Separations

27 pages, 3231 KB

Open AccessEditor’s ChoiceReview

Towards Greener Sample Preparation: A Review on Micro-QuEChERS Advances and Applications in Food, Environmental, and Biological Matrices

by Athina Papadopoulou, Vasiliki Boti and Christina Nannou

Separations 2025, 12(12), 339; https://doi.org/10.3390/separations12120339 - 14 Dec 2025

Viewed by 402

Abstract

This review provides a comprehensive evaluation of recent advances in miniaturized Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) sample preparation techniques applied across food, environmental, and biological matrices. Covering developments within 2020–2025, it focuses on analytical performance, environmental impact, and alignment with [...] Read more.

This review provides a comprehensive evaluation of recent advances in miniaturized Quick, Easy, Cheap, Effective, Rugged, and Safe (QuEChERS) sample preparation techniques applied across food, environmental, and biological matrices. Covering developments within 2020–2025, it focuses on analytical performance, environmental impact, and alignment with principles of sustainable and green analytical chemistry. Central to this review is the significant reduction in solvent and sample volumes achieved through miniaturization, thus decreasing the reagent consumption and hazardous waste generation. The integration of eco-friendly extraction solvents and sorbent materials enhances selectivity and reduces the environmental footprint. These methods are often coupled with high-resolution mass spectrometers, enabling sensitive, multi-residue, and suspect analysis. Challenges associated with complex matrices, low analyte concentrations, and the need for robust clean-up procedures are addressed through innovative hybrid workflows and advanced materials, e.g., polymeric electrospun fibers and deep eutectic solvents. The growing adoption of greener protocols is highlighted. Moreover, it underscores their potential to improve routine analytical workflows while reducing environmental burden. Future research should focus on the development of sustainable sample preparation with improved sensitivity, broader applicability, and minimal ecological impacts. This comprehensive assessment supports the ongoing transformation of analytical chemistry towards more sustainable practices without compromising analytical reliability and efficacy. Full article

(This article belongs to the Special Issue Optimization of Advanced Separation Technologies for the Analysis of Emerging Contaminants)

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43 pages, 1255 KB

Open AccessEditor’s ChoiceReview

Waste-Derived Photocatalysts for Light-Driven Water Treatment: A Comprehensive Review of Green Materials from Agri-Food, Industrial, and E-Waste

by Szabolcs Bognár, Vesna Despotović, Nina Finčur, Predrag Putnik, Dušica Jovanović, Katarina Hainz and Daniela Šojić Merkulov

Separations 2025, 12(12), 337; https://doi.org/10.3390/separations12120337 - 9 Dec 2025

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Abstract

The growing prevalence of emerging contaminants in the aquatic environment poses a critical challenge to global water security. Conventional treatment methods often fail to remove persistent pollutants, necessitating the development of sustainable and efficient alternatives. Heterogeneous photocatalysis, one of the advanced oxidation processes, [...] Read more.

The growing prevalence of emerging contaminants in the aquatic environment poses a critical challenge to global water security. Conventional treatment methods often fail to remove persistent pollutants, necessitating the development of sustainable and efficient alternatives. Heterogeneous photocatalysis, one of the advanced oxidation processes, driven by the light-induced generation of reactive species, has emerged as a promising solution. However, the high cost and environmental footprint of conventional photocatalysts limit large-scale implementation. This review explores the innovative use of waste-derived materials, originating from agricultural residues, industrial by-products, food waste, and electronic waste, as green precursors for photocatalyst synthesis. These materials offer unique structural and chemical properties, including a high surface area, tunable bandgaps, and enhanced stability, while supporting circular economy principles. Recent advances in synthesis strategies, performance optimization, and hybrid system integration are critically analyzed, alongside challenges related to scalability, environmental safety, and process standardization. Waste-to-resource approaches in photocatalysis represent a transformative pathway toward sustainable water treatment and resource recovery. Full article

(This article belongs to the Special Issue Eco-Friendly Innovations for Water Purification: Advanced Oxidation and Sustainable Cleanup Solutions)

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14 pages, 1618 KB

Open AccessEditor’s ChoiceArticle

Fast Analytical Separation of Selected Agricultural Pesticides Using Supercritical Fluid Chromatography

by Ana Jano, Manuel Badiola, Ana M. Ares, José Bernal, María Teresa Martín, Laura Toribio and Adrián Fuente-Ballesteros

Separations 2025, 12(12), 333; https://doi.org/10.3390/separations12120333 - 4 Dec 2025

Viewed by 270

Abstract

Pesticides are chemical substances widely used to control, prevent, or eliminate pests in agriculture, gardening, and other sectors. However, their use poses risks to human health, and recent regulatory efforts have focused on minimizing exposure and monitoring residue levels. In this study, the [...] Read more.

Pesticides are chemical substances widely used to control, prevent, or eliminate pests in agriculture, gardening, and other sectors. However, their use poses risks to human health, and recent regulatory efforts have focused on minimizing exposure and monitoring residue levels. In this study, the separation of seven pesticides was investigated using supercritical fluid chromatography coupled to diode-array detection (SFC-DAD). The influence of six different stationary phases and various organic modifiers, as well as additional parameters such as temperature, pressure, and the presence of additives, was systematically evaluated to optimize the chromatographic conditions. The best separation performance was achieved using a LiChrospher^® 100 DIOL column with methanol as the organic modifier under a gradient program. Analyses were carried out at a flow rate of 3 mL/min, a column temperature of 35 °C, and a system back pressure of 150 bar, resulting in a total analysis time of approximately 4 min. The optimized method allowed for a faster separation of the selected agricultural pesticides by SFC-DAD compared to conventional chromatographic techniques. Full article

(This article belongs to the Special Issue Optimization of Advanced Separation Technologies for the Analysis of Emerging Contaminants)

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13 pages, 1304 KB

Open AccessEditor’s ChoiceArticle

Anticoagulant Potential of the Isolate with Green Solvents from Prosthechea karwinskii

by Anel Karina Bernal-Martínez, Luicita Lagunez-Rivera, Rodolfo Solano, Gabriela Soledad Barragán-Zárate and Jesús Hernández-Juárez

Separations 2025, 12(12), 329; https://doi.org/10.3390/separations12120329 - 28 Nov 2025

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Abstract

Prosthechea karwinskii is an orchid endemic to Mexico used for medicinal purposes. The objective of this study was to determine the anticoagulant potential ex vivo of the extract isolated using green solvents. Coagulometric assays were performed to evaluate the anticoagulant activity: activated partial [...] Read more.

Prosthechea karwinskii is an orchid endemic to Mexico used for medicinal purposes. The objective of this study was to determine the anticoagulant potential ex vivo of the extract isolated using green solvents. Coagulometric assays were performed to evaluate the anticoagulant activity: activated partial thromboplastin time (APTT), prothrombin time (PT), and thrombin time (TT). For each assay, different concentrations of the extract were evaluated (0.5, 1.0, 1.5, 2.5, 3.5, 4.5, 5.5, 7.5, and 8.5 mg/mL) using platelet-poor plasma from healthy donors. The P. karwinskii leaves extract showed an anticoagulant effect by significantly prolonging (p < 0.05) the APTT and TT from a concentration of 3.5 and 2.5 mg/mL, respectively, compared to basal. The anticoagulant activity was concentration dependent. In addition, the hydroethanolic extract of P. karwinskii leaves inhibited factor XI activity by 86.10 ± 2.3%. The compounds in the extract were identified by ultra-high-performance liquid chromatography coupled with electrospray ionization and quadrupole time-of-flight mass spectrometry (UPLC-ESI-qTOF-MS/MS). The compounds identified were quinic acid, malic acid, succinic acid, L (-)-phenylalanine, guanosine, neochlorogenic acid, chlorogenic acid, rutin, kaempferol-3-O-rutinoside, azelaic acid, sebacic acid, pinellic acid, and embelin. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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14 pages, 1523 KB

Open AccessEditor’s ChoiceArticle

Composition- and Temperature-Dependent Solubility of Sinomenine Hydrochloride in Ethanol–Water Mixtures

by Yuxin Bian, Honggen Wu and Wenlong Li

Separations 2025, 12(12), 324; https://doi.org/10.3390/separations12120324 - 21 Nov 2025

Viewed by 316

Abstract

Sinomenine Hydrochloride is a bioactive alkaloid extracted from the root and stem of the medicinal plant sinomenium acutum, and is widely used to treat rheumatoid arthritis. Relevant studies were consulted, and the solubility data of Sinomenine Hydrochloride in ethanol–water mixed solvent have not [...] Read more.

Sinomenine Hydrochloride is a bioactive alkaloid extracted from the root and stem of the medicinal plant sinomenium acutum, and is widely used to treat rheumatoid arthritis. Relevant studies were consulted, and the solubility data of Sinomenine Hydrochloride in ethanol–water mixed solvent have not been reported. It is essential to choose a proper solvent in the process of crystallization that has a significant influence on the purity and productivity. Therefore, it is necessary to determine the solubility of Sinomenine Hydrochloride under the conditions of different ratios of ethanol–water mixed solvent and temperature. In this study, the solubility of Sinomenine Hydrochloride in ethanol–water mixed solvent was determined using high-performance liquid chromatography within the temperature range of 283.15 K–308.15 K. At the same time, the CNIBS/R-K model, Modified Apelblat model, Yaws model, and Apelblat–Jouyban–Acree model were used to fit the solubility data, and the relevant thermodynamic parameters were calculated using the Van’t Hoff model. The results showed that the solubility of Sinomenine Hydrochloride was higher in pure water than in pure ethanol. Moreover, with the increase in the mass fraction of ethanol in the mixed solvent, the solubility of Sinomenine Hydrochloride showed a trend of increasing first and then decreasing. When the ethanol–water ratio was 5:5, the solubility of the compound reached the maximum. In addition, experimental data showed that the solubility of Sinomenine Hydrochloride was affected by temperature. In the experimental temperature range, the solubility increased with the increase in temperature. Among these four solubility models, the CNIBS/R-K model had the best fitting effect; the maximum RAD and RMSD were 4.622 × 10⁻³ and 4.079 × 10⁻³, respectively. The thermodynamic model fitting results showed that the predicted values were in good agreement with the experimental data, and the thermodynamic parameters ΔHd, ΔSd, and ΔGd were all positive values. This indicated that the dissolution of Sinomenine Hydrochloride in the ethanol–water mixture was a non-spontaneous and endothermic process. A proper ratio of ethanol–water and temperature improved the solubility of Sinomenine Hydrochloride. The data determined in this study can provide basic data for the industrial purification of Sinomenine Hydrochloride. Full article

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

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14 pages, 1584 KB

Open AccessEditor’s ChoiceArticle

UHPLC-QTOF-MS/MS Metabolomic Profiling Reveals Environmental, Morphological, and Taxonomic Drivers of Chemical Diversity in Neotropical Banisteriopsis and Stigmaphyllon

by Jaqueline Munise Guimarães da Silva, Grazielle Jesus dos Santos, Rafael Felipe de Almeida and Maria Luiza Zeraik

Separations 2025, 12(11), 323; https://doi.org/10.3390/separations12110323 - 20 Nov 2025

Viewed by 445

Abstract

Banisteriopsis and Stigmaphyllon are among the most species-rich liana genera in the Neotropical Malpighiaceae family, known for their diverse chemical and biological activities. However, metabolomic information correlating these genera with their biome of occurrence, humidity levels, and plant habit (liana vs. shrub) remains [...] Read more.

Banisteriopsis and Stigmaphyllon are among the most species-rich liana genera in the Neotropical Malpighiaceae family, known for their diverse chemical and biological activities. However, metabolomic information correlating these genera with their biome of occurrence, humidity levels, and plant habit (liana vs. shrub) remains limited. This study explored in detail the metabolomic profiles of 15 species (29 specimens) of Banisteriopsis and 26 species (35 specimens) of Stigmaphyllon using Partial Least Squares Discriminant Analysis (PLS-DA). Leaf extracts obtained with ethanol/water (4:1, v/v) were analyzed by Ultra Performance Liquid Chromatography coupled to Quadrupole Time-of-Flight Mass Spectrometry (UHPLC-QTOF-MS/MS). Comparative analyses were performed at the genus level and across biome, humidity, and plant habit variables. The UHPLC-MS/MS profiling enabled the annotation of compounds, including previously unreported metabolites identified in B. quadriglandula and S. saxicola. Shared metabolites between the two genera were also characterized. PLS-DA revealed discriminant metabolites associated with the different comparative parameters, notably glucose (plant habit), coumaroyl hexoside, myricetin-3-galactoside, quercetin (genus), and quercetin-3-O-robinobioside (environment). With 95% confidence, our results demonstrate that environmental and morphological factors significantly influence metabolite biosynthesis in Banisteriopsis and Stigmaphyllon, providing valuable insights for future phytochemical and ecological research in the Neotropics. Full article

(This article belongs to the Special Issue Natural Product Separation and Characterization of Bioactive Plant Compounds)

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20 pages, 1458 KB

Open AccessEditor’s ChoiceArticle

Comparison and Validation of QuEChERS Extraction Methods Coupled with UHPLC/Orbitrap HR-MS for the Determination of Antibiotics and Related Compounds in Fish and Fish Feed

by Kleopatra Miserli, Vasiliki Boti, Dimitra Hela, Triantafyllos Albanis and Ioannis Konstantinou

Separations 2025, 12(11), 321; https://doi.org/10.3390/separations12110321 - 18 Nov 2025

Viewed by 544

Abstract

The widespread presence of pharmaceutical active compounds (PhACs) in aquatic environments raises significant environmental and public health concerns, particularly through their accumulation in marine biota and potential transfer to humans via seafood. In aquaculture, fish feed is essential for production but may also [...] Read more.

The widespread presence of pharmaceutical active compounds (PhACs) in aquatic environments raises significant environmental and public health concerns, particularly through their accumulation in marine biota and potential transfer to humans via seafood. In aquaculture, fish feed is essential for production but may also act as a pathway for contaminants in the marine environment. This study aimed to develop and validate an analytical method for the extraction and quantification of 14 antibiotics and ethoxyquin antioxidant in fish tissue and feed. Two QuEChERS-based extraction protocols were compared: the AOAC 2007.01 method (Method A) using Z-Sep⁺ as clean-up, and the original QuEChERS method (Method B) employing Enhanced Matrix Removal (EMR)-lipid. Ultra-performance liquid chromatography coupled with Orbitrap mass spectrometry using electrospray ionization in positive and negative mode was applied for identification and quantification. Validation included assessment of recovery, linearity, precision, limits of detection and quantification, uncertainty, matrix effects, and process efficiency. Both methods showed good linearity (R² > 0.9899) and precision (<19.7%). Method B achieved superior recoveries for most analytes in both fish tissue (70–110%) and feed (69–119%), with lower uncertainties (<18.4%) compared to Method A. Overall, the original QuEChERS method demonstrated better analytical performance, supporting its application as a green, robust tool for monitoring emerging contaminants in aquaculture products. Full article

(This article belongs to the Special Issue Optimization of Advanced Separation Technologies for the Analysis of Emerging Contaminants)

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17 pages, 3037 KB

Open AccessEditor’s ChoiceArticle

Fluid Flow Dynamics and Micro-Dust Separation in Multi-Module Cyclone-Separators: Experimental Research and Comparative Analysis

by Aleksandras Chlebnikovas

Separations 2025, 12(11), 313; https://doi.org/10.3390/separations12110313 - 11 Nov 2025

Viewed by 523

Abstract

An improved multi-module gas purification device is capable of removing micro-particles with an overall efficiency of over 95% at an average velocity of 16 m/s under a flow distribution ratio of 50/50. Its operation is based on the separation and filtration effect, and [...] Read more.

An improved multi-module gas purification device is capable of removing micro-particles with an overall efficiency of over 95% at an average velocity of 16 m/s under a flow distribution ratio of 50/50. Its operation is based on the separation and filtration effect, and the multi-module design increases gas flow processing capacity without increasing the size of the device, and ensures good sustainable development as an innovation. The effects of one, dual, and triple-module configurations were experimentally investigated in terms of gas flow and distribution in channels, including pressure drag and separation level. For a comparative analysis of three pilot models of the device, granite micro-dust and wood ash were used as test particles. At an average micro-dust concentration of 4.5 g/m³, a pressure drop of less than 1600 Pa and a separation level of more than 93% were achieved. Full article

(This article belongs to the Special Issue Advances in Gas–Solid Separation for Solid Waste Recovery)

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20 pages, 7539 KB

Open AccessEditor’s ChoiceArticle

Design, Simulation, and Parametric Analysis of an Ultra-High Purity Phosphine Purification Process with Dynamic Control

by Jingang Wang, Jinyu Guo, Yu Liu, Shuyue Zhou, Yawei Du and Xuejiao Tang

Separations 2025, 12(11), 309; https://doi.org/10.3390/separations12110309 - 7 Nov 2025

Viewed by 426

Abstract

Phosphine (PH₃) is an important functional material that plays a pivotal role in semiconductor fields. As semiconductor technology rapidly advances toward smaller sizes and higher performance, the requirements for the purity of phosphine in chip manufacturing are becoming increasingly stringent. To [...] Read more.

Phosphine (PH₃) is an important functional material that plays a pivotal role in semiconductor fields. As semiconductor technology rapidly advances toward smaller sizes and higher performance, the requirements for the purity of phosphine in chip manufacturing are becoming increasingly stringent. To address this, this study has designed a purification process for ultra-high purity phosphine, capable of achieving a purity level of 6N (99.9999%) for phosphine products. The process was simulated and analyzed using Aspen Plus to investigate the influence of various factors on the purity of phosphine products. In this design, the sensitivity analysis function was used to determine the optimal number of theoretical stages, feed stage, and reflux ratios for each rectifying column in the process. It was also found that an increase in rectifying column pressure is detrimental to the removal of low-boiling-point substances such as N₂ and O₂ from phosphine. Furthermore, a double-effect distillation process was designed. After adopting the double-effect distillation process, the heat duty on all condensers and reboilers would decrease by 27%, but the purity of the phosphine product would decrease from 99.999943% to 99.999936%. Finally, a control scheme was designed for the distillation column used to extract phosphine products, and the control effect was dynamically simulated and tested using Aspen Plus Dynamics. The test results showed that disturbances caused by a decrease in feed were much more difficult to control than those caused by an increase in feed, and that low-boiling-point impurities had a much greater impact on the purity of phosphine products than high-boiling-point impurities. In addition, the results of steady-state simulation indicate that CO₂ in phosphine is difficult to remove through distillation processes. Adding adsorption processes or membrane separation processes after distillation to remove CO₂ from phosphine is a research direction for improving the purity of phosphine. Full article

(This article belongs to the Special Issue Novel Solvents and Methods in Distillation Process)

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17 pages, 1552 KB

Open AccessEditor’s ChoiceArticle

Ultrasound Impact on Extraction Yield and Properties of Starch and Polyphenols from Canna indica L. Rhizomes

by Vigna Nivetha Chandrasekaran, Charlotte Silvestre, Julien Antih, Prakash Maran Jeganathan, Karine Portet, Gaelle Vesta, Hippolyte Kodja, Thomas Petit, Kaies Souidi, Florence Bichon and Patrick Poucheret

Separations 2025, 12(11), 307; https://doi.org/10.3390/separations12110307 - 6 Nov 2025

Viewed by 421

Abstract

In this present study, the efficiency of ultrasound-assisted extraction (UAE) in increasing the yields of extraction of starch and polyphenols from Canna indica L. (Canna) rhizomes were analyzed, along with its influence on the physiochemical properties of the extracted compounds. Extraction parameters (temperature, [...] Read more.

In this present study, the efficiency of ultrasound-assisted extraction (UAE) in increasing the yields of extraction of starch and polyphenols from Canna indica L. (Canna) rhizomes were analyzed, along with its influence on the physiochemical properties of the extracted compounds. Extraction parameters (temperature, time, and solid-to-liquid ratio) were optimized through Box–Behnken response surface design (BBD). The physiochemical and functional properties of starch and polyphenols were investigated through scanning electron microscopy (SEM), the swelling and solubility index, oil and water absorption index, total polyphenol yield, and antioxidant activity assays (DPPH and ORAC). The starch yield obtained from Canna at the optimum extraction conditions (temperature 40 °C, time 10 min, and solid-to-liquid ratio 1:30 g/mL) was 19.81%. The obtained starch yield was found to be significantly higher than the yield attained through the conventional extraction method without adverse changes in the physicochemical and functional properties. The total polyphenol extraction yield from the Canna rhizome, through UAE, was significantly higher (1061.72 mg GAE/100 g) than that of the conventional method. The antioxidant activity of bioactive compounds was proportional to the attained polyphenol yield. Our results suggest that UAE optimized conditions efficiently and improved Canna starch and polyphenol extraction yields while preserving their functional properties. Full article

(This article belongs to the Special Issue Isolation and Identification of Biologically Active Natural Compounds)

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16 pages, 3577 KB

Open AccessEditor’s ChoiceArticle

Recovery of Phenolic Compounds from Rowan Fruits (Sorbus aucuparia L.): A Comparison of Pretreatment and Extraction Methods

by Bartłomiej Zieniuk and Dorota Kowalska

Separations 2025, 12(11), 305; https://doi.org/10.3390/separations12110305 - 5 Nov 2025

Viewed by 415

Abstract

Phenolic compounds contribute significantly to the nutritional value of underused rowan (Sorbus aucuparia L.), but their extraction depends heavily on pre-processing and extraction methods. This study examined convective drying (CD) and freeze-drying (FD) of fruits, followed by ethanol extraction using rotor–stator homogenization, [...] Read more.

Phenolic compounds contribute significantly to the nutritional value of underused rowan (Sorbus aucuparia L.), but their extraction depends heavily on pre-processing and extraction methods. This study examined convective drying (CD) and freeze-drying (FD) of fruits, followed by ethanol extraction using rotor–stator homogenization, ultrasound-assisted extraction (UAE), or Soxhlet, to measure total phenolics (TPC), total flavonoids (TFC), and DPPH antioxidant activity (AA). AGREEprep benchmarking was included to assess method greenness. FD samples outperformed CD samples, increasing TPC by ≈2× (α = 0.05). For CD samples, Soxhlet extraction produced the highest averages, while for FD samples, UAE resulted in the highest AA (>58 μmol TE/g DW), and Soxhlet with 16 cycles maximized TPC and TFC (22.82 mg CGA/g DW; 4.24 mg QE/g DW). AA correlated strongly with TPC (R = 0.860) but only exhibited a moderate correlation with TFC. Multivariate analysis revealed that extracts mainly differed based on drying method and extraction intensity. AGREEprep scores were 0.45 for homogenization/UAE and 0.35 for Soxhlet. Overall, drying and extraction methods jointly influence results: FD combined with UAE offers a robust antioxidant profile with a lower environmental impact, whereas FD with Soxhlet maximizes phenolic and flavonoid yields at a higher environmental cost. Full article

(This article belongs to the Special Issue Extraction and Characterization of Food Components)

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14 pages, 1186 KB

Open AccessEditor’s ChoiceArticle

Optimizing Iron Dosage in Photo-Fenton Treatment of 2,6-Dichlorobenzoquinone for Sustainable Wastewater Remediation

by Unai Duoandicoechea and Natalia Villota

Separations 2025, 12(11), 297; https://doi.org/10.3390/separations12110297 - 29 Oct 2025

Viewed by 1172

Abstract

Chlorinated benzoquinones, such as 2,6-dichlorobenzoquinone (DCBQ), are toxic disinfection byproducts of growing concern in aquatic environments. Advanced oxidation processes, particularly photo-Fenton treatment, provide sustainable alternatives for their degradation. However, optimization is required to ensure not only the removal of the parent compound but [...] Read more.

Chlorinated benzoquinones, such as 2,6-dichlorobenzoquinone (DCBQ), are toxic disinfection byproducts of growing concern in aquatic environments. Advanced oxidation processes, particularly photo-Fenton treatment, provide sustainable alternatives for their degradation. However, optimization is required to ensure not only the removal of the parent compound but also the reduction in harmful intermediates. This study evaluated the degradation of DCBQ (1.0 mM H₂O₂, 150 W UV, pH 3.0, 25 °C) with ferrous ion between 0 and 1.0 mg/L. DCBQ removal followed a second-order kinetic model, reaching complete degradation. Aromaticity-loss and water color degradation adjusted to kinetics of second-order, reflecting the sequential reduction in chlorinated hydroquinones and chlorophenols type intermediates, with marked decreases after 120 min at 0.8 mg/L. Results showed that increasing iron dosage enhanced both the rate of DCBQ disappearance and the removal of aromaticity, with complete pollutant degradation. Importantly, optimal ferrous ion dosages (20 mol DCBQ: 70 mol H₂O₂: 1 mol Fe²⁺) effectively limited the persistence of intermediates, as evidenced by significant decreases in color and aromaticity, while avoiding excessive turbidity. These findings demonstrate that fine-tuning iron dosage in photo-Fenton systems can maximize contaminant elimination and minimize secondary byproducts, reinforcing their role as sustainable solutions for wastewater remediation. Full article

(This article belongs to the Special Issue Sustainable and Intelligent Process Control of Pollutant Separation and Purification)

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20 pages, 1440 KB

Open AccessEditor’s ChoiceArticle

Phenolic Compounds in Plant-Based Milk Alternatives from the Greek Market

by Velisaria-Eleni Gerogianni, Christiana Mantzourani, Maria A. Theodoropoulou, Antonia Chiou and Maroula G. Kokotou

Separations 2025, 12(10), 282; https://doi.org/10.3390/separations12100282 - 11 Oct 2025

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Abstract

Plant-based milk alternatives (PBMAs) are plant-based fluid products that are marketed as substitutes for regular milk. The nutrient composition of PBMA products can vary widely, depending on the plant source, processing methods, potential additives, etc., and in recent years, considerable research effort has [...] Read more.

Plant-based milk alternatives (PBMAs) are plant-based fluid products that are marketed as substitutes for regular milk. The nutrient composition of PBMA products can vary widely, depending on the plant source, processing methods, potential additives, etc., and in recent years, considerable research effort has been devoted to the exploration of the nutritional content of PBMAs, which are increasingly consumed worldwide. In the present study, an established UHPLC–Orbitrap MS method was employed for the extensive characterization of phenolic compounds in PBMAs available in the Greek market. Twenty-eight PBMAs were studied, including a variety of almond-, soy-, coconut-, oat-, walnut-, and rice-based products. In almond-based milk products, low total concentrations and a broad distribution across compound classes were observed, with trans-chlorogenic acid and neochlorogenic acid being the most abundant constituents, whereas coconut-based milk samples were generally not rich in phenolic compounds. In soy-based milk samples, the presence of isoflavones including daidzein, genistein, and glycitein was uniquely detected, while oat-based products were the samples richer in phenolic content, in particular for hydroxycinnamic acids, such as trans-chlorogenic acid and neochlorogenic acid. In addition, a suspect screening approach, using Exactive Plus Orbitrap, enabled the exploration and semi-quantification of three avenanthramides (A, B, C) in the studied oat-based milk samples and six isoflavonoids, namely daidzein and genistein derivatives, in soy-based milk. Such compounds are known for their antioxidant and anti-inflammatory properties, and their occurrence in PBMAs highlights the potential health-promoting effects of these dairy alternatives. Full article

(This article belongs to the Special Issue Extraction, Purification and Functional Substances of Natural Products and Plants)

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18 pages, 1969 KB

Open AccessEditor’s ChoiceReview

Artemisia frigida Willd.: Advances in Traditional Uses, Phytochemical Constituents, Extraction and Separation Methods, and Pharmacological Activities

by Wei Tian, Mengjie Zhang, Tongcun Zhang, Xianglong Li, Haiying Zhang and Xiumei Li

Separations 2025, 12(10), 280; https://doi.org/10.3390/separations12100280 - 11 Oct 2025

Viewed by 569

Abstract

Artemisia frigida Willd. (A. frigida), a traditional medicinal herb widely distributed in northern China, Mongolia, and Siberia, has garnered increasing scientific interest due to its diverse phytochemical profile and extensive pharmacological potential. Modern studies have identified a wide range of bioactive [...] Read more.

Artemisia frigida Willd. (A. frigida), a traditional medicinal herb widely distributed in northern China, Mongolia, and Siberia, has garnered increasing scientific interest due to its diverse phytochemical profile and extensive pharmacological potential. Modern studies have identified a wide range of bioactive compounds in A. frigida, including flavonoids, sesquiterpene lactones and phenolic acids. These compounds exhibit various biological activities, such as antioxidant, anti-inflammatory, anticancer, and antimicrobial effects. This review systematically summarizes the research progress on the chemical constituents of A. frigida and their extraction and separation methods, including solvent extraction, ultrasonic-assisted extraction, macroporous resin adsorption, and chromatography-based techniques. By integrating traditional knowledge with modern pharmacological evidence, this review provides a scientific foundation for the further development and utilization of A. frigida in functional food, pharmaceuticals, and ethnomedicine. Full article

(This article belongs to the Special Issue Extraction, Purification and Functional Substances of Natural Products and Plants)

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14 pages, 2341 KB

Open AccessEditor’s ChoiceArticle

Application of Bio-Based Activated Carbon from Cocoa Husk Waste for High-Efficiency Adsorption in Water Treatment

by Daniela Angelova, Vesislava Toteva and Georgi Georgiev

Separations 2025, 12(10), 278; https://doi.org/10.3390/separations12100278 - 10 Oct 2025

Viewed by 745

Abstract

This research presents the study of utilizing the cocoa husk biomass waste to obtain active carbon through carbonization method, followed by chemical–thermal activation. The activated carbon (CH) was characterized using BET, SEM–EDX, XPS, and Raman techniques. The obtained material showed a high specific [...] Read more.

This research presents the study of utilizing the cocoa husk biomass waste to obtain active carbon through carbonization method, followed by chemical–thermal activation. The activated carbon (CH) was characterized using BET, SEM–EDX, XPS, and Raman techniques. The obtained material showed a high specific surface area of 1661 m²·g⁻¹, and XPS confirmed the presence of oxygen-containing surface functionalities. The adsorption of reactive dye Drimaren Red K-7B by CH was studied to assess the impact of the initial concentration in water solution, temperature, and contact time. The adsorbent achieved over 90% removal within three minutes at 40 °C. The experimental data for the adsorption of Drimaren Red K-7B using CH showed a good fit with the Dubinin–Radushkevich isotherm and a pseudo-second-order kinetic model. This research offers a promising approach for advancing the circular economy through the obtaining of eco-friendly adsorbents derived from biomass waste, exhibiting high initial adsorption efficiency and rapid uptake kinetics towards reactive dye. Full article

(This article belongs to the Special Issue Application of Adsorption and Separation Technologies in Water Treatment)

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22 pages, 3564 KB

Open AccessEditor’s ChoiceArticle

Development of a Green Extraction Process from Residues of Assyrtiko Wine Production for Cosmetic Applications

by Styliani Kalafateli, Agni-Areti Freri, Georgios Stavropoulos, Andromachi Tzani and Anastasia Detsi

Separations 2025, 12(10), 265; https://doi.org/10.3390/separations12100265 - 30 Sep 2025

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Abstract

Vitis vinifera L. cultivar, “Assyrtiko”, is a famous grape variety native to Santorini island. Its wine production residues are rich in bioactive polyphenols, making them valuable for extraction and use in cosmetics. The aim of this work was the development and optimization of [...] Read more.

Vitis vinifera L. cultivar, “Assyrtiko”, is a famous grape variety native to Santorini island. Its wine production residues are rich in bioactive polyphenols, making them valuable for extraction and use in cosmetics. The aim of this work was the development and optimization of an extraction process from “Assyrtiko” Wine Production Residue (AWPR), using a Natural Deep Eutectic Solvent (NaDES) as the extraction medium. Four NaDESs were synthesized and screened for the extraction, and the extracts were evaluated for Total Phenolic Content (TPC) and Total Flavonoid Content (TFC). The NaDES comprising betaine and 1,3-propanediol was chosen for further analysis because of its effectiveness as an extraction solvent. The extraction process was optimized using a Box–Behnken experimental design. The NaDES %w/w content in the NaDES/water system was found to play the most statistically significant role in the quality of the extracts, assessed via TPC and TFC values. The quality of the extract obtained from the optimal conditions was practically stable with respect to TPC and TFC after long storage, suggesting that NaDESs have a potential “protective” effect for the extracted phytochemicals and give energy-efficient character to the process. This extract was also directly incorporated into a moisturizing cosmetic formulation, which remained homogeneous and stable after testing, demonstrating the extract’s potential for cosmetic applications. Full article

(This article belongs to the Special Issue Novel Solvents and Methods for Extraction of Chemicals)

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18 pages, 2919 KB

Open AccessEditor’s ChoiceArticle

Development of an Efficient HPLC-MS/MS Method for the Detection of a Broad Spectrum of Hydrophilic and Lipophilic Contaminants in Marine Waters: An Experimental Design Approach

by Daniel Bona, Marina Di Carro, Emanuele Magi and Barbara Benedetti

Separations 2025, 12(10), 257; https://doi.org/10.3390/separations12100257 - 23 Sep 2025

Viewed by 1782

Abstract

The present study develops and optimizes a targeted chromatographic method coupled with mass spectrometry, employing design of experiments, for the determination of several emerging contaminants in environmental waters. Their widespread presence poses environmental and health risks due to their pseudo-persistence and unknown long-term [...] Read more.

The present study develops and optimizes a targeted chromatographic method coupled with mass spectrometry, employing design of experiments, for the determination of several emerging contaminants in environmental waters. Their widespread presence poses environmental and health risks due to their pseudo-persistence and unknown long-term effects. Therefore, sensitive and selective analytical methods are essential for their reliable environmental monitoring. This work focuses on 40 organic micro-contaminants with a wide range of polarities, including drugs, pesticides and UV-filters. Chromatographic separation was performed on a pentafluorophenyl column, and a Face-Centered Design was applied for multivariate optimization. Mobile phase flow and temperature were chosen as the study factors, and retention time and peak width as the responses, as indicators of analytical performance. Two optimized runs (for positive and negative electrospray ionization modes) were obtained, enabling the analysis of all 40 analytes in a total of 29 min. The final method was successfully applied to seawater samples from different sites of the Genoa harbor area. Several analytes were detected and quantified, down to the ng L⁻¹ level, with tracers and pharmaceuticals showing the highest concentrations. The method demonstrated satisfactory accuracy, precision and specificity and is suitable for routine monitoring of a broad range of emerging contaminants in seawater. Full article

(This article belongs to the Special Issue Optimization of Advanced Separation Technologies for the Analysis of Emerging Contaminants)

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24 pages, 1470 KB

Open AccessEditor’s ChoiceReview

Recent Trends in Solid-Phase Microextraction for the Monitoring of Drugs of Abuse in Wastewater

by Pedro Dinis, Eugenia Gallardo and Cláudia Margalho

Separations 2025, 12(9), 256; https://doi.org/10.3390/separations12090256 - 22 Sep 2025

Viewed by 1865

Abstract

Wastewater analysis plays a central role in monitoring patterns of drug use within specific populations. It provides objective and real-time estimates of consumption, with minimal ethical concerns. In the current European context, drugs of abuse continue to be detected in wastewater, with varying [...] Read more.

Wastewater analysis plays a central role in monitoring patterns of drug use within specific populations. It provides objective and real-time estimates of consumption, with minimal ethical concerns. In the current European context, drugs of abuse continue to be detected in wastewater, with varying incidences across countries. Their monitoring enables the prioritisation of public health and legal interventions by healthcare professionals and drug monitoring agencies. Therefore, the development and implementation of efficient methodologies for monitoring drugs of abuse in wastewater samples is of critical importance. This systematic review aims to explore the use of miniaturised sample extraction techniques based on solid-phase microextraction for the determination of drugs of abuse in wastewater. In fact, the extraction procedure must be fast, effective, and selective in order to retain the analytes of interest. Miniaturised techniques have thus emerged as promising alternatives to conventional methods. Magnetic solid-phase extraction (MSPE) and molecularly imprinted polymers (MIPs) represent the most widely applied solid-phase microextraction techniques in recent years for the analysis of drugs of abuse in wastewater. Looking ahead, future perspectives include the development of eco-friendly workflows, automated and time-efficient techniques, increasingly selective sorbents, and robust analytical methods. Full article

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

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26 pages, 13045 KB

Open AccessEditor’s ChoiceArticle

Carp Scales Modified with Cerium Oxide Nanoparticles as a New Bio-Adsorbent for Arsenic and Chromium Separation from Water

by Zoran Bajić, Uroš Z. Veličković, Veljko Djokić, Mihael Bučko, Jovica Bogdanov, Krstimir Pantić and Aleksandar D. Marinković

Separations 2025, 12(9), 253; https://doi.org/10.3390/separations12090253 - 19 Sep 2025

Viewed by 574

Abstract

Different treatments of fish scales from carps (Cyprinus carpio) (FS)—mechanical milling, modified with cerium dioxide (CeO₂) nanoparticles and controlled carbonization of FS and modification with CeO₂—were applied to obtain FS, FS-CeO₂ and CFS-CeO₂ bio-adsorbents. The [...] Read more.

Different treatments of fish scales from carps (Cyprinus carpio) (FS)—mechanical milling, modified with cerium dioxide (CeO₂) nanoparticles and controlled carbonization of FS and modification with CeO₂—were applied to obtain FS, FS-CeO₂ and CFS-CeO₂ bio-adsorbents. The synthesized adsorbents were used for As(V) and Cr(VI) oxyanion separation from water. Porosity and the amount of CeO₂ nanoparticles deposition were controlled using different experimental conditions. Response surface methodology (RSM) was used to select optimal parameters for adsorbent synthesis to obtain the highest adsorption capacity. The structural and surface characteristics of the synthesized adsorbents were examined using FTIR, XRD and SEM techniques. The efficiency of pollutant removal was analyzed in terms of varying experimental conditions: the mass of adsorbent, pH, temperature and contact time. RSM was also used to optimize adsorption and desorption processes. The adsorption data, obtained at 25, 35 and 45 °C, were processed using Langmuir, Freundlich, Temkin and Dubinin–Radushkevich isotherm and Van’t Hoff thermodynamic models. The FS-CeO₂ bio-adsorbent showed good adsorption capacities of 92.61 and 65.50 mg g⁻¹ for As(V) and Cr(VI) ion removal, respectively, obtained by using the Langmuir model. Thermodynamic parameters proved that adsorption was a viable, spontaneous and endothermic process. The results from kinetic modeling indicated that both adsorbate and surface functional group concentration determine overall kinetic law with the highest participation of intra-particle diffusion resistance to pollutant transport. Exceptional adsorption and desorption performances of FS-CeO₂ in conjunction with the bio-based origin of synthesized adsorbents offer valuable alternatives for the remediation of polluted water. Full article

(This article belongs to the Section Materials in Separation Science)

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12 pages, 1446 KB

Open AccessEditor’s ChoiceArticle

Investigation on Li Recovery from Greek Coal Fly Ash Under a Circular Economy Framework: An Experimental Study

by Despina Pentari, Pagona Makri, Panagiotis Xanthopoulos and Despina Vamvuka

Separations 2025, 12(9), 251; https://doi.org/10.3390/separations12090251 - 15 Sep 2025

Viewed by 696

Abstract

Lithium is classified as a critical element and is widely used in a variety of high-tech applications. Within the framework of a circular economy, demand is rising for technologies capable of recovering high-tech metals from waste materials and industrial byproducts. Coal fly ash [...] Read more.

Lithium is classified as a critical element and is widely used in a variety of high-tech applications. Within the framework of a circular economy, demand is rising for technologies capable of recovering high-tech metals from waste materials and industrial byproducts. Coal fly ash (CFA) has attracted significant attention as a promising secondary resource for this purpose. Effective recovery requires the assessment of both metal enrichment levels and the underlying binding and leaching characteristics. The present study aims to contribute to advancing lithium recovery technology using coal fly ash as a secondary resource, thereby promoting waste valorization. Fourteen samples of coal fly ash from different power plants were collected and their mineralogy was studied by X-ray powder diffraction (XRD), their major constituents were analyzed by X-ray fluorescence spectroscopy (XRF), and their Li content was determined by inductively coupled plasma mass spectrometry (ICP-MS). Leaching experiments were conducted for selected samples using mineral acids (HCl and HF) and citric acid. Lithium concentrations in the analyzed samples ranged from 80 to 256 mg/kg, indicating enrichment relative to both global ash averages (enrichment factor > 1) and the Earth’s crust (enrichment factor > 2). Li in the samples, could be mainly associated with the amorphous fraction present in the samples. Leaching behavior across the samples follows a consistent trend, with hydrofluoric acid exhibiting the highest lithium extraction efficiency—reaching up to 79.9%. Full article

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19 pages, 13378 KB

Open AccessEditor’s ChoiceArticle

Semi-Pilot Scale Extraction of Pinocembrin and Galangin from Populus alba L. × berolinensis K. Koch via Enzymatic Pretreatment and Ultrasonication

by Ru Zhao, Xiaoli Li, Yazhou Bao, Wenjun Xu, Chen Xu, Rongrong Wang, Tianlan Xia, Tingli Liu and Ailing Ben

Separations 2025, 12(9), 249; https://doi.org/10.3390/separations12090249 - 11 Sep 2025

Viewed by 545

Abstract

In this investigation, pinocembrin and galangin were efficiently extracted from the male inflorescence of Populus alba L. × berolinensis K. Koch through an enzymatic pretreatment–ultrasonic-assisted strategy (EP-UAS), and the feasibility of their pilot-scale application was validated. The optimal parameters (ethanol volume fraction, cellulase [...] Read more.

In this investigation, pinocembrin and galangin were efficiently extracted from the male inflorescence of Populus alba L. × berolinensis K. Koch through an enzymatic pretreatment–ultrasonic-assisted strategy (EP-UAS), and the feasibility of their pilot-scale application was validated. The optimal parameters (ethanol volume fraction, cellulase dosage, incubation temperature, incubation time, pH, liquid‒solid ratio, ultrasonic irradiation power during incubation, duty cycle, ultrasonic irradiation power and time during extraction) affecting pinocembrin and galangin yields were systematically explored. The Box–Behnken design (BBD) results provided optimal parameters for the EP-UAS process. Under the optimal conditions, the actual yields of pinocembrin and galangin were 2158.33 ± 0.13 μg/g and 1257.96 ± 0.06 μg/g, respectively. Stability, recovery and reproducibility were determined under the above optimized conditions to evaluate the proposed EP-UAS method. Moreover, laboratory-scale experimental results revealed that the conditions selected via single-factor and response surface experiments were also applicable to pilot-scale production, facilitating industrialization. Full article

(This article belongs to the Special Issue Green Extraction Techniques for Bioactive Products from Natural Sources)

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14 pages, 4696 KB

Open AccessEditor’s ChoiceArticle

Efficient Photocatalytic Reduction of Cr(VI) on N-Doped Sludge/Cellulose-Derived Porous Carbon Using Synergistic Experimental–Deep Learning Approach

by Na Huang, Shengwen Chen and Wanhe Du

Separations 2025, 12(9), 247; https://doi.org/10.3390/separations12090247 - 9 Sep 2025

Cited by 1 | Viewed by 795

Abstract

The photocatalytic reduction of hexavalent chromium (Cr(VI)) in wastewater represents a critical environmental challenge, given its high toxicity and mobility in wastewater. Conventional optimization methods relying on repetitive batch experiments with excessive reagent consumption. Herein, we proposed a synergistic experimental–deep learning approach to [...] Read more.

The photocatalytic reduction of hexavalent chromium (Cr(VI)) in wastewater represents a critical environmental challenge, given its high toxicity and mobility in wastewater. Conventional optimization methods relying on repetitive batch experiments with excessive reagent consumption. Herein, we proposed a synergistic experimental–deep learning approach to realize efficient photocatalytic reduction of Cr(VI). Sludge and cellulose precursors were used to prepare N-doped porous carbon through a green fabrication method at low temperature. After optimizing the composition and experimental factors, the removal efficiency of Cr(VI) could reach 92.7% after visible light irradiation in an acidic environment. The high efficiency originated from the coupled adsorption and photocatalytic mechanism. Innovatively, after comparing three algorithms, TCN and Transformer were employed to predict the desirable removal efficiency with <5% prediction error under different reaction conditions. This work highlights the novel experimental–deep learning method for heavy metal remediation using N-doped waste-derived porous carbon. Full article

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22 pages, 7600 KB

Open AccessEditor’s ChoiceArticle

Experimental Study on Spatiotemporal Evolution Mechanisms of Roll Waves and Their Impact on Particle Separation Behavior in Spiral Concentrators

by Jian Wang, Huizhong Liu, Qihua Zou and Jun Hu

Separations 2025, 12(9), 245; https://doi.org/10.3390/separations12090245 - 8 Sep 2025

Cited by 3 | Viewed by 956

Abstract

Spiral concentrators are gravity and centrifugal force-based devices designed for mineral concentration. During processing operations, dynamic variations in the slurry’s liquid film thickness can induce hydrodynamic instability, generating roll waves on the free surface that compromise particle separation efficiency. To ensure operational stability [...] Read more.

Spiral concentrators are gravity and centrifugal force-based devices designed for mineral concentration. During processing operations, dynamic variations in the slurry’s liquid film thickness can induce hydrodynamic instability, generating roll waves on the free surface that compromise particle separation efficiency. To ensure operational stability and efficacy, this study establishes a theoretical shallow-water flow model for slurry dynamics in spiral concentrators based on hydraulic principles. Through L₂₇(3¹³) orthogonal experiments and real-time ultrasonic film thickness monitoring, the influence of key parameters on roll wave evolution is quantified. Results indicate that roll waves follow an “instability-development-dissipation” sequence. The pitch-to-diameter ratio (P/D) exerts a highly significant effect on roll wave intensity, while particle properties (density and size) exhibit moderate significance. In contrast, feed flow rate and solid concentration show negligible impacts. Roll waves amplify fluid turbulence, triggering stochastic migration of particles (especially low-density grains), which increases the standard deviation of zonal recovery rates (ZRR) and degrades separation precision. This work provides critical insights into particle behavior under roll wave conditions and offers a theoretical foundation for optimizing spiral concentrator design and process control. Full article

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21 pages, 3693 KB

Open AccessEditor’s ChoiceArticle

Electrochemistry–Mass Spectrometry for Generation and Identification of Metabolites of Selected Drugs from Different Therapeutic Groups in Comparison with In Vitro and In Vivo Approaches

by Małgorzata Szultka-Młyńska

Separations 2025, 12(9), 243; https://doi.org/10.3390/separations12090243 - 5 Sep 2025

Viewed by 952

Abstract

The metabolism of antibiotics, antidepressants, and cardiovascular drugs has been investigated widely over the last few decades. The aim of this study was to develop an efficient analytical protocol based on the combination of electrochemistry (EC) and mass spectrometry for the identification of [...] Read more.

The metabolism of antibiotics, antidepressants, and cardiovascular drugs has been investigated widely over the last few decades. The aim of this study was to develop an efficient analytical protocol based on the combination of electrochemistry (EC) and mass spectrometry for the identification of electrochemical products (potential pharmacologically active metabolites) of selected drugs (enalapril, metronidazole, midazolam, propranolol, venlafaxine). The electrochemical mimicry of the oxidative phase I and II metabolism was achieved in a thin-layer cell equipped with different working electrodes (magic diamond (MD), glassy carbon (GC), gold (Au), platinum (Pt)). The structures of the electrochemically generated metabolites were elucidated based on accurate mass ion data and tandem mass spectrometry (MS/MS) experiments. The in silico prediction of the main sites of selected drugs’ metabolism was performed using Biotransformer 3.0, GLORYx, and Xenosite software. Moreover, incubation with liver microsomes (LMs) was performed to examine the proposed metabolic pathways of target compounds. The data from in vitro experiments agreed with the data from electrochemical oxidation, which predicted some potential metabolites found in the real samples from patients. For enzymatic incubation, N-dealkylation, O-demethylation, and hydroxylation were the metabolic pathways involved mainly in their metabolism. Their in vitro phase II metabolites were identified as glucuronic acid conjugates. Finally, different in vivo phase I and II metabolites were identified for the studied drugs, including metabolic pathways for in vivo phase I N-demethylation, N-dealkylation, O-demethylation, and hydroxylation, while the metabolic pathways for in vivo phase II metabolites were identified as glucuronic acid conjugates. Full article

(This article belongs to the Special Issue Separation Techniques in Drug Analysis)

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18 pages, 4673 KB

Open AccessEditor’s ChoiceArticle

Effect of Iron–Carbon–Zeolite Substrate Configuration on Cadmium Removal in Vertical-Flow Constructed Wetlands

by Mengyi Li, Shiyu Chen, Jundan Chen, Naifu Zhou and Guanlong Yu

Separations 2025, 12(8), 223; https://doi.org/10.3390/separations12080223 - 21 Aug 2025

Cited by 1 | Viewed by 785

Abstract

The excessive emission of cadmium (Cd²⁺) poses a serious threat to the aquatic environment due to its high toxicity and bioaccumulation potential. This study constructed three types of vertical-subsurface-flow constructed wetlands configured with iron–carbon–zeolite composite substrates, including an iron–carbon–zeolite constructed wetland [...] Read more.

The excessive emission of cadmium (Cd²⁺) poses a serious threat to the aquatic environment due to its high toxicity and bioaccumulation potential. This study constructed three types of vertical-subsurface-flow constructed wetlands configured with iron–carbon–zeolite composite substrates, including an iron–carbon–zeolite constructed wetland (TF-CW), a zeolite–iron–carbon constructed wetland (FT-CW), and an iron–carbon–zeolite mixed constructed wetland (H-CW), to investigate the purification performance and mechanisms of constructed wetlands for cadmium-containing wastewater (0~6 mg/L). The results demonstrated that iron–carbon–zeolite composite substrates significantly enhanced Cd²⁺ removal efficiency (>99%) through synergistic redox-adsorption mechanisms, where the iron–carbon substrate layer dominated Fe-Cd co-precipitation, while the zeolite layer achieved short-term cadmium retention through ion-exchange adsorption. FT-CW exhibited superior NH₄⁺-N removal efficiency (77.66%~92.23%) compared with TF-CW (71.45%~88.05%), while iron–carbon micro-electrolysis effectively inhibited NO₃⁻-N accumulation (<0.1 mg/L). Under cadmium stress, Typha primarily accumulated cadmium through its root systems (>85%) and alleviated oxidative damage by dynamically regulating antioxidative enzyme activity, with the superoxide dismutase (SOD) peak occurring at 3 mg/L Cd²⁺ treatment. Microbial community analysis revealed that iron–carbon substrates promoted the relative abundance of Bacteroidota and Patescibacteria as well as the enrichment of Saccharimonadales, Thauera, and Rhodocyclaceae (genera), enhancing system stability. This study confirms that iron–carbon–zeolite CWs provide an efficient and sustainable technological pathway for heavy metal-contaminated water remediation through multidimensional mechanisms of “chemical immobilization–plant enrichment–microbial metabolism”. Full article

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28 pages, 10833 KB

Open AccessEditor’s ChoiceArticle

Optimization and Component Identification of Ultrasound-Assisted Extraction of Polyphenols from Coriander (Coriandrum sativum L.) and Evaluation of Polyphenol Content Changes and Antioxidant Activity During Storage

by Heng Yuan, Chunzhi Xie, Yue Ma, Yaqi Miao, Xuehong Chen, Hao Gong and Jun Wang

Separations 2025, 12(8), 217; https://doi.org/10.3390/separations12080217 - 16 Aug 2025

Cited by 1 | Viewed by 1037

Abstract

Coriander (Coriandrum sativum L.) has significant value in the food industry due to its unique flavor and health benefits. However, its polyphenol content and antioxidant activity have not been systematically analyzed during storage. This study optimized the extraction process of coriander polyphenols [...] Read more.

Coriander (Coriandrum sativum L.) has significant value in the food industry due to its unique flavor and health benefits. However, its polyphenol content and antioxidant activity have not been systematically analyzed during storage. This study optimized the extraction process of coriander polyphenols using ultrasound-assisted extraction combined with response surface methodology. The polyphenol composition was systematically identified, and changes in polyphenol content and antioxidant activity during storage were investigated. The optimal process conditions for extracting coriander polyphenols were determined as 40% ethanol concentration, 1:121 g/mL material-to-liquid ratio, 81 °C extraction temperature, and 10 min extraction time. This optimized protocol yielded 16.231 mg GAE/g, a 119.28% increase over conventional methods using the same raw material. Fifty polyphenolic compounds were identified using high-resolution mass spectrometry. The main types of polyphenols identified were quercetin, kaempferol, and hydroxycinnamic acid derivatives. Notably, 41 of these compounds were reported in coriander for the first time. In vitro tests revealed that coriander polyphenols exhibit potent antioxidant properties, with IC₅₀ values of 73.43 μg/mL for DPPH and 82.15 μg/mL for ABTS. Furthermore, the polyphenol content and antioxidant capacity of coriander increased significantly during storage, with total phenolic content rising by 40.5%, DPPH activity by 32.5%, and ABTS activity by 56.5%. Key individual polyphenols showed differential changes: rutin continuously accumulated, while chlorogenic acid and ferulic acid exhibited an initial increase followed by a decrease. This study provides strong technical support for the use of coriander polyphenols in functional foods and medicines. Full article

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12 pages, 1561 KB

Open AccessEditor’s ChoiceArticle

Effect of Performance and Fouling Mechanisms of Thermo-Responsive Membranes on Treating Secondary Effluent Containing Added Sulfamethoxazole

by Lian Yang, Haoran Qiu, Yingjie Yang, Lijun Zhao, Ping Xiao, Guoliang Liu, Jiang Chang, Shaoxia Yang and Feng Xiao

Separations 2025, 12(8), 218; https://doi.org/10.3390/separations12080218 - 16 Aug 2025

Viewed by 610

Abstract

Wastewater treatment plants generally lack a specialized design for the efficient removal of sulfamethoxazole (SMX), a toxic and bio-resistant compound. In this study, secondary effluent from a Beijing wastewater reclamation treatment plant was spiked with SMX and used to investigate the filtration performance [...] Read more.

Wastewater treatment plants generally lack a specialized design for the efficient removal of sulfamethoxazole (SMX), a toxic and bio-resistant compound. In this study, secondary effluent from a Beijing wastewater reclamation treatment plant was spiked with SMX and used to investigate the filtration performance and fouling mechanisms of thermo-responsive membranes. Thermo-responsive materials were prepared using polyvinylidene fluoride, N-isopropylacrylamide (NIPAM), and graphene oxide through Ce (IV)-induced redox radical polymerization. The results showed that the removal of SMX and COD reached 42% and 92%, respectively, with a NIPAM dosage of 1 g, and the removal of UV₂₅₄ reached its highest value at 57.9%. Additionally, the filtration flux was higher at a temperature of 35 °C with a NIPAM dosage of 1 g. The fluorescence intensity of the organic matter from the secondary effluent spiked with SMX and decreased after the thermo-responsive membranes were implemented, and filtration with the membrane containing 1 g of NIPAM achieved a lower intensity at a value of 3074.6, according to the analysis of three-dimensional fluorescence excitation–emission spectroscopy. According to the extended Derjaguin–Laudau–Verwey–Overbeek theory analysis, the interfacial free energies of the thermo-responsive membrane with a 1 g dose of NIPAM were higher than the others during filtration. Full article

(This article belongs to the Special Issue Application of Adsorption and Separation Technologies in Water Treatment)

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17 pages, 3206 KB

Open AccessEditor’s ChoiceArticle

Inverse Punicines: Isomers of Punicine and Their Application in LiAlO₂, Melilite and CaSiO₃ Separation

by Maximilian H. Fischer, Ali Zgheib, Iliass El Hraoui, Alena Schnickmann, Thomas Schirmer, Gunnar Jeschke and Andreas Schmidt

Separations 2025, 12(8), 202; https://doi.org/10.3390/separations12080202 - 30 Jul 2025

Viewed by 987

Abstract

The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. [...] Read more.

The transition to sustainable energy systems demands efficient recycling methods for critical raw materials like lithium. In this study, we present a new class of pH- and light-switchable flotation collectors based on isomeric derivatives of the natural product Punicine, termed inverse Punicines. These amphoteric molecules were synthesized via a straightforward four-step route and structurally tuned for hydrophobization by alkylation. Their performance as collectors was evaluated in microflotation experiments of lithium aluminate (LiAlO₂) and silicate matrix minerals such as melilite and calcium silicate. Characterization techniques including ultraviolet-visible (UV-Vis), nuclear magnetic resonance (NMR) and electron spin resonance (ESR) spectroscopy as well as contact angle, zeta potential (ζ potential) and microflotation experiments revealed strong pH- and structure-dependent interactions with mineral surfaces. Notably, N-alkylated inverse Punicine derivatives showed high flotation yields for LiAlO₂ at pH of 11, with a derivative possessing a dodecyl group attached to the nitrogen as collector achieving up to 86% recovery (collector conc. 0.06 mmol/L). Preliminary separation tests showed Li upgrading from 5.27% to 6.95%. Radical formation and light-response behavior were confirmed by ESR and flotation tests under different illumination conditions. These results demonstrate the potential of inverse Punicines as tunable, sustainable flotation reagents for advanced lithium recycling from complex slag systems. Full article

(This article belongs to the Special Issue Application of Green Flotation Technology in Mineral Processing)

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27 pages, 1893 KB

Open AccessEditor’s ChoiceArticle

Separating 2-Propanol and Water: A Comparative Study of Extractive Distillation, Salting-Out, and Extraction

by Aleksandra Sander, Marko Rogošić, Leonarda Frljak, Daniela Vasiljević, Iva Blažević and Jelena Parlov Vuković

Separations 2025, 12(8), 196; https://doi.org/10.3390/separations12080196 - 26 Jul 2025

Cited by 1 | Viewed by 2103

Abstract

Separating azeotropes is an important, difficult, and expensive task, in particular for the 2-propanol–water mixture. The literature on the problem is rich in modeling studies but often lacking even the simplest experimental confirmation. In this paper, extractive distillation, liquid–liquid equilibrium-based extraction, and salting-out [...] Read more.

Separating azeotropes is an important, difficult, and expensive task, in particular for the 2-propanol–water mixture. The literature on the problem is rich in modeling studies but often lacking even the simplest experimental confirmation. In this paper, extractive distillation, liquid–liquid equilibrium-based extraction, and salting-out were experimentally tested for the desired separation. Among the four tested extractive distillation entrainers, none was able—in the investigated experimental setup—to push the system over the azeotropic composition threshold. Four novel hydrophobic deep eutectic extraction media were tested for the desired separation, and those based on menthol or thymol with decanoic acid were found most promising. Among 16 tested salting-out agents, 5 of them produced two-liquid phases, and only 4 hydrophilic inorganic salts promoted 2-propanol separation, with sodium carbonate being the most promising candidate. The purity of the products was tested with FTIR and ¹H-NMR. The experimental findings were compared with COSMO-RS model predictions, with moderate success. Full article

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14 pages, 4700 KB

Open AccessEditor’s ChoiceArticle

Pilot-Scale Phycocyanin Extraction by the Green Two-Step Ultrasound-Based UltraBlu Process

by Rosaria Lauceri, Melissa Pignataro, Antonio Giorgi, Antonio Idà and Lyudmila Kamburska

Separations 2025, 12(8), 194; https://doi.org/10.3390/separations12080194 - 25 Jul 2025

Viewed by 1130

Abstract

Phycocyanin is a natural, non-toxic, blue pigment-protein with many commercial applications. Its exploitation in various biotechnological sectors strongly depends on its purity grade (P). Phycocyanin is largely used in food industry where a low purity grade is required, while its widespread use in [...] Read more.

Phycocyanin is a natural, non-toxic, blue pigment-protein with many commercial applications. Its exploitation in various biotechnological sectors strongly depends on its purity grade (P). Phycocyanin is largely used in food industry where a low purity grade is required, while its widespread use in sectors requiring a higher purity is hampered by the cost of large-scale industrial production. Industry, in fact, needs simple, easily scalable and cost-effective procedures to ensure sustainable production of high-quality pigment. In this work we applied the innovative two-step ultrasound-based process UltraBlu to the pilot-scale production of phycocyanin. A total of 50 L of biomass suspension of commercial Spirulina were processed in batch mode. The pigment extract was obtained in one day, including the biomass harvesting. Food/cosmetic grade (P = 1.41–1.76) and a good yield (Y = 59.2–76.1%) were achieved. The initial results obtained suggest that UltraBlu can be an effective scalable process suitable to produce phycocyanin also on an industrial scale. Full article

(This article belongs to the Special Issue Application of Sustainable Separation Techniques in Food Processing)

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21 pages, 727 KB

Open AccessEditor’s ChoiceArticle

Seasonal and Cultivar-Dependent Phenolic Dynamics in Tuscan Olive Leaves: A Two-Year Study by HPLC-DAD-MS for Food By-Product Valorization

by Tommaso Ugolini, Lorenzo Cecchi, Graziano Sani, Irene Digiglio, Barbara Adinolfi, Leonardo Ciaccheri, Bruno Zanoni, Fabrizio Melani and Nadia Mulinacci

Separations 2025, 12(8), 192; https://doi.org/10.3390/separations12080192 - 24 Jul 2025

Cited by 3 | Viewed by 1102

Abstract

Olive tree leaf is a phenol-rich, high-potential-value biomass that can be used to formulate food additives and supplements. Leaf phenolic content varies depending on numerous factors, like cultivar, geographical origin, year, and season of harvest. The aim of this research was to evaluate [...] Read more.

Olive tree leaf is a phenol-rich, high-potential-value biomass that can be used to formulate food additives and supplements. Leaf phenolic content varies depending on numerous factors, like cultivar, geographical origin, year, and season of harvest. The aim of this research was to evaluate the variations in phenolic profile of four major Tuscan cultivars (Frantoio, Leccio del Corno, Leccino, and Moraiolo) over four different phenological phases and across two years. All 96 olive leaf samples were harvested from trees grown in the same orchard located in Florence. After drying, their phenolic profile was characterized using HPLC-DAD-MS, and the obtained data were processed by ANOVA, GA-LDA, and RF methods. A total of 25 phenolic derivatives were analyzed, with total contents ranging 16,674.0–50,594.3 mg/kg and oleuropein (4570.0–27,547.7 mg/kg) being the predominant compound regardless of cultivar, year, and season of harvest. Oleuropein and hydroxytyrosol glucoside showed inverse proportionality and similar behavior across years in all cultivars, and therefore were highlighted as main phenolic compounds correlated with the seasonal variability in studied cultivars. Interesting behavior was also pointed out for apigenin rutinoside. Application of GA-LDA and RF methods allowed pointing out the excellent performance of leaf phenols in discriminating samples based on cultivar, harvest year, and harvesting season. Full article

(This article belongs to the Special Issue Extraction and Isolation of Nutraceuticals from Plant Foods)

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14 pages, 4274 KB

Open AccessEditor’s ChoiceArticle

The Role of Freezing Temperature in Modulating Chitosan Gel Structure and Evaporation Performance for Seawater Desalination

by Jiaonan Cai, Yong Bai and Fang Li

Separations 2025, 12(8), 193; https://doi.org/10.3390/separations12080193 - 24 Jul 2025

Viewed by 1012

Abstract

Interfacial solar evaporation has emerged as a promising strategy for freshwater production, where 3D evaporators offer distinct advantages in heat management and salt rejection. Freeze–thaw cycling is a widely adopted fabrication method for 3D hydrogel evaporators, yet the impact of preparation conditions (e.g., [...] Read more.

Interfacial solar evaporation has emerged as a promising strategy for freshwater production, where 3D evaporators offer distinct advantages in heat management and salt rejection. Freeze–thaw cycling is a widely adopted fabrication method for 3D hydrogel evaporators, yet the impact of preparation conditions (e.g., freezing temperature) on their evaporation performance remains poorly understood, hindering rational optimization of fabrication protocols. Herein, we report the fabrication of chitosan-based hydrogel evaporators via freeze–thaw cycles at different freezing temperatures (−20 °C, −40 °C, and −80 °C), leveraging its low cost and environmental friendliness. Characterizations of crosslinking density and microstructure reveal a direct correlation between freezing temperature and network porosity, which significantly influences evaporation rate, photothermal conversion efficiency, and anti-salt performance. It is noteworthy that the chitosan hydrogel prepared at −80 °C demonstrates an excellent evaporation rate in high-salinity environments and exhibits superior salt resistance during continuous evaporation testing. Long-term cyclic experiments indicate that there was an average evaporation rate of 3.76 kg m⁻² h⁻¹ over 10 cycles, with only a 2.5% decrease observed in the 10th cycle. This work not only elucidates the structure–property relationship of freeze–thaw fabricated hydrogels but also provides a strategic guideline for tailoring evaporator architectures to different salinity conditions, bridging the gap between material design and practical seawater desalination. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Materials in Separation Science')

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11 pages, 1292 KB

Open AccessEditor’s ChoiceArticle

Flotation Behaviours of Ilmenite and Associated Solution Chemistry Properties Using Saturated Fatty Acids as the Collector

by Jihua Zhai, Hao He, Pan Chen, Lin Song, Xiaohai Yao and Hongxian Zhang

Separations 2025, 12(8), 191; https://doi.org/10.3390/separations12080191 - 24 Jul 2025

Cited by 1 | Viewed by 817

Abstract

A series of homologous saturated fatty acids were introduced and evaluated as collectors for ilmenite flotation using a combination of micro-flotation tests and surface tension measurements. The results showed that ilmenite exhibited good flotation behaviour when decanoic and dodecanoic acids were used as [...] Read more.

A series of homologous saturated fatty acids were introduced and evaluated as collectors for ilmenite flotation using a combination of micro-flotation tests and surface tension measurements. The results showed that ilmenite exhibited good flotation behaviour when decanoic and dodecanoic acids were used as collectors; however, saturated fatty acids with shorter or longer carbon chains were not suitable for ilmenite flotation (caused either by poor collection ability or limited solubility in water). The optimum flotation pH range was also dependent on the carbon chain length of saturated fatty acids, and the solution surface tension did not always match well with the ilmenite flotation behaviour when using a series of saturated fatty acids as the collector. The associated solution chemistry properties under series saturated fatty acid flotation systems were discussed, and the adsorption mechanism of decanoic acid onto the ilmenite surface was also investigated via FTIR, zeta potential, and contact angle measurements. Full article

(This article belongs to the Section Separation Engineering)

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14 pages, 1840 KB

Open AccessEditor’s ChoiceArticle

Volatilomic Fingerprint of Tomatoes by HS-SPME/GC-MS as a Suitable Analytical Platform for Authenticity Assessment Purposes

by Gonçalo Jasmins, Tânia Azevedo, José S. Câmara and Rosa Perestrelo

Separations 2025, 12(8), 188; https://doi.org/10.3390/separations12080188 - 22 Jul 2025

Viewed by 949

Abstract

Tomatoes are globally esteemed not only for their nutritional value but also for their complex and appealing aroma, a key determinant of consumer preference. The present study aimed to comprehensively characterise the volatilomic fingerprints of three tomato species—Solanum lycopersicum L., S. lycopersicum [...] Read more.

Tomatoes are globally esteemed not only for their nutritional value but also for their complex and appealing aroma, a key determinant of consumer preference. The present study aimed to comprehensively characterise the volatilomic fingerprints of three tomato species—Solanum lycopersicum L., S. lycopersicum var. cerasiforme, and S. betaceum—encompassing six distinct varieties, through the application of headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME/GC-MS). A total of 55 volatile organic compounds (VOCs) spanning multiple chemical classes were identified, of which only 28 were ubiquitously present across all varieties examined. Carbonyl compounds constituted the predominant chemical family, with hexanal and (E)-2-hexenal emerging as putative key contributors to the characteristic green and fresh olfactory notes. Notably, esters were found to dominate the unique volatile fingerprint of cherry tomatoes, particularly methyl 2-hydroxybenzoate, while Kumato and Roma varieties exhibited elevated levels of furanic compounds. Multivariate statistical analyses, including principal component analysis (PCA) and partial least squares discriminant analysis (PLS-DA), demonstrated clear varietal discrimination and identified potential aroma-associated biomarkers such as phenylethyl alcohol, 3-methyl-1-butanol, hexanal, (E)-2-octenal, (E)-2-nonenal, and heptanal. Collectively, these findings underscore the utility of volatilomic fingerprint as a robust tool for varietal identification and quality control within the food industry. Full article

(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)

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19 pages, 735 KB

Open AccessEditor’s ChoiceReview

Nanoplastics: From Separations to Analysis—Challenges and Limitations

by Justyna Ośko, Kornelia Kadac-Czapska, Katarzyna Jażdżewska, Natalia Nowak, Piotr Kowalczyk and Małgorzata Grembecka

Separations 2025, 12(7), 185; https://doi.org/10.3390/separations12070185 - 15 Jul 2025

Cited by 5 | Viewed by 4401

Abstract

The issue of nanoplastics (NPs) in the environment, following that of microplastics (MPs), is receiving increasing attention in the scientific community. Due to their size, these particles require the development and application of new methods for both quantitative and qualitative determination. Consequently, techniques [...] Read more.

The issue of nanoplastics (NPs) in the environment, following that of microplastics (MPs), is receiving increasing attention in the scientific community. Due to their size, these particles require the development and application of new methods for both quantitative and qualitative determination. Consequently, techniques commonly used for analyzing MPs may prove ineffective in the context of NPs. Isolating NPs from samples with complex matrices poses a significant challenge that directly affects analytical outcomes. This paper aims to discuss the main challenges encountered during the analysis of NPs in environmental samples. Various methods for the visualization and identification of NPs are examined, with a focus on microscopic, spectroscopic, and thermal techniques. The advantages and limitations of analytical approaches reported in the literature are summarized, offering guidance for the future development and standardization of methods used to determine NPs in environmental contexts. Full article

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16 pages, 1369 KB

Open AccessEditor’s ChoiceArticle

Optimized Ethyl Chloroformate Derivatization Using a Box–Behnken Design for Gas Chromatography–Mass Spectrometry Quantification of Gallic Acid in Wine

by Sofia Botta, Roberta Piacentini, Chiara Cappelletti, Alessio Incocciati, Alberto Boffi, Alessandra Bonamore and Alberto Macone

Separations 2025, 12(7), 183; https://doi.org/10.3390/separations12070183 - 9 Jul 2025

Cited by 2 | Viewed by 962

Abstract

Gallic acid, a major phenolic compound in wine, significantly influences its sensory profile and health-related properties, making its accurate measurement essential for both enological and nutritional studies. In this context, a derivatization protocol for gallic acid using ethyl chloroformate (ECF) was developed and [...] Read more.

Gallic acid, a major phenolic compound in wine, significantly influences its sensory profile and health-related properties, making its accurate measurement essential for both enological and nutritional studies. In this context, a derivatization protocol for gallic acid using ethyl chloroformate (ECF) was developed and optimized for GC-MS analysis, with experimental conditions refined through a Box–Behnken Design (BBD). The BBD systematically investigated the effects of three critical reagent volumes: ethyl chloroformate, pyridine, and ethanol. This approach elucidated complex interactions and quadratic effects, leading to a predictive second-order polynomial model and identifying the optimal derivatization conditions for maximum yield (137 µL of ethyl chloroformate, 51 µL of pyridine, and 161 µL of ethanol per 150 µL of wine). The BBD-optimized GC-MS method was validated and successfully applied to quantify gallic acid in diverse commercial wine samples (white, red, conventional, natural). A key finding was the method’s wide dynamic range, enabling accurate quantification from 5 up to over 600 µg/mL without sample dilution. This work represents, to our knowledge, the first application of a BBD for optimizing the ethyl chloroformate derivatization of gallic acid, providing a robust, efficient, and widely applicable analytical tool for routine quality control and enological research. Full article

(This article belongs to the Special Issue Innovative Analytical Strategies Based on Mass Spectrometry in Food Analysis)

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22 pages, 1203 KB

Open AccessEditor’s ChoiceReview

Impact of Use of Ultrasound-Assisted Extraction on the Quality of Brazil Nut Oil (Bertholletia excelsa HBK)

by Orquidea Vasconcelos dos Santos, Sara Camila Vidal Freires, Helen Cristina de Oliveira Palheta and Paulo Henrique de Melo Ferreira

Separations 2025, 12(7), 182; https://doi.org/10.3390/separations12070182 - 8 Jul 2025

Cited by 3 | Viewed by 3707

Abstract

The quality of materials extracted from plant sources, such as oilseeds, is significantly affected by the extraction techniques employed. Thermo-photosensitive bioactive compounds are especially susceptible, often resulting in a loss of functional properties during conventional processing. In this context, studies involving unconventional or [...] Read more.

The quality of materials extracted from plant sources, such as oilseeds, is significantly affected by the extraction techniques employed. Thermo-photosensitive bioactive compounds are especially susceptible, often resulting in a loss of functional properties during conventional processing. In this context, studies involving unconventional or “innovative” extraction methods have emerged as a strategic approach to preserve the quality of the extracted material (whether by-product or biomass) by aligning with the core principles of green chemistry and the expansion of sustainable production chains. This approach promotes both raw material integrity and the protection of human and environmental health. These efforts contribute to a virtuous cycle of technological innovation and environmentally sound practices. This review focuses on how ultrasound-assisted extraction affects the quality of plant-derived materials, particularly Brazil nut oil. The article compiles data published over the last five years (2020–2025), following the PRISMA methodology. Recent studies highlight the synergistic potential of ultrasound as a green technology for isolating Brazil nut oil, offering enhanced nutritional and functional properties. This aligns with the growing demand for healthier food products obtained through sustainable industrial processes and presents opportunities for diverse applications across several industry sectors. Full article

(This article belongs to the Special Issue Extraction and Characterization of Food Components)

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12 pages, 2841 KB

Open AccessEditor’s ChoiceArticle

Extraction of Rubidium and Cesium Ions by Adsorption–Flotation Separation in Titanosilicate-Hexadecyltrimethylammonium Bromide System

by Dezhen Fang, Haining Liu, Xiushen Ye, Yanping Wang and Wenjie Han

Separations 2025, 12(7), 181; https://doi.org/10.3390/separations12070181 - 7 Jul 2025

Cited by 1 | Viewed by 818

Abstract

This study centers on the adsorption–flotation coupling extraction of rubidium (Rb⁺) and cesium (Cs⁺) within a titanium silicate (CTS)–cetyltrimethylammonium bromide (CTAB) system, systematically investigating the impacts of pH, aeration rate, CTAB concentration, and flotation time on the extraction efficiency [...] Read more.

This study centers on the adsorption–flotation coupling extraction of rubidium (Rb⁺) and cesium (Cs⁺) within a titanium silicate (CTS)–cetyltrimethylammonium bromide (CTAB) system, systematically investigating the impacts of pH, aeration rate, CTAB concentration, and flotation time on the extraction efficiency of these elements. Single-factor experiments revealed that the optimal flotation efficiency was achieved when the pH ranged from 6 to 10, the aeration rate was set at 1000 r/min, the CTAB concentration was 0.2 mmol/L, and the flotation duration was 18 min. Under these conditions, the adsorption capacities for Rb⁺ and Cs⁺ were recorded as 128.32 mg/g and 185.47 mg/g, respectively. Employing the response surface optimization method to analyze the interactive effects of these four factors, we found that their order of significance was as follows: pH > aeration rate > CTAB concentration > flotation time. The optimized parameters were determined as pH 8.64, bubble formation rate 1121 r/min, CTAB concentration 0.26 mmol/L, and flotation time 18.47 min. Under these refined conditions, the flotation efficiency for both CTS–Rb and CTS–Cs surpassed any single-factor experiment scenario, with the flotation efficiencies for Rb⁺ and Cs⁺ reaching 95.05% and 94.82%, respectively. This methodology effectively extracts Rb⁺ and Cs⁺ from low-concentration liquid systems, while addressing the challenges of solid–liquid separation for powdered adsorption materials. It holds significant theoretical and practical reference value for enhancing the separation processes of low-grade valuable components and boosting overall separation performance. Full article

(This article belongs to the Special Issue Green and Efficient Separation and Extraction of Salt Lake Resources)

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26 pages, 7085 KB

Open AccessEditor’s ChoiceReview

Advances in Electrolytic Manganese Residue: Harmless Treatment and Comprehensive Utilization

by Weijian Yu, Xiaoya Li, Wenting Xu, Qingjun Guan, Fujia Zhou, Jiani Zhang, Li Wang, Yanxiu Wang and Honghu Tang

Separations 2025, 12(7), 180; https://doi.org/10.3390/separations12070180 - 7 Jul 2025

Cited by 1 | Viewed by 1547

Abstract

Electrolytic manganese residue (EMR) is a byproduct of electrolytic manganese production, rich in soluble pollutants such as manganese and ammonia nitrogen. Traditional stockpiling methods result in contaminant leaching and water pollution, threatening ecosystems. Meanwhile, EMR has significant resource-recovery potential. This paper systematically reviews [...] Read more.

Electrolytic manganese residue (EMR) is a byproduct of electrolytic manganese production, rich in soluble pollutants such as manganese and ammonia nitrogen. Traditional stockpiling methods result in contaminant leaching and water pollution, threatening ecosystems. Meanwhile, EMR has significant resource-recovery potential. This paper systematically reviews the harmless process and resource technology of EMR, efficiency bottlenecks, and the current status of industrial applications. The mechanisms of chemical leaching, precipitation, solidification, roasting, electrochemistry, and microorganisms were analyzed. Among these, electrochemical purification stands out for its efficiency and environmental benefits, positioning it as a promising option for broad industrial use. The mechanisms of chemical leaching, precipitation, solidification, roasting, electrochemistry, and microorganisms were analyzed, revealing the complementarity between building materials and chemical materials (microcrystalline glass) in scale and high-value-added production. But the lack of impurity separation accuracy and market standards restricts its promotion. Finally, it proposes future directions for EMR resource utilization based on practical and economic considerations. Full article

(This article belongs to the Special Issue Solid Waste Recycling and Strategic Metal Extraction)

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12 pages, 23410 KB

Open AccessEditor’s ChoiceArticle

Recycling and Separation of Valuable Metals from Spent Cathode Sheets by Single-Step Electrochemical Strategy

by Neng Wei, Yaqun He, Guangwen Zhang, Jiahao Li and Fengbin Zhang

Separations 2025, 12(7), 178; https://doi.org/10.3390/separations12070178 - 5 Jul 2025

Viewed by 779

Abstract

The conventional spent lithium-ion batteries (LIBs) recycling method suffers from complex processes and excessive chemical consumption. Hence, this study proposes an electrochemical strategy for achieving reductant-free leaching of high-valence transition metals and efficient separation of valuable components from spent cathode sheets (CSs). An [...] Read more.

The conventional spent lithium-ion batteries (LIBs) recycling method suffers from complex processes and excessive chemical consumption. Hence, this study proposes an electrochemical strategy for achieving reductant-free leaching of high-valence transition metals and efficient separation of valuable components from spent cathode sheets (CSs). An innovatively designed sandwich-structured electrochemical reactor achieved efficient reductive dissolution of cathode materials (CMs) while maintaining the structural integrity of aluminum (Al) foils in a dilute sulfuric acid system. Optimized current enabled leaching efficiencies exceeding 93% for lithium (Li), cobalt (Co), manganese (Mn), and nickel (Ni), with 88% metallic Al foil recovery via cathodic protection. Multi-scale characterization systematically elucidated metal valence evolution and interfacial reaction mechanisms, validating the technology’s tripartite innovation: simultaneous high metal extraction efficiency, high value-added Al foil recovery, and organic removal through single-step electrochemical treatment. The process synergized the dissolution of CM particles and hydrogen bubble-induced physical liberation to achieve clean separation of polyvinylidene difluoride (PVDF) and carbon black (CB) layers from Al foil substrates. This method eliminates crushing pretreatment, high-temperature reduction, and any other reductant consumption, establishing an environmentally friendly and efficient method of comprehensive recycling of battery materials. Full article

(This article belongs to the Special Issue Innovative Separation Techniques for Sustainable Recycling of Solid Waste)

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11 pages, 2330 KB

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

Viewed by 1020

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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27 pages, 3488 KB

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

Cited by 1 | Viewed by 4364

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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16 pages, 1616 KB

Open AccessEditor’s ChoiceArticle

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

Cited by 1 | Viewed by 964

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 K_OW 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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13 pages, 1875 KB

Open AccessEditor’s ChoiceArticle

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 950

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, 815 KB

Open AccessEditor’s ChoiceArticle

Mixed-Mode Chromatography: Studies on Hybrid Retention Mechanisms of Some Antihypertensive Drugs

by Irinel Adriana Badea, Andrei Mihăilă, Dana Elena Popa, Anca Monica Tencaliec and Mihaela Buleandră

Separations 2025, 12(6), 136; https://doi.org/10.3390/separations12060136 - 22 May 2025

Viewed by 702

Abstract

The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary [...] Read more.

The antihypertensive drugs indapamide, atenolol, metoprolol, propranolol and bisoprolol were considered in this research. Because they have structures that are affected by pH, developing a chromatographic method was challenging. Based on the speciation diagram of these compounds versus pH scale, a mixed-mode stationary phase (hydrophobic stationary phase, C18 and strong cation exchanger (SCX)) was our first choice. Design of Experiments (DoE) was used to estimate how various factors such as pH, mobile phase composition and flow rate influenced chromatographic performance. As a result, the separation was achieved in 24 min using an aqueous phosphate buffer phase (pH 7.20) and 20 mM triethylamine, with methanol being used as organic modifier (30%). Their retention mechanism was investigated. The new method was validated in term of linearity, limits of detection and quantification, precision, accuracy, and robustness. The method was applied to river water samples, and good results were obtained. Full article

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18 pages, 3393 KB

Open AccessEditor’s ChoiceArticle

Development of a High-Performance Immunoaffinity Separation Technique for Rare Cell Capture

by Dora Szerenyi, Paul Stolk, Jozsef Tovari, Laszlo Takacs and Andras Guttman

Separations 2025, 12(5), 134; https://doi.org/10.3390/separations12050134 - 20 May 2025

Viewed by 950

Abstract

Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by [...] Read more.

Circulating tumor cell enrichment and enumeration are advancing early detection of cancer, monitoring of therapy response, and even next-generation therapies. Efficiently capturing rare cells from complex biological fluids is essential in both diagnostic and therapeutic applications. EpCAM-positive tumor cells are specifically captured by utilizing covalently immobilized anti-EpCAM monoclonal antibodies onto the surface of chemically modified glass microbeads. To maximize the capture efficiency, bead geometry, immobilization conditions, flow rate, and anticoagulant dosage were systematically optimized. An in vitro flow-capture system was designed and used to evaluate the capture efficiency of the proposed technology by utilizing HTC116 colon cancer cell-spiked model media. The effect of substrate surface pretreatment was characterized by goniometry, while the capture performance was monitored by flow cytometry and fluorescent microscopy. The specific capture ability of the bioactive microbead substrate reached over 130,000 cells in the laboratory-scale cartridge (V(cartridge) = 2.6 cm³; m(bead) = 4 g). This capture efficiency suggests a promising rare-cell capture utilization of the proposed technology and may be used for research, diagnostic, and therapeutic purposes. In this paper, we reported on the development and feasibility test of a high-performance bioactive glass-microbead cell capture substrate. Due to the relevance and novelty of the reported results, with further development, the versatile platform technology presented could be readily implemented to capture tumor cells from complex biological samples and represent an additional complementary tool to existing cancer diagnostics and therapies. Full article

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24 pages, 1664 KB

Open AccessEditor’s ChoiceReview

Microextraction and Eco-Friendly Techniques Applied to Solid Matrices Followed by Chromatographic Analysis

by Attilio Naccarato, Rosangela Elliani and Antonio Tagarelli

Separations 2025, 12(5), 124; https://doi.org/10.3390/separations12050124 - 14 May 2025

Cited by 7 | Viewed by 2106

Abstract

In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, [...] Read more.

In this review, a 5-year overview on environmentally friendly approaches for the extraction of the most relevant organic pollutants in soil, sediment, particulate matter, and sewage sludge coupled with chromatographic analysis is reported. Organic contaminants encompass various compounds derived from personal care products, industrial chemicals, microplastics, organic matter combustion, agricultural practices, and plasticizer material. The principles of green analytical chemistry (GAC) and green sample preparation (GSP) serve as a guideline for the development of more environmentally sustainable analytical protocols. This study focuses attention on microwave-assisted extraction (MAE), ultrasound-assisted extraction (UAE), matrix solid-phase dispersion (MSPD), and microextraction techniques, such as solid-phase microextraction (SPME), stir bar sorptive extraction (SBSE), hollow-fiber liquid-phase microextraction (HF-LPME), spray-assisted droplet formation-based liquid-phase microextraction (SADF-LPME), and dispersive liquid–liquid extraction (DLLME). These approaches represent the most relevant eco-friendly sample preparation for the advanced extraction of target analytes from environmental solid samples. Full article

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

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11 pages, 1447 KB

Open AccessEditor’s ChoiceArticle

Development and Validation of a Sensitive LC-MS/MS Method for the Determination of N-Nitroso-Atenolol in Atenolol-Based Pharmaceuticals

by Soonho Kwon, Sang-Hyun Ahn, Yongha Chang, Joon-Sang Park, Hwangeui Cho and Jung-Bok Kim

Separations 2025, 12(5), 122; https://doi.org/10.3390/separations12050122 - 12 May 2025

Cited by 1 | Viewed by 2820

Abstract

The recent detection of N-nitroso-atenolol, a mutagenic and potentially carcinogenic impurity in atenolol-based pharmaceuticals, has raised serious safety concerns and emphasized the need for stringent analytical control. This study developed and validated a highly sensitive LC-MS/MS method for quantifying N-nitroso-atenolol in both active [...] Read more.

The recent detection of N-nitroso-atenolol, a mutagenic and potentially carcinogenic impurity in atenolol-based pharmaceuticals, has raised serious safety concerns and emphasized the need for stringent analytical control. This study developed and validated a highly sensitive LC-MS/MS method for quantifying N-nitroso-atenolol in both active pharmaceutical ingredients (APIs) and finished products. Quantification was carried out using multiple reaction monitoring (MRM) under positive-mode electrospray ionization (ESI). Separation was performed on a C18 reversed-phase column with a gradient of water and methanol containing 0.1% formic acid. The method was validated to meet a specification limit of 15 ng/mg, with a linear range of 0.5–80 ng/mL, effectively covering 10–400% of the regulatory threshold. The method exhibited an excellent performance in terms of specificity, accuracy, precision, linearity, and robustness. It achieved a limit of detection (LOD) of 0.2 ng/mL (0.30 ng/mg) and a limit of quantification (LOQ) of 0.5 ng/mL (0.75 ng/mg), alongside a comprehensive uncertainty analysis with an expanded uncertainty of ±3.86 mg/kg. Application to commercial atenolol products confirmed the reliability and practical utility of the method. This validated approach offers a critical tool for pharmaceutical manufacturers and regulatory agencies to monitor and control N-nitroso-atenolol, ensuring compliance and enhancing patient safety. Full article

(This article belongs to the Section Analysis of Natural Products and Pharmaceuticals)

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17 pages, 2794 KB

Open AccessEditor’s ChoiceArticle

Defluoridation of Water Using Al-Mg-Ca Ternary Metal Oxide-Coated Sand in Adsorption Column Study

by Kiana Modaresahmadi, Amid P. Khodadoust and James Wescott

Separations 2025, 12(5), 119; https://doi.org/10.3390/separations12050119 - 7 May 2025

Viewed by 1054

Abstract

Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent [...] Read more.

Defluoridation of water was investigated in an adsorption column study using Al-Mg-Ca-coated sand (AMCCS), a ternary metal oxide adsorbent with eco-friendly components that were shown to be effective for water defluoridation, in a batch adsorption study. A packed column of the AMCCS sorbent was evaluated as function of column flow rate, solution type, and sorbent recyclability. Adsorption column experiments included two column flow rates of 2 mL/min and 10 mL/min using two different solutions: deionized water and a synthetic solution representative of groundwater. Greater fluoride column adsorption capacity was obtained at the lower flow rate for both solutions, mainly due to longer contact times between solution and AMCCS sorbent. Adsorption of fluoride occurred through physical adsorption, which followed the Langmuir adsorption model and second-order kinetics for deionized water and synthetic solution. A lower AMCCS column fluoride adsorption capacity was observed for the synthetic solution due to the competition from adsorption of other ions in the synthetic solution, whereas fluoride adsorption by the AMCCS column was influenced by interphase mass transfer to a lesser extent using the synthetic solution than deionized water. The re-coating of spent AMCCS sorbent in the adsorption column resulted in effective recycling and reuse of the AMCCS adsorption column for both deionized water and the synthetic solution, rendering the AMCCS adsorption column a recyclable and sustainable flow through water defluoridation system. Full article

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17 pages, 2019 KB

Open AccessEditor’s ChoiceArticle

Free Fatty Acid Determination in Alcoholic and Non-Alcoholic Beers via Liquid Chromatography–High-Resolution Mass Spectrometry Analysis

by Christiana Mantzourani and Maroula G. Kokotou

Separations 2025, 12(5), 114; https://doi.org/10.3390/separations12050114 - 1 May 2025

Cited by 1 | Viewed by 3333

Abstract

In recent years, non-alcoholic beers have been gaining popularity. Among the various components that affect the flavor and sensory characteristics of beers, free fatty acids (FFAs) are minor components. However, due to their involvement in beer quality, fast and simple methods for analyzing [...] Read more.

In recent years, non-alcoholic beers have been gaining popularity. Among the various components that affect the flavor and sensory characteristics of beers, free fatty acids (FFAs) are minor components. However, due to their involvement in beer quality, fast and simple methods for analyzing FFAs in beers are of importance. In this work, we present a liquid chromatography–high-resolution mass spectrometry (LC-HRMS) method for the rapid determination of FFAs in beers, avoiding a tedious sample preparation and derivatization and allowing the simultaneous study of a large set of FAs, including medium-chain, long-chain, saturated, monounsaturated and polyunsaturated FAs. The method was applied in the analysis of twelve non-alcoholic and nine alcoholic beer samples from the local market, permitting the comparison of their FFA profiling. Among the 37 FAs studied, 29 were quantified, and palmitic, stearic, oleic and myristic acids were identified as the predominant FAs in both alcoholic and non-alcoholic beers. The majority of the predominant long-chain FAs, including palmitic, stearic and myristic acids, were found in decreased amounts in non-alcoholic beers, compared to the alcoholic ones, with the marked exception of oleic acid, which was increased in non-alcoholic beers. Among the medium-chain FAs, octanoic acid was found at lower concentrations in non-alcoholic beers, comparing to regular beers, while lauric acid was slightly increased. Principal component analysis (PCA) suggested the correlation of FFAs with the type of beer (alcoholic or non-alcoholic beer). Full article

(This article belongs to the Special Issue Chromatography/Mass Spectrometry for the Determination of Food Authenticity and Food Analysis)

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