This research highlights the potential of utilizing poultry industry residues as sustainable and efficient sorbents for environmental remediation, contributing to waste valorization and eco-friendly wastewater treatment solutions. Full article
(This article belongs to the Special Issue Application of Sustainable Separation Techniques in Food Processing)
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13 pages, 3427 KiB  
Article
Preparation, Characterization, and Mechanism of SMS Titanium–Manganese Nanocomposite for Antimony Removal from Water
by Yannan Lv, Wenqing Wen, Shenrui Han, Kaixin Li, Ziyu Fu, Fansong Mu and Meng Luo
Separations 2025, 12(2), 38; https://doi.org/10.3390/separations12020038 - 6 Feb 2025
Viewed by 212
Abstract
This study investigates the synthesis of SMS-Ti-Mn (SMS-Ti-Mn stands for spent mushroom substrate activated carbon-Ti-Mn) nanocomposites and their application in removing the heavy metal antimony from water. In the process of antimony mining and smelting, the concentration of antimony in the waste residue [...] Read more.
This study investigates the synthesis of SMS-Ti-Mn (SMS-Ti-Mn stands for spent mushroom substrate activated carbon-Ti-Mn) nanocomposites and their application in removing the heavy metal antimony from water. In the process of antimony mining and smelting, the concentration of antimony in the waste residue can still reach as high as 80.5 mg/L. In addition, the soil in the electronic waste dismantling area is severely contaminated with antimony. In short, antimony enters the environment in various ways from mining, smelting, and manufacturing to the final waste process and continuously migrates in different environmental media, increasing the environmental exposure risk of antimony pollution. Single-factor experiments and response surface methodology were employed to determine the optimal conditions, including the adsorption time, pH, and solid–liquid ratio. Material characterization was performed to understand the role of nano-metals, and adsorption kinetics were analyzed using the quasi-first-order kinetic model. The research results revealed that the optimal conditions for antimony removal were an adsorption time of 40 min, a pH of 4, and a solid–liquid ratio of 2:1 (mg/mL). Under these conditions, the nanocomposites showed an adsorption capacity of 10.502 mg/g, which was 5.8 times higher than that of iron coagulants, 11 times higher than that of manganese-modified activated carbon, and 1.7 times higher than that of iron–manganese sludge adsorbents. Characterization revealed enhanced functional groups (carbonyl, Ti=O, Mn=O), contributing to improved adsorption. Kinetic analysis indicated physical adsorption as the dominant mechanism, and the regression model accurately predicted the adsorption capacity. SMS-Ti-Mn nanocomposites offer a promising strategy for treating antimony-contaminated water, with strong potential for practical applications in water treatment. They can decompose naturally after use, reduce secondary pollution, and promote ecological balance. Secondly, agricultural waste treated with heavy metal removal can be used as a fertilizer and soil amendment to improve soil quality and promote sustainable agricultural development. Full article
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12 pages, 1237 KiB  
Article
Systematic Isolation and Characterization of Regenerated Hemicellulose and Lignin from Soybean Feedstocks Using Ionic Liquids
by Victor Essel and Douglas E. Raynie
Separations 2025, 12(2), 37; https://doi.org/10.3390/separations12020037 - 4 Feb 2025
Viewed by 414
Abstract
The use of ionic liquids in biomass pretreatment for ethanol production has seen increased attention in recent years. In this work, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-allyl-3-methylimidazolium chloride ([Amim]Cl), and 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) were used to regenerate and recover significant amount of hemicellulose and lignin [...] Read more.
The use of ionic liquids in biomass pretreatment for ethanol production has seen increased attention in recent years. In this work, 1-butyl-3-methylimidazolium chloride ([Bmim]Cl), 1-allyl-3-methylimidazolium chloride ([Amim]Cl), and 1-ethyl-3-methylimidazolium acetate ([Emim]Ac) were used to regenerate and recover significant amount of hemicellulose and lignin from soybean meal, flakes, and hulls. The regenerated lignin and hemicellulose were characterized using Fourier-transform infrared (FTIR) spectroscopy and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). For all three ionic liquids, the amount of regenerated hemicellulose and lignin ranged from approximately 6 to 12% and 8 to 19% respectively. Lignin characteristic bands 1738.8, 1652.6, 1516.4, 1455.2 and 1174.9 cm−1 were identified in the FTIR spectrum. The regenerated hemicellulose showed the characteristic bands 1658.31, 1434.14, 1167.98, and 865.20 cm−1. Py-GC/MS analysis of the regenerated lignin showed the characteristic grass lignin pyrolyzates phenol, 2-methoxyphenol, 4-methylphenol, 2-benzaldehyde, 2-methoxy-4-vinylphenol, phenol-2,6-dimethoxy, and ethylvanillin. Full article
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18 pages, 3696 KiB  
Article
Investigation of Impurities in Peptide Pools
by Gaby Bosc-Bierne and Michael G. Weller
Separations 2025, 12(2), 36; https://doi.org/10.3390/separations12020036 - 2 Feb 2025
Viewed by 619
Abstract
Peptide pools are important research tools in different biomedical fields. They consist of a complex mixture of defined peptides, which places high demands on the production and quality control of these products. Previously it has been shown that the combination of UHPLC with [...] Read more.
Peptide pools are important research tools in different biomedical fields. They consist of a complex mixture of defined peptides, which places high demands on the production and quality control of these products. Previously it has been shown that the combination of UHPLC with high-resolution mass-spectrometry (HRMS) is a fast and powerful method to confirm the relative concentration and the structural identity of all peptides expected to be in the pool. In this work, the additional information contained in the UV chromatograms and mass spectra is used to search for impurities due to synthesis by-products and degradation during storage and transportation and to identify possible analytical artifacts. It was shown that most impurities are only present in trace amounts and can be considered uncritical for most applications. The most frequent and perhaps unexpected impurities were homo- and heterodimers caused by the free cysteines contained in these peptide pools. Furthermore, pyroglutamate and aspartimide formation, deamidation, methionine oxidation, and amino acid deletions could be found. This list is not intended to be comprehensive, but rather a brief guide to quickly identify impurities and, in the long term, to suggest possible changes in the composition of the peptide pools to avoid such impurities by design or by special precautions. Full article
(This article belongs to the Special Issue Peptide Synthesis, Separation and Purification)
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22 pages, 1284 KiB  
Article
Critical Insights into Untargeted GC-HRMS Analysis: Exploring Volatile Organic Compounds in Italian Ambient Air
by Marina Cerasa, Catia Balducci, Benedetta Giannelli Moneta, Serena Santoro, Mattia Perilli and Vladimir Nikiforov
Separations 2025, 12(2), 35; https://doi.org/10.3390/separations12020035 - 2 Feb 2025
Viewed by 378
Abstract
This study critically examines the workflow for untargeted analysis of volatile organic compounds (VOCs) in ambient air, from sampling strategies to data interpretation by using GC-HRMS. While untargeted approaches are well-established in liquid chromatography (LC) due to advanced-deconvolution tools and extensive metabolomic libraries, [...] Read more.
This study critically examines the workflow for untargeted analysis of volatile organic compounds (VOCs) in ambient air, from sampling strategies to data interpretation by using GC-HRMS. While untargeted approaches are well-established in liquid chromatography (LC) due to advanced-deconvolution tools and extensive metabolomic libraries, their application in gas chromatography (GC) remains less developed, particularly for VOCs. The high structural isomerism of VOCs and the relative novelty of GC-based untargeted methodologies present unique challenges, including limited software tools and reference libraries. Air samples from suburban and rural sites in central Italy were analyzed to explore chemical diversity and address methodological gaps. This study evaluates critical decisions, such as sampling strategies, extraction techniques, and data-processing workflows, highlighting the limitations of automated deconvolution tools and the need for manual validation. Results revealed distinct source contributions, with suburban areas showing higher levels of anthropogenic compounds and rural areas dominated by biogenic emissions. This work underscores the potential of GC-HRMS untargeted analysis to advance environmental chemistry, while addressing key pitfalls and providing practical recommendations for reliable application. By bridging methodological gaps, it offers a roadmap for future studies aiming to integrate untargeted and targeted approaches in air quality research. Full article
18 pages, 6241 KiB  
Article
Optimizing Quercetin Extraction from Taraxacum mongolicum Using Ionic Liquid–Enzyme Systems and Network Pharmacology Analysis
by Jingwei Hao, Yifan Sun, Nan Dong, Yingying Pei, Xiangkun Zhou, Yi Zhou and Heming Liu
Separations 2025, 12(2), 34; https://doi.org/10.3390/separations12020034 - 28 Jan 2025
Viewed by 489
Abstract
Quercetin in Taraxacum mongolicum was extracted by ultrasound-assisted extraction in synergy with an ionic liquid–enzyme complex system, and the antioxidant function of quercetin was investigated based on network pharmacology. From 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium tetrafluoroborate, the first [...] Read more.
Quercetin in Taraxacum mongolicum was extracted by ultrasound-assisted extraction in synergy with an ionic liquid–enzyme complex system, and the antioxidant function of quercetin was investigated based on network pharmacology. From 1-butyl-3-methylimidazolium chloride, 1-butyl-3-methylimidazolium acetate, 1-butyl-3-methylimidazolium tetrafluoroborate, 1-butyl-3-methylimidazolium bromide, and 1-butyl-3-methylimidazolium tetrafluoroborate, the first step was to choose the appropriate ionic liquid. Subsequently, a response surface methodology and single-factor experiment were used to optimize the extraction process. The quercetin and the key targets for antioxidants were obtained from a public database. Antioxidant activity was assessed by measuring the scavenging rate of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals and hydroxyl radicals(•OH). The approach revealed that the optimal extraction process was the liquid–solid ratio of 31.62:1 mL/g, enzymatic temperature of 55 °C, and the amount of cellulase added was 14.79% of the dry weight of dandelion. Under this condition, the yield of quercetin was 0.24 ± 0.011 mg/g, which was 1.3 times higher than that of the conventional reflux extraction method of 0.185 ± 0.015 mg/g. Pharmacological findings showed 57 cross-targets of quercetin with antioxidants. Gene ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis indicated that antioxidant function may be related to chemical carcinogenesis-reactive oxygen species, and the Phosphoinositide 3-kinase/protein kinase B signaling pathway. Quercetin has strong DPPH and •OH radical scavenging activity. The development and use of industrial dandelion are supported by this sustainable and effective method of extracting quercetin from dandelion. Full article
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22 pages, 1194 KiB  
Review
Research Progress in Tritium Processing Technologies: A Review
by Ziqian Zhao, Yandong Sun, Qi Chen, Tianchi Li, Fang Liu, Taihong Yan and Weifang Zheng
Separations 2025, 12(2), 33; https://doi.org/10.3390/separations12020033 - 27 Jan 2025
Viewed by 389
Abstract
Recent advancements in tritium separation technologies have significantly improved efficiency, particularly through the integration of vapor phase catalytic exchange (VPCE), liquid phase catalytic exchange (LPCE), and combined electrolysis catalytic exchange (CECE) methods. Combining these techniques overcomes individual limitations, enhancing separation efficiency and reducing [...] Read more.
Recent advancements in tritium separation technologies have significantly improved efficiency, particularly through the integration of vapor phase catalytic exchange (VPCE), liquid phase catalytic exchange (LPCE), and combined electrolysis catalytic exchange (CECE) methods. Combining these techniques overcomes individual limitations, enhancing separation efficiency and reducing energy consumption. The CECE process, which integrates electrolysis with catalytic exchange, offers high separation factors, making it effective for high-concentration tritiated water treatment. Solid polymer electrolyte (SPE) technology has also gained prominence for its higher efficiency, smaller equipment size, and longer lifespan compared to traditional alkaline electrolysis. While electrolysis offers high separation factors, its high energy demand limits its cost-effectiveness for large-scale operations. As a result, electrolysis is often combined with other methods like CECE to optimize both energy consumption and separation efficiency. Future research will focus on improving the energy efficiency of electrolysis for large-scale, low-cost tritiated water treatment. Full article
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29 pages, 5477 KiB  
Review
Production of Algae-Derived Biochar and Its Application in Pollutants Adsorption—A Mini Review
by Luyang Li, Jinfeng Wang, Weiming Sun, Xinhong Peng and Xinhua Qi
Separations 2025, 12(2), 32; https://doi.org/10.3390/separations12020032 - 27 Jan 2025
Viewed by 1072
Abstract
Developing algae cultivation for food, chemicals, and bio-energy generates a significant amount of algal waste/residue after utilization. Meanwhile, harmful algal blooms caused by abnormal proliferation of various algae produce a large amount of algal biomass, posing serious harm to human health, the environment [...] Read more.
Developing algae cultivation for food, chemicals, and bio-energy generates a significant amount of algal waste/residue after utilization. Meanwhile, harmful algal blooms caused by abnormal proliferation of various algae produce a large amount of algal biomass, posing serious harm to human health, the environment and the economy. Converting algae body to biochar is a crucial method with which to take advantage of this resource. Biochar usually has a large specific surface area, developed pore structure, high cation exchange capacity and rich surface functional groups. With the advantage of stable physical/chemical properties and easy modification techniques, biochar posited as an ideal adsorption material. From the perspective of algal biomass utilization, this paper reviews the preparation and modification methods, structural characteristics, physicochemical properties and environmental implications of algal biochar. The adsorption effect and mechanisms of algal biochar on nutrients, heavy metals, and organic matter in water are introduced. In light of the current research status, the challenges faced in practical application of algae-derived biochar adsorption materials are pointed out, and a research direction for preparation and application is also developed, with a view to providing a reference for the further utilization of algae-derived biochar. Full article
(This article belongs to the Section Environmental Separations)
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13 pages, 44994 KiB  
Article
Tuning the Inlet Flow Pattern of Cyclones for Boosted Particle Rotation Behaviors with High Purification Performances of Oily Sludge
by Rui Ye, Wan Zheng and Bi Shi
Separations 2025, 12(2), 31; https://doi.org/10.3390/separations12020031 - 26 Jan 2025
Viewed by 327
Abstract
Cyclone separation is a widely utilized separation technique, which enables the self-rotation behaviors of particles in the internal flow field, in order to realize high-performance separation of mixtures. Oily sludges are solid wastes generated by the shale gas industry, which need to be [...] Read more.
Cyclone separation is a widely utilized separation technique, which enables the self-rotation behaviors of particles in the internal flow field, in order to realize high-performance separation of mixtures. Oily sludges are solid wastes generated by the shale gas industry, which need to be properly treated for environmental protection. In the present investigation, we demonstrated that tuning the inlet flow pattern of the cyclone from linear flow to vortex flow is an effective approach to boost the rotation speed of oily sludge particles for obtaining significantly improved separation effects. Numerical simulations were carried out to investigate the influences of inlet flow pattern on the rotation behaviors of particles, which manifested in the rotation speed of particles being evidently increased up to 4500 rad/s when the inlet flow was tuned from a unidirectional pattern into vortex pattern. The effective rotation zone’s area was also found to increase significantly, with the area of the effective rotation zone enlarged by up to 400%. Further separation experiments on oily sludge were carried out using a cyclone equipped with a worm shell that generated vortex inlet flow with rotating blades. Separation results confirmed that the oily sludge was successfully purified by the cyclone equipped with a worm shell, which provided an extremely high oil removal percentage of 99.9%, showing a 49.1% enhancement in oil removal capability over the individual cyclone separation. Our investigations demonstrated an effective method for realizing oily sludge treatment and oil resource recovery by conventional cyclone separation. Full article
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23 pages, 3236 KiB  
Technical Note
Techno-Economic and Feasibility Assessment of Membrane-Based Wastewater Treatment and Reuse in the Automotive Industry
by Sara Carvalho, Mário Eusébio and Svetlozar Velizarov
Separations 2025, 12(2), 30; https://doi.org/10.3390/separations12020030 - 26 Jan 2025
Viewed by 303
Abstract
The gradual increase in water scarcity due to depletion and/or inadequate use of water resources has affected the automotive sector. In this context, possibilities for water reuse in the pre-treatment tunnel in an automotive painting process were studied and compared with the primary [...] Read more.
The gradual increase in water scarcity due to depletion and/or inadequate use of water resources has affected the automotive sector. In this context, possibilities for water reuse in the pre-treatment tunnel in an automotive painting process were studied and compared with the primary goal of finding the most appropriate and economically viable water recovery solutions, considering a circular economy metric approach. To this end, an experimental campaign of aqueous effluent characterization, with determinations of most relevant chemical and physical parameters, was conducted in a company in the automotive industry sector. To reduce alkalinity and remove surfactants from the effluent of the washing phase, a cation exchange on a weak-acid-based resin was proposed along with a microfiltration membrane system with a recovery efficiency of 88%. The inclusion of subsequent ultrafiltration and reverse osmosis steps proved to be the most suitable for removing salts and biocides from the water of the cooling towers, treating approximately 68% of the water. The techno-economic feasibility was comprehensively evaluated according to the type of treatment used. A cost of EUR 245 thousand was estimated for the treatment of water from the degreasing washing phase (EUR 1.06 per manufactured car), and a cost of EUR 582 thousand was estimated for the treatment of the cooling towers’ water (EUR 2.52 per car). The estimated water income after the treatment systems’ implementation was estimated to be equal to EUR 0.07 per car for the washing stage and EUR 0.13 per car for the cooling towers. Ultimately, this study clearly demonstrated the beneficial contribution of using membrane treatment in the automotive sector’s environmental policy, leading to water reuse and much lower effluent discharge according to the principles of the circular economy. Full article
(This article belongs to the Special Issue Membranes Used in Water Purification)
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20 pages, 3734 KiB  
Article
Strengthened Effect of Surface-Active Ionic Liquids on Curcumin Solubility and Extraction Performance of Curcuminoids
by Dan Li, Yuxin Qin, Jingxing Li, Subhan Mahmood, Jianqin Shi, Yu Cao and Shun Yao
Separations 2025, 12(2), 29; https://doi.org/10.3390/separations12020029 - 26 Jan 2025
Viewed by 251
Abstract
As a kind of bioactive component in the rhizome of natural plant Curcuma longa L. (turmeric), curcumin is almost insoluble in water at neutral and acidic pH, which limits its further utilization and development. At the same time, traditional extraction and separation processes [...] Read more.
As a kind of bioactive component in the rhizome of natural plant Curcuma longa L. (turmeric), curcumin is almost insoluble in water at neutral and acidic pH, which limits its further utilization and development. At the same time, traditional extraction and separation processes typically require the use of a large number of organic solvents. Ionic liquids (ILs) are organic molten salts with melting points below 100 °C. When an ionic liquid exists in a liquid state at or near room temperature, it is referred to as a room-temperature ionic liquid (RTIL). They have a temperature range, good physical and chemical stability, and good structural designability. They have a strong solubilization enhancement effect for many organic compounds. This study first explored the molecular forms of curcumin in ionic liquid aqueous solutions and the intermolecular interactions between curcumin and ionic liquids using spectral analysis and computational chemistry methods; furthermore, using an ionic liquid aqueous solution as an extraction agent, curcumin-like substances (curcuminoids) were extracted from turmeric powders under ultrasound assisted conditions, revealing the relationship between the structure of the ionic liquid and the extraction efficiency. After that, a kinetic study was conducted for the extraction of curcuminoids from turmeric powders, using second-order kinetics fitting to obtain the rate constant and initial extraction rate during the extraction process. Finally, the comparison with a ComplexGAPI tool and antioxidant experiment was performed on the extraction by using ionic liquids and traditional solvent. The full results can provide reference for the design of IL extractants and their application for natural products. Full article
(This article belongs to the Special Issue Green Separation and Purification Technology)
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16 pages, 14086 KiB  
Article
Effect of Washing Process on the Release of Microplastics from Polyester Fabrics
by Tanja Pušić, Nino Dimitrov, Ana Šaravanja, Ivona Vidić Štrac and Tihana Dekanić
Separations 2025, 12(2), 28; https://doi.org/10.3390/separations12020028 - 26 Jan 2025
Viewed by 301
Abstract
Microplastics (MP), consisting of particles under 5 mm in size, and fibrous microplastics (FMPs), which originate from textiles and are shed during the washing process, are acknowledged as a new and expanding category of pollutants. This study aimed to conduct an analytical evaluation [...] Read more.
Microplastics (MP), consisting of particles under 5 mm in size, and fibrous microplastics (FMPs), which originate from textiles and are shed during the washing process, are acknowledged as a new and expanding category of pollutants. This study aimed to conduct an analytical evaluation of the defragmentation process of polyester fabrics featuring a prominent tri-color pile surface. The evaluation involved washing the fabrics with detergent and water and employing various methods to assess the fabric, wastewater, and filter cake both prior to, and following, cryogenization. The specificity of a pile polyester fabric provided a baseline for evaluating the detergent and water system. Subjecting the polyester fabric to five cycles of washing in a detergent solution and water resulted in a measurable loss of mass. The pristine polyester fabric was analyzed microscopically and by FTIR, while the fabrics before and after washing were subjected to gravimetric analysis. The physico–chemical characteristics of the wastewater, such as the conductivity, turbidity, and chemical oxygen demand, were impacted by the composition of the washing bath. The application of pyrolysis, combined with gas chromatography and mass spectrometry (Py-GC/MS), on the filter cake demonstrated the value of using blank samples. The results indicated that both the detergent and the water significantly affected the release of FMPs during the washing process. Polyester fabric sample 1, which was washed in a detergent solution for five cycles, exhibited a mass loss of 1619 mg kg−1. In contrast, sample 2, consisting of a polyester fabric washed solely in water, showed a mass loss of 1707 mg kg−1 over the same number of cycles. Full article
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13 pages, 3850 KiB  
Article
Electromigration Separation of Lithium Isotopes with the Benzo-12-Crown-4-Ether (B12C4) System
by Zhiyu Zhao, Lianjing Mao, Tianyu Zheng, Xiao Li, Chunsen Ye, Pengrui Zhang, Huifang Li, Wei Sun and Jinhe Sun
Separations 2025, 12(2), 27; https://doi.org/10.3390/separations12020027 - 26 Jan 2025
Viewed by 308
Abstract
Enriched lithium isotopes (6Li and 7Li) are essential in the nuclear energy industry, where 6Li is bombarded with neutrons to produce tritium for fusion reactions, while 7Li is used as a core coolant and pH regulator. Separation of [...] Read more.
Enriched lithium isotopes (6Li and 7Li) are essential in the nuclear energy industry, where 6Li is bombarded with neutrons to produce tritium for fusion reactions, while 7Li is used as a core coolant and pH regulator. Separation of 6Li and 7Li by electromigration is a promising method for producing enriched lithium isotopes that fulfill industrial needs. In this work, based on a previously proposed biphasic system electromigration routine, a three-stage system of ‘LiCl aqueous solution (anolyte)|B12C4-[EMIm][NTf2] organic solution|NH4Cl aqueous solution (catholyte)’ was constructed and the rules of lithium isotope separation and lithium-ion migration investigated. It was shown that the isotope enrichment effect of the catholyte was greatly affected by the experimental conditions, while that of the organic solution was less affected. As the B12C4 concentration increased, enhancement of 7Li enrichment in the catholyte and 6Li enrichment in the organic solution was observed, and α(C/O) and α(O/A) reached 0.975 and 1.018 at B12C4 of 0.5 mol/L. With the increase in current, migration time, and LiCl concentration, the isotope that was enriched in the catholyte trended from 7Li to 6Li (about 6 mA, 12 h or LiCl of 5 mol/L). Taking lithium-ion transport efficiency and lithium isotope separation effect into consideration together, a current of at least 6 mA, duration of at least 12 h, LiCl concentration of at least 1 mol/L and B12C4 concentration of 0.2 mol/L are suggested for the electromigration process. The work provides an important reference for system construction and experimental design of a biphasic electromigration separation method, which is expected to be an industrial alternative because of its environmental protection and high efficiency. Full article
(This article belongs to the Special Issue Green and Efficient Separation and Extraction of Salt Lake Resources)
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13 pages, 873 KiB  
Article
HILIC-DAD Method for Simultaneous Determination of Acid and Basic Drugs: Application to the Quantitation of Ibuprofen, Atenolol, and Salbutamol in Urine After Solid-Phase Extraction
by Noelia Rosales-Conrado, Laura Pedrera-Cajas, Elvira Soliño-Rodríguez and María Eugenia León-González
Separations 2025, 12(2), 26; https://doi.org/10.3390/separations12020026 - 26 Jan 2025
Viewed by 488
Abstract
A simple method has been developed for the simultaneous analysis of ibuprofen (acid drug), and salbutamol and atenolol (basic drugs) in urine samples at concentrations of 0.40 µg·mL−1. Simultaneous chromatographic separation has been possible using hydrophilic interaction liquid chromatography (Kinetex HILIC [...] Read more.
A simple method has been developed for the simultaneous analysis of ibuprofen (acid drug), and salbutamol and atenolol (basic drugs) in urine samples at concentrations of 0.40 µg·mL−1. Simultaneous chromatographic separation has been possible using hydrophilic interaction liquid chromatography (Kinetex HILIC® column (2.1 mm × 150 mm, 2.6 μm particle size diameter and 100 Å pore size) combined with gradient elution by employing a mixture of acetonitrile–acetate buffer 5 mM at pH 6 (from 95:5 to 75:25 (v/v)) as the mobile phase. Detection was performed at 227 and 275 nm. The simultaneous preconcentration and cleaning of the sample has been possible by solid-phase extraction using the HLB ExtraBond® polymeric-type sorbent (which is a pyrrolidone-modified divinylbenzene polystyrene type). It has provided recoveries between (63 ± 9)% for salbutamol, (74 ± 8)% for ibuprofen, and (96 ± 9)% for atenolol in 10 mL of synthetic urine containing 4.0 μg of each of the drugs analyzed. The detection limits were 0.025 µg·mL−1 for ibuprofen, µg·mL−1 for salbutamol, and 0.007 µg·mL−1 for atenolol. The detection limits obtained allow the evaluation of the free forms of ibuprofen, atenolol, and salbutamol at the excreted concentration levels at the therapeutic doses usually administered. The coefficients of variation between days were in the range 4.5–10.9%. Full article
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17 pages, 2312 KiB  
Article
Green Chemistry Method for Analyzing Bisphenol A in Milk
by Angela M. Encerrado Manriquez and Wen-Yee Lee
Separations 2025, 12(2), 25; https://doi.org/10.3390/separations12020025 - 25 Jan 2025
Viewed by 333
Abstract
A simple, fast, green, and sensitive method for determining Bisphenol A (BPA) levels in commercial milk was developed using a solventless sample preparation technique known as stir bar sorptive extraction, coupled with thermal desorption–gas chromatography/mass spectrometry. BPA was selected due to its ubiquitous [...] Read more.
A simple, fast, green, and sensitive method for determining Bisphenol A (BPA) levels in commercial milk was developed using a solventless sample preparation technique known as stir bar sorptive extraction, coupled with thermal desorption–gas chromatography/mass spectrometry. BPA was selected due to its ubiquitous presence in the environment and its classification as an endocrine-disrupting chemical of concern (i.e., its ability to mimic hormone functions). Studies have reported that BPA can leach into various food sources, including milk, a dietary staple for infants. It is critical to have an effective and efficient process for monitoring the presence of BPA in milk to protect children’s health. Current detection methods for BPA in milk are lengthy and tedious and tend to require the use of organic solvents for the extraction of BPA. This optimized “green” method provides an effective alternative for BPA detection in a challenging matrix, e.g., milk. Factors such as pH (1.5, 6, and 13), temperature (70–80 °C), and sonication (1 h, 2 h, and 3 h) were studied with a BPA-spiked whole milk sample (final concentration of 8 ppb) to optimize the extraction efficiency without the use of solvents. The developed methodology improves BPA recovery from whole milk by over 50%, with a detection limit in the parts per trillion range (45 ng/L). The sample preparation developed in this report rendered a more sensitive option for analyzing BPA in milk, with a limit of detection in the parts per trillion range (compared to low ppb) even though the recovery performance is not as good as in reported studies (54% vs. >85%); nonetheless, it provides a green alternative for future studies assessing BPA exposure through dairy products. Full article
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16 pages, 6027 KiB  
Article
Efficient Separation of Hydroxylamine from Metal Ions by PIM-ED Process
by Lilei Yang, Zhongwei Ding, Zhengtao Zhu and Weidong Zhang
Separations 2025, 12(2), 24; https://doi.org/10.3390/separations12020024 - 24 Jan 2025
Viewed by 591
Abstract
Selective separation of hydroxylamine (HA) from metal ions to prepare high-purity HA remains a challenge. In this study, given that HA can react with carbonyl compounds, TTA (thenoyltrifluoroacetone) was screened as a carrier to prepare the polymer inclusion membrane (PIM), which was used [...] Read more.
Selective separation of hydroxylamine (HA) from metal ions to prepare high-purity HA remains a challenge. In this study, given that HA can react with carbonyl compounds, TTA (thenoyltrifluoroacetone) was screened as a carrier to prepare the polymer inclusion membrane (PIM), which was used to separate HA from metal and inorganic acid ions. The experimental results demonstrated that the PIM exhibited good selectivity for HA. During the PIM process, the proton gradient served as a driving force to transport NH2OH(I). The electrodialysis (ED) process was used to efficiently and continuously provide proton gradient without introducing other ions, which coupled with PIM to separate HA. Under the optimum conditions, the separation factors of NH2OH(I)/Na(I) and NH2OH(I)/K(I) were 30.81 and 35.11; the purity of HA was 99.4%, indicating that the PIM-ED process can be used for high-purity preparation of HA. Full article
(This article belongs to the Section Separation Engineering)
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14 pages, 2253 KiB  
Article
Antimicrobial Steroids from Poisonous Mushroom Gymnopilus orientispectabilis and Their Molecular Docking Studies
by Bowon Jung, Eun Jin Heo, Dieu Linh Nguyen, Ui Joung Youn, Ki Hyun Kim, Boram Son and Seulah Lee
Separations 2025, 12(2), 23; https://doi.org/10.3390/separations12020023 - 24 Jan 2025
Viewed by 327
Abstract
In this study, three fungal steroids (13) were isolated from the fruiting bodies of the poisonous mushroom Gymnopilus orientispectabilis, based on bioactivity-guided isolation methods. The chemical structures of the isolates (13) were determined using [...] Read more.
In this study, three fungal steroids (13) were isolated from the fruiting bodies of the poisonous mushroom Gymnopilus orientispectabilis, based on bioactivity-guided isolation methods. The chemical structures of the isolates (13) were determined using NMR spectroscopic methods. Compounds 13 exhibited inhibition activity against E. coli, and their interactions with several bacterial drug targets were studied via in silico molecular docking, where the lowest binding energies were observed for penicillin binding protein 3 (PBP3) (−62.89, −75.89 and −74.47 kcal/mol, for compounds 1, 2 and 3, respectively). An MD simulation was performed to examine the conformational stability, motion and flexibility of protein–ligand complexes. In conclusion, this study investigates fungal steroids from G. orientaspectabilis as potential sources for new antimicrobial agents, encouraging further research to develop novel therapies. Full article
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15 pages, 2543 KiB  
Article
Comprehensive Quantitative Analysis of Coal-Based Liquids by Mask R-CNN-Assisted Two-Dimensional Gas Chromatography
by Huan-Huan Fan, Xiang-Ling Wang, Jie Feng and Wen-Ying Li
Separations 2025, 12(2), 22; https://doi.org/10.3390/separations12020022 - 24 Jan 2025
Viewed by 295
Abstract
A comprehensive understanding of the compositions and physicochemical properties of coal-based liquids is conducive to the rapid development of multipurpose, high-performance, and high-value functional chemicals. However, because of their complex compositions, coal-based liquids generate two-dimensional gas chromatography (GC × GC) chromatograms that are [...] Read more.
A comprehensive understanding of the compositions and physicochemical properties of coal-based liquids is conducive to the rapid development of multipurpose, high-performance, and high-value functional chemicals. However, because of their complex compositions, coal-based liquids generate two-dimensional gas chromatography (GC × GC) chromatograms that are very complex and very time consuming to analyze. Therefore, the development of a method for accurately and rapidly analyzing chromatograms is crucial for understanding the chemical compositions and structures of coal-based liquids, such as direct coal liquefaction (DCL) oils and coal tar. In this study, DCL oils were distilled and qualitatively analyzed using GC × GC chromatograms. A deep-learning (DL) model was used to identify spectral features in GC × GC chromatograms and predominantly categorize the corresponding DCL oils as aliphatic alkanes, cycloalkanes, mono-, bi-, tri-, and tetracyclic aromatics. Regional labels associated with areas in the GC × GC chromatograms were fed into the mask-region-based convolutional neural network’s (Mask R-CNN’s) algorithm. The Mask R-CNN accurately and rapidly segmented the GC × GC chromatograms into regions representing different compounds, thereby automatically qualitatively classifying the compounds according to their spots in the chromatograms. Results show that the Mask R-CNN model’s accuracy, precision, recall, F1 value, and Intersection over Union (IoU) value were 93.71%, 96.99%, 96.27%, 0.95, and 0.93, respectively. DL is effective for visually comparing GC × GC chromatograms to analyze the compositions of chemical mixtures, accelerating GC × GC chromatogram interpretation and compound characterization and facilitating comparisons of the chemical compositions of multiple coal-based liquids produced in the coal and petroleum industry. Applying DL to analyze chromatograms improves analysis efficiency and provides a new method for analyzing GC × GC chromatograms, which is important for fast and accurate analysis. Full article
(This article belongs to the Section Chromatographic Separations)
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21 pages, 531 KiB  
Review
Plant Sample Preparation for Metabolomics, Lipidomics, Ionomics, Fluxomics, and Peptidomics
by Walace Breno da Silva, Gabriel Felipe Hispagnol, Emanuel Victor dos Santos Nunes, Ian Castro-Gamboa and Alan Cesar Pilon
Separations 2025, 12(2), 21; https://doi.org/10.3390/separations12020021 - 24 Jan 2025
Viewed by 395
Abstract
Plant metabolomics, lipidomics, ionomics, fluxomics, and peptidomics are essential approaches for exploring how plants respond to epigenetic, pathological, and environmental stimuli through comprehensive chemical profiling. Over the past decades, significant progress has been made in protocols and methodologies to address the challenges in [...] Read more.
Plant metabolomics, lipidomics, ionomics, fluxomics, and peptidomics are essential approaches for exploring how plants respond to epigenetic, pathological, and environmental stimuli through comprehensive chemical profiling. Over the past decades, significant progress has been made in protocols and methodologies to address the challenges in sample collection and extraction. Despite these advancements, sample preparation remains intricate, with ongoing debates about the most effective strategies. This review emphasizes the importance of clear research questions and well-designed experiments to minimize complexity, save time, and enhance reproducibility. It provides an overview of the key steps in these fields, including harvesting, drying, extraction, and data pre-acquisition for major analytical platforms. By discussing best practices and common challenges, this review aims to streamline methods and promote more consistent and reliable research outcomes. Full article
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24 pages, 7207 KiB  
Review
Fabrications and Properties of Heteroatom-Based Co-Doped Biochar for Environmental Application: A Review
by Meizhi Yang, Suxing Luo, Ping Zeng and Yuanhui Wu
Separations 2025, 12(2), 20; https://doi.org/10.3390/separations12020020 - 22 Jan 2025
Viewed by 480
Abstract
For the past few years, biochar has emerged as a promising material for the removal of various pollutants from aquatic environments, owing to its advantageous characteristics, such as tunable porosity, abundant surface functional groups, ease of modification, and relative stability. Co-doping biochar with [...] Read more.
For the past few years, biochar has emerged as a promising material for the removal of various pollutants from aquatic environments, owing to its advantageous characteristics, such as tunable porosity, abundant surface functional groups, ease of modification, and relative stability. Co-doping biochar with heteroatoms significantly enhances its surface properties by introducing additional functional groups and surface defects, which facilitate the adsorption and catalytic degradation of pollutants. This review conducts bibliometric analyses of relevant publications, synthesis methodologies, applications, and reaction mechanisms of co-doped biochar as an adsorbent and catalyst for contaminant removal, due to the synergistic effects of doping elements and biochar features. Furthermore, co-doping strategies and associated properties including specific surface area (SSA), surface functional groups, and defects of biochar are analyzed. Finally, future research directions are proposed to improve the efficiency of biochar in water and soil remediation applications. In summary, this review advances the frontier of research on heteroatom-based co-doped biochar and offers new insights into strategies for effective contaminant removal. Full article
(This article belongs to the Special Issue Adsorption Process in Chemical Engineering)
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14 pages, 1399 KiB  
Article
Development of a Validated HPLC-UV Method for the Determination of Panthenol, Hesperidin, Rutin, and Allantoin in Pharmaceutical Gel-Permeability Study
by Sofia Almpani, Pavlina-Ioanna Agiannitou, Paraskevi Kyriaki Monou, Georgios Kamaris and Catherine K. Markopoulou
Separations 2025, 12(2), 19; https://doi.org/10.3390/separations12020019 - 22 Jan 2025
Viewed by 548
Abstract
A pressure ulcer is the necrosis of the skin and tissues due to prolonged pressure. Its prevention and treatment are of great importance not only for the health but also for the patient’s quality of life and are considered the highest priority. In [...] Read more.
A pressure ulcer is the necrosis of the skin and tissues due to prolonged pressure. Its prevention and treatment are of great importance not only for the health but also for the patient’s quality of life and are considered the highest priority. In the present study, a reliable analytical method is developed for the quantitative determination of panthenol, hesperidin, rutin, and allantoin by HPLC and UV detectors. The substances were formulated into a pharmaceutical gel, with healing and regenerative properties recommended for first- and second-degree bedsores. Their separation was achieved with a ZIC-Hilic column (150 × 4.6 mm), 5 μm, and a gradient elution system (Solvent A: CH3CN-H2O, 90:10 v/v/v and Solvent B: CH3CN-H2O, 10:90 v/v). The method was evaluated based on the required specifications (%RSD < 2, % Recovery > 96.7%) and was applied for the quantitative extraction of the active substances in the gel. The purification of the samples was carried out using experimental design and Cross-D-Optimal methodology (%RSD < 2.2, % Recovery > 96.9%). Subsequently, the gel was studied in terms of the transdermal permeation of the active pharmaceutical ingredients (APIs) through vertical Franz cells and their behavior (Papp values) was compared with a similar aqueous suspension product (reference formulation). The samples were reconstituted by lyophilization and extraction with methanol. According to the results, the drugs exhibit satisfactory penetration, ensuring the healing of problems that may occur in the skin and dermis. Full article
(This article belongs to the Collection State of the Art in Separation Science)
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13 pages, 4476 KiB  
Article
Green Preparation of ZnO Nanoparticles Using Citrus aurantium L. Extract for Dye Adsorption, Antibacterial, and Antioxidant Activities
by Xitao Yang, Liangliang Liu, Chenxiao Chen, Liping Liao and Siqi Huang
Separations 2025, 12(2), 18; https://doi.org/10.3390/separations12020018 - 21 Jan 2025
Viewed by 417
Abstract
In this study, ZnO nanoparticles (ZnO NPs) were synthesized using a green method employing fresh Citrus aurantium L. aqueous extract (CA) as a reducing agent. After preparation, the ZnO NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray [...] Read more.
In this study, ZnO nanoparticles (ZnO NPs) were synthesized using a green method employing fresh Citrus aurantium L. aqueous extract (CA) as a reducing agent. After preparation, the ZnO NPs were characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray analysis (EDAX), X-ray diffraction (XRD), and infrared spectroscopy (IR). The products displayed irregular particle shapes on a nanoscale. The adsorption ability of ZnO NPs was tested with amaranth red dye, and the result showed that it had a satisfied capacity for amaranth red. The adsorption data followed the pseudo-second-order model and the Langmuir model, which indicated the adsorption process was controlled by a chemical adsorption process and occurred homogeneously on the surface of absorbents. In addition, the prepared ZnO NPs also exhibited antibacterial abilities against Staphylococcus aureus and Escherichia coli bacteria; antioxidant activities were observed in 2-2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-di(3-ethylbenzthiazoline sulphonate) (ABTS) radicals scavenging assays and the ferric ion reducing antioxidant power (FRAP) assay, which were better than those of traditional ZnO NPs except in the FRAP assay. Based on these findings, the ZnO NPs fabricated with CA aqueous extract displayed promising abilities in the environmental remediation of dye wastewater. Full article
(This article belongs to the Special Issue Removal of Organic Pollutants from Aqueous Systems)
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