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Volume 12
Issue 6
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Separations, Volume 12, Issue 6 (June 2025) – 33 articles

Cover Story (view full-size image): The development of chromatographic processes to purify biopharmaceuticals requires tremendous experimental effort. The state-of-the-art approach, Design of Experiments, enables a systematic procedure limited to a design space described by a statistical, interpolating model; however, the experimental burden remains high. Process development would benefit from extrapolating models to reduce this burden and enable deeper process understanding and knowledge transfer. Nevertheless, such models currently lack predictive power. In an academic–industrial collaboration, we present a new biophysics-based adsorption model for developing ion-exchange chromatography processes for pharmaceuticals at a preparative scale. This model achieves high predictive power across low and high antibody load densities and even captures charge variant behavior. View this paper
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11 pages, 2330 KiB  
Article
Separations of Strategic Metals from Spent Electronic Waste Using “Green Methods”
by Urszula Domańska, Anna Wiśniewska and Zbigniew Dąbrowski
Separations 2025, 12(6), 167; https://doi.org/10.3390/separations12060167 - 18 Jun 2025
Viewed by 323
Abstract
Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing [...] Read more.
Next-generation recycling technologies must be urgently innovated to tackle huge volumes of spent batteries, photovoltaic panels or printed circuit boards (WPCBs). Current e-waste recycling industrial technology is dominated by traditional recycling technologies. Herein, ionic liquids (ILs), deep eutectic solvents (DESs) and promising oxidizing additives that can overcome some traditional recycling methods of metal ions from e-waste, used in our works from last year, are presented. The unique chemical environments of ILs and DESs, with the application of low-temperature extraction procedures, are important environmental aspects known as “Green Methods”. A closed-loop system for recycling zinc and manganese from the “black mass” (BM) of waste, Zn-MnO2 batteries, is presented. The leaching process achieves a high efficiency and distribution ratio using the composition of two solvents (Cyanex 272 + diethyl phosphite (DPh)) for Zn(II) extraction. High extraction efficiency with 100% zinc and manganese recovery is also achieved using DESs (cholinum chloride/lactic acid, 1:2, DES 1, and cholinum chloride/malonic acid, 1:1, DES 2). New, greener recycling approaches to metal extraction from the BM of spent Li-ion batteries are presented with ILs ([N8,8,8,1][Cl], (Aliquat 336), [P6,6,6,14][Cl], [P6,6,6,14][SCN] and [Benzet][TCM]) eight DESs, Cyanex 272 and D2EHPA. A high extraction efficiency of Li(I) (41–92 wt%) and Ni(II) (37–52 wt%) using (Cyanex 272 + DPh) is obtained. The recovery of Ni(II) and Cd(II) from the BM of spent Ni-Cd batteries is also demonstrated. The extraction efficiency of DES 1 and DES 2, contrary to ILs ([P6,6,6,14][Cl] and [P6,6,6,14][SCN]), is at the level of 30 wt% for Ni(II) and 100 wt% for Cd(II). In this mini-review, the option to use ILs, DESs and Cyanex 272 for the recovery of valuable metals from end-of-life WPCBs is presented. Next-generation recycling technologies, in contrast to the extraction of metals from acidic leachate preceded by thermal pre-treatment or from solid material only after thermal pre-treatment, have been developed with ILs and DESs using the ABS method, as well as Cyanex 272 (only after the thermal pre-treatment of WPCBs), with a process efficiency of 60–100 wt%. In this process, four new ILs are used: didecyldimethylammonium propionate, [N10,10,1,1][C2H5COO], didecylmethylammonium hydrogen sulphate, [N10,10,1,H][HSO4], didecyldimethylammonium dihydrogen phosphate, [N10,10,1,1][H2PO4], and tetrabutylphosphonium dihydrogen phosphate, [P4,4,4,4][H2PO4]. The extraction of Cu(II), Ag(I) and other metals such as Al(III), Fe(II) and Zn(II) from solid WPCBs is demonstrated. Various additives are used during the extraction processes. The Analyst 800 atomic absorption spectrometer (FAAS) is used for the determination of metal content in the solid BM. The ICP-OES method is used for metal analysis. The obtained results describe the possible application of ILs and DESs as environmental media for upcycling spent electronic wastes. Full article
(This article belongs to the Section Materials in Separation Science)
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10 pages, 4055 KiB  
Article
Simulation of Helical-Baffle Inlet Structure Cyclone Separator
by Guohua Li, Jie Gong, Zijuan Wang and Ran Liu
Separations 2025, 12(6), 166; https://doi.org/10.3390/separations12060166 - 18 Jun 2025
Viewed by 323
Abstract
In developing spacecraft dust environment testing equipment, cyclone separators serve as critical particulate separation devices. To optimize cyclone performance, this study investigates the impact of inlet configurations on internal flow fields. We propose a novel helical-baffle inlet design and comparatively analyze it against [...] Read more.
In developing spacecraft dust environment testing equipment, cyclone separators serve as critical particulate separation devices. To optimize cyclone performance, this study investigates the impact of inlet configurations on internal flow fields. We propose a novel helical-baffle inlet design and comparatively analyze it against volute baffle inlets and conventional single-channel inlets using Eulerian–Lagrangian multiphase simulations. Three-dimensional streamline visualization reveals internal flow patterns, while the Q-criterion identifies vortical structures. Results demonstrate that both volute and helical configurations effectively eliminate inlet gas funneling effects. The flow-splitting baffles mitigate flow field asymmetry, with the helical-baffle design exhibiting optimal performance: it maintains vortex stability, enhances fluid dynamic equilibrium, reduces pressure drop and improves separation efficiency to 95.92% for 4 μm particles. Full article
(This article belongs to the Special Issue Research on New Technology and Equipment of Multiphase Flow Separation)
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14 pages, 1915 KiB  
Article
Parameter Optimization Considering the Variations Both from Materials and Process: A Case Study of Scutellaria baicalensis Extract
by Xuecan Zhang, Zhilong Tang, Bo Chen and Xingchu Gong
Separations 2025, 12(6), 165; https://doi.org/10.3390/separations12060165 - 17 Jun 2025
Viewed by 485
Abstract
The Quality by Design (QbD) concept has been widely applied to the optimization of traditional Chinese medicine production processes recently. This work focused on optimizing the critical purification process of Scutellaria baicalensis extract used in the preparation of Zhusheyong Shuanghuanglian. Considering the impact [...] Read more.
The Quality by Design (QbD) concept has been widely applied to the optimization of traditional Chinese medicine production processes recently. This work focused on optimizing the critical purification process of Scutellaria baicalensis extract used in the preparation of Zhusheyong Shuanghuanglian. Considering the impact of noise parameters and changes in herbal properties, an experimental design method was employed for optimization. Multiple batches of Scutellaria baicalensis decoction were prepared in this research, and quantitative models of Scutellaria baicalensis herbal properties, critical process parameters (CPPs), and process evaluation indicators were established. The R2 of the quantitative models were all higher than 0.80. According to the model, the yield of baicalin was identified as a critical material property (CMA). The pH of first acid precipitation (X1), first temperature holding time (X2), pH of alkalization (X3), ethanol amount (X4), and end pH of ethanol washing (X5) were CPPs. Considering the difficulty in controlling the end pH of the ethanol washing, it was considered to be a noise parameter. The Monte Carlo probability-based method was used to calculate the design space, determining the range of controllable parameters, which was successfully validated through experiments. Normal operation ranges for controllable parameters are recommended as follows: X1 of 0.8–2.2, X2 of 25–35 min, X3 of 6.5–7.5, and X4 of 0.8–1.2 g/g. Full article
(This article belongs to the Section Purification Technology)
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23 pages, 1098 KiB  
Article
Separation of Bioactive Compounds from Pfaffia glomerata: Drying, Green Extraction, and Physicochemical Properties
by Marcela Moreira Terhaag, Ana Catarina Mosquera dos Santos, Daniel Gonzaga de Lima, Otavio Akira Sakai, Giselle Giovanna do Couto de Oliveira, Cristiane Mengue Feniman Moritz, Bogdan Demczuk Junior, Jorcilene dos Santos Silva, Suelen Pereira Ruiz, Maria Graciela Iecher Faria, Beatriz Cervejeira Bolanho Barros and Erica Marusa Pergo Coelho
Separations 2025, 12(6), 164; https://doi.org/10.3390/separations12060164 - 17 Jun 2025
Viewed by 328
Abstract
Leaves (LV), stems (STs), and inflorescences (IFs) of Pfaffia glomerata are usually discarded despite containing various bioactive compounds, especially β-ecdysone saponin. The objective was to optimize by desirability (DI) the ultrasound-assisted extraction (UAE) of bioactive compounds (total phenolics (TPCs), antioxidant activity (AA), and [...] Read more.
Leaves (LV), stems (STs), and inflorescences (IFs) of Pfaffia glomerata are usually discarded despite containing various bioactive compounds, especially β-ecdysone saponin. The objective was to optimize by desirability (DI) the ultrasound-assisted extraction (UAE) of bioactive compounds (total phenolics (TPCs), antioxidant activity (AA), and total saponins) from the aerial parts (LV, ST, and IF) of P. glomerata. Ideal drying conditions were determined and the drying kinetics were evaluated. LV, STs, and IFs were dried and extracted (0.06 g/mL 80% EtOH) in a USS (6 cm × 12 mm, pulse 3/6 s) by Central Composite Design (CCD), varying sonication power (140–560 W) and time (11–139 min), with TPC, AA by DPPH, and total saponin content as responses. The DI indicated that the higher TPC, AA, and saponin levels were obtained at 136.5 min and 137.87 W (STs), and 138.6 min and 562.32 W (LV and IFs). IF extracts contained higher saponin, TPCs, and AA. Higher β-ecdysone levels (3.90 mg g−1) were present in the leaves. Several phenolics were detected in area parts of P. glomerata, the most abundant being p-coumaric acid (LV) and nicotinic acid (STs and IFs). These compounds provide potential health benefits. Phytol was found in all extracts. Extracts by UAE from leaves have antibacterial potential, with demonstrated inhibitory effects against S. aureus, E. coli, L. monocytogenes, S. Typhi, and P. aeruginosa, and presented bactericidal effects against E. coli, L. monocytogenes, and S. Typhi. Aerial parts of P. glomerata can be used to obtain extracts by UAE rich in bioactive compounds, providing complete utilization of the plant and sustainability to cultivation. This work represents the first report on the application of ecofriendly UAE techniques to extract bioactive compounds from the aerial parts of Brazilian ginseng. Full article
(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)
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13 pages, 1169 KiB  
Article
The Selective Extraction of Natural Sesquiterpenic Acids in Complex Matrices: A Novel Strategy for Isolating Zizanoic Acid in Vetiver Essential Oil
by Ian Gardel Carvalho Barcellos-Silva, Ananda da Silva Antonio, Mateus Curty Cariello da Silva, Fernanda de Melo Regazio Cariello, Fernando Hallwass, Monica Costa Padilha and Valdir Florencio Veiga-Junior
Separations 2025, 12(6), 163; https://doi.org/10.3390/separations12060163 - 17 Jun 2025
Viewed by 266
Abstract
Essential oils are complex mixtures of apolar components, mainly phenylpropanoids, monoterpenes, and sesquiterpenes. Vetiver (Vetiveria zizanioides (L.) Nash) is a non-endemic grass in several tropical regions, widely used for slope stabilization and erosion control because of its long and deep roots that [...] Read more.
Essential oils are complex mixtures of apolar components, mainly phenylpropanoids, monoterpenes, and sesquiterpenes. Vetiver (Vetiveria zizanioides (L.) Nash) is a non-endemic grass in several tropical regions, widely used for slope stabilization and erosion control because of its long and deep roots that help to bind the soil together, preventing landslides and soil loss. From these roots, vetiver essential oil is obtained, which is extracted and produced worldwide and highly valued for its diverse range of bioactive substances used by the cosmetics and perfume industries. These substances, present in a very complex mixture, are difficult to isolate. Zizanoic acid is a very rare substance in nature and also very interesting because of the biological properties already described. In the present study, zizanoic acid was selectively isolated with 84–87% purity from vetiver commercial essential oils, in which it was present at less than 10%, using KOH-impregnated silica gel column chromatography alone. The experiments were monitored using GC-MS and UHPLC-HRMS, and the isolated substances (zizanoic and valerenic acids) were further determined by NMR experiments. The whole methodology and analytical approach proved to be very efficient for natural product complex mixture analysis and also very selective, allowing for a distinct capacity to recover carboxylic acids from complex biological samples. Full article
(This article belongs to the Special Issue Extraction and Characterization of Food Components)
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25 pages, 1879 KiB  
Review
Integration and Operational Application of Advanced Membrane Technologies in Military Water Purification Systems
by Mirela Volf, Silvia Morović and Krešimir Košutić
Separations 2025, 12(6), 162; https://doi.org/10.3390/separations12060162 - 16 Jun 2025
Viewed by 364
Abstract
Membrane technologies are used in the production of potable water and the treatment of wastewater in the military forces, providing the highest level of contaminant removal at an energy-efficient cost. This review examines the integration and application of membrane technologies, including reverse osmosis, [...] Read more.
Membrane technologies are used in the production of potable water and the treatment of wastewater in the military forces, providing the highest level of contaminant removal at an energy-efficient cost. This review examines the integration and application of membrane technologies, including reverse osmosis, nanofiltration, ultrafiltration, electrodialysis and advanced hybrid systems, in the treatment of wastewater generated at military bases, naval vessels and submarines. Special emphasis is placed on purification technologies for chemically, biologically and radiologically contaminated wastewater, as well as on the recycling and treatment of wastewater streams by mobile systems used in military applications. Given the specific requirements of complex military infrastructures, particularly in terms of energy efficiency, unit self-sufficiency and reduced dependence on logistical supply chains, this work analyses the latest advances in membrane technologies. Innovations such as nanographene membranes, biomimetic membranes, antifouling membrane systems and hybrid configurations of forward osmosis/reverse osmosis and electrodialysis/reverse electrodialysis offer unique potential for implementation in modular and mobile water treatment systems. In addition, the integration and operational use of these advanced technologies serve as a foundation for the development of autonomous military water supply strategies tailored to extreme operational conditions. The continued advancement and optimization of membrane technologies in military contexts is expected to significantly impact operational sustainability while minimizing environmental impact. Full article
(This article belongs to the Special Issue Design and Preparation of Sustainable Separation Membrane for Efficient Water Purification)
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20 pages, 3883 KiB  
Article
Optimization and Dynamic Adjustment of Tandem Columns for Separating an Ethylbenzene–Styrene Mixture Using a Multi-Objective Particle Swarm Algorithm
by Guangsheng Jiang, Yibo She, Zhongwen Song, Liwen Zhao and Guilian Liu
Separations 2025, 12(6), 161; https://doi.org/10.3390/separations12060161 - 15 Jun 2025
Viewed by 383
Abstract
This study focuses on optimizing two tandem columns to separate ethylbenzene and styrene. A steady-state model is developed to minimize total energy consumption (TEC) and total annualized cost (TAC) by optimizing the reflux flow rates. An integrated dynamic model is created using the [...] Read more.
This study focuses on optimizing two tandem columns to separate ethylbenzene and styrene. A steady-state model is developed to minimize total energy consumption (TEC) and total annualized cost (TAC) by optimizing the reflux flow rates. An integrated dynamic model is created using the Multi-Objective Particle Swarm Optimization (MOPSO) algorithm. This model is designed to account for transitions in operating conditions and to identify optimal dynamic strategies for adjusting operations to maintain optimal performance. The optimization considers factors such as fluctuation amplitude, the number of fluctuations, and fluctuation duration. The aim is to reduce fluctuation amplitudes while ensuring higher energy efficiency and stable operation. The results reveal that the optimal reflux flow rates are 41,152.2 kg/h and 1012.7 kg/h, leading to reductions in TEC and TAC by 16.7% and 17.4%, respectively. Compared with the industry standard level, the energy consumption has decreased by 11.25%. Against the backdrop of increasingly strict global carbon emission control, the market competitiveness of ethylbenzene/styrene production has been significantly enhanced. The variable-step adjustment method requires less time to reach a stable state, while the equal-step fluctuation method provides more stability. The Pareto solution set derived from the two optimization techniques can be used to select the most suitable adjustment strategy, ensuring a fast and smooth transition. Full article
(This article belongs to the Special Issue Novel Solvents and Methods in Distillation Process)
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27 pages, 3488 KiB  
Review
Current Perspectives on the Extraction, Isolation, and Identification of Fats and Fatty Acids Using Conventional and Green Methods
by Ytaiara Lima-Pereira, Esther Maria Oliveira de Souza, David Silva dos Reis, Ian Gardel Carvalho Barcellos-Silva, Karine Sayuri Lima Miki, Valdir F. Veiga-Júnior and Barbara Elisabeth Teixeira-Costa
Separations 2025, 12(6), 160; https://doi.org/10.3390/separations12060160 - 13 Jun 2025
Viewed by 699
Abstract
The global demand for oils and lipids, particularly those derived from vegetable sources with high polyunsaturated fatty acid content, has posed significant challenges for the food industry. This trend is largely driven by growing consumer awareness of health and nutrition. To meet this [...] Read more.
The global demand for oils and lipids, particularly those derived from vegetable sources with high polyunsaturated fatty acid content, has posed significant challenges for the food industry. This trend is largely driven by growing consumer awareness of health and nutrition. To meet this demand, it is essential to not only identify richer sources of lipids but also develop efficient, sustainable, and environmentally friendly methods for their extraction, isolation, and characterization. In this context, the present work provides a comprehensive review of current perspectives on the extraction, isolation, and identification of lipids and fatty acids, comparing conventional and green methodologies for food applications. Ideally, analytical and processing methodologies for obtaining food-grade materials should prioritize low energy consumption, minimal or no use of hazardous substances, and the generation of non-polluting residues, thereby safeguarding both human health and the environment. In recent years, green extraction techniques have emerged as promising alternatives to conventional methods, offering partial or complete replacements, such as ultrasound-assisted extraction, microwave-assisted extraction, supercritical and subcritical fluid extraction, and others. However, significant advancements are still required to fully address these concerns. Techniques such as chromatography and spectrometry play pivotal roles in the isolation and identification process, especially gas chromatography coupled with mass spectrometry or with flame ionization detectors; while separating individual fatty acids based on their chain length and degree of unsaturation, reversed-phase high-performance liquid chromatography (HPLC) is quite a helpful approach. Furthermore, the isolation and structural elucidation of fatty acids are critical steps in ensuring the nutritional quality and commercial viability of lipid products. Full article
(This article belongs to the Special Issue Extraction and Characterization of Food Components)
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14 pages, 498 KiB  
Article
Multivariate Analysis of UPLC-MS/MS Metabolomic Profiles in Four Hiraea Species (Malpighiaceae)
by Jaqueline Munise Guimarães da Silva, Rafael Felipe de Almeida and Maria Luiza Zeraik
Separations 2025, 12(6), 159; https://doi.org/10.3390/separations12060159 - 11 Jun 2025
Viewed by 288
Abstract
The presence of bioactive compounds is reported in several Malpighiaceae species. However, little metabolomic information is documented in the genus Hiraea (Malpighiaceae). Thus, the objective was to identify secondary metabolites in the leaves of Hiraea cuiabensis, H. hatschbachii, H. reclinata, [...] Read more.
The presence of bioactive compounds is reported in several Malpighiaceae species. However, little metabolomic information is documented in the genus Hiraea (Malpighiaceae). Thus, the objective was to identify secondary metabolites in the leaves of Hiraea cuiabensis, H. hatschbachii, H. reclinata, and H. restingae using ultra-performance liquid chromatography coupled to mass spectrometry (UPLC-MS/MS) and to compare the profiles by VIP score (partial least squares discriminant analysis, PLS-DA). Leaves were extracted with ethanol–water (4:1 v/v) and subjected to UPLC-MS/MS. The UPLC-MS/MS chromatographic profiles (in both positive and negative ionization modes) were separately processed and compared using the VIP score (PLS-DA). Fifty compounds were annotated, forty-five for the first time in the genus Hiraea, including flavonoids and phenolic acids, such as chlorogenic acid. The VIP score analysis revealed differences in the intensities of the compounds identified in Hiraea leaves (95% confidence), with rutin and myricitrin as the key metabolites for distinguishing among the four Hiraea species. These findings contributed to an understanding of the chemical diversity within Hiraea, suggesting possible ecological adaptations and potential pharmacological applications. Full article
(This article belongs to the Special Issue Extraction and Characterization of Bioactive Compounds from Plant and Natural Sources)
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16 pages, 1616 KiB  
Article
Comparison of Extraction Techniques for Wide Screening of 230 Pesticides in Water
by Caterina Cacciatori, Jackie Myers, Giulio Mariani, Hung Vu, Bernd Manfred Gawlik and Vincent Pettigrove
Separations 2025, 12(6), 158; https://doi.org/10.3390/separations12060158 - 9 Jun 2025
Viewed by 346
Abstract
In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas [...] Read more.
In this study, weekly grab samples extracted by solid-phase extraction (SPE) and stir bar sorptive extraction (SBSE) were compared for the analysis of 230 pesticides in surface waters. Samples were collected from three different locations around Melbourne, Australia. Analysis was performed using Gas Chromatography Quadrupole Time of Flight High Resolution Mass Spectrometry (GC-QToF-HRMS). The two extraction techniques were compared, among others, for their limits of detection, recovery, extraction, and quantification efficiency of pesticides, as well as spatial and temporal differences in detected compounds. The target compounds screened were pesticides belonging mainly to the categories of fungicides, insecticides, and herbicides. Although SBSE extracted more pesticides at two out of three sites, SPE extracted total concentrations up to four times higher than SBSE over all sampling sites. The log KOW of detected pesticides only partially explained the differences in detection, with SBSE performing better in the absorption of hydrophobic compounds. In addition, matrix effects, in particular turbidity, appeared to hinder extraction of contaminants, especially for SBSE. Spatially, SBSE detected 10 pesticides more than SPE at two locations, while the opposite was true at the third location, where turbidity was higher. The types of pesticides detected varied slightly between techniques and locations. The study highlights the complementarity of SBSE and SPE for monitoring pesticides in natural environments. SBSE is an easy-to-use technique and allows for extraction of a higher number of pesticides at trace level, but it might not be the preferred option for highly turbid waters. SPE requires more tedious and complex sample processing but allows for a more accurate quantification of a broader range of pesticides. Full article
(This article belongs to the Special Issue New Techniques for Extraction and Removal of Pesticide Residues)
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22 pages, 4495 KiB  
Article
The Application of Sn2− in Autotrophic Denitrification Process for Advanced Nitrogen Removal in Wastewater Treatment
by Yingxue Sun, Xiaolei Zhang, Chenli Ye, Ziying He, Hongjie Wang and Ji Li
Separations 2025, 12(6), 157; https://doi.org/10.3390/separations12060157 - 8 Jun 2025
Viewed by 376
Abstract
This study presents a cost-effective and feasible technique for the deep denitrification of wastewater, based on sulfur autotrophic denitrification mediated by polysulfides (Sn2−). Various polysulfides were used as electron donors in an aerobic/anoxic sequencing batch reactor (SBR) to [...] Read more.
This study presents a cost-effective and feasible technique for the deep denitrification of wastewater, based on sulfur autotrophic denitrification mediated by polysulfides (Sn2−). Various polysulfides were used as electron donors in an aerobic/anoxic sequencing batch reactor (SBR) to simulate nitrification and denitrification processes. The performance of different polysulfide species and their respective dosages were evaluated to determine the optimal conditions for nitrogen removal. Under optimal nitrogen removal conditions with a dosing of 19.2 mg S/L from Na2S3, the system was operated continuously for 38 days, with low sludge production during the process. During stable operation, the system achieved an average removal of 7.3 mg/L of NO3−-N, corresponding to a removal efficiency of 23.1%. No significant accumulation of NO2−-N was observed in the effluent, and the average utilization efficiency of Na2S3 reached 83.7%. Continuous dosing of Na2S3 promoted the enrichment of sulfur autotrophic denitrification-related microorganisms within the system. Full article
(This article belongs to the Topic Sustainable Technologies for Water Purification)
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26 pages, 948 KiB  
Review
Antimony Recovery from Industrial Residues—Emphasis on Leaching: A Review
by Marinela Panayotova, Serhii Pysmennyi and Vladko Panayotov
Separations 2025, 12(6), 156; https://doi.org/10.3390/separations12060156 - 8 Jun 2025
Viewed by 662
Abstract
Antimony (Sb) is a metalloid widely used in different areas—from the cutting-edge renewable energy technologies to “classical” lead acid batteries. Its availability in primary sources is limited, and these sources are geographically unevenly distributed worldwide. Antimony use will increase in the future. That [...] Read more.
Antimony (Sb) is a metalloid widely used in different areas—from the cutting-edge renewable energy technologies to “classical” lead acid batteries. Its availability in primary sources is limited, and these sources are geographically unevenly distributed worldwide. Antimony use will increase in the future. That is why Sb is included in the critical raw material lists of the European Union and the USA. In order to mitigate the future Sb shortage, Sb recovery from industrial residues is worth considering. This paper presents the availability of Sb in nonferrous metals extraction waste and the applicability of the hydrometallurgical route for Sb recovery from such sources. Leaching is emphasized. The use of acidic and alkaline leaching methods, their recent modifications, and the effect of different process parameters (reagents’ type, solid-to-liquid ratio, temperature, and the addition of oxidizing reagents) are highlighted. The use of new leaching systems, such as deep eutectic solvents and non-aqueous solutions, is presented. Initial attempts to apply bioleaching are described. Finally, some proposals for future investigations are given. Full article
(This article belongs to the Special Issue Solid Waste Recycling and Strategic Metal Extraction)
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21 pages, 1368 KiB  
Article
Green Extraction Combined with Chemometric Approach: Profiling Phytochemicals and Antioxidant Properties of Ten Species of the Lamiaceae Family
by Branislava Teofilović, Emilia Gligorić, Martina Ninić, Saša Vukmirović, Žarko Gagić, Nebojša Mandić-Kovačević, Biljana Tubić, Đorđe Đukanović and Nevena Grujić-Letić
Separations 2025, 12(6), 155; https://doi.org/10.3390/separations12060155 - 8 Jun 2025
Viewed by 366
Abstract
The pharmacological potential of Lamiaceae plants is primarily linked to their high content of phenolic acids and flavonoids, known for strong antioxidant properties. This study investigated the antioxidant activity of ten widely used Lamiaceae herbs—oregano, lavender, basil, savory, garden thyme, wild thyme, sage, [...] Read more.
The pharmacological potential of Lamiaceae plants is primarily linked to their high content of phenolic acids and flavonoids, known for strong antioxidant properties. This study investigated the antioxidant activity of ten widely used Lamiaceae herbs—oregano, lavender, basil, savory, garden thyme, wild thyme, sage, rosemary, lemon balm, and mint—prepared as traditional infusions and microwave-assisted extracts. The antioxidant capacity was evaluated using spectrophotometric assays, and total phenolics and flavonoids were quantified via spectrophotometry and HPLC. Chemometric analysis (PCA) was applied to explore correlations among antioxidant parameters. The results demonstrated excellent antioxidant activity across all samples. The IC50 for DPPH radicals was in the range from 3.73(0.13) to 8.03(0.17) μg/mL and that for ABTS radicals was from 2.89(0.12) to 8.55(0.34). The CUPRAC antioxidant assay delivered values in the range from 351.93(11.85) to 1129.68(44.46) μg TE/mg DE. The FRAP method produced values from 1.27(0.03) to 6.60(0.26) μmol Fe/mg DE. The presence of gallic acid was detected in all examined samples, with lemon balm and lavender exhibiting the highest concentrations across both applied extraction methods. Notably, lavender showed especially high levels of p-hydroxybenzoic acid and chlorogenic acid. Microwave-assisted extraction generally yielded higher levels of bioactive compounds compared to infusion. These findings highlight the potential of Lamiaceae herbal extracts, particularly those obtained through microwave-assisted extraction, as valuable sources of dietary antioxidants for everyday use. Full article
(This article belongs to the Special Issue Extraction and Characterization of Bioactive Compounds from Plant and Natural Sources)
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13 pages, 959 KiB  
Article
Use of Mixed Micelles in Micellar Electrokinetic Chromatography Method for Determination of Dexamethasone, Prednisolone and Triamcinolone in Pharmaceutical Formulations
by Karen A. Escamilla-Lara, Israel S. Ibarra, Jorge Lopez-Tellez and Jose A. Rodriguez
Separations 2025, 12(6), 154; https://doi.org/10.3390/separations12060154 - 6 Jun 2025
Viewed by 359
Abstract
The unregulated consumption of corticosteroids causes significant adverse effects on human health. Therefore, it is important to develop methodologies that allow their analysis in pharmaceutical matrices with competitive analysis times and costs. The determination of corticosteroids by micellar electrokinetic chromatography (MEKC) using a [...] Read more.
The unregulated consumption of corticosteroids causes significant adverse effects on human health. Therefore, it is important to develop methodologies that allow their analysis in pharmaceutical matrices with competitive analysis times and costs. The determination of corticosteroids by micellar electrokinetic chromatography (MEKC) using a background electrolyte (BGE) composed of phosphate buffer and a micellar pseudo-stationary phase constituted by a mixture of surfactants is proposed as an alternative quantification technique. The variables involved in the BGE: phosphate concentration, surfactant (sodium dodecyl sulfate (SDS) or sodium lauryl ether sulfate (SLES)), sodium taurocholate (STC) and the pH value were optimized using a Taguchi L9 (34) experimental design. Employing the optimal BGE, the separation of the three corticosteroids is possible in a linear range of 1.05–10.0 mg L−1, with limits of detection (LOD) of 0.28–0.35 mg L−1. The relative standard deviation (RSD) values obtained for the repeatability (n = 3) and intermediate precision (n = 9) were less than 5.0%. Pharmaceutical formulations (ointments, injectable solution and ophthalmic solution) were analyzed using the proposed methodology (MEKC) and the official methodology (high-performance liquid chromatography, HPLC), and no significant differences were found between the corticosteroid contents obtained from both methods. Full article
(This article belongs to the Special Issue Development and Applications of Chromatographic Materials and Analytical Methods)
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11 pages, 2568 KiB  
Article
Hydrothermal Conversion of Sn-Bearing Sludge into Fe/S Rods for Efficient Heavy Metal Removal in Wastewater
by Shengyao Ma, Wu Yang, Weilu Yang and Yu Chen
Separations 2025, 12(6), 153; https://doi.org/10.3390/separations12060153 - 6 Jun 2025
Viewed by 313
Abstract
Hydrothermal conversion is an effective strategy to transform heavy metals in electroplating sludge into catalytic materials and use them to treat electroplating wastewater. This study presents a one-step hydrothermal method for converting Sn-bearing sludge, containing 23.41% Sn, 52.12% Fe, and other impurities, into [...] Read more.
Hydrothermal conversion is an effective strategy to transform heavy metals in electroplating sludge into catalytic materials and use them to treat electroplating wastewater. This study presents a one-step hydrothermal method for converting Sn-bearing sludge, containing 23.41% Sn, 52.12% Fe, and other impurities, into Fe/S rods using a NaOH/Na2S solution. The resulting Fe/S rods, with a diameter of 50–100 nm and length of 0.5–2.5 μm, showed excellent performance in wastewater treatment. In the presence of 50 mg/L EDTA, the Fe/S rods removed 22.9% of Ni, 30.2% of Cu, and 41.5% of Zn. When activated with PMS, the removal efficiencies increased significantly to 68.9%, 90.9%, and 91.6% for Ni, Cu, and Zn, respectively. The optimal rod dosage (1 g/L) achieved removal efficiencies of 94.2%, 78.5%, and 99.7% for Cu, Ni, and Zn, while increasing PMS dosage led to nearly 100% removal within 60 min. Additionally, the process allowed for the complete recycling of the alkaline solution, with regenerated rods showing similar performance to the original ones in wastewater treatment. This method offers an efficient and sustainable approach to sludge resource utilization and heavy metal removal from wastewater. Full article
(This article belongs to the Section Environmental Separations)
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20 pages, 15403 KiB  
Article
Computational Study on the Separation of Pentane Isomers in Functionalized UiO-66 Metal-Organic Frameworks
by Néstor Ariel Pérez-Chávez, Matias Rafti and Alberto Gustavo Albesa
Separations 2025, 12(6), 152; https://doi.org/10.3390/separations12060152 - 4 Jun 2025
Viewed by 332
Abstract
The efficient separation of light hydrocarbons, particularly alkanes from their isomers (C5–C6), represents a significant and energy-intensive challenge for the petrochemical industry. Metal-Organic Frameworks (MOFs) offer promising solutions due to their exceptional porosity, surface area, and, crucially, their structural [...] Read more.
The efficient separation of light hydrocarbons, particularly alkanes from their isomers (C5–C6), represents a significant and energy-intensive challenge for the petrochemical industry. Metal-Organic Frameworks (MOFs) offer promising solutions due to their exceptional porosity, surface area, and, crucially, their structural and chemical tunability. This study employs advanced computational methods, including Grand Canonical Monte Carlo (GCMC) simulations and Molecular Dynamics (MD), to systematically investigate the adsorption and separation of pentane isomers (n-pentane, isopentane, and neopentane) in the UiO-66 MOF family. Specifically, the impact of organic linker functionalization with -H (parent), -NH2, -CH3, and -COOH groups on adsorption isotherms, isosteric heats, and competitive behavior in mixtures is evaluated. The analysis provides a molecular-level view of host-guest and guest-guest interactions, elucidating the recognition and selectivity mechanisms governing the separation of these C5 isomers and the potential for engineering MOF materials for this application. Full article
(This article belongs to the Special Issue Recent Advances in Gas Separation and Purification)
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14 pages, 1004 KiB  
Article
Physicochemical and Phytochemical Determinations of Greek “Kollitsida’’ (Arctium lappa L.) from Different Regions and Evaluation of Its Antimicrobial Activity
by Dimitrios G. Lazaridis, Sokratis D. Giannoulis, Maria Simoni, Vassilios K. Karabagias, Nikolaos D. Andritsos, Vasileios Triantafyllidis and Ioannis K. Karabagias
Separations 2025, 12(6), 151; https://doi.org/10.3390/separations12060151 - 4 Jun 2025
Viewed by 411
Abstract
The present study aimed to investigate Greek Kollitsida root samples from different geographical regions based on physicochemical and antibacterial analyses. For this purpose, samples were treated with different solvents, deionized water (solvent A) and ethanol of grape origin (solvent B), to monitor if [...] Read more.
The present study aimed to investigate Greek Kollitsida root samples from different geographical regions based on physicochemical and antibacterial analyses. For this purpose, samples were treated with different solvents, deionized water (solvent A) and ethanol of grape origin (solvent B), to monitor if the physicochemical and phytochemical parameter values can be affected by the type of solvent. Results showed that the extraction solvent affected the physicochemical and phytochemical profile of Kollitsida. In addition, the aqueous and ethanolic extracts showed antibacterial activity against Salmonella typhimurium and Staphylococcus aureus, which was also affected by the geographical origin of Kollitsida samples. Finally, the application of multivariate analysis on the data obtained using deionized water or ethanol of grape origin as an extraction solvent for the analyses classified samples according to their geographical origin by 100%, using the cross-validation method of linear discriminant analysis. The study brings new knowledge regarding the physicochemical, phytochemical, and antibacterial profiles, along with the authenticity, of Greek Kollitsida. Full article
(This article belongs to the Special Issue Extraction and Characterization of Bioactive Compounds from Plant and Natural Sources)
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19 pages, 533 KiB  
Review
Extraction of Phenolic Compounds from Agro-Industrial By-Products Using Natural Deep Eutectic Solvents: A Review of Green and Advanced Techniques
by Fernanda de Sousa Bezerra and Maria Gabriela Bello Koblitz
Separations 2025, 12(6), 150; https://doi.org/10.3390/separations12060150 - 3 Jun 2025
Cited by 1 | Viewed by 676
Abstract
As sustainability gains prominence, the circular economy has encouraged the valorization of agri-food by-products, which are rich in phenolic compounds known for their antioxidant and anti-inflammatory properties. Conventional extraction methods commonly employ organic solvents, which contradict green chemistry principles. Natural deep eutectic solvents [...] Read more.
As sustainability gains prominence, the circular economy has encouraged the valorization of agri-food by-products, which are rich in phenolic compounds known for their antioxidant and anti-inflammatory properties. Conventional extraction methods commonly employ organic solvents, which contradict green chemistry principles. Natural deep eutectic solvents (NaDESs) have emerged as environmentally friendly alternatives for recovering bioactive compounds from food waste. This review investigated recent studies (2020–2024) on ultrasound (UAE), microwave (MAE), and pressurized liquid extraction (PLE) using NaDESs to extract phenolic compounds from agri-food by-products. A total of 116 publications were initially identified, of which 19 met the inclusion criteria. UAE combined with NaDESs proved effective, particularly for fruit and oilseed residues. MAE achieved good yields for phenolic acids and flavonoids but showed limitations on high temperatures. PLE, though less explored, demonstrated promising results when optimized for temperature, pressure, and NaDES composition. The combination of NaDESs with assisted extraction techniques enhanced yield, selectivity, and environmental performance compared to conventional approaches. These findings highlight a greener and more efficient strategy for phenolic recovery within a biorefinery framework. Ultimately, this approach contributes to the sustainable management and valorization of agri-food by-products, supporting circular economy principles and the development of cleaner extraction technologies for functional ingredients. Full article
(This article belongs to the Special Issue Green Extraction Processes to Recover Natural Bioactive Compounds from Food By-Products)
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19 pages, 3970 KiB  
Article
Effect of Vortex Finder Wall Thickness on Internal Flow Field and Classification Performance in a Hydrocyclone
by Zaihai Wu, Zhitao Liang, Peiyang Li, Feng Li and Huanbo Yang
Separations 2025, 12(6), 149; https://doi.org/10.3390/separations12060149 - 3 Jun 2025
Viewed by 364
Abstract
The hydrocyclone generally exhibits limited separation efficiency and classification sharpness. As the discharge channel for fine particles, the vortex finder plays a critical role in influencing the classification performance through its structural parameters. However, the influence of vortex finder wall thickness on fly [...] Read more.
The hydrocyclone generally exhibits limited separation efficiency and classification sharpness. As the discharge channel for fine particles, the vortex finder plays a critical role in influencing the classification performance through its structural parameters. However, the influence of vortex finder wall thickness on fly ash classification within the hydrocyclone has not yet been reported. In this study, computational fluid dynamics (CFDs) were employed to investigate the variations in pressure field, velocity field, and separation efficiency with respect to changes in vortex finder wall thickness. The results indicate that the radial velocity increases with vortex finder wall thickness, which facilitates the rapid formation of a particle-size stratification, thereby reducing the number of misclassified particles. The cut size initially decreases and then increases as the wall thickness of the vortex finder increases. A minimum cut size of 17.2 µm was observed when the wall thickness reached 10 mm. The classification sharpness improves progressively with increasing wall thickness. At a wall thickness of 15 mm, the steepness index reaches 0.68. Experimental results demonstrate that a thick-walled vortex finder structure can significantly enhance the classification sharpness of the hydrocyclone. Specifically, the content of −19 µm particles in the underflow decreased by 32.17% when the vortex finder wall thickness increased from 5 mm to 15 mm. Meanwhile, the proportion of −19 µm particles in the overflow increased by 12.72%. Therefore, employing a thick-walled vortex finder structure can not only enhance the cut size precision but also effectively improve the classification performance of the hydrocyclone. Full article
(This article belongs to the Topic Advances in Separation Engineering)
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20 pages, 2180 KiB  
Article
Effective Liquid–Liquid Extraction for the Recovery of Grape Pomace Polyphenols from Natural Deep Eutectic Solvents (NaDES)
by Alessandro Frontini, Giulio Tarentini, Carmine Negro, Andrea Luvisi, Massimiliano Apollonio and Luigi De Bellis
Separations 2025, 12(6), 148; https://doi.org/10.3390/separations12060148 - 2 Jun 2025
Viewed by 508
Abstract
Natural deep eutectic solvents (NaDESs) are emerging solvents for their yield when used for extraction of different molecules, including polyphenols. NaDESs are a cutting-edge technology that offers numerous advantages, including cheap cost, safety, effectiveness and environmental friendliness. However, due to NaDES’ high boiling [...] Read more.
Natural deep eutectic solvents (NaDESs) are emerging solvents for their yield when used for extraction of different molecules, including polyphenols. NaDESs are a cutting-edge technology that offers numerous advantages, including cheap cost, safety, effectiveness and environmental friendliness. However, due to NaDES’ high boiling point, the recovery and separation of compounds after the extraction is the bottleneck of the process. In this work, two affordable methods were tested for the recovery of phenolic compounds from three binary NaDESs (composed of choline chloride mixed separately with lactic acid, tartaric acid or glycerol as hydrogen bond donors): the antisolvent and the liquid–liquid extraction methods. The former was assessed by diluting the extracts with different aliquots of water, employed as antisolvent, which was ineffective. For the liquid–liquid extraction method, ethyl acetate (EtOAc), acetonitrile (ACN), 2-chlorobutane (2-CB) and 2-methyltetrahydrofuran (2-MeTHF) were compared. Except for ACN, all solvents were perfectly immiscible with the three NaDESs, forming biphasic systems that were analyzed by colorimetric assays and HPLC/MS. 2-MeTHF applied on a 10-fold water dilution of the NaDES extract reached recovery percentages higher than 90% for most of the non-anthocyanin phenols and good recovery (up to 80%) for some anthocyanins. 2-MeTHF appears to be the first known solvent capable of extracting anthocyanins from NaDESs. Finally, a two-step liquid–liquid extraction performed firstly with EtOAc and subsequently with 2-MeTHF is proposed for the separation of different phenolic fractions. Full article
(This article belongs to the Special Issue Novel Green Solvents for the Separation and Purification of Valuable Natural Ingredients)
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23 pages, 5238 KiB  
Article
A Self-Consistent, High-Fidelity Adsorption Model for Chromatographic Process Predictions: Low-to-High Load Density and Charge Variants in a Preparative Cation Exchanger
by Gregor M. Essert, Marko Tesanovic, Sonja Berensmeier, Isabell Hagemann and Peter Schwan
Separations 2025, 12(6), 147; https://doi.org/10.3390/separations12060147 - 1 Jun 2025
Viewed by 496
Abstract
The development of ion exchange chromatography to polish biopharmaceuticals requires extensive experimental benchmarking. As part of the Design of Experiments (DoE), statistical models increased efficiency somewhat and are still state of the art; however, the capability to predict process conditions is limited due [...] Read more.
The development of ion exchange chromatography to polish biopharmaceuticals requires extensive experimental benchmarking. As part of the Design of Experiments (DoE), statistical models increased efficiency somewhat and are still state of the art; however, the capability to predict process conditions is limited due to their nature as interpolating models. Applying the DoE still requires numerous experiments and is constrained to the design space, posing a risk of missing the potential optimum. To make a leap in model-based process development, applying extrapolating models can tremendously extend the design space and also allow for process understanding and knowledge transfer. While existing chromatography modeling software explains experimental data, it often lacks predictive power for new conditions. In academic–industrial cooperation, we demonstrate a new high-fidelity model based on biophysics for developing ion-exchange chromatography in biomanufacturing, making it a general tool in rationalizing process development for the present demand of recombinant proteins and monoclonal antibodies and the emerging demand of new modalities. Using the new computational tool, we achieved predictability and attained high accuracy; with minimal experimental effort to calibrate the system, the mathematical model predicted sensitive process conditions, and even described product-related impurities, antibody charge variants. Thus, the computational tool can be deployed for process-by-design and material-by-design approaches. Full article
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18 pages, 3582 KiB  
Article
Insights into the Adsorptive Separation of Ethylene/Ethane in LTA-Type Zeolites
by Xiaohui Zhao, Shixue Zhou, Magdy Abdelghany Elsayed, Zhongyuan Chen, Chunhui Jiang, Yongli Hu and Gumawa Windu Manggada
Separations 2025, 12(6), 146; https://doi.org/10.3390/separations12060146 - 1 Jun 2025
Viewed by 379
Abstract
Understanding the competitive adsorption mechanism is essential for the development of adsorptive separation of ethylene (C2H4) and ethane (C2H6). In this work, density functional theory calculations and molecular dynamics simulations were employed to investigate the [...] Read more.
Understanding the competitive adsorption mechanism is essential for the development of adsorptive separation of ethylene (C2H4) and ethane (C2H6). In this work, density functional theory calculations and molecular dynamics simulations were employed to investigate the adsorption of C2H4 and C2H6 in two LTA-type zeolites, ITQ-29 and 5A. The results show that the adsorption energies of the gas molecules in zeolite 5A are more negative than in ITQ-29, and the difference in adsorption energy between C2H4 and C2H6 in zeolite 5A is significantly larger than in ITQ-29, 13.3 versus 6.2 kJ/mol. Zeolite ITQ-29 demonstrates high C2H4/C2H6 ideal selectivity (43.5 at 5 ns) while exhibiting slow C2H4 uptake efficiency due to the small pore windows, hindering C2H4 diffusion (1.05 × 10−10 m2/s at 298 K). In contrast, zeolite 5A facilitates the faster diffusion of C2H4 molecules (3.25 × 10−9 m2/s at 298 K) and exhibits a modest C2H4/C2H6 selectivity of 1.11 at 5 ns in single-gas adsorption and 2.72 in equimolar binary mixture adsorption. To enhance C2H4/C2H6 selectivity, methyl phosphonic acid is introduced onto zeolite 5A to add a sieving layer that enables the C2H4 molecules to preferentially permeate, and the optimal coverage of methyl phosphonic acid is 50%, yielding a C2H4/C2H6 selectivity of 17.5 at 5 ns in mixture adsorption and preserving the C2H4 uptake efficiency. The insights into the competitive diffusion of molecules in the coating layer and inside the zeolites provide a theoretical basis for the rational design of high-performance adsorbents. Full article
(This article belongs to the Topic Oil, Gas and Water Separation Research)
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15 pages, 715 KiB  
Article
Essential Oils as Nature’s Dual Powerhouses for Agroindustry and Medicine: Volatile Composition and Bioactivities—Antioxidant, Antimicrobial, and Cytotoxic
by Javier Rocha-Pimienta, Javier Espino, Sara Martillanes and Jonathan Delgado-Adámez
Separations 2025, 12(6), 145; https://doi.org/10.3390/separations12060145 - 1 Jun 2025
Viewed by 416
Abstract
Essential oils (EOs), which are complex mixtures of plant-derived volatile compounds, have been utilized for centuries in the medical, food, and pharmaceutical industries because of their diverse biological properties. In recent years, there has been growing interest in elucidating the bioactivities of essential [...] Read more.
Essential oils (EOs), which are complex mixtures of plant-derived volatile compounds, have been utilized for centuries in the medical, food, and pharmaceutical industries because of their diverse biological properties. In recent years, there has been growing interest in elucidating the bioactivities of essential oils and their underlying mechanisms of action. This study aimed to investigate the antioxidant, antimicrobial, and cytotoxic characteristics of Laurus nobilis, Eucalyptus camaldulensis, Rosmarinus officinalis, and Mentha suaveolens oils and relate them to their volatile compound content. The volatile compounds of the essential oils were characterized and quantified by gas chromatography, the antioxidant activity was quantified using the ABTS assay, the antibacterial activity was quantified using broth microdilution and agar diffusion techniques, and the MTT assay was used to establish the cytotoxic potential. This study revealed a significant antioxidant capacity, which correlated with the proportion of terpenes known for their antioxidant properties. The antioxidant potency was ranked in descending order: R. officinalis, M. suaveolens, E. camaldulensis, and L. nobilis. Antimicrobial testing demonstrated that all the examined essential oils were effective against the evaluated microbial species, including both Gram-positive (Listeria innocua) and Gram-negative (Escherichia coli) bacteria. Additionally, all the tested essential oils triggered cell death in the human epithelioid cervical carcinoma (HeLa) cell line. Collectively, this article highlights the promising therapeutic and alimentary potential of essential oils and underscores the need for further research to fully harness their benefits in industrial settings. Full article
(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)
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16 pages, 2258 KiB  
Review
Adsorption and Absorption Techniques for the Separation of Gaseous C2–C5 Olefins
by Fengxiang Guo, Chao Sun, Mo Xian and Huibin Zou
Separations 2025, 12(6), 144; https://doi.org/10.3390/separations12060144 - 1 Jun 2025
Viewed by 603
Abstract
Volatile C2–C5 olefins are important bulk chemicals in the polymer industry. Traditionally, C2–C5 olefins are produced from cracked petroleum resources using an energy-consuming and hazardous distillation method. Currently, volatile olefins can be produced from renewable biomass. To obtain polymer-grade volatile olefins from diversified [...] Read more.
Volatile C2–C5 olefins are important bulk chemicals in the polymer industry. Traditionally, C2–C5 olefins are produced from cracked petroleum resources using an energy-consuming and hazardous distillation method. Currently, volatile olefins can be produced from renewable biomass. To obtain polymer-grade volatile olefins from diversified resources, more sustainable and feasible separation techniques need to be developed. This review focuses on two updated separation techniques for C2–C5 olefins: (a) adsorption separation, which separates olefins through porous affinity, the pi complexation effect, and size-exclusion and gate-opening sieving, and (b) liquid absorption separation, which utilizes either organic solvents or ionic liquids for olefin separation. In this review, different separation techniques are compared in terms of their mechanisms and operation conditions in the separation of different types of C2–C5 olefins from variable resources, such as cracked ethylene/propylene/butylene/isoprene and bio-isoprene. Full article
(This article belongs to the Topic Advances in Separation Engineering)
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11 pages, 1644 KiB  
Article
Analysis on the Main Components of Selenium-Enriched Premna microphylla Leaves and Processed Tofu
by Jianan Wang, Chunli Chen, Fangjie Mou, Bin Wang and Jingzhou Dong
Separations 2025, 12(6), 143; https://doi.org/10.3390/separations12060143 - 28 May 2025
Viewed by 274
Abstract
Premna microphylla is a medicinal plant species distributed in Southeast Asia and China. P. microphylla leaves have been widely used for processing edible gels called Chai tofu, which have many medicinal values, such as clearing heat and detoxifying. However, the main functional components [...] Read more.
Premna microphylla is a medicinal plant species distributed in Southeast Asia and China. P. microphylla leaves have been widely used for processing edible gels called Chai tofu, which have many medicinal values, such as clearing heat and detoxifying. However, the main functional components of P. microphylla leaves and Chai tofu are still unknown. In this study, selenium-enriched cultivation of P. microphylla was conducted, and the main compositions of pectins, flavonoids, total phenolics, carotenoids, chlorophylls, and proteins were separated and comparatively analyzed. The results are that kaempferol was the main composition of flavonoids, with the average contents of 5.19% DW (dried weight) in leaves and 3.83% DW in Chai tofu; the composition of the Chai tofu pectin included glucose, fructose, and mannose. Contents of phenolics, kaempferol, chlorophyll, and carotenoids were significantly increased by the selenium enrichment cultivation in a concentration-dependent manner (R2 = 0.989, 0.994, 0.94, 0.948). Moreover, selenium enrichment produced selenized pectins with Se-O bonds. Selenium-enriched P. microphylla is an important plant source for functional foods. Related processing and extraction techniques deserve further research. Full article
(This article belongs to the Topic Advances in Analysis of Food and Beverages, 2nd Edition)
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13 pages, 1875 KiB  
Article
Development and Validation of a Method for the Analysis of Multiple Pesticides in Fishery Products Using Gas Chromatography with Micro-Electron Capture Detection and Gas Chromatography–Tandem Mass Spectrometry
by Myungheon Kim, Mihyun Cho, Changkyo Seo, Jaebin Im, Changhyeon Park, Yoonmi Lee, Mi-Ra Jo, Yong-Sun Moon and Moo-Hyeog Im
Separations 2025, 12(6), 142; https://doi.org/10.3390/separations12060142 - 28 May 2025
Viewed by 292
Abstract
This study aims to develop a simultaneous analytical method for detecting 19 pesticides, including 4,4′-DDD, in fishery products using gas chromatography with micro-electron capture detection (GC-μECD) and gas chromatography–tandem mass spectrometry (GC-MS/MS). A new analytical method was developed to measure pesticide residues in [...] Read more.
This study aims to develop a simultaneous analytical method for detecting 19 pesticides, including 4,4′-DDD, in fishery products using gas chromatography with micro-electron capture detection (GC-μECD) and gas chromatography–tandem mass spectrometry (GC-MS/MS). A new analytical method was developed to measure pesticide residues in fishery products based on the modified Association of Official Analytical Chemists protocol combining quick, easy, cheap, effective, rugged, and safe (QuEChERS) and the Pesticide Analytical Manual for extraction and purification. Extraction was performed using acetonitrile containing 0.1% acetic acid, and purification was conducted with Florisil cartridges. The Florisil cartridges were more effective than QuEChERS in removing impurities and pigments during purification and also resulted in a reduced matrix effect. The validation followed Codex guidelines (CAC/GL 40). The limit of detection ranged from 2 to 3 ng/g, and the limit of quantification (LOQ) from 7 to 10 ng/g. Matrix-matched calibration curves exhibited linearity with coefficients of determination exceeding 0.99 for all target analytes. Accuracy was assessed based on recovery rates, while precision was evaluated using relative standard deviations (RSD) at three spiking levels (LOQ, 10×LOQ, and 50×LOQ). The recovery rates ranged from 62.6 to 119.1%, with RSDs of 0.4 to 19.5%, conforming to Codex guidelines. Full article
(This article belongs to the Special Issue Chemical and Contaminant Residue Analysis via Chromatography)
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14 pages, 1702 KiB  
Article
The Development and Validation of a High-Performance Liquid Chromatographic Method for the Determination of Urinary Levels of Etoricoxib After Fabric Phase Sorptive Extraction
by Anastasia Korpeti, Natalia Manousi, Abuzar Kabir, Constantinos K. Zacharis and Erwin Rosenberg
Separations 2025, 12(6), 141; https://doi.org/10.3390/separations12060141 - 27 May 2025
Viewed by 407
Abstract
Herein, a simple and effective analytical method was developed to monitor etoricoxib concentrations in human urine samples. Etoricoxib is a nonsteroidal anti-inflammatory drug for pain and inflammation relief in conditions such as osteoarthritis and rheumatoid arthritis. To determine its concentration, fabric phase sorptive [...] Read more.
Herein, a simple and effective analytical method was developed to monitor etoricoxib concentrations in human urine samples. Etoricoxib is a nonsteroidal anti-inflammatory drug for pain and inflammation relief in conditions such as osteoarthritis and rheumatoid arthritis. To determine its concentration, fabric phase sorptive extraction (FPSE) was combined with high-performance liquid chromatography and diode array detection (HPLC-DAD). FPSE is a green sample preparation technique that utilizes sol–gel-coated fabric substrates as extraction devices, offering numerous benefits in bioanalysis. Initially, different materials were tested for their affinity towards etoricoxib. The most critical FPSE parameters (i.e., sample amount, stirring rate, and adsorption time) were optimized using a face-centered central composite design (FC-CCD), while the remaining ones were explored by means of the one-variable-at-a-time approach. Afterwards, the analytical method was validated in terms of its selectivity, linearity, sensitivity, accuracy, and precision, while the environmental sustainability and the practicality of the method were also examined. The limit of detection was 0.03 μg mL−1, and the lower limit of quantification was 0.10 μg mL−1. The relative standard deviation was less than 7.2% in all cases, showing good precision. The proposed approach was successfully used to monitor urinary etoricoxib concentrations in real samples obtained from a volunteer after oral drug administration. Full article
(This article belongs to the Section Chromatographic Separations)
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15 pages, 3216 KiB  
Article
Multi-Template Molecularly Imprinted Polymers Coupled with a Solid-Phase Extraction System in the Selective Determination of Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) in Environmental Water Samples
by David Aurelio-Soria, Giaan A. Alvarez-Romero, Maria E. Paez-Hernandez, I. Perez-Silva, Miriam Franco-Guzman, Gabriela Islas and Israel S. Ibarra
Separations 2025, 12(6), 140; https://doi.org/10.3390/separations12060140 - 25 May 2025
Viewed by 407
Abstract
A simple, fast, and low-cost pre-concentration methodology based on the application of multi-template molecularly imprinted polymers (mt-MIP) in a solid-phase extraction system coupled with capillary electrophoresis was developed for the determination of naproxen, diclofenac, and ibuprofen in environmental water samples. A systematic study [...] Read more.
A simple, fast, and low-cost pre-concentration methodology based on the application of multi-template molecularly imprinted polymers (mt-MIP) in a solid-phase extraction system coupled with capillary electrophoresis was developed for the determination of naproxen, diclofenac, and ibuprofen in environmental water samples. A systematic study of the mt-MIP composition was conducted using a second-order simplex lattice experiment design (fraction of the functional monomer methacrylic acid (MAA), the total moles of functional monomers, and the total moles of the cross-linker agent). The optimal mt-MIP, consisting of 0.025 mmol of each analyte, with 2.40 mmol of methacrylic acid (MAA) and 3.60 mmol of 4-vinylpyridine (4VP) and 23.00 mmol of the cross-linker agent (EGDMA), was coupled to an SPE system under the optimal conditions: pH = 3.5; 20 mg of mt-MIP; and an eluent (MeOH/NaOH [0.001]). This methodology provides limits of detection from 3.00 to 12.00 µg L−1 for the studied NSAIDs. The methodology’s precision was evaluated in terms of inter- and intra-day repeatability, with %RSD < 10% in all cases. Finally, the proposed method can be successfully applied in the analysis of environmental water samples (bottle, tap, cistern, well, and river water samples), which demonstrates the developed method’s robustness. Full article
(This article belongs to the Section Materials in Separation Science)
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18 pages, 1505 KiB  
Article
An Optimized Pathway for Nitrate Removal from Aqueous Solution by Environmentally Friendly Calabash Gourd Shell Adsorbent Based on Experimental Design Methodology
by Goran S. Nikolić, Nataša Simonović, Miloš Durmišević, Nada Nikolić, Dragana Marković Nikolić, Milena Nikolić, Grozdanka Bogdanović and Aleksandar Bojić
Separations 2025, 12(6), 139; https://doi.org/10.3390/separations12060139 - 23 May 2025
Viewed by 348
Abstract
The aim of this research is to optimize the process parameters for nitrate adsorption from aqueous solutions using ammonium modified calabash gourd shell (CGS). Two types of experimental design (DoE) methodology were implemented in the optimization. A full factorial design (FFD) assessed the [...] Read more.
The aim of this research is to optimize the process parameters for nitrate adsorption from aqueous solutions using ammonium modified calabash gourd shell (CGS). Two types of experimental design (DoE) methodology were implemented in the optimization. A full factorial design (FFD) assessed the influence of the main factors on the process response. The efficiency of nitrate adsorption at the predicted optimal conditions by FFD was 78.93%. The study was extended to a central composite design (CCD) within the response surface methodology (RSM) to capture the factors nonlinear effects and optimize the adsorption parameters. The quadratic polynomial model using CCD proved to be useful for understanding the adsorption system’s behavior, locating the optimal process factors, and predicting the adsorption efficiency (R2 > 0.95). The significance of the model terms (A, B, C, D, B2, and C2) is confirmed by F = 74.95 and p < 0.0001. According to the CCD, the optimal adsorption conditions were estimated in the range: initial nitrate concentration 10–20 mg/L, pH 6–7, temperature 20–25 °C, and contact time 25–30 min (desirability 0.996). The predicted and obtained values using FFD and CCD models are very close, which confirms their practical applicability. The repeated test found the nitrate adsorption efficiency (84.9%) using CCD model in the predicted range (80.1–89.6%), which confirms the adequacy and significance of the model. This model could find potential application in real processes for the treatment of nitrate-contaminated water using the environmentally friendly CGS cationic adsorbent. Full article
(This article belongs to the Special Issue Adsorption/Degradation Methods for Water and Wastewater Treatment)
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Article
Rapid Two-Step Isolation of Kaempferol from the Hosta plantaginea Flower and Its Anti-Inflammatory Mechanism: Evidence from Network Pharmacology, Molecular Docking, Molecular Dynamics Simulation, and Experimental Validation
by Yating Yang, Bowei Xia, Huan Ouyang, Junyu Guo, Qingya Hu, Li Yang and Junwei He
Separations 2025, 12(6), 138; https://doi.org/10.3390/separations12060138 - 23 May 2025
Viewed by 331
Abstract
The rapid isolation of target constituents from natural products poses a significant challenge and is a key focus in current research. The Hosta plantaginea flower (HPF), a traditional Chinese medicinal herb, is primarily used to treat inflammatory diseases, with kaempferol as one of [...] Read more.
The rapid isolation of target constituents from natural products poses a significant challenge and is a key focus in current research. The Hosta plantaginea flower (HPF), a traditional Chinese medicinal herb, is primarily used to treat inflammatory diseases, with kaempferol as one of its major bioactive constituents. In this study, macroporous adsorption resin was used to purify total flavonoids (TF) from the HPFs. The 50% ethanol–water elution fraction of the TF was then recrystallized to yield kaempferol with a purity of 99.44%. Network pharmacology analysis identified 61 potential kaempferol-inflammation targets, which were linked to the PI3K-Akt and TNF signaling pathways. Molecular docking and molecular dynamics simulations revealed the stability and binding of kaempferol to PI3K, Akt, and TNF-α proteins. The analysis metrics included binding ability, the root mean square deviation (RMSD), radius of gyration, free energy landscape, solvent-accessible surface area, hydrogen bond count, RMS fluctuation, free binding energy, amino acid residue free energy decomposition, and principal component analysis. The anti-inflammatory mechanism of kaempferol was further validated in an LPS-induced RAW264.7 cell model, where it was shown to inhibit the PI3K-Akt and TNF-α signaling pathways. This study provides new insights into the anti-inflammatory mechanism of kaempferol and presents novel strategies for the rapid isolation of target constituents from natural products. Full article
(This article belongs to the Special Issue Green Extraction of Natural Products for Application in Pharmaceuticals, Foods, Cosmetics and Agriculture)
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