Separations

15 pages, 1691 KiB

Open AccessArticle

Thermodynamic Characteristics of the Ion-Exchange Process Involving REMs of the Light Group

by Olga V. Cheremisina, Maria A. Ponomareva, Yulia A. Mashukova, Nina A. Nasonova and Maria D. Burtseva

Separations 2025, 12(7), 177; https://doi.org/10.3390/separations12070177 - 4 Jul 2025

Abstract

Rare earth metals (REMs) are vital for high-tech industries, but their extraction from secondary sources is challenging due to environmental and technical constraints. This study investigates the ion-exchange extraction of light REMs (neodymium, praseodymium, and samarium) from sulfuric and phosphoric acid solutions, modeling [...] Read more.

Rare earth metals (REMs) are vital for high-tech industries, but their extraction from secondary sources is challenging due to environmental and technical constraints. This study investigates the ion-exchange extraction of light REMs (neodymium, praseodymium, and samarium) from sulfuric and phosphoric acid solutions, modeling industrial leachates from apatite concentrates and phosphogypsum. The study considers the use of anion- and cation-exchange resins with different functional groups for efficient and environmentally safe REM separation. Experimental sorption isotherms were obtained under static conditions at 298 K and analyzed using a thermodynamic model based on the linearization of the mass action equation. Equilibrium constants and Gibbs energy were calculated, which reveals the spontaneity of the processes. Cation-exchange resins demonstrated high selectivity towards individual REMs, while anion-exchange resins were suitable for group extraction. Infrared spectral analysis confirmed the presence of sulfate and phosphate complexes in the resin matrix, clarifying the ion-exchange mechanisms. Thermal effect measurements indicated exothermic sorption on anion-exchange resins with negative entropy and endothermic sorption on cation-exchange resins with positive entropy. The findings highlight the potential of ion-exchange resins for selective and sustainable REM recovery, offering a safer alternative to liquid extraction and enabling the valorization of industrial wastes like phosphogypsum for resource recovery. Full article

(This article belongs to the Special Issue Recent Advances in Rare Earth Separation and Extraction)

18 pages, 605 KiB

Open AccessArticle

Validation of a Method for the Determination of Artificial Sweeteners and Caffeine in Soft Drinks: The Impact of Regression Function Selection on Quantification Limits Considering Trueness and Precision

by Natàlia Hernández and Juan M. Sanchez

Separations 2025, 12(7), 176; https://doi.org/10.3390/separations12070176 - 2 Jul 2025

Abstract

Background: Method quantification limits are typically determined by measuring variability at blank level only, without accounting for the uncertainties associated with the parameters of the calibration function applied. Methods: A method for the determination of artificial sweeteners and caffeine in soft drinks was [...] Read more.

Background: Method quantification limits are typically determined by measuring variability at blank level only, without accounting for the uncertainties associated with the parameters of the calibration function applied. Methods: A method for the determination of artificial sweeteners and caffeine in soft drinks was validated. The effect of chosen regression function on quantification limits was assessed, considering both trueness and precision. Results: The validated method exhibited heteroscedasticity for all analytes, which is common in experimental methods. A linear response was observed within the working range for sweeteners, while a quadratic regression was required for caffeine. Due to the heteroscedasticity nature of the responses, weighted regressions were necessary to obtain the lowest method quantification limits, allowing for accurate (i.e., unbiased and precise) estimates at the lower end of the calibration range. Under weighted conditions, the regression equations obtained, with an upper range set at 600 mg·L⁻¹, were as follows: y = 3.9 + 58.9x for acesulfame K; y = 0.8 + 185.1x for saccharin; y = 3.5 + 43.3x for aspartame, and y = −7 + 159x − 0.242x² for caffeine. The method quantification limits determined using weighted regressions were 2 mg·L⁻¹ for each analyte, whereas these limits increased to 20 mg·L⁻¹ when non-weighted regressions were applied. Conclusions: The choice of regression function for transforming instrumental signals into analyte concentrations significantly affects the determination of quantification limits, owing to the inherent heteroscedasticity of analytical and bioanalytical calibrations. Weighted regressions are essential for producing accurate estimates at lower concentration levels. Applying weighted regression in the context of heteroscedastic calibrations can lead to quantification limits that are more than 10 times lower than unweighted approaches. Full article

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13 pages, 988 KiB

Open AccessArticle

Extraction, Isolation, and Purification of Furanocoumarins from Invasive Heracleum sosnowskyi

by Vida Vickackaite, Karina Pilaityte and Vilius Poskus

Separations 2025, 12(7), 175; https://doi.org/10.3390/separations12070175 - 1 Jul 2025

Abstract

Heracleum sosnowskyi Manden. (Sosnowsky’s hogweed), originally introduced to Central and Eastern Europe as a fodder crop, has become a highly invasive species due to its ecological adaptability, high reproductive capacity, and efficient seed dispersal. Despite its negative impact on native flora and its [...] Read more.

Heracleum sosnowskyi Manden. (Sosnowsky’s hogweed), originally introduced to Central and Eastern Europe as a fodder crop, has become a highly invasive species due to its ecological adaptability, high reproductive capacity, and efficient seed dispersal. Despite its negative impact on native flora and its health risks to humans and animals, the species also represents a valuable source of biologically active compounds. In this study, we demonstrate that the leaves of H. sosnowskyi contain substantial amounts of furanocoumarins—phototoxic compounds with notable therapeutic potential, particularly as natural photosensitizers in anticancer therapies. To extract furanocoumarins from H. sosnowskyi, microwave-assisted extraction (MAE) was employed, with optimization of key parameters including extraction solvent (hexane), temperature (70 °C), extraction time (10 min), and solvent-to-solid ratio (20:1). Four major compounds—angelicin (2.3 mg/g), psoralen (0.15 mg/g), methoxsalen (0.76 mg/g), and bergapten (3.14 mg/g)—were identified and quantified using gas chromatography–mass spectrometry and gas chromatography with flame ionization detection. To purify the extract and selectively isolate the target compounds, a solid-phase extraction method was developed using a Strata Eco-Screen sorbent and stepwise elution with a hexane–acetone mixture. As a result, pure angelicin, pure methoxsalen, and various mixtures of the furanocoumarins were obtained. These findings highlight the potential of H. sosnowskyi as a sustainable source of furanocoumarins for pharmaceutical applications. Full article

(This article belongs to the Special Issue Sample Preparation and Chromatographic Analysis of Environmental Samples)

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15 pages, 2034 KiB

Open AccessArticle

Heterogeneous Interactions During Bubble–Oil Droplet Contact in Water

by Tao Yang, Hao Xiao, Chunyu Jiang, Ming Ma, Guangwen Zhang, Chun Wang, Yi Zheng and Xiangdi Zhao

Separations 2025, 12(7), 174; https://doi.org/10.3390/separations12070174 - 29 Jun 2025

Abstract

Oily wastewater is extensively generated during the petroleum extraction and refining processes, as crude oil production water and from the effluent systems in petrochemical enterprises. The discharge standards for such wastewater are stringent, with the Oslo–Paris Convention stipulating that the oil content must [...] Read more.

Oily wastewater is extensively generated during the petroleum extraction and refining processes, as crude oil production water and from the effluent systems in petrochemical enterprises. The discharge standards for such wastewater are stringent, with the Oslo–Paris Convention stipulating that the oil content must be below 30 mg/L for permissible discharge. Flotation, a conventional oil–water separation method, relies on the collision and adhesion of rising bubbles with oil droplets in water to form low-density aggregates that float to the surface for separation. The collision and adhesion mechanisms between bubbles and oil droplets are fundamental to this process. However, systematic studies on their interactions remain scarce. This study employs the extended Derjaguin–Landau–Verwey–Overbeek theory to analyze the three mechanical interactions during the collision–adhesion process theoretically and investigates the heterogeneous interaction dynamics experimentally. Furthermore, given the diverse liquid-phase environments of oily wastewater, the effects of salinity, pH, and surfactant concentration are decoupled and individually explored to clarify their underlying mechanisms. Finally, a solution is proposed to enhance the flotation efficiency fundamentally. This work systematically elucidates the influence of liquid-phase environments on the adhesion behavior for the first time through the unification of theoretical and experimental approaches. The findings provide critical insights for advancing flotation theory and guiding the development of novel coagulants. Full article

(This article belongs to the Section Separation Engineering)

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13 pages, 1017 KiB

Open AccessArticle

Separation of Exhaust Gas Pollutants from Urea Prilling Process with Gasified Biochar for Slow-Release Fertilizer: Adsorption Characteristics, Process Improvement, and Economic Assessment

by Tong Lou, Bingtao Zhao, Zixuan Zhang, Mengqi Wang, Yanli Mao, Baoming Chen, Xinwei Guo, Tuo Zhou and Fengcui Li

Separations 2025, 12(7), 173; https://doi.org/10.3390/separations12070173 - 29 Jun 2025

Abstract

To address severe ammonia gas and dust pollution coupled with resource waste in exhaust gases from urea prilling towers, a production process for gasified biochar-based slow-release fertilizer is proposed to achieve resource recovery of exhaust pollutants. Through phosphoric acid impregnation modification applied to [...] Read more.

To address severe ammonia gas and dust pollution coupled with resource waste in exhaust gases from urea prilling towers, a production process for gasified biochar-based slow-release fertilizer is proposed to achieve resource recovery of exhaust pollutants. Through phosphoric acid impregnation modification applied to gasified biochar, its ammonia gas adsorption capacity was significantly enhanced, with saturated adsorption capacity increasing from 0.61 mg/g (unmodified) to 32 mg/g. Coupled with the tower-top bag filter, the modified biochar combines with ammonia gas and urea dust in exhaust gases, subsequently forming biochar-based slow-release fertilizer through dehydration and granulation processes. Material balance analysis demonstrates that a single 400,000-ton/year urea prilling tower achieves a daily fertilizer production capacity of 55 tons, with 18% active ingredient content. The nitrogen content can be upgraded to national standards through urea supplementation. Economic analysis demonstrates a total capital investment of USD1.2 million, with an annual net profit of USD0.88 million and a static payback period of 1.36 years. This process not only achieves ammonia gas emission reduction but also converts waste biochar into high-value fertilizer. It displays dual advantages of environmental benefits and economic feasibility and provides an innovative solution for resource utilization of the exhaust gases from the urea prilling process. Full article

(This article belongs to the Section Environmental Separations)

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22 pages, 4877 KiB

Open AccessArticle

Sponge-like Modified White-Rot Fungi Adsorbent for Rapid Removal of Pb(II) and Cd(II) from Solution: Selective Performance and Mechanistic Insights

by Chunxiao Wang, Zhirong Chen, Nana Wang, Jianqiao Wang, Runshen He, Yu Chen, Haerfosai Nuhu, Hang Chen, Zhixuan Lin, Minqi Fan and Mingdong Chang

Separations 2025, 12(7), 172; https://doi.org/10.3390/separations12070172 - 28 Jun 2025

Abstract

Heavy metal pollution, especially from Pb(II) and Cd(II), poses significant risks due to its persistence and bioaccumulation potential. Traditional removal methods face challenges like high costs and secondary pollution. This study developed a novel three-dimensional porous adsorbent XBS, derived from xanthate-modified Phanerochaete sordida [...] Read more.

Heavy metal pollution, especially from Pb(II) and Cd(II), poses significant risks due to its persistence and bioaccumulation potential. Traditional removal methods face challenges like high costs and secondary pollution. This study developed a novel three-dimensional porous adsorbent XBS, derived from xanthate-modified Phanerochaete sordida YK-624 (a white-rot fungus), for the rapid and efficient removal of Pb(II) and Cd(II) from wastewater. Characterization showed that XBS has a sponge-like structure with abundant functional groups, significantly enhancing its adsorption capacity and kinetics. XBS achieved 96% Pb(II) and 32% Cd(II) removal within 1 min at a 0.25 g/L dose, reaching over 95% of the maximum adsorption capacity within 30 min for Pb(II) and 240 min for Cd(II). The maximum capacities were 224.72 mg/g for Pb(II) and 82.99 mg/g for Cd(II). Kinetic and thermodynamic analyses indicated a chemisorption-driven process, which was both endothermic and spontaneous. XBS exhibited high selectivity for Pb(II) over Cd(II) and other metals (Tl(I), Cu(II)), attributed to stronger covalent interactions with sulfur- and nitrogen-containing groups. Mechanistic analyses (XRD, FTIR, and XPS) revealed that removal occurs via ion exchange, complexation, and precipitation, forming stable compounds like PbS/CdS and PbCO₃/CdCO₃. Given its cost-effectiveness, scalability, and high efficiency, XBS represents a promising adsorbent for heavy metal remediation, particularly in Pb(II)-contaminated wastewater treatment applications. Full article

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13 pages, 1434 KiB

Open AccessArticle

Simultaneous Determination of 23 Trans Fatty Acids in Common Edible Oils by Gas Chromatography-Mass Spectrometry

by Yanping Cao, Xia Li, Kun Wang, Xianpeng Wu, Jie Zhang and Fengen Wang

Separations 2025, 12(7), 171; https://doi.org/10.3390/separations12070171 - 28 Jun 2025

Abstract

Trans fatty acids (TFAs) pose significant health risks, including cardiovascular disease and metabolic disorders. However, the lack of high-resolution, high-sensitivity, and high-throughput quantitative methods for TFA analysis has led to fragmented data on TFA content in edible oils, which constrains research on the [...] Read more.

Trans fatty acids (TFAs) pose significant health risks, including cardiovascular disease and metabolic disorders. However, the lack of high-resolution, high-sensitivity, and high-throughput quantitative methods for TFA analysis has led to fragmented data on TFA content in edible oils, which constrains research on the quality assessment of edible oils. In this study, we developed a high-resolution and high-sensitivity gas chromatography-mass spectrometry method to simultaneously determine 23 TFA isomers. The method validation demonstrated good sensitivity, linearity, accuracy, and precision. Based on the proposed method, we analyzed 170 samples of 11 common edible oils, establishing a comprehensive TFA profile for each type. Ruminant fats (beef tallow, mutton tallow, butter) had high TFA levels (0.8–4.8 g/100 g), dominated by vaccenic acid (C18:1 t11) and conjugated linoleic acid, while vegetable oils (soybean, corn, peanut and sesame oil) exhibited lower concentrations (0.5–2.2 g/100 g), especially monounsaturated TFAs. Particularly, soybean oil was rich in C18:3 isomers, while shortening presented the closest similarity to sesame oil. Cluster analysis distinguished oils by TFA composition, highlighting low-TFA clusters (sunflower oil, pork lard, cream). In conclusion, the high-resolution, high-sensitivity, and high-throughput TFA quantification method developed in this study provides technical support for establishing characteristic TFA profiles in edible oils, while offering data support to further quality assessment. Full article

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15 pages, 2912 KiB

Open AccessArticle

Profiling the Differential Distribution of Ginsenosides Across Ginseng Tissues Using High-Resolution Mass Spectrometry

by Hang Xu, Zheng Li, Chong Liu, Yukun Wang, Siwei Qiao and Hao Zhang

Separations 2025, 12(7), 170; https://doi.org/10.3390/separations12070170 - 26 Jun 2025

Abstract

This study investigates the compositional characteristics and quantitative differences of ginsenosides across various ginseng tissues, with a particular focus on the specific accumulation patterns of malonyl ginsenosides. Five tissue samples—ginseng fruit (F), leaf (L), taproot (TR), lateral root (LR), and fibrous root (FR)—were [...] Read more.

This study investigates the compositional characteristics and quantitative differences of ginsenosides across various ginseng tissues, with a particular focus on the specific accumulation patterns of malonyl ginsenosides. Five tissue samples—ginseng fruit (F), leaf (L), taproot (TR), lateral root (LR), and fibrous root (FR)—were analyzed using Orbitrap Fusion high-resolution liquid chromatography–mass spectrometry. A total of 413 ginsenosides, including 33 standards, were identified, encompassing 172 protopanaxadiol (PPD)-type, 188 protopanaxatriol (PPT)-type, 14 oleanolic acid (OA)-type, and 12 ocotillol (OT)-type ginsenosides, of which 160 were malonyl ginsenosides. Statistical analysis revealed significant variations in the relative content per unit mass of malonyl ginsenosides across tissues, with the highest levels in fibrous roots, followed by fruits, lateral roots, leaves, and taproots. Distinct tissue-specific differences in malonyl ginsenoside types and quantities were observed: fruits exhibited 51 malonyl ginsenosides with significantly higher levels, compared to 8, 14, and 17 in lateral roots, fibrous roots, and leaves, whereas TR showed no significant enrichment. This study elucidates the diversity and unique distribution of malonyl ginsenosides in ginseng roots, leaves, and fruits, providing a valuable basis for the targeted selection of tissues with high malonyl ginsenoside content and the development of functional food and medicinal products. Full article

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20 pages, 4330 KiB

Open AccessArticle

Extraction of Terpenoids from Pine Needle Biomass Using Dimethyl Ether

by Gary S. Groenewold, Christopher Orme, Caleb Stetson, Rebecca M. Brown, Lynn M. Wendt and Aaron D. Wilson

Separations 2025, 12(7), 169; https://doi.org/10.3390/separations12070169 - 26 Jun 2025

Abstract

Pine needles are an industrial feedstock for extracts used in a variety of applications, but conventional extraction methods often result in a degradation of the terpenoid compounds that naturally occur in loblolly pine (Pinus taeda). Separation of these compounds from pine [...] Read more.

Pine needles are an industrial feedstock for extracts used in a variety of applications, but conventional extraction methods often result in a degradation of the terpenoid compounds that naturally occur in loblolly pine (Pinus taeda). Separation of these compounds from pine biomass is an energy-intensive operation, typically requiring a significant input of thermal energy. An alternative separation approach with potential energy savings is extraction with a condensable gas, namely, dimethyl ether. Biomass materials are exposed to liquid dimethyl ether under pressure, which mobilizes the organics. The extract is then separated from the insoluble pine matter, and dimethyl ether is volatilized away from the separated organic species. A variety of terpene derivatives were extracted from pine needle biomass using this approach, including monoterpenes, sesquiterpenes, and related oxygenates, which were identified using two-dimensional gas chromatography/mass spectrometry. Additionally, the dimethyl ether-treated needles resemble needles subjected to low-temperature drying, whereas needles treated with a high-temperature drying method appear to have shrunken structures. The results suggest that dimethyl ether extraction has significant potential for separating valuable organics from complex matrices without the application of thermal energy during treatment. 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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11 pages, 1107 KiB

Open AccessArticle

Content Determination and Impurity Profiling of Compound Glycyrrhizin Tablets by Ion-Pair High-Performance Liquid Chromatography, Coupled with Corona-Charged Aerosol Detector

by Limin Zuo, Wenling Su, Yongsheng Gu, Xiaodan Qiu, Ting Zhao, Xiaofang Lian, Huiyi Liu, Qingying Jia, Ruifang Zheng and Guangzhi Shan

Separations 2025, 12(7), 168; https://doi.org/10.3390/separations12070168 - 25 Jun 2025

Abstract

Compound Glycyrrhizin tablets (CGTs) are a combination of glycyrrhizin, glycine and methionine. Glycine and methionine have relatively high polarity and lack chromophore; therefore, it is difficult to simultaneously determine the various components using traditional reversed-phase chromatography and ultraviolet detectors. In addition, it is [...] Read more.

Compound Glycyrrhizin tablets (CGTs) are a combination of glycyrrhizin, glycine and methionine. Glycine and methionine have relatively high polarity and lack chromophore; therefore, it is difficult to simultaneously determine the various components using traditional reversed-phase chromatography and ultraviolet detectors. In addition, it is even more challenging to obtain a comprehensive and systematic impurity profiling for the CGTs. In this study, an ion-pair high-performance liquid chromatography (HPLC)–charged aerosol detection (CAD) method was established to determine the content of glycyrrhizin, glycine and methionine. The impurities of CGTs were also identified using mass spectrometry. By optimizing the content of trifluoroacetic acid (TFA) in the mobile phase and optimizing the CAD parameter settings, the developed method was verified in accordance with the guidelines outlined in ICH Q2 (R2). The results indicated that the method demonstrated high accuracy and sensitivity. Glycine, methionine and glycyrrhizin all showed a good linear relationship within the labeled range of 50–200%, and the average recoveries of the three components were 97.62–100.6%. The impurity detection was quantified via the principal component control method. The limit of detection (LOD) method showed an equivalent to 0.05% of the glycyrrhizin in CGTs, approximately 12.5 ng. The ion-pair HPLC–CAD method developed in this study simultaneously determined the content of the main component and the impurities of CGTs, without necessitating derivatization. This has provided a research basis for further improving the quality standards of CGTs. Full article

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12 pages, 2330 KiB

Open AccessEditor’s ChoiceArticle

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

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 ([N_8,8,8,1][Cl], (Aliquat 336), [P_6,6,6,14][Cl], [P_6,6,6,14][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 ([P_6,6,6,14][Cl] and [P_6,6,6,14][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, [N_10,10,1,1][C₂H₅COO], didecylmethylammonium hydrogen sulphate, [N_10,10,1,H][HSO₄], didecyldimethylammonium dihydrogen phosphate, [N_10,10,1,1][H₂PO₄], and tetrabutylphosphonium dihydrogen phosphate, [P_4,4,4,4][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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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

Open AccessArticle

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

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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27 pages, 1879 KiB

Open AccessReview

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

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

Open AccessArticle

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

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

Open AccessEditor’s ChoiceReview

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

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

Open AccessArticle

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

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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