Separations

15 pages, 3410 KB

Open AccessArticle

Application of Calcium Alginate Spheres Modified with 2,4-Dinitrophenylhydrazine During the Determination of Fatty Aldehydes in Edible Oils by HPLC-DAD

by F. Esmeralda Santiago-Martinez, Jose A. Rodriguez, Eva M. Santos, Alicia C. Mondragon-Portocarrero and Jorge Lopez-Tellez

Separations 2026, 13(2), 75; https://doi.org/10.3390/separations13020075 - 21 Feb 2026

Viewed by 653

Abstract

Saturated fatty aldehydes are products from lipid oxidation that negatively affect the organoleptic properties and nutritional quality of food and represent a risk to human health. For this reason, they are frequently used as indicators of oxidation in food safety. Usually, their determination [...] Read more.

Saturated fatty aldehydes are products from lipid oxidation that negatively affect the organoleptic properties and nutritional quality of food and represent a risk to human health. For this reason, they are frequently used as indicators of oxidation in food safety. Usually, their determination is carried out by derivatization using an excess of 2,4-dinitrophenylhydrazine (DNPH), but the excessive use of derivatizing agents requires a high proportion compared to the analyte concentration to ensure a complete reaction, which causes interferences and limits the chromatographic separation of derivatized products. In this context, the encapsulation of DNPH in alginate spheres is proposed to determine aldehydes concentration in edible vegetable oil samples, allowing the gradual release of DNPH to form the corresponding hydrazones, which were subsequently separated and analyzed by HPLC-DAD. The proposed method was optimized by a Taguchi L₉(3⁴) experimental design, validated, and applied for the determination of aldehydes in edible oils. Limits of detection in the intervals of 0.77 to 1.41 mg L⁻¹ were obtained with adequate precision (expressed as relative standard deviation < 10%), which are suitable values for monitoring lipid oxidation in foods The proposed methodology represents a viable alternative to apply in quality control studies and lipid degradation profiles. Full article

(This article belongs to the Special Issue Development of Materials for Separation and Analysis Applications)

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20 pages, 4270 KB

Open AccessArticle

Separation and Reutilization of Nitrogen and Phosphorus in Stormwater/Greywater Using Chinese Herbal Plant-Based Green Roof Wetland System

by Bingjie Li, Pu Yang, Binjie Wang, Wenqian Kang, Changzhi Li, Li Liu, Huashan Gao, Suqing Wu and Chunzhen Fan

Separations 2026, 13(2), 74; https://doi.org/10.3390/separations13020074 - 20 Feb 2026

Viewed by 403

Abstract

Stormwater and greywater are increasingly recognized as freshwater resources, and the effective separation and reutilization of nitrogen (N) and phosphorus (P) from these streams is vital for water quality improvement and urbanization sustainability. In this study, we constructed a pilot-scale hydroponic green roof [...] Read more.

Stormwater and greywater are increasingly recognized as freshwater resources, and the effective separation and reutilization of nitrogen (N) and phosphorus (P) from these streams is vital for water quality improvement and urbanization sustainability. In this study, we constructed a pilot-scale hydroponic green roof wetland system planted with two economically important Chinese herbal plant species (Mentha spicata L. (ML) and Basella alba L. (BL)) to separate and reutilize N and P from synthetic stormwater/greywater. The results reveal that the highest plant biomass was obtained at an ML:BL ratio of 1:3, indicating their superior adaptation to rooftop hydroponics with synthetic stormwater/greywater. This configuration also achieved the strongest water purification, with substantial separation and reutilization efficiency of N (82.09%) and P (81.90%). Furthermore, the lowest microbial richness in the ML roots at this specific plant ratio suggested that increasing BL may enhance ML’s allelopathic effects. An increase in the BL proportion was further associated with a gradual shift in the dominant ML root-associated microorganisms toward microeukaryotic taxa. The green vegetation of the two plant species also effectively suppressed algal blooms (especially diatoms) in the hydroponic rooftop system. This study demonstrates that a Chinese herb-based green roof wetland system can effectively separate and reuse N and P from stormwater/greywater while concurrently purifying water and producing economic crops. Full article

(This article belongs to the Section Environmental Separations)

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16 pages, 6019 KB

Open AccessArticle

CFD-DEM Simulation of the Effect of Transverse Inclination Angle on Particle Moving Behavior in Spiral Separation

by Wanzhong Liu, Guichuan Ye and Penghui Liu

Separations 2026, 13(2), 73; https://doi.org/10.3390/separations13020073 - 19 Feb 2026

Cited by 1 | Viewed by 479

Abstract

Spiral separators commonly face the issue of particle misplacement during fine particle separation, which severely limits separation accuracy. This study employs a coupled CFD-DEM numerical simulation method to systematically investigate the influence mechanism of transverse inclination angle (10°, 15°, 20°) on particle moving [...] Read more.

Spiral separators commonly face the issue of particle misplacement during fine particle separation, which severely limits separation accuracy. This study employs a coupled CFD-DEM numerical simulation method to systematically investigate the influence mechanism of transverse inclination angle (10°, 15°, 20°) on particle moving behavior. The results show that the separation process exhibits distinct stage characteristics, which can be divided into an initial stage (first 1/3 turn), a transition stage (1/3 to 2 turns), and a quasi-steady stage (after 2 turns). A steeper angle (20°) optimizes the flow field, reducing the inner low-velocity zone and widening the high-velocity core, which promotes inward migration of particles. This enhances the enrichment of high-density particles while effectively suppressing their mixing into the clean coal product at the outer edge. For difficult-to-separate fine particles below 0.1 mm, although complete separation is challenging, increasing the transverse inclination angle still shows a clear reduction in the misplacement of high-density particles, providing a controllable approach for improving the quality of the outer edge product. This study offers theoretical insights and design guidance for optimizing spiral separator structures and enhancing fine coal separation efficiency. Full article

(This article belongs to the Special Issue Separation Technology in Mineral Processing)

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16 pages, 2336 KB

Open AccessArticle

Isolation of (+)-Catechin from Food Waste Using Ionic Liquid-Modified ZIF67 Covered Silica

by Mengshuai Liu, Xiaoman Li, Mengmeng Zhao, Xuyang Jiu, Chuang Yao and Minglei Tian

Separations 2026, 13(2), 72; https://doi.org/10.3390/separations13020072 - 19 Feb 2026

Viewed by 357

Abstract

Background: Food waste contains abundant (+)-catechin, but its efficient recovery remains challenging. This study aimed to prepare ionic liquid (IL)-modified sorbents and establish an efficient method for (+)-catechin recovery from chocolate waste via solid-phase extraction (SPE). Methods: Three series of IL-modified sorbents (Sil-IL, [...] Read more.

Background: Food waste contains abundant (+)-catechin, but its efficient recovery remains challenging. This study aimed to prepare ionic liquid (IL)-modified sorbents and establish an efficient method for (+)-catechin recovery from chocolate waste via solid-phase extraction (SPE). Methods: Three series of IL-modified sorbents (Sil-IL, ZIF67-IL, Sil@ZIF67-IL) were synthesized. Their adsorption performance was evaluated under different conditions; adsorption isotherm and kinetic data were fitted to Langmuir/Freundlich and pseudo-first/second-order models, respectively. Sorbent stability and (+)-catechin recovery from chocolate waste extracts were tested. Results: Sil@ZIF67-Hmim showed the highest adsorption capacity (154.4 mg/g) at 25 °C within 120 min. Adsorption followed the Langmuir model (R² = 0.99), indicating chemisorption. Sil@ZIF67-Hmim was subjected to repeated solid-phase extraction (SPE) for five consecutive days; the recovery rate ranged from 98.1% to 99.2%, and the relative standard deviation (RSD) was 3.2–4.4%. Conclusions: Sil@ZIF67-Hmim is a high-efficiency sorbent for (+)-catechin recovery from chocolate waste, providing a novel approach for food waste valorization and highlighting the application potential of IL-modified MOF-silica composites. Full article

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

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14 pages, 45671 KB

Open AccessArticle

Efficient Removal of Sr²⁺ by a Layered Metal Sulfide K_1.36Cd_1.12Bi_2.80S₆ via Ion Exchange

by Lenian Qu, Yuxin Fang, Ziyi Wan, Meiling Feng and Xiaoying Huang

Separations 2026, 13(2), 71; https://doi.org/10.3390/separations13020071 - 18 Feb 2026

Viewed by 597

Abstract

As a fission product of ²³⁵U or ²³⁹Pu, ⁹⁰Sr is a β-emitting radionuclide with a relatively long half-life (t_1/2 = 28.9 years). Due to its high solubility, easy environmental mobility, and propensity for bioaccumulation within the food [...] Read more.

As a fission product of ²³⁵U or ²³⁹Pu, ⁹⁰Sr is a β-emitting radionuclide with a relatively long half-life (t_1/2 = 28.9 years). Due to its high solubility, easy environmental mobility, and propensity for bioaccumulation within the food chain, the development of efficient materials for the selective capture of ⁹⁰Sr²⁺ is critical for the safe disposal of nuclear waste and environmental protection. In this study, a layered metal sulfide, K_1.36Cd_1.12Bi_2.80S₆ (denoted as KCBS), was synthesized via the high-temperature solid-phase method using K₂CO₃ as the potassium source. KCBS demonstrates high adsorption performance towards Sr²⁺, achieving a maximum adsorption capacity (q_m^Sr = 77 mg·g⁻¹). Moreover, it can maintain high adsorption efficiency (R^Sr > 84.15%) across a broad pH range of 2.98–12.01. In addition, KCBS exhibits the outstanding selectivity for Sr²⁺ removal in the presence of excessive Na⁺ ions and even in actual water samples. KCBS also possesses regenerability, maintaining its superior adsorption capacity for Sr²⁺ ions over three cycles. The mechanism study by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analyses indicates that the efficient Sr²⁺ capture is attributed to the ion exchange between Sr²⁺ and interlayer K⁺ ions in KCBS. This research further highlights the potential of layered metal sulfide ion exchange materials for radionuclide remediation. Full article

(This article belongs to the Special Issue Separation Technology for Resource Utilization and Recovery)

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16 pages, 2652 KB

Open AccessArticle

Separation and Recovery of Fe and REEs from a Hydrochloric Acid Leachate of NdFeB Waste Using Aliquat 336-Based Solvent Extraction

by Lushuai Yao, Zishuai Liu, Zhihui Zhao, Qianwen Li, Enhao Li and Huiyang Lin

Separations 2026, 13(2), 70; https://doi.org/10.3390/separations13020070 - 16 Feb 2026

Viewed by 568

Abstract

Neodymium–iron–boron (NdFeB) waste represents a valuable secondary source of rare earth elements (REEs). However, existing recovery technologies face several challenges, such as the difficulty of selectively recovering REEs, the generation of large volumes of secondary iron-rich slag, and an overall low level of [...] Read more.

Neodymium–iron–boron (NdFeB) waste represents a valuable secondary source of rare earth elements (REEs). However, existing recovery technologies face several challenges, such as the difficulty of selectively recovering REEs, the generation of large volumes of secondary iron-rich slag, and an overall low level of comprehensive resource utilization. In this study, Aliquat 336 was applied for the selective extraction and separation of REEs and iron (Fe) from hydrochloric acid leachate derived from NdFeB waste. Experimental results showed that under optimized conditions—specifically, a 15% Aliquat 336 concentration, an organic-to-aqueous phase ratio of 1:2, and a 2 min extraction time—Fe extraction efficiency reached 99.93% after three-stage countercurrent extraction, while REEs were predominantly retained in the aqueous phase. Subsequent oxalic acid precipitation of the raffinate yielded RE₂(C₂O₄)₃·10H₂O with a purity of 99.60%. Moreover, under stripping conditions of 2 mol/L NaOH, a phase ratio of 2:1 (aqueous to organic), and a 2 min contact time, over 99.21% of Fe was stripped after three-stage countercurrent stripping, resulting in Fe(OH)₃ with a purity of 99.26%. The extraction mechanism followed an anion-exchange process: under high chloride ion concentrations, Fe³⁺ formed anionic FeCl₄⁻ complexes, which were exchanged with Cl⁻ ions in Aliquat 336 and transferred into the organic phase, whereas RE³⁺ cations remained in the aqueous phase, enabling efficient separation of Fe and REEs. These findings provide important insights for improving the comprehensive utilization of NdFeB waste and promoting the green and sustainable development of secondary rare earth resource recycling. Full article

(This article belongs to the Special Issue Efficient Extraction, Separation and Purification of Critical Metal Resources)

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17 pages, 8016 KB

Open AccessArticle

Synergistic Adsorption and Bioreduction of Cr(VI) by a New Composite Material: Effect of Biochar and Immobilized Bacillus subtilis

by Huanlian Wang, Fang Wang, Lu Di, Chuanyun Gao, Deli Zhang, Shaoqing Wang, Min Lv and Weiming Yi

Separations 2026, 13(2), 69; https://doi.org/10.3390/separations13020069 - 16 Feb 2026

Viewed by 580

Abstract

This study investigates the preparation of a composite material by immobilizing Bacillus subtilis on biochar derived from chicken manure biogas residue for the removal of Cr(VI) from wastewater. The results demonstrated that the composite material (Bacillus subtilis immobilized biochar, BIB) achieved a [...] Read more.

This study investigates the preparation of a composite material by immobilizing Bacillus subtilis on biochar derived from chicken manure biogas residue for the removal of Cr(VI) from wastewater. The results demonstrated that the composite material (Bacillus subtilis immobilized biochar, BIB) achieved a maximum Cr(VI) removal efficiency of 94.1% in a 100 mg/L Cr(VI) solution within 4 h. The chicken manure-derived biochar not only served as an effective carrier for Bacillus subtilis but also enhanced the Cr(VI) removal efficiency through a synergistic effect with the microorganism. Functional groups such as phosphorus, carboxyl, and hydroxyl groups on the biochar surface played a key role in the sorption of Cr(VI). Bacillus subtilis primarily reduced Cr(VI) to Cr(III) by secreting cellular reductases. The combined action of biochar and Bacillus subtilis increased the Cr(VI) removal rate by 13.71% compared to biochar alone. This study presents a promising approach for Cr(VI) remediation in contaminated water and lays a theoretical foundation for the development of composite materials for Cr(VI) reduction. Full article

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15 pages, 686 KB

Open AccessArticle

An Efficient and Greener Alternative for the Extraction of Polycyclic Aromatic Compounds from Sediments

by Zhe Xia, Xinyu Gao, Thor Halldorson, Nipuni Vitharana, Chris Marvin, Philippe J. Thomas and Gregg T. Tomy

Separations 2026, 13(2), 68; https://doi.org/10.3390/separations13020068 - 15 Feb 2026

Viewed by 420

Abstract

This study details the validation of a novel microbead beating extraction (MBE) technique for the analysis of polycyclic aromatic compounds (PACs) in sediments. The method’s performance was evaluated against international analytical validation criteria, including trueness, precision, measurement uncertainty and robustness. Limits of detection [...] Read more.

This study details the validation of a novel microbead beating extraction (MBE) technique for the analysis of polycyclic aromatic compounds (PACs) in sediments. The method’s performance was evaluated against international analytical validation criteria, including trueness, precision, measurement uncertainty and robustness. Limits of detection and quantitation were consistently low (≤6.5 and 21 ng g⁻¹, respectively), trueness for the majority of analytes fell within accepted performance criteria, and repeatability values for most analytes were generally <10%. Analytical data confirm the method’s reliability, with more than 80% of certified analytes in two certified reference materials (CRMs) meeting the satisfactory z-score (∣z∣ ≤ 2.0). Furthermore, the method’s inter-laboratory repeatability, as measured by HorRat values, fell within the range recommended by the Association for Official Analytical Chemist for most analytes, and combined measurement uncertainties showed no statistical difference from the certified uncertainties of the CRMs. Incorporating an in situ cleanup step enabled the MBE method to substantially reduce extraction times (<15 min) and reduces solvent consumption by ~60% compared with conventional pressurize fluid extraction while maintaining good quality data objectives. By meeting or exceeding well-established metrics for good laboratory performance, the MBE method demonstrates reliability, efficiency, and a greener approach for the routine analysis of PACs in sediments. Full article

(This article belongs to the Special Issue Advancements in Microextraction Techniques for Environmental and Food Sample Analysis)

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26 pages, 3728 KB

Open AccessArticle

Chiral Separation of Menthol Enantiomers by Simulated Moving Bed Chromatography: Mathematical Modeling and Experimental Study

by Linhe Sun, Ying Yang and Jianguo Yu

Separations 2026, 13(2), 67; https://doi.org/10.3390/separations13020067 - 14 Feb 2026

Cited by 1 | Viewed by 622

Abstract

l-menthol is one of the most popular flavors in the world. The separation of menthol enantiomers is crucial because of the unpleasant taste of d-menthol. This work presents the chiral separation of racemic menthol by simulated moving bed chromatography for the first time. [...] Read more.

l-menthol is one of the most popular flavors in the world. The separation of menthol enantiomers is crucial because of the unpleasant taste of d-menthol. This work presents the chiral separation of racemic menthol by simulated moving bed chromatography for the first time. Six preparative columns packed with amylose 3,5-dimethylphenylcarbamate coated on silica gel were used for separation, and a mixture of n-hexane/isopropanol was selected as the mobile phase. The hydrodynamic properties of the SMB columns were studied to minimize the packing asymmetry in the SMB experiment. The binary adsorption isotherm of menthol enantiomers was measured by the adsorption–desorption method. Fixed-bed batch chromatography was carried out to evaluate the adsorption kinetic behavior. Mathematical models, considering the mass transfer resistance and axial dispersion, were applied to describe the dynamics of the chromatographic separation process. The SMB process for chiral separation of racemic menthol was designed by evaluating the separation region using simulations. Reasonable agreements were achieved between the predicted results and the experimental results. Purities for both the extract and raffinate were above 99.0%, and a productivity of 0.267 g_racemate/(L_CSP∙min) and a solvent consumption of 0.431 L/g_racemate were achieved. Full article

(This article belongs to the Topic Processing Design and Intensification in Chemical Engineering)

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16 pages, 2173 KB

Open AccessReview

A Review of the Application of Oxalic Acid in Hydrometallurgical Processes

by Muling Sheng, Zishuai Liu, Zhihui Zhao, Qianwen Li, Wenbin Liu, Heng Luo and Yancheng Lv

Separations 2026, 13(2), 66; https://doi.org/10.3390/separations13020066 - 12 Feb 2026

Cited by 1 | Viewed by 1546

Abstract

Conventional hydrometallurgical processes typically employ inorganic acids as leaching agents; however, these processes are frequently associated with significant environmental pollution and suffer from poor metal selectivity. Oxalic acid, as a green alternative leaching agent, demonstrates considerable application potential owing to its mild acidity, [...] Read more.

Conventional hydrometallurgical processes typically employ inorganic acids as leaching agents; however, these processes are frequently associated with significant environmental pollution and suffer from poor metal selectivity. Oxalic acid, as a green alternative leaching agent, demonstrates considerable application potential owing to its mild acidity, strong reducing capability, and superior complexing properties. This paper presents a systematic review of recent advances in the application of oxalic acid in hydrometallurgy, encompassing the coordination chemistry between oxalic acid and metal ions, its role as a selective leaching agent, and strategies for handling multicomponent oxalate-rich solutions. Furthermore, the industrial prospects of oxalic acid-based leaching technologies are discussed. Research indicates that oxalic acid exhibits high selectivity and efficient leaching performance for critical metals—including vanadium, lithium, cobalt, nickel, and gallium—from both primary ores and solid secondary resources. The underlying leaching mechanism primarily involves the formation of stable chelation complexes between oxalate anions and high charge-density metal ions, or valence state modulation via reduction, enabling selective dissolution and separation of target metals. In multicomponent oxalate systems, where metals predominantly exist as anionic complexes, established enrichment and purification approaches include anion exchange extraction, as well as precipitation techniques based on valence adjustment and double salt crystallization. To advance the industrial implementation of oxalic acid leaching technologies, further in-depth investigation is required into the recycling mechanisms of oxalic acid and the fundamental reaction pathways governing leaching and metal recovery processes. Full article

(This article belongs to the Special Issue Efficient Extraction, Separation and Purification of Critical Metal Resources)

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7 pages, 816 KB

Open AccessArticle

Performance Benchmarking for Thermal Modulators in Comprehensive Two-Dimensional Gas Chromatography: Evaluation of the Solid-State Modulator

by Jason Devers and Philip J. Marriott

Separations 2026, 13(2), 65; https://doi.org/10.3390/separations13020065 - 12 Feb 2026

Viewed by 525

Abstract

The recently introduced solid-state modulator (SSM) is a compact and relatively simple all-in-one solution to thermal modulation for use in comprehensive two-dimensional gas chromatography (GC×GC). In this work, we assess the performance of this modulator through a detailed assessment of its temperature stability [...] Read more.

The recently introduced solid-state modulator (SSM) is a compact and relatively simple all-in-one solution to thermal modulation for use in comprehensive two-dimensional gas chromatography (GC×GC). In this work, we assess the performance of this modulator through a detailed assessment of its temperature stability and temperature programming capabilities, and corresponding retention time reproducibility. Through replicate analysis, ²D retention time standard deviation was determined to be 0.014 s (ranging from 0.000–0.023 s), corresponding to less than a single acquisition datapoint. Additionally, ¹D retention time repeatability in GC×GC was assessed using a ‘super-resolution method’ designed to predict ¹D retention based on the modulated peak distribution, and was determined to be comparable to that of conventional GC-MS analysis. A benchmarking framework was developed, which can be applied to future performance evaluations of thermal and other modulators, allowing for a more systematic comparison of modulation strategies. Full article

(This article belongs to the Section Chromatographic Separations)

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25 pages, 2500 KB

Open AccessArticle

Evaluation of Blood Odor Signatures from Cadaveric Origin

by Lakshmi Reddi, Rex Johnson, Kerry K. Gilbert and Paola A. Prada-Tiedemann

Separations 2026, 13(2), 64; https://doi.org/10.3390/separations13020064 - 11 Feb 2026

Viewed by 1915

Abstract

Blood is a key biological specimen in forensic analysis for both living and deceased individuals, playing a crucial role in drug testing, blood typing, DNA analysis, and bloodstain pattern examination. In forensics, the decomposition of blood holds particular importance because it is a [...] Read more.

Blood is a key biological specimen in forensic analysis for both living and deceased individuals, playing a crucial role in drug testing, blood typing, DNA analysis, and bloodstain pattern examination. In forensics, the decomposition of blood holds particular importance because it is a major biological fluid in the human body and undergoes early chemical changes that attract insects and microorganisms to cadaveric sources. The odor signatures produced during the putrefactive process have recently gained forensic relevance, prompting studies to investigate volatile organic compounds (VOCs) from blood, tissues, animal proxies, and human cadavers to enhance human remains detection and recovery via technological or biological means. This study focuses on cadaveric blood odor profiling, evaluating VOC signatures from human cadavers in an anatomy laboratory using solid-phase micro-extraction (SPME) and gas chromatography–mass spectrometry (GC/MS) upon body receipt. A second phase entailed a degradation analysis using 7 human cadavers and a total of 28 postmortem samples repeatedly sampled over a 4-week period. The findings revealed an increasingly complex odor profile as decomposition progresses, with a notable rise in both the variety and concentration of VOCs. Room temperature samples exhibited a more diverse and rapid VOC release, while refrigerated samples showed slower degradation. These insights contribute to a deeper understanding of decomposition patterns and ultimately refine human remains detection methodologies. Full article

(This article belongs to the Section Chromatographic Separations)

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12 pages, 2369 KB

Open AccessArticle

Simultaneously Activating Semiconductor/Electrocatalyst/Electrolyte Interfaces by F Engineering for Efficient Solar Water Splitting

by Jingjing Quan, Yuting Zheng, Lan Yao, Lianqing Li and Xingming Ning

Separations 2026, 13(2), 63; https://doi.org/10.3390/separations13020063 - 11 Feb 2026

Viewed by 377

Abstract

The highly efficient performance of photoelectrochemical (PEC) water splitting is largely governed by the construction of active interfaces, especially for the star semiconductor/electrocatalyst system. However, traditional strategies struggle to optimize this critical process. To overcome this challenge, we report a fluorine (F) engineering [...] Read more.

The highly efficient performance of photoelectrochemical (PEC) water splitting is largely governed by the construction of active interfaces, especially for the star semiconductor/electrocatalyst system. However, traditional strategies struggle to optimize this critical process. To overcome this challenge, we report a fluorine (F) engineering strategy that enables the synchronous modulation of charge transfer and surface catalytic reaction dynamics in a BiVO₄/FeCoOOH-integrated photoanode. Various characterization methods confirm that F engineering can activate the BiVO₄/FeCoOOH/electrolyte interfaces. Benefiting from these positive effects, the optimized BiVO₄/FeCoOOH-F photoanode achieves a relatively high photocurrent density of 5.46 mA/cm² at 1.23 V vs. RHE, along with outstanding photostability and a small Tafel slope of 96.5 mV dec⁻¹. This study provides new insights into F-based interface manipulation, offering a promising route to developing high-performance semiconductor/electrocatalyst systems for efficient and stable PEC water splitting applications. Full article

(This article belongs to the Special Issue Photoelectrocatalytic Organic Pollutant Degradation and Water Splitting)

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21 pages, 4031 KB

Open AccessReview

Research Progress in Flocculation Treatment of Aggregate Washing Wastewater: Mechanisms, Innovations, and Challenges

by Luogeng Ge, Fengsheng Guo, Jiawei Wang, Jing Zhang, Qi Lu, Yuanyi Wang, Xingdong Lv, Ziling Peng, Xian Zhou, Xia Chen, Wei Han and Zeyu Fan

Separations 2026, 13(2), 62; https://doi.org/10.3390/separations13020062 - 10 Feb 2026

Viewed by 944

Abstract

Rapid growth of water conservancy/hydropower projects has spurred rising demand for sand-gravel aggregates. Under strict water use and zero-waste policies, treating wet-process aggregate washing wastewater is challenging. Flocculants—key chemicals in this process—directly influence treatment efficiency and operational costs via their type, dosage, and [...] Read more.

Rapid growth of water conservancy/hydropower projects has spurred rising demand for sand-gravel aggregates. Under strict water use and zero-waste policies, treating wet-process aggregate washing wastewater is challenging. Flocculants—key chemicals in this process—directly influence treatment efficiency and operational costs via their type, dosage, and efficacy. Further development of the intelligent control system for flocculant dosing can reduce flocculant consumption by 50% to 67%. However, existing studies have an insufficient understanding of the identification of emerging contaminants in aggregate washing wastewater and the migration of flocculants in multi-medium environments, as well as a lack of research on the synergistic effects of multiple flocculants. Another key core challenge lies in the accurate identification of the impact of flocculant residues on concrete performance, along with the problems of high cost and poor adaptability of intelligent systems. Future research directions will focus on precise flocculation, residue control and resource utilization to drive the development of efficient and environmentally friendly treatment technologies. Full article

(This article belongs to the Section Separation Engineering)

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19 pages, 3028 KB

Open AccessArticle

Structural and Surface Properties of CeO₂ Nanoparticles for Enhanced Lead Ion Removal

by Bakheit Mustafa and Ard Elshifa M. E. Mohammed

Separations 2026, 13(2), 61; https://doi.org/10.3390/separations13020061 - 9 Feb 2026

Cited by 1 | Viewed by 1054

Abstract

In this study, cerium oxide (CeO₂) nanoparticles were successfully synthesized using a simple and cost-effective hydroxide-mediated precipitation method. Comprehensive characterization (XRD, SEM, TEM, FTIR, BET, and UV–Vis) confirmed the formation of uniformly distributed nanoparticles with an average size of ~100 nm, [...] Read more.

In this study, cerium oxide (CeO₂) nanoparticles were successfully synthesized using a simple and cost-effective hydroxide-mediated precipitation method. Comprehensive characterization (XRD, SEM, TEM, FTIR, BET, and UV–Vis) confirmed the formation of uniformly distributed nanoparticles with an average size of ~100 nm, a well-defined crystalline structure, and a high specific surface area of 118.96 m²/g. The CeO₂ nanoparticles also exhibited a mesoporous framework with a pore volume of 0.39 cm³/g and an average pore radius of 2.27 nm, demonstrating favorable properties for adsorption applications. Adsorption experiments showed that CeO₂ nanoparticles effectively removed Pb²⁺ from aqueous solutions, achieving a maximum experimental adsorption capacity of 192 mg/g and a removal efficiency of 80% at pH 6 under the tested conditions. Kinetic analysis revealed that the pseudo-second-order model best described the adsorption process, suggesting chemisorption as the dominant mechanism, while equilibrium data were more accurately represented by the Langmuir isotherm model, which predicted a theoretical monolayer capacity (Qm) of 714.2 mg/g. Overall, the findings demonstrate that CeO₂ nanoparticles possess a strong affinity toward Pb²⁺ ions and exhibit promising adsorption performance, indicating their potential applicability for the treatment of lead-contaminated wastewater and their suitability for reuse following regeneration. Full article

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14 pages, 3775 KB

Open AccessArticle

Understanding and Mitigating Corona Quenching in ESPs Under High Fly Ash Concentrations in a 660 MW Coal-Fired Unit

by Haibao Zhao, Peiyuan Li, Hanxiao Liu, Tao Liu and Zhengda Yang

Separations 2026, 13(2), 60; https://doi.org/10.3390/separations13020060 - 8 Feb 2026

Viewed by 498

Abstract

Corona quenching is a major obstacle to the stable and efficient operation of electrostatic precipitators (ESPs) in coal-fired power plants, particularly under high-ash coal combustion. This study evaluates a novel double-V labyrinth pre-collection device as an active strategy to mitigate corona quenching. Field [...] Read more.

Corona quenching is a major obstacle to the stable and efficient operation of electrostatic precipitators (ESPs) in coal-fired power plants, particularly under high-ash coal combustion. This study evaluates a novel double-V labyrinth pre-collection device as an active strategy to mitigate corona quenching. Field measurements from a 660 MW ultra-supercritical coal-fired unit, combined with computational fluid dynamics (CFD) simulations, demonstrate that the retrofit significantly improved inlet flow uniformity and reduced fly ash concentration before the ESP. Consequently, corona discharge stability was enhanced, overall collection efficiency increased from 99.42% to 99.92%, and outlet fly ash concentration decreased from 81 mg/m³ to 20.5 mg/m³. Although the pressure drop rose modestly (128 Pa to 187.5 Pa), the overall ESP energy demand was reduced due to more stable operation at lower voltages. These results confirm the technical feasibility and engineering applicability of pre-collection technology, providing a cost-effective solution to overcome corona quenching and ensure ultra-low emission compliance in large coal-fired units. Full article

(This article belongs to the Special Issue Numerical Modeling and Computation in Separation and Adsorption)

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15 pages, 2961 KB

Open AccessArticle

Lanthanum Nitrate Modification of Soybean Protein Activated Carbon for Enhanced Fluoride Adsorption

by Zhengnan Jiang, Guanyu Zhou, Wenchao Bu, Zhenhai Huang and Chunlin He

Separations 2026, 13(2), 59; https://doi.org/10.3390/separations13020059 - 7 Feb 2026

Viewed by 486

Abstract

Water with a high fluoride content poses a serious threat to both public health and the natural environment. To enhance fluoride ion removal efficiency, a modified activated carbon adsorbent (HPAC-La) was synthesized by impregnating soybean protein in a lanthanum nitrate solution, followed by [...] Read more.

Water with a high fluoride content poses a serious threat to both public health and the natural environment. To enhance fluoride ion removal efficiency, a modified activated carbon adsorbent (HPAC-La) was synthesized by impregnating soybean protein in a lanthanum nitrate solution, followed by freezing–drying and carbonization. The results confirmed that lanthanum nitrate modification significantly improved the adsorption performance. Under optimised experimental conditions (pH = 2.0, [F⁻] = 300 mg·L⁻¹, 12 h, 298 K), HPAC-La exhibited a maximum adsorption capacity for fluoride ions of 126.7 mg·L⁻¹, significantly higher than that of unmodified HPAC (86.1 mg·L⁻¹). The adsorption process followed the pseudo-second-order kinetic model and the Langmuir isotherm model, indicating monolayer chemisorption. The mechanism involves ion exchange via surface hydroxyl groups and fluoride coordination with La sites. This study proposes a method for developing highly efficient adsorbents for the treatment of fluoride-contaminated wastewater. Full article

(This article belongs to the Special Issue Adsorption Methods for Environmental Purification)

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11 pages, 800 KB

Open AccessArticle

Determination of Paracetamol and Orphenadrine Citrate in Tablets via a Novel RP-HPLC Method: Development Following Box–Behnken Design, Validation, Robustness Testing, and Greenness Assessment

by Dimitris Valatsos, Kostas Gkountanas and Yannis Dotsikas

Separations 2026, 13(2), 58; https://doi.org/10.3390/separations13020058 - 6 Feb 2026

Viewed by 847

Abstract

Paracetamol (PAR) and orphenadrine citrate (ORPH) are two active substances commonly used in combination medicinal products, due to the analgesic effect of paracetamol and the muscle relaxant effect of orphenadrine, with a therapeutic indication of mild to moderate acute musculoskeletal pain. The aim [...] Read more.

Paracetamol (PAR) and orphenadrine citrate (ORPH) are two active substances commonly used in combination medicinal products, due to the analgesic effect of paracetamol and the muscle relaxant effect of orphenadrine, with a therapeutic indication of mild to moderate acute musculoskeletal pain. The aim of this work is to develop and validate an isocratic HPLC method for the simultaneous determination of PAR and ORPH in tablet formulation. Preliminary experiments showed that an analytical column with a chemically bound phenyl phase was required. A Box–Behnken design (BBD) was utilized to optimize the analytical method for two key responses, PAR asymmetry factor (Asym_PAR) and ORPH capacity factor (k_ORPH), with three numerical factors: percentage of ACN in mobile phase (A); pH (B); and salt concentration in the aqueous solution (C). The optimized method consists of a Pinnacle DB Biphenyl (250 × 4.6 mm) 5 µm column, and a mobile phase of 37%/63% v/v ACN-NaH₂PO4·H₂O in 29 mM aqueous solution, pH = 2.5. The flow rate was set to 1.5 mL/min and detection occurred at 215 nm. After the optimization process the following chromatographic conditions were selected and the method was validated for various ICH parameters covering system suitability, specificity, linearity (R² = 1.00), precision (%RSD ≤ 2), accuracy (98% ≤ %Recovery ≤ 102%), and robustness. Finally, the environmental friendliness of the novel method was assessed by using the Analytical GREEnness (AGREE) metric tool, obtaining a score of 0.67. Full article

(This article belongs to the Special Issue Determination and Quantification of Pharmaceuticals Using Chromatography Methods)

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21 pages, 3584 KB

Open AccessArticle

Efficient and Rapid Removal of Cationic Methylene Blue from Aqueous Solution by Alkali-Treated Bamboo Powders as Biosorbents

by Qin Wang, Yaohui Xu, Jinqiang Yu, Runhong Xia, Zhiyun Jiang, Yuan Zhang and Fangyu Xiong

Separations 2026, 13(2), 57; https://doi.org/10.3390/separations13020057 - 6 Feb 2026

Cited by 1 | Viewed by 519

Abstract

To develop low-cost and renewable materials for treating dye wastewater, an efficient biosorbent was prepared from Bambusa emeiensis bamboo powders (BPs) via a simple alkali pretreatment. Systematic investigation revealed that NaOH concentration was critical for enhancing adsorption performance. Under optimal conditions (NaOH ≥ [...] Read more.

To develop low-cost and renewable materials for treating dye wastewater, an efficient biosorbent was prepared from Bambusa emeiensis bamboo powders (BPs) via a simple alkali pretreatment. Systematic investigation revealed that NaOH concentration was critical for enhancing adsorption performance. Under optimal conditions (NaOH ≥ 0.2 mol/L, dosage = 10.0 g/L), the BPs achieved over 96% removal of cationic Methylene Blue (MB, 20 mg/L) within 20 min, demonstrating rapid kinetics. The adsorption process followed the Langmuir isotherm model with a maximum adsorption capacity of 4.1 mg/g without adjusting the pH of the solution and complied with the pseudo-second-order kinetic model. Thermodynamic analysis confirmed the spontaneous (ΔG < 0) and exothermic (ΔH = −52.73 kJ/mol) nature of the adsorption. Notably, the alkali-treated BPs exhibited a pronounced preference for the cationic dye, achieving a high removal rate of 96.5% for MB, in contrast to a much lower removal of 23.6% for the anionic dye AO7 under identical single-dye conditions, attributed to the enhanced surface negative charge after alkali treatment. Furthermore, the BPs maintained a high removal efficiency of 91.2% after eight adsorption-desorption cycles using 0.1 mol/L HCl as eluent, demonstrating excellent reusability. This study presents a feasible and sustainable strategy for designing regenerative bamboo-based biosorbents with rapid and preferential adsorption capabilities for cationic dye wastewater. Full article

(This article belongs to the Special Issue Environmental Functional Materials for Pollutant Separation and Remediation)

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20 pages, 6659 KB

Open AccessArticle

Tetraethylenepentamine-Grafted Magnetic Polymer Composite as Promising Sorbent for CO₂ Capture

by Nenad Radić, Aleksandra Nastasović, Tamara Tadić, Zorica Vuković, Jugoslav Krstić and Bojana Marković

Separations 2026, 13(2), 56; https://doi.org/10.3390/separations13020056 - 5 Feb 2026

Viewed by 661

Abstract

In this study, magnetic porous glycidyl methacrylate and ethylene glycol dimethacrylate copolymer (mP) grafted with tetraethylenepentamine (mP-TEPA) obtained in a two-step procedure was tested as the CO₂ sorbent. The morphological, textural, structural, and thermal characterization of the sample was determined by scanning [...] Read more.

In this study, magnetic porous glycidyl methacrylate and ethylene glycol dimethacrylate copolymer (mP) grafted with tetraethylenepentamine (mP-TEPA) obtained in a two-step procedure was tested as the CO₂ sorbent. The morphological, textural, structural, and thermal characterization of the sample was determined by scanning electron microscopy with energy-dispersive X-ray analysis (SEM-EDS), mercury intrusion porosimetry (MIP), nitrogen physisorption at 77 K, Fourier transform infrared spectroscopy in ATR mode (FTIR-ATR), X-ray photoelectron spectroscopy (XPS), elemental analysis, and thermogravimetric analysis (TGA). The effects of thermodynamic and kinetic parameters, as well as the adsorption/desorption mechanism on the CO₂ sorption ability of mP-TEPA, were investigated using a pulse gas chromatographic method. Under optimal adsorption conditions, the CO₂ sorption capacity reached 6.20 mmol CO₂/g (6.20 × 10⁻² mmol CO₂/m²). Temperature-programmed desorption (TPD) experiments were conducted to calculate the activation energy of CO₂ desorption. The low desorption activation energy of 18.80 kJ/mol and high desorption rate, with stable CO₂ uptake after ten adsorption/desorption cycles, suggest that mP-TEPA is a potentially excellent sorbent for CO₂ adsorption. Full article

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

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15 pages, 1701 KB

Open AccessReview

Selective Recovery Lithium from Mother Liquor via Solvent Extraction: A Review on Extractants, Mechanisms, and Efficiency

by Xiaofei Meng, Xiaoping Zou, Yingping Jiang, Haitao Zhou, Jiantao Zhao, Shengmei Zhang and Junqi Zhang

Separations 2026, 13(2), 55; https://doi.org/10.3390/separations13020055 - 5 Feb 2026

Viewed by 926

Abstract

With the rapid expansion of the global lithium battery industry, the demand for lithium as a critical raw material continues to grow. Lithium precipitation mother liquor still contains considerable concentrations of lithium ions (Li⁺), but they generally exhibit a high sodium-to-lithium [...] Read more.

With the rapid expansion of the global lithium battery industry, the demand for lithium as a critical raw material continues to grow. Lithium precipitation mother liquor still contains considerable concentrations of lithium ions (Li⁺), but they generally exhibit a high sodium-to-lithium ratio, which makes the separation of lithium from sodium particularly challenging. Solvent extraction is recognized as a viable approach for challenging Li⁺/Na⁺ separation due to its high selectivity, operational flexibility, and scalability. A comprehensive assessment and comparison of various extraction systems are therefore essential to facilitate the sustainable recovery of lithium from precipitation mother liquor. This review summarizes the commonly used extraction systems, including organophosphorus extractants, ketone-based extractants, macrocyclic compounds, ionic liquids, and deep eutectic solvents. A systematic analysis is provided regarding their extraction mechanisms, applicable conditions, and respective advantages and disadvantages. Finally, perspectives and suggestions are offered on future research directions and improvement strategies for different extraction systems, along with an outlook on the potential of combined enhancement technologies. Full article

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11 pages, 386 KB

Open AccessArticle

Flavonoid Characterization of Primula vulgaris Growing in the Biodiversity Hotspot of Prespa Lake Region (NW Greece)

by Elli Katsouli, Konstantia Graikou, Evgenia Panou, Nikolas Fokialakis and Ioanna Chinou

Separations 2026, 13(2), 54; https://doi.org/10.3390/separations13020054 - 2 Feb 2026

Viewed by 642

Abstract

Primula vulgaris Huds., one of the 33 Primula L. species native to Europe, occurs across diverse habitats, including the biodiversity hotspot of the Prespa Lake region (NW Greece). Building on previous phytochemical studies, the present work provides the first detailed characterization of flavonoids [...] Read more.

Primula vulgaris Huds., one of the 33 Primula L. species native to Europe, occurs across diverse habitats, including the biodiversity hotspot of the Prespa Lake region (NW Greece). Building on previous phytochemical studies, the present work provides the first detailed characterization of flavonoids from the aerial parts of the species growing wild in the area. Using classical chromatographic separation methods combined with spectrometric techniques, seven metabolites were isolated and structurally elucidated from the dichloromethane and methanol extracts. These included flavone (1), 2′-methoxyflavone (2), 3′-methoxyflavone (3), 3′-hydroxy-4′,5′-dimethoxyflavone (4), kaempferol-3-O-β-glucopyranosyl-(1→2)-β-glucopyranosyl-(1→6)-β-glucopyranoside (6), 3′-hydroxyflavone-4′-O-β-glucopyranoside (7) and 5,6,2′,3′,6′-pentamethoxyflavone (5), which was reported for the first time in this species. Additionally, the total phenolic content (TPC) of the methanol extract was determined using the Folin–Ciocalteu method, demonstrating 46.46 ± 2.48 mg GAE/g extract, while through the DPPH radical scavenging assay, it expressed moderate activity. Overall, these results provide novel insights into the flavonoid composition of Greek P. vulgaris and support its potential for further pharmacological investigations and herbal applications. Full article

(This article belongs to the Special Issue Advances in the Analysis of Bioactive Plant Extracts: Separation Techniques and Their Applications)

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23 pages, 1808 KB

Open AccessArticle

Adsorption of Nystatin from Aqueous Solutions Using Nanoclay: Performance, Mechanisms, and Sustainability Aspects

by Anna Karoline Freires de Sousa, Anna Katharina Medeiros de Brito, Hugo Guimarães Matos, José Lázaro da Silva Fernandes, Francisco Lucas de Lima Carneiro, Francimarcio Geraldo da Silva Gambarra, Wagner Brandão Ramos, Tellys Lins Almeida Barbosa and Meiry Gláucia Freire Rodrigues

Separations 2026, 13(2), 53; https://doi.org/10.3390/separations13020053 - 2 Feb 2026

Viewed by 690

Abstract

The continuous release of pharmaceutical compounds into aquatic environments poses significant challenges to environmental sustainability, as conventional wastewater treatment plants are often ineffective in removing recalcitrant and bioactive molecules. In this study, the adsorption performance of nanoclay was systematically evaluated for the removal [...] Read more.

The continuous release of pharmaceutical compounds into aquatic environments poses significant challenges to environmental sustainability, as conventional wastewater treatment plants are often ineffective in removing recalcitrant and bioactive molecules. In this study, the adsorption performance of nanoclay was systematically evaluated for the removal of nystatin, a polyene antifungal of emerging environmental concern, from aqueous solutions. The effects of solution pH, adsorption kinetics, equilibrium isotherms, and adsorption mechanisms were investigated under environmentally relevant conditions. Nanoclay exhibited outstanding removal efficiency, exceeding 98% across a wide pH range (3–11), thereby demonstrating strong operational robustness and minimal sensitivity to pH variations. Structural and spectroscopic analyses (XRD and FTIR) confirmed that adsorption occurred predominantly on the external surface of the nanoclay, without significant disruption of its lamellar structure, and was governed mainly by hydrophobic interactions and hydrogen bonding. Kinetic data were best described by the pseudo-second-order model, with rapid equilibrium achieved within approximately 20 min, indicating high affinity between nystatin and the adsorbent surface. Equilibrium data were best fitted by the Sips isotherm model, reflecting surface heterogeneity and a favorable adsorption process, with a high maximum adsorption capacity of approximately 911 mg/g. A preliminary cost analysis revealed low raw material costs, while energy consumption, particularly during drying, was identified as the main economic limitation. Overall, the results highlight Nanoclay as an efficient, robust, and promising adsorbent for the sustainable removal of hydrophobic pharmaceutical contaminants from water and wastewater. Full article

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12 pages, 1910 KB

Open AccessArticle

Isolation and Identification of a Strain of Isaria cateniobliqua, Culture Condition Optimization and the Effect of Subculture on Its Active Compounds

by Jie Shang, Hui Zhao and Dun Wang

Separations 2026, 13(2), 52; https://doi.org/10.3390/separations13020052 - 2 Feb 2026

Viewed by 536

Abstract

The genus Isaria is a group of abundant and widely distributed entomopathogenic fungi that plays an important role in the history of traditional Chinese medicine. Entomopathogenic fungi with medicinal value were collected from the field, and optimal temperature and growth media compositions were [...] Read more.

The genus Isaria is a group of abundant and widely distributed entomopathogenic fungi that plays an important role in the history of traditional Chinese medicine. Entomopathogenic fungi with medicinal value were collected from the field, and optimal temperature and growth media compositions were investigated to establish a theoretical foundation for the future development of these strains. A strain of Isaria cateniobliqua, designated ICF, was isolated from soil in the Hualongshan National Nature Reserve in southern Shaanxi. The optimal cultivation temperature and nutrient solution were screened, and the effects of subcultivation on mycelium production, metabolite production, and hydroxyl radical scavenging activity of strain ICF were investigated. The optimal growth temperature for strain ICF was determined to be 21 °C, with the ideal culture medium consisting of glucose and tussah silkworm pupa powder supplemented with KH₂PO₄ and MgSO₄. Mycelium production and cordycepin content peaked in the fourth generation (G4), whereas peak metabolite production and cordycepic acid production occurred in the fifth generation (G5). Polysaccharide content was highest in the first generation (G1), and hydroxyl radical scavenging activity was optimal in G4. Exploring the optimal culture conditions of the strain provides a theoretical basis for its development, utilization, and industrial production for medicinal applications. Full article

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

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19 pages, 803 KB

Open AccessReview

Analytical Strategies for the Determination of Herbicides in Water: Advances in Sample Preparation, Separation, and Detection

by José Luís Guedes, Luís Durão, Luana M. Rosendo, Tiago Rosado and Eugenia Gallardo

Separations 2026, 13(2), 51; https://doi.org/10.3390/separations13020051 - 1 Feb 2026

Viewed by 874

Abstract

Herbicides are widely used agrochemicals and are increasingly recognised as contaminants of emerging concern in aquatic environments due to their extensive application, environmental persistence, and potential ecological and human health impacts. Their determination in water presents significant analytical challenges, as these compounds occur [...] Read more.

Herbicides are widely used agrochemicals and are increasingly recognised as contaminants of emerging concern in aquatic environments due to their extensive application, environmental persistence, and potential ecological and human health impacts. Their determination in water presents significant analytical challenges, as these compounds occur at trace to ultra-trace levels and encompass a wide range of chemical properties, including highly polar and ionic species as well as transformation products. This review provides a critical overview of recent advances in separation technologies for the analysis of herbicides in water, based on peer-reviewed studies published between 2020 and 2025 retrieved from the PubMed and Scopus databases. The discussion focuses on developments in sample preparation, extraction strategies, chromatographic separation, and detection techniques, with particular attention to analytical performance and sustainability. The reviewed studies demonstrate that solid-phase extraction remains central to achieving the lowest detection limits, while miniaturised and greener extraction approaches are increasingly adopted to reduce solvent consumption and simplify workflows. Advances in chromatographic separation and detection, especially liquid chromatography coupled to tandem mass spectrometry, have further enhanced sensitivity and selectivity for a broad range of herbicides. Overall, this review highlights current analytical capabilities and emerging trends, outlining future directions for reliable and sustainable monitoring of herbicides in aquatic environments. Full article

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

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16 pages, 2076 KB

Open AccessArticle

Machine Learning-Driven Prediction of Organic Compound Adsorption onto Microplastics in Freshwater

by Ya Wang, Peng Zhao, Honghong Yi and Xiaolong Tang

Separations 2026, 13(2), 50; https://doi.org/10.3390/separations13020050 - 1 Feb 2026

Cited by 1 | Viewed by 735

Abstract

Obtaining the adsorption equilibrium coefficient (K_d) of organic compounds on microplastics (MPs) is critical for understanding their environmental behaviors. Given the limited availability of these K_d values, it is imperative to develop predictive models for rapid acquisition of K [...] Read more.

Obtaining the adsorption equilibrium coefficient (K_d) of organic compounds on microplastics (MPs) is critical for understanding their environmental behaviors. Given the limited availability of these K_d values, it is imperative to develop predictive models for rapid acquisition of K_d values for different MPs. Herein, seven machine learning-based algorithms, i.e., MLR, RF, GBDT, XGBoost, CatBoost, LightGBM and SVM, were used to establish predictive models on the basis of 173 logK_d values in freshwater. The evaluation parameters, including R²_t, RMSE_t, Q²_v, RMSE_v and Q², indicate that the developed models have a satisfactory predictive capability. The developed MLR models can predict the logK_d values for chlorinated polyethylene (CPE), polybutylene succinate (PBS), polycaprolactone (PCL) and low-density polyethylene (LDPE) MPs. Given the limited performance of MLR in predicting adsorption on PE MPs, RF, GBDT, XGBoost, CatBoost, LightGBM and SVM were employed to develop predictive models, which significantly enhanced the predictive accuracy. The predictive models for PE MPs have a wider AD, covering organic compounds with different functional groups than previous models. Hydrogen bonding, hydrophobic, electrostatic and dispersion interactions may be involved in adsorption. The developed models can serve as efficient tools for estimating the K_d values for different MPs in freshwater, thereby providing the necessary data for evaluating the environmental risks of organic compounds and MPs. Full article

(This article belongs to the Section Environmental Separations)

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14 pages, 1927 KB

Open AccessArticle

Microwave-Assisted Rapid Extraction of Chlorinated Solvents from Low Permeability Rock Samples

by Yongdong Liu, Maria Górecka, Jonathan Kennel, Merrik Kobarfard, Tadeusz Górecki and Beth Parker

Separations 2026, 13(2), 49; https://doi.org/10.3390/separations13020049 - 30 Jan 2026

Viewed by 439

Abstract

Rock matrices, as low-permeability media, play a critical role in controlling the persistence and fate of groundwater contaminants. Accurately quantifying contaminant mass stored in these matrices is therefore essential for understanding contamination transport processes. In this study, a microwave-assisted extraction (MAE) method was [...] Read more.

Rock matrices, as low-permeability media, play a critical role in controlling the persistence and fate of groundwater contaminants. Accurately quantifying contaminant mass stored in these matrices is therefore essential for understanding contamination transport processes. In this study, a microwave-assisted extraction (MAE) method was developed to accelerate the complete extraction of trichloroethylene (TCE) from rock samples. Because microwave–sample interactions depend on multiple factors, extraction conditions, including solvent type, temperature, and extraction time, were optimized using dolostone samples collected from industrial sites with decades-old contamination in Guelph, Canada. Method performance was evaluated through extensive comparison of the newly developed MAE procedure with a conventional shake-flask extraction method used as a reference. In addition, the necessity of field preservation was assessed, given its importance in the overall analytical workflow and accuracy of total mass concentrations and mass stored. The MAE method provided recoveries comparable to or greater than those obtained with the reference method, while avoiding several drawbacks of the shake-flask approach, such as sample cross-contamination during prolonged extraction times over several weeks. Its shorter processing time and faster turnaround support rapid, field-based decision-making. Field preservation was determined to be essential, as non-preserved samples consistently yielded lower measured concentrations than preserved samples. Full article

(This article belongs to the Section Environmental Separations)

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15 pages, 3632 KB

Open AccessArticle

Comparison of Dynamic Controllability of Extractive Distillation and Pressure-Swing Distillation for the Separation of Dimethyl Carbonate/Methanol Azeotrope

by Jiancai Sui, Yang Liu, Zhenhua Wang, Tao Li, Kun-Yu Gao, Jin-Ke Chu, Yang-Guang Zhang, Hui Shi, Jihai Tang and Ming Xia

Separations 2026, 13(2), 48; https://doi.org/10.3390/separations13020048 - 27 Jan 2026

Viewed by 559

Abstract

Dimethyl carbonate (DMC) and methanol (MeOH) form a binary minimum-boiling homogeneous azeotrope, and thus conventional distillation cannot achieve complete separation. The extractive distillation (ED) with o-xylene as a heavy entrainer in our recent work possesses significant energy saving and achieves a high purity [...] Read more.

Dimethyl carbonate (DMC) and methanol (MeOH) form a binary minimum-boiling homogeneous azeotrope, and thus conventional distillation cannot achieve complete separation. The extractive distillation (ED) with o-xylene as a heavy entrainer in our recent work possesses significant energy saving and achieves a high purity of 99.9% DMC compared with the pressure-swing distillation (PSD). For a fair comparison, both ED and PSD were evaluated against the same minimum product specifications (DMC ≥ 99.5 wt% and MeOH ≥ 98.0 wt%), noting that the recovered MeOH stream was recycled to the reactive distillation column rather than treated as a final product. However, the dynamic performance of this ED is still unclear, and all the benefits of the ED are reasonable only under good dynamic controllability. In this work, the dynamic controllability of the ED process was compared with that of the PSD one. Both processes were evaluated under a unified temperature-control philosophy, including conventional fixed R. Closed-loop dynamic simulations were performed under ±10% step disturbances in feed flowrate and composition. It was revealed that under the tested disturbances, DMC purity was maintained close to the high-purity target (≈99.9 wt%) in the ED process, whereas larger deviations and a lower attainable DMC purity were obtained in PSD. The results provide a control-oriented basis for the selection and further development of special distillation schemes for MeOH/DMC azeotropic separation. Full article

(This article belongs to the Special Issue Separation Technology in Chemical Engineering)

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14 pages, 4221 KB

Open AccessArticle

Selective Chloride Removal by a NiFe LDH/BiOCl Composite Film via Electrically Switched Ion Exchange

by Xiangrong Li, Xiaoyang Guo, Xiaowei An, Peifen Wang, Xuli Ma, Xin Du, Xuejin Ren and Xuemei Wang

Separations 2026, 13(2), 47; https://doi.org/10.3390/separations13020047 - 27 Jan 2026

Viewed by 446

Abstract

The development of electrode materials that combine high capacity with high anion selectivity is critical for chloride separation from complex aqueous matrices. Here, a NiFe LDH/BiOCl composite film electrode was fabricated on carbon paper via sequential electrodeposition and employed for electrically switched ion [...] Read more.

The development of electrode materials that combine high capacity with high anion selectivity is critical for chloride separation from complex aqueous matrices. Here, a NiFe LDH/BiOCl composite film electrode was fabricated on carbon paper via sequential electrodeposition and employed for electrically switched ion exchange (ESIX) of chloride. The composite delivers higher reversible chloride uptake than either NiFe LDH or BiOCl alone under identical electrochemical conditions, together with enhanced selectivity in mixed−anion solutions. Mechanistically, the synergy originates from the combination of (i) the high anion−exchange capacity and redox−tunable layer charge of NiFe LDH and (ii) halide−affinitive BiOCl domains that facilitate voltage−gated uptake/release; the heterointerface further improves charge/ion transport, enabling more effective electrochemical utilization. The electrode maintains stable cycling performance with high regeneration efficiency over repeated ESIX operation. Compared with representative LDH− or BiOX−based ESIX electrodes reported for halide capture, the proposed composite shows competitive chloride selectivity and reversible cycling, supporting its potential for electrochemical separations and water treatment. Full article

(This article belongs to the Topic Sustainable Technologies for Water Purification)

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41 pages, 1578 KB

Open AccessReview

Separation Strategies for Polyphenols from Plant Extracts: Advances, Challenges, and Applications

by Sasa Savic, Sanja Petrovic and Zorica Knezevic-Jugovic

Separations 2026, 13(2), 46; https://doi.org/10.3390/separations13020046 - 27 Jan 2026

Cited by 2 | Viewed by 1807

Abstract

Polyphenols are a structurally diverse group of plant secondary metabolites widely recognized for their antioxidant, anti-inflammatory, antimicrobial, and chemoprotective properties, which have stimulated their extensive use in food, pharmaceutical, nutraceutical, and cosmetic products. However, their chemical heterogeneity, wide polarity range, and strong interactions [...] Read more.

Polyphenols are a structurally diverse group of plant secondary metabolites widely recognized for their antioxidant, anti-inflammatory, antimicrobial, and chemoprotective properties, which have stimulated their extensive use in food, pharmaceutical, nutraceutical, and cosmetic products. However, their chemical heterogeneity, wide polarity range, and strong interactions with plant matrices pose major challenges for efficient extraction, separation, and reliable analytical characterization. This review provides a critical overview of contemporary strategies for the extraction, separation, and identification of polyphenols from plant-derived matrices. Conventional extraction methods, including maceration, Soxhlet extraction, and percolation, are discussed alongside modern green technologies such as ultrasound-assisted extraction, microwave-assisted extraction, pressurized liquid extraction, and supercritical fluid extraction. Particular emphasis is placed on environmentally friendly solvents, including ethanol, natural deep eutectic solvents, and ionic liquids, as sustainable alternatives that improve extraction efficiency while reducing environmental impact. The review further highlights chromatographic separation approaches—partition, adsorption, ion-exchange, size-exclusion, and affinity chromatography—and underlines the importance of hyphenated analytical platforms (LC–MS, LC–MS/MS, and LC–NMR) for comprehensive polyphenol profiling. Key analytical challenges, including matrix effects, compound instability, and limited availability of reference standards, are addressed, together with perspectives on industrial implementation, quality control, and standardization. Full article

(This article belongs to the Special Issue Advances in the Analysis of Bioactive Plant Extracts: Separation Techniques and Their Applications)

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