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Separations
Volume 13
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Separations, Volume 13, Issue 1 (January 2026) – 40 articles

Cover Story (view full-size image): The distillates of a fermented mash from a 5-gallon pot still were characterized using 1H NMR spectroscopy and GC-MS. Key congeners, such as acetaldehyde, ethyl acetate, furfural, phenylethanol, and 1,1-diethoxyethane, showed expected distillation behavior across ten fractions, based on their respective pure-component boiling points. However, methanol and 1-propanol showed a fairly flat concentration profile across all ten fractions. White dog (unaged whiskey) fractions from column and combination stills were also analyzed, and the results demonstrate that the small 5-gallon still separates congeners as well as these stills. Our data show that while GC-MS and NMR do reveal similar overall trends in congener concentrations across the distillation fractions, the concentration magnitude, as determined from these techniques, can vary. View this paper
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13 pages, 607 KB  
Article
Phospholipid Profiling: A Computationally Assisted LC-HRMS Approach in Lecithin
by Ana Šijanec and Matevž Pompe
Separations 2026, 13(1), 40; https://doi.org/10.3390/separations13010040 - 21 Jan 2026
Viewed by 93
Abstract
The use of lecithin as an emulsifier in food supplements has increased in recent years. However, successful formation of liposomes or micelles requires an appropriate mixture of phospholipids in lecithin. To evaluate the emulsification properties of lecithin for food supplements, a reliable analytical [...] Read more.
The use of lecithin as an emulsifier in food supplements has increased in recent years. However, successful formation of liposomes or micelles requires an appropriate mixture of phospholipids in lecithin. To evaluate the emulsification properties of lecithin for food supplements, a reliable analytical procedure for characterizing phospholipids is necessary. A liquid chromatography–mass spectrometry method was developed to identify phospholipids in lecithin without standard reference materials. For efficient separation of phospholipids before mass spectrometric analysis, a reverse-phase high-performance liquid chromatography method was optimized using a Waters XBridge Protein BEH C4 column. The optimized chromatographic method demonstrated good linearity and precision. Molecular ions were detected in full scan mode to determine accurate mass-to-charge ratios for individual peaks in the chromatogram. A custom Python program was then used to generate a list of possible phospholipid species for each peak based on the measured mass-to-charge ratios. Tandem mass spectrometry was performed to confirm the identity of specific phospholipids by comparing experimental fragmentation patterns with theoretical predictions. Identification of the phospholipids was also confirmed with four commercially available standard reference compounds, demonstrating the reliability of the proposed approach. The developed method offers a practical and cost-effective strategy for identifying phospholipids in complex matrices, especially when standard reference compounds are unavailable. Additionally, it enables targeted selection of standard compounds for future quantitative analyses, making it a valuable tool for comprehensive lipid profiling. Full article
(This article belongs to the Special Issue Innovative Analytical Strategies Based on Mass Spectrometry in Food Analysis)
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44 pages, 502 KB  
Review
Chromatographic Applications Supporting ISO 22002-100:2025 Requirements on Allergen Management, Food Fraud, and Control of Chemical and Packaging-Related Contaminants
by Eftychia G. Karageorgou, Nikoleta Andriana F. Ntereka and Victoria F. Samanidou
Separations 2026, 13(1), 39; https://doi.org/10.3390/separations13010039 - 20 Jan 2026
Viewed by 394
Abstract
ISO 22002-100:2025 introduces stringent and more technically explicit prerequisite programme (PRP) requirements for allergen management, food fraud mitigation, and the control of chemical and packaging-related contaminants across the food, feed, and packaging supply chain. This review examines how advanced chromatographic methods provide the [...] Read more.
ISO 22002-100:2025 introduces stringent and more technically explicit prerequisite programme (PRP) requirements for allergen management, food fraud mitigation, and the control of chemical and packaging-related contaminants across the food, feed, and packaging supply chain. This review examines how advanced chromatographic methods provide the analytical basis required to meet these requirements and to support alignment with GFSI-recognized certification schemes. Recent applications of liquid and gas chromatography coupled with mass spectrometry for allergen quantification, authenticity assessment, and the determination of packaging migrants, auxiliary chemical residues, lubricants, and indoor pest-control pesticides are presented to demonstrate their relevance as verification tools. Across these PRP-related controls, chromatographic methods enable trace-level detection, structural specificity, and reproducible measurement performance, thereby shifting PRP compliance from a documentation-based activity to a process verified through measurable analytical evidence. The review highlights significant progress in method development and simultaneous multi-target analytical approaches while also identifying remaining challenges related to matrix-appropriate validation, harmonization, and analytical coverage for chemical contamination, which is now formally defined as a measurable PRP requirement under ISO 22002-100:2025. Overall, the findings demonstrate that chromatographic analysis has become essential to demonstrating PRP effectiveness under ISO 22002-100:2025, supporting the broader shift toward evidence-based, scientifically robust food safety assurance. Full article
(This article belongs to the Collection Feature Paper Collection in Section ‘Chromatographic Separations’)
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15 pages, 3376 KB  
Article
Sustainable and Energy-Efficient Capacitive Deionization Enabled Through Upcycled Wheat Straw Biochar via Ammonium Ferric Citrate Modification
by Jie Lu, Ping Wen, Jiong Wang, Pin Zhang, Shengyong Liu, Chunyao Qing, Hongge Tao, Yifeng Wu, Sihan Ma and Binglin Chen
Separations 2026, 13(1), 38; https://doi.org/10.3390/separations13010038 - 20 Jan 2026
Viewed by 126
Abstract
Capacitive deionization (CDI) technology represents an emerging and energy-efficient solution for seawater desalination and wastewater treatment. To further enhance its sustainability and economic viability, it is very important to develop high-performance electrodes made from low-cost and renewable raw materials. Herein, a new electrode [...] Read more.
Capacitive deionization (CDI) technology represents an emerging and energy-efficient solution for seawater desalination and wastewater treatment. To further enhance its sustainability and economic viability, it is very important to develop high-performance electrodes made from low-cost and renewable raw materials. Herein, a new electrode material is introduced; the material was derived from wheat straw and modified via a simple and green process using ammonium ferric citrate (AFC) as a synergistic activator and modifier. The modification of AFC significantly enhanced the physicochemical properties of biochar. At the optimal AFC concentration of 1 mol·L−1, the specific surface area reached 321.27 m2·g−1, with a specific capacitance of 208.19 F·g−1. In the NaCl desalination experiment, the MWC-1.0 electrode exhibited a desalination capacity of 13.62 mg g−1 under the conditions of 1.2 V voltage and 2 mm electrode spacing in an initial solution concentration of 500 mg L−1. After 20 cycles of adsorption/desorption, the deionization capacity of the material was still retained at 90.5% of its initial capacity, demonstrating excellent regeneration performance. This work provides a sustainable method for preparing efficient and stable biochar electrodes, further highlighting its potential application in energy-saving seawater desalination technology. Full article
(This article belongs to the Special Issue Electrochemical Separation and Recovery Technology in Wastewater Treatment)
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15 pages, 4660 KB  
Article
Bismuth Oxychloride@Graphene Oxide/Polyimide Composite Nanofiltration Membranes with Excellent Self-Cleaning Performance
by Runlin Han, Faxiang Feng, Zanming Zhu, Jiale Li, Yiting Kou, Chaowei Yan and Hongbo Gu
Separations 2026, 13(1), 37; https://doi.org/10.3390/separations13010037 - 16 Jan 2026
Viewed by 200
Abstract
Organic pollution poses a serious threat to global water safety, while traditional treatment technologies suffer from low efficiency, high costs, and secondary pollution issues. This study successfully develops a highly efficient separation and photocatalytic degradation composite bismuth oxychloride@graphene oxide/polyimide (BiOCl@GO/PI) membrane by loading [...] Read more.
Organic pollution poses a serious threat to global water safety, while traditional treatment technologies suffer from low efficiency, high costs, and secondary pollution issues. This study successfully develops a highly efficient separation and photocatalytic degradation composite bismuth oxychloride@graphene oxide/polyimide (BiOCl@GO/PI) membrane by loading GO and BiOCl photocatalysts onto PI supporting membrane. The results show that this composite membrane achieves a rejection of 99.8% for methylene blue (MB) and 87.6% for tetracycline hydrochloride (TC). Under UV irradiation, the membrane exhibits a retention rate decline of only 6.8% after five cycles, with water flux stably maintaining at 605 L m−2 h−1 bar−1. Compared to dark conditions, it demonstrates remarkable flux recovery. This is attributed to the membrane’s excellent photocatalytic degradation activity under UV irradiation. After five degradation cycles, the degradation efficiency is decreased from 97.5 to 88.3%. Studies on radical scavengers indicate that UV irradiation generates free radicals, thereby conferring excellent catalytic activity to the membrane. Its unique synergistic effect between separation and photocatalysis endows it with outstanding self-cleaning performance. This research provides an innovative integrated solution for antibiotic pollution control, demonstrating significant potential for environmental applications. Full article
(This article belongs to the Section Materials in Separation Science)
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27 pages, 8939 KB  
Article
A Comprehensive GC-MS Approach for Monitoring Legacy and Emerging Halogenated Contaminants in Human Biomonitoring
by Rossana Comito, Nicholas Kassouf, Alessandro Zappi, Nicolò Interino, Emanuele Porru, Jessica Fiori, Dora Melucci and Francesco Saverio Violante
Separations 2026, 13(1), 36; https://doi.org/10.3390/separations13010036 - 16 Jan 2026
Viewed by 295
Abstract
Human exposure to persistent organic pollutants such as polychlorinated biphenyls (PCB) and brominated flame retardants (BFR), including both legacy and emerging compounds, remains a concern due to their bioaccumulative nature and potential health effects. Comprehensive analytical methods are necessary to monitor these substances [...] Read more.
Human exposure to persistent organic pollutants such as polychlorinated biphenyls (PCB) and brominated flame retardants (BFR), including both legacy and emerging compounds, remains a concern due to their bioaccumulative nature and potential health effects. Comprehensive analytical methods are necessary to monitor these substances in complex biological matrices, such as human serum. A gas chromatography–mass spectrometry (GC-MS) method was developed for the simultaneous determination of 44 analytes, encompassing PCB and a broad spectrum of BFR with diverse physicochemical properties. The extraction procedure and GC-MS parameters were optimized using a design of experiments approach to maximize performance while minimizing analysis time. The method demonstrated high sensitivity, precision, and accuracy, thereby meeting internationally recognized validation criteria for biomonitoring applications. To further ensure analytical reliability, compound confirmation was achieved using gas chromatography–high-resolution mass spectrometry, providing enhanced selectivity and confidence in identification, particularly for low-level analytes. Key advantages of the method include its applicability to analytes with significantly different chemical behaviors and its capacity to quantify a large number of target compounds simultaneously. This makes it a powerful tool for assessing human exposure to both regulated and emerging halogenated contaminants. Full article
(This article belongs to the Special Issue Novel Solvents and Methods for Extraction of Chemicals)
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12 pages, 556 KB  
Article
Isolation of Neuroprotective Constituents from Dryopteris crassirhizoma Rhizomes Inhibiting Beta-Amyloid Production and BACE1 Activity
by Hwan Bin Joo, Tae Eun Park, Min Sung Ko, Chung Hyeon Lee, Kwang Woo Hwang and So-Young Park
Separations 2026, 13(1), 35; https://doi.org/10.3390/separations13010035 - 16 Jan 2026
Viewed by 151
Abstract
Alzheimer’s disease (AD) is a prevalent neurodegenerative condition that progressively impairs cognitive processes, particularly learning and memory. A key pathological feature of AD involves senile plaques mainly composed of β-amyloid (Aβ) peptides, generated via the amyloidogenic pathway from amyloid precursor protein (APP) through [...] Read more.
Alzheimer’s disease (AD) is a prevalent neurodegenerative condition that progressively impairs cognitive processes, particularly learning and memory. A key pathological feature of AD involves senile plaques mainly composed of β-amyloid (Aβ) peptides, generated via the amyloidogenic pathway from amyloid precursor protein (APP) through sequential β-secretase (BACE1) and γ-secretase cleavage, positioning BACE1 inhibition as a prime therapeutic target. In this study, we applied bioassay-guided fractionation of the butanol-soluble fraction from Dryopteris crassirhizoma rhizomes, previously reported to inhibit Aβ production, to isolate and characterize Aβ-lowering constituents. Through successive chromatographic steps, nine compounds were isolated and structurally classified into flavonoids, chromones, and phloroglucinols, including epicatechin (1), β-carboxymethyl-(-)-epicatechin (2), 7-methoxy-isobiflorin (3), biflorin (4), eriodictyol (5), noreugenin (6), phloroglucinols (butyrylphloroglucinol (7), 2-propionyl-4-methylphloroglucinol (8), and 2-butyryl-4-methylphloroglucinol (9) by comprehensive spectroscopic analysis (NMR, MS, UV, IR). These compounds were assessed for effects on sAPPβ and BACE1 (β-secretase) levels by Western blot, with Aβ production quantified via ELISA in a cellular AD model (APP-CHO cells). Compounds 5–9 significantly reduced sAPPβ and BACE1 expression while potently suppressing Aβ generation. These results demonstrate that diverse constituents from D. crassirhizoma rhizomes inhibited Aβ production through BACE1 suppression, highlighting their potential as natural lead compounds for AD prevention or therapy. Full article
(This article belongs to the Special Issue Isolation and Identification of Biologically Active Natural Compounds)
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13 pages, 1204 KB  
Article
Real-Time Correction Algorithm for a Chromatographic Background Based on Numerical Algorithm
by Jinlin Chen, Yiquan Wu and Xinmei Xu
Separations 2026, 13(1), 34; https://doi.org/10.3390/separations13010034 - 16 Jan 2026
Viewed by 143
Abstract
Although numerous baseline correction methods exist, most are confined to static post-elution processing and fail to meet real-time analysis requirements. To address this, we propose a real-time baseline estimation method based on the Informer time-series prediction model that performs correction during data acquisition [...] Read more.
Although numerous baseline correction methods exist, most are confined to static post-elution processing and fail to meet real-time analysis requirements. To address this, we propose a real-time baseline estimation method based on the Informer time-series prediction model that performs correction during data acquisition without waiting for complete elution. Our work focuses on three key aspects: chromatographic dataset construction, model training, and baseline prediction. Simulation experiments demonstrate that the proposed method achieves comparable accuracy to conventional static processing approaches while exhibiting significant real-time advantages. In processing real chromatographic data, the model achieves a 98.3% chromatographic peak retention rate, with a single computation time of approximately 35 ms—substantially shorter than typical chromatographic sampling cycles (600–900 ms), thus fully satisfying the quantitative analysis requirements for real-time background subtraction. Full article
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22 pages, 5183 KB  
Article
Fluid Domain Characteristics and Separation Performance of an Eccentric Pipe Separator Handling a Crude Oil-Water Mixture
by Qi-Lin Wu, Zheng-Jia Ou, Ye Liu, Shuo Liu, Meng Yang and Jing-Yu Xu
Separations 2026, 13(1), 33; https://doi.org/10.3390/separations13010033 - 15 Jan 2026
Viewed by 187
Abstract
This study presents an eccentric pipe separator (EPS) designed according to the shallow pool principle and Stokes’ law as a compact alternative to conventional gravitational tank separators for offshore platforms. To investigate the internal oil-water flow characteristics and separation performance of the EPS, [...] Read more.
This study presents an eccentric pipe separator (EPS) designed according to the shallow pool principle and Stokes’ law as a compact alternative to conventional gravitational tank separators for offshore platforms. To investigate the internal oil-water flow characteristics and separation performance of the EPS, both field experiments with crude oil on an offshore platform and computational fluid dynamics (CFD) simulations were conducted, guided by dimensional analysis. Crude oil volume fractions were measured using a Coriolis mass flow meter and the fluorescence method. The CFD analysis employed an Eulerian multiphase model coupled with the renormalization group (RNG) k-ε turbulence model, validated against experimental data. Under the operating conditions examined, the separated water contained less than 50 mg/L of oil, while the separated crude oil achieved a purity of 98%, corresponding to a separation efficiency of 97%. The split ratios between the oil and upper outlets were found to strongly influence the phase distribution, velocity field, and pressure distribution within the EPS. Higher split ratios caused crude oil to accumulate in the upper core region and annulus. Maximum separation efficiency occurred when the combined split ratio of the upper and oil outlets matched the inlet oil volume fraction. Excessively high split ratios led to excessive water entrainment in the separated oil, whereas excessively low ratios resulted in excessive oil entrainment in the separated water. Crude oil density and inlet velocity exhibited an inverse relationship with separation efficiency; as these parameters increased, reduced droplet settling diminished optimal efficiency. In contrast, crude oil viscosity showed a positive correlation with the pressure drop between the inlet and oil outlet. Overall, the EPS demonstrates a viable, space-efficient alternative for oil-water separation in offshore oil production. Full article
(This article belongs to the Section Separation Engineering)
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13 pages, 7158 KB  
Article
Gas–Liquid Coalescing Filter with Wettability-Modified Gradient Pore Structure: Achieving Low Resistance, High Efficiency and Long Service Life
by Ziqi Yang, Jian Li, Shuaiyi Ma and Zhen Wang
Separations 2026, 13(1), 32; https://doi.org/10.3390/separations13010032 - 15 Jan 2026
Viewed by 147
Abstract
Widely used in treating oil mist aerosols generated from metalworking processes, conventional gas–liquid coalescing filters face drawbacks such as increased energy consumption, performance limitations, and shortened service life due to high steady-state pressure drop. To address these issues, this study proposes an innovative [...] Read more.
Widely used in treating oil mist aerosols generated from metalworking processes, conventional gas–liquid coalescing filters face drawbacks such as increased energy consumption, performance limitations, and shortened service life due to high steady-state pressure drop. To address these issues, this study proposes an innovative design for a filter based on wettability-regulated gradient pore structure. Using glass fiber filter media with different pore size parameters as the substrate and incorporating an intermediate mesh layer, a three-layer filtration structure of “large-pore filtration layer—mesh layer—small-pore filtration layer” was constructed. The surface wettability of each layer was regulated by a self-developed surface modifier, producing gradient pore structure filters with different wettability configurations. The variations in key performance parameters, including steady-state pressure drop, filtration efficiency, saturation, and service life, were systematically evaluated for these configurations. Experimental results demonstrated that the configuration with an “oleophobic large-pore filtration layer—mesh layer—oleophilic small-pore filtration layer” yielded the best overall performance. Analysis based on the “jump-channel” model indicated that the gradient pore structure achieves progressive droplet filtration and optimizes droplet coalescence and capture through wettability differences. Consequently, while maintaining exceptional filtration efficiency (>99%), this configuration significantly reduces the steady-state pressure drop by over 34% and effectively extends the service life by more than 66%. This wettability-regulated gradient pore structure provides a novel technical pathway for addressing the challenges of balancing pressure drop and filtration efficiency, as well as extending the service life, in gas–liquid coalescing filters. Full article
(This article belongs to the Special Issue Development of Functionalized Porous Materials for Adsorption and Separations)
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18 pages, 10429 KB  
Article
Intelligent Pulsed Electrochemical Activation of NaClO2 for Sulfamethoxazole Removal from Wastewater Driven by Machine Learning
by Naboxi Tian, Congyuan Zhang, Wenxiao Yang, Yunfeng Shen, Xinrong Wang and Junzhuo Cai
Separations 2026, 13(1), 31; https://doi.org/10.3390/separations13010031 - 15 Jan 2026
Viewed by 217
Abstract
Sulfamethoxazole (SMX), a widely used antibiotic, poses potential threats to ecosystems and human health due to its persistence and residues in aquatic environments. This study developed a novel intelligent water treatment system, namely Intelligent Pulsed Electrochemical Activation of NaClO2 (IPEANaClO2), [...] Read more.
Sulfamethoxazole (SMX), a widely used antibiotic, poses potential threats to ecosystems and human health due to its persistence and residues in aquatic environments. This study developed a novel intelligent water treatment system, namely Intelligent Pulsed Electrochemical Activation of NaClO2 (IPEANaClO2), which integrates a FeCuC-Ti4O7 composite electrode with machine learning (ML) to achieve efficient SMX removal and energy consumption optimization. Six key operational parameters—initial SMX concentration, NaClO2 dosage, reaction temperature, reaction time, pulsed potential, and pulsed frequency—were systematically investigated to evaluate their effects on removal efficiency and electrical specific energy consumption (E-SEC). Under optimized conditions (SMX 10 mg L−1, NaClO2 60~90 mM, pulsed frequency 10 Hz, temperature 313 K) for 60 min, the IPEANaClO2 system achieved an SMX removal efficiency of 89.9% with a low E-SEC of 0.66 kWh m−3. Among the ML models compared (back-propagation neural network, BPNN; gradient boosting decision tree, GBDT; random forest, RF), BPNN exhibited the best predictive performance for both SMX removal efficiency and E-SEC, with a coefficient of determination (R2) approaching 1 on the test set. Practical application tests demonstrated that the system maintained excellent stability across different water matrices, achieved a bacterial inactivation rate of 98.99%, and significantly reduced SMX residues in a simulated agricultural irrigation system. This study provides a novel strategy for the intelligent control and efficient removal of refractory organic pollutants in complex water bodies. Full article
(This article belongs to the Special Issue Photo-/Electro-/Photoelectro-Catalytic Removal of Pollutants in Environmental Matrices)
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21 pages, 8110 KB  
Article
Study on the Performance of Bi2O3/BiOBrγIx Adsorptive Photocatalyst for Removal of 2,4-Dichlorophenoxyacetic Acid
by Rixiong Mo, Yuanzhen Li, Bo Liu, Yi Yang, Yaoyao Zhou, Yuxi Cheng, Haorong Shi and Guanlong Yu
Separations 2026, 13(1), 30; https://doi.org/10.3390/separations13010030 - 14 Jan 2026
Viewed by 109
Abstract
In this study, a novel Bi2O3/BiOBr0.9I0.1 (BO0.9−BBI0.1) composite photocatalyst was successfully synthesized via a single-pot solvothermal method for the efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under visible light. The structure, morphology, and optical properties of the [...] Read more.
In this study, a novel Bi2O3/BiOBr0.9I0.1 (BO0.9−BBI0.1) composite photocatalyst was successfully synthesized via a single-pot solvothermal method for the efficient degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) under visible light. The structure, morphology, and optical properties of the photocatalyst were characterized through X-ray diffraction (XRD), Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), UV–vis diffuse reflectance spectra (DRS), Steady-state photoluminescence (PL), and Electrochemical Impedance Spectroscopy (EIS). The composite exhibits a 3D hierarchical morphology with increased specific surface area and optimized pore structure, enhancing pollutant adsorption and providing more active sites. Under visible light irradiation, BO0.9−BBI0.1 achieved a 92.4% removal rate of 2,4-D within 2 h, with a reaction rate constant 5.3 and 4.6 times higher than that of pure BiOBr and BiOI, respectively. Mechanism studies confirm that photogenerated holes (h+) and superoxide radicals (·O2−) are the primary active species, and the Z-scheme charge transfer pathway significantly promotes the separation of electron-hole pairs while maintaining strong redox capacity. The catalyst also demonstrated good stability over multiple cycles. This work provides a feasible dual-modification strategy for designing efficient bismuth-based photocatalysts for pesticide wastewater treatment. Full article
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20 pages, 1941 KB  
Article
Comparison of Methods for the Extraction of Saponins from Sechium spp. Genotypes and Their Spectrophotometric Quantification
by Fátima Azucena Rasgado-Bonilla, Ramón Marcos Soto-Hernández, Luis Francisco Salomé-Abarca, Jorge Cadena-Íñiguez, Víctor A. González-Hernández, Lucero del Mar Ruiz-Posadas and Sara Elisa Herrera-Rodríguez
Separations 2026, 13(1), 29; https://doi.org/10.3390/separations13010029 - 14 Jan 2026
Viewed by 230
Abstract
Saponins are valuable health-promoting metabolites. The genus Sechium spp. is a valuable source of such metabolites. Unfortunately, there is no established method for the extraction of saponins from the fruits of this species. Therefore, this research aimed to compare three gravimetric extraction methods [...] Read more.
Saponins are valuable health-promoting metabolites. The genus Sechium spp. is a valuable source of such metabolites. Unfortunately, there is no established method for the extraction of saponins from the fruits of this species. Therefore, this research aimed to compare three gravimetric extraction methods for saponins in two Sechium genotypes. The analysis included FT-MIR and HPTLC fingerprinting, as well as spectrophotometric quantification. Independent of the extraction method, bagasse produced higher extraction yields than juice. Among the gravimetric methods, M3 produced the highest yields, while M1 captured the most remarkable diversity and abundance of saponins. The spectrophotometric quantification corroborated the higher total saponin content in bagasse extracts. This data highlights the use of fruit bagasse as the primary source of saponin extraction in Sechium. In addition, we recommend extracting bagasse through M3 for scalable pre-enrichment, while M1 extraction must be used when preserving chemical diversity is critical. Full article
(This article belongs to the Section Analysis of Food and Beverages)
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17 pages, 3923 KB  
Article
Silver-Functionalized Ionic Liquid@MCM-41 Adsorbents for C2H4/C2H6 Separation
by Yelin Yang, Zongxu Wang, Dan Li, Mengyu Ren, Defu Chen and Haifeng Dong
Separations 2026, 13(1), 28; https://doi.org/10.3390/separations13010028 - 13 Jan 2026
Viewed by 200
Abstract
Ionic liquids (ILs) have attracted considerable attention for light olefin separation owing to their negligible vapor pressure, excellent thermal stability, and tunable molecular structures. However, their intrinsically high viscosity severely restricts gas diffusion, leading to poor mass-transfer efficiency and limited separation performance in [...] Read more.
Ionic liquids (ILs) have attracted considerable attention for light olefin separation owing to their negligible vapor pressure, excellent thermal stability, and tunable molecular structures. However, their intrinsically high viscosity severely restricts gas diffusion, leading to poor mass-transfer efficiency and limited separation performance in bulk form. Herein, we report the develop a high-performance adsorbent by immobilizing a silver-functionalized ionic liquid within ordered mesoporous MCM-41 to overcome the diffusion limitations of bulk ILs. The IL@MCM-41 composites were prepared via an impregnation–evaporation strategy, and their mesostructural integrity and textural evolution were confirmed by XRD and N2 sorption analyses. Their C2H4/C2H6 separation performance was subsequently evaluated. The composite with a 70 wt% IL loading achieves a high C2H4 uptake of 25.68 mg/g and a C2H4/C2H6 selectivity of 15.59 in breakthrough experiments (298 K, 100 kPa). X-ray photoelectron spectroscopy results are consistent with the presence of reversible Ag+–π interactions, which governs the selective adsorption of C2H4. Additionally, the composite exhibits excellent thermal stability (up to 570 K) and maintains stable separation performance over 10 adsorption–desorption cycles. These IL@MCM-41 composites have significant potential for designing sorbent materials for efficient olefin/paraffin separation applications. Full article
(This article belongs to the Special Issue Development of Functionalized Porous Materials for Adsorption and Separations)
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15 pages, 2706 KB  
Article
Analysis of Distillate Fractions Collected from a Small Commercial Pot Still Using NMR and GC-MS
by Hina Ali, Mohamed A. Abdelaziz, J. Andrew Jones, Neil D. Danielson and Michael W. Crowder
Separations 2026, 13(1), 27; https://doi.org/10.3390/separations13010027 - 12 Jan 2026
Viewed by 198
Abstract
In an effort to evaluate the performance of a 5-gallon pot still in separating yeast-derived congeners during the distillation of a grain-based distiller’s beer, the distillates of a fermented mash of cracked corn, malted barley, and wheat were characterized using 1H NMR [...] Read more.
In an effort to evaluate the performance of a 5-gallon pot still in separating yeast-derived congeners during the distillation of a grain-based distiller’s beer, the distillates of a fermented mash of cracked corn, malted barley, and wheat were characterized using 1H NMR spectroscopy and GC-MS. A quantitative comparison using these two techniques is uncommon. Results revealed significant variation in congener concentrations across runs, with a notable discrepancy in the third run possibly due to bacterial contamination, as indicated by high 1-propanol levels. Key congeners, such as acetaldehyde, ethyl acetate, furfural, phenylethanol, and 1,1-diethoxyethane, showed expected distillation behavior across ten fractions, based on their respective boiling points. However, methanol and 1-propanol showed a fairly flat concentration profile across all ten fractions, while those for ethyl octanoate and ethyl hexanoate decreased rapidly and were undetected at fraction 5. White dog (unaged whiskey) fractions from column and combination stills were also analyzed, and the results demonstrate that the small 5-gallon still separates congeners as well as these stills. Finally, a comparison of congener concentrations demonstrates that NMR and GC-MS do not yield identical concentrations of congeners, despite exhibiting similar trends in congener concentrations in the fractions from the still, with GC-MS suggesting higher levels. Full article
(This article belongs to the Section Analysis of Food and Beverages)
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12 pages, 1097 KB  
Article
Rapid Separation of Non-Sweet Glycosides from Siraitia grosvenorii by Two-Step Medium-Pressure Liquid Chromatography
by Wanzhen Cai, Xiaoling Tan, Xinghua Dai, Xuerong Yang, Xiaohua Jiang, Yulu Wei, Haiying Jiang and Fenglai Lu
Separations 2026, 13(1), 26; https://doi.org/10.3390/separations13010026 - 12 Jan 2026
Viewed by 139
Abstract
Siraitia grosvenorii (Swingle) C. Jeffrey is widely recognized for its anti-inflammatory properties, as well as its roles in lung purification, phlegm elimination, intestinal function regulation, and anti-tumor activity. Its pharmacological activity is attributed to a diversity of functional components. However, due to the [...] Read more.
Siraitia grosvenorii (Swingle) C. Jeffrey is widely recognized for its anti-inflammatory properties, as well as its roles in lung purification, phlegm elimination, intestinal function regulation, and anti-tumor activity. Its pharmacological activity is attributed to a diversity of functional components. However, due to the extensive application of sweet glycosides in food additives, there have been few studies on non-sweet glycosides, particularly those with high polarity. This paper investigates the chemical constituents in the non-sweet glycosides fraction of S. grosvenorii juice. First, an MCI GEL CHP20P chromatographic column was utilized to enrich the non-sweet glycosides fraction. Furthermore, two-step medium-pressure liquid chromatography (MPLC) was performed for the efficient preparative separation of high-polarity non-sweet glycosides with similar structures, using C18 and silica gel as stationary phases, respectively. Seven non-sweet glycoside compounds were identified through NMR and mass spectrometry analyses, including three new compounds (4-hydroxyphenylethanol 4-O-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside, 4-hydroxyphenylethanol 4-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside and n-butanol 1-O-β-D-glucopyranosyl-(1→2)-β-D-glucopyranosyl-(1→6)-β-D-glucopyranoside), as well as four known ones (α-D-glucopyranosyl-(1→4)-D-glucose, α-D-glucopyranosyl-(1→2)-β-D-fructofuranoside, methoxy hydroquinone diglucoside, and β-D-glucopyranoside). The results demonstrate that mixed-mode MPLC using different stationary phases is an efficient approach for separating non-sweet glycosides from S. grosvenorii. Full article
(This article belongs to the Special Issue Design and Optimization of Extraction/Separation Processes for Natural Products)
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15 pages, 5038 KB  
Article
Investigation of the Effects of Hydrogen-Based Mineral Phase Transformation Cooling on the Grinding Characteristics of Specific Iron Ore
by Shijie Zhou, Pengcheng Tian, Jianping Jin and Da Li
Separations 2026, 13(1), 25; https://doi.org/10.3390/separations13010025 - 9 Jan 2026
Viewed by 198
Abstract
Grinding is an essential process in mineral processing. Hydrogen-based mineral phase transformation, used to efficiently process refractory iron ores, can alter the physical and chemical properties of the ore, affecting its grinding characteristics. This paper uses iron ore from Baoshan, Shanxi Province, as [...] Read more.
Grinding is an essential process in mineral processing. Hydrogen-based mineral phase transformation, used to efficiently process refractory iron ores, can alter the physical and chemical properties of the ore, affecting its grinding characteristics. This paper uses iron ore from Baoshan, Shanxi Province, as the raw material for laboratory-scale hydrogen-based mineral phase transformation (HMPT) experiments and grinding tests. It examines the impact of four cooling methods on the ore’s grinding characteristics. The results show that samples cooled in a reducing atmosphere to 200 °C and then water-quenched exhibit the best relative grindability. For the same grinding time, the content of coarse-sized particles (+0.074 mm) in the product is lowest, while the fine-sized particles (−0.030 mm) is highest. The grinding kinetic parameters of the samples with this cooling method are the highest. After 2 min of grinding, the value of n is 1.3363, and the particle size distribution of the product is the most uniform. The BET and SEM test results indicate that samples with this cooling method have more internal pores, the largest pore size, and the most surface cracks and pores. This paper clarifies the effects of the HMPT cooling methods on grinding characteristics, providing a theoretical foundation for the efficient separation of iron ores. Full article
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26 pages, 1584 KB  
Review
Current Research on NO2 Removal from Flue Gas Using Adsorption Methods
by Xibin Ma, Yulin Tong, Zhe Su, Hongbin Tang, Hui He, Shangwen Chang, Yulong Chang, Bangda Wang and Gaoliang Li
Separations 2026, 13(1), 24; https://doi.org/10.3390/separations13010024 - 8 Jan 2026
Viewed by 234
Abstract
Nitrogen dioxide (NO2) is a major atmospheric pollutant and also a recoverable nitrogen resource, for which adsorption offers a promising technical pathway. This review systematically summarizes the recent progress in the removal of NO2 from flue gas by adsorption methods, [...] Read more.
Nitrogen dioxide (NO2) is a major atmospheric pollutant and also a recoverable nitrogen resource, for which adsorption offers a promising technical pathway. This review systematically summarizes the recent progress in the removal of NO2 from flue gas by adsorption methods, with a focus on material-level and process-level advancements. From the material perspective, three representative adsorbents—zeolites, activated carbons, and metal oxides—are comparatively evaluated in terms of their physicochemical properties, active sites, and adsorption mechanisms. Emphasis is placed on their adsorption capacity, selectivity, and hydrothermal stability, supported by both experimental and theoretical insights. From the process perspective, four adsorption-based technologies—Pressure Swing Adsorption (PSA), Temperature Swing Adsorption (TSA), Vacuum Pressure Swing Adsorption (VPSA), and Vacuum Temperature Swing Adsorption using multiple Gas circulations (GVTSA)—are analyzed regarding their principles, operational workflows, and engineering applications, with particular attention to the process intensification potential of GVTSA. The review identifies existing challenges in terms of material stability under complex conditions and process scalability, especially for severe environments such as nuclear reprocessing tail gases. Finally, future research directions are proposed toward developing multifunctional composite adsorbents with high capacity, strong environmental tolerance, and excellent regenerability, along with optimized and integrated adsorption processes, to achieve efficient NO2 abatement and high-value recovery. Full article
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18 pages, 2492 KB  
Article
Chromium Removal by Dunaliella salina in High-Salinity Environments: An Investigation Based on Microalgal Cytotoxic Responses and Adsorption Capacity
by Yongfu Li, Dingning Fan, Delong Li, Lu Wang, Kexin Chen and Xingkai Che
Separations 2026, 13(1), 23; https://doi.org/10.3390/separations13010023 - 7 Jan 2026
Viewed by 275
Abstract
Chromium (Cr) is a widespread heavy metal contaminant in aquatic environments, posing serious risks to phytoplankton due to its persistence, biotoxicity, and mutagenic potential. Microalgae have emerged as promising biological agents for Cr remediation. In this study, the Cr removal potential of living [...] Read more.
Chromium (Cr) is a widespread heavy metal contaminant in aquatic environments, posing serious risks to phytoplankton due to its persistence, biotoxicity, and mutagenic potential. Microalgae have emerged as promising biological agents for Cr remediation. In this study, the Cr removal potential of living Dunaliella salina (D. salina) was evaluated by examining the toxic effects and adsorption behavior of trivalent Cr(III) and hexavalent Cr(VI) through short-term exposure experiments. This study elucidated the mechanisms by which Cr disrupts key photosynthetic metabolic pathways, quantified the short-term toxicity thresholds of Cr(III) and Cr(VI) to D. salina, and characterized the saturation adsorption capacity and adsorption kinetics of Cr on algal cells. The results showed that Cr(VI) at concentrations of 5–20 mg/L inhibited the growth of D. salina in a dose-dependent manner throughout the culture period, with inhibition rates ranging from 22.8% to 70.9%. After 72 h of exposure, the maximum growth inhibition rates caused by Cr(III) and Cr(VI) reached 42.5% and 52%, respectively. Interestingly, low concentrations of Cr(VI) (0.1–1 mg/L) slightly enhanced the growth of D. salina. However, Cr(VI) exhibited stronger biotoxicity than Cr(III). Exposure to both Cr species significantly reduced the levels of chlorophyll a (Chl a), chlorophyll b (Chl b), and carotenoids (Car), resulting in damage to the photosynthetic reaction centers and suppression of the photosynthetic electron transport system. The adsorption of Cr(VI) by D. salina followed a pseudo-second-order kinetic model, with a maximum adsorption capacity of 38.09 mg/g. The process was primarily governed by monolayer chemisorption. These findings elucidate the toxic mechanisms of Cr in D. salina and highlight its potential application as an effective bioremediation agent for heavy metal pollution, particularly Cr(VI), in marine environments. Full article
(This article belongs to the Special Issue Biological Removal of Emerging Contaminants: Toxicological Effects and Process Mechanisms)
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20 pages, 4803 KB  
Article
Process Intensification and Multivariable Interaction Analysis for Platinum Extraction from Spent Catalysts Using Ultrasound-Assisted Leaching
by Xiaoping Zhu, Xiaolong Sai, Chuan Liu, Yige Yang, Bei Ren, Ke Shi, Shaobo Wen and Hao Pan
Separations 2026, 13(1), 22; https://doi.org/10.3390/separations13010022 - 6 Jan 2026
Viewed by 208
Abstract
The efficient recovery of platinum (Pt) from spent catalysts is of critical strategic importance to alleviate resource scarcity and supply chain dependencies. This study developed an ultrasonic-assisted leaching process using a H2SO4-NaCl system for Pt extraction from spent petroleum [...] Read more.
The efficient recovery of platinum (Pt) from spent catalysts is of critical strategic importance to alleviate resource scarcity and supply chain dependencies. This study developed an ultrasonic-assisted leaching process using a H2SO4-NaCl system for Pt extraction from spent petroleum catalysts. Single-factor experiments were first conducted to identify the preliminary effects of key parameters. Subsequently, Response Surface Methodology (RSM) based on a Box–Behnken design was employed to model and optimize the interactive effects of ultrasonic power, sulfuric acid concentration, leaching time and NaCl concentration. The results demonstrated that ultrasonic power had the most significant influence on Pt leaching efficiency. The optimized conditions were determined as ultrasonic power of 300 W, H2SO4 concentration of 60%, leaching time of 100 min, and NaCl concentration of 0.10 mol/L. Under these optimal parameters, the Pt leaching rate reached approximately 99.8%, validating the model’s high accuracy and reliability. This work provides an efficient and stable technical pathway for the sustainable recycling of platinum from secondary resources. Full article
(This article belongs to the Special Issue Efficient Extraction, Separation and Purification of Critical Metal Resources)
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19 pages, 656 KB  
Review
Pharmaceuticals in Food and Water: Monitoring, Analytical Methods of Detection and Quantification, and Removal Strategies
by Ines Varga, Nina Bilandžić, Silvia Morović and Krešimir Košutić
Separations 2026, 13(1), 21; https://doi.org/10.3390/separations13010021 - 1 Jan 2026
Viewed by 509
Abstract
Pharmaceuticals, classified as emerging pollutants, are extensively applied in both human and veterinary medicine to treat various diseases. Their widespread application has led to their occurrence in water, soil, sediments, and living organisms. Even at trace levels (ng·L−1–μg·L−1), pharmaceuticals [...] Read more.
Pharmaceuticals, classified as emerging pollutants, are extensively applied in both human and veterinary medicine to treat various diseases. Their widespread application has led to their occurrence in water, soil, sediments, and living organisms. Even at trace levels (ng·L−1–μg·L−1), pharmaceuticals can significantly impact ecosystems and present threats to the environment and public health. Reliable analytical methods, such as liquid chromatography–tandem mass spectrometry (LC-MS/MS) and high-resolution mass spectrometry (LC-HRMS), are crucial for detecting and monitoring these compounds, including new or unknown substances. Removing pharmaceuticals from water remains challenging, as no single technique can completely eliminate all compounds and their toxic transformation products. Therefore, combining different treatment approaches, including membrane technologies, advanced oxidation processes (AOPs), and adsorption, into hybrid systems is necessary to improve removal efficiency and mitigate impacts on ecosystems and public health. In this review, a comprehensive overview of the occurrence of pharmaceuticals, their monitoring in food and water, and wastewater treatment is provided, highlighting current challenges and the need for further research. Full article
(This article belongs to the Special Issue Optimization of Advanced Separation Technologies for the Analysis of Emerging Contaminants)
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15 pages, 1611 KB  
Article
Optimization of Ultra-High-Pressure Extraction and Comparative Evaluation of Antioxidant Activity and Flavonoid Composition in Guanxiang Leaves
by Jinyan Zhang, Jiyao Kang, Haoqian Yan, Yang Zhang, Zhenhu Guo, Lihui Liu, Guifeng Zhang and Yu Zhang
Separations 2026, 13(1), 20; https://doi.org/10.3390/separations13010020 - 1 Jan 2026
Viewed by 250
Abstract
This paper aimed to optimize the ultra-high-pressure extraction process of flavonoids from guanxiang leaves, evaluate their antioxidant capacity, and identify the flavonoids. Methods: Guanxiang leaves were used as the raw material. The extraction process was optimized through single-factor experiments and a response surface [...] Read more.
This paper aimed to optimize the ultra-high-pressure extraction process of flavonoids from guanxiang leaves, evaluate their antioxidant capacity, and identify the flavonoids. Methods: Guanxiang leaves were used as the raw material. The extraction process was optimized through single-factor experiments and a response surface methodology. Ascorbic acid (Vc) was employed as a positive control, and the in vitro antioxidant activity of flavonoids was assessed by determining the DPPH radical-scavenging rate, ABTS radical-scavenging rate, and FRAP ferric-reducing ability. Results: The optimal extraction conditions were determined as follows: ethanol concentration of 50%, solid-to-liquid ratio of 1:60 (g/mL), extraction pressure of 300 MPa, and pressure-holding time of 3 min. Under these conditions, the yield of guanxiang leaf flavonoids was found to be 2.21%, better than the solvent extraction method (1.94%). The antioxidant test results indicated that the IC50 values of the extract from the ultra-high-pressure treatment of guanxiang leaves were 11.8 and 50.72 μg·mL−1 on DPPH and ABTS scavenging, which were lower than those of the solvent’s extract (13.40 and 54.29 μg·mL−1). Moreover, the antioxidant ability could also be confirmed by Fe3+ ion reduction. Mass spectrometry results indicate that ultra-high-pressure extraction can yield components such as spiraeoside, scutellarin, luteolin, and nepetin, which are not present in solvent extraction methods. Conclusions: Therefore, the ultra-high-pressure extraction method can help to improve the flavonoid yield and antioxidant activity as well as to obtain special product types, including spiraeoside, scutellarin, luteolin, and nepetin, than the solvent extraction method. Full article
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16 pages, 2516 KB  
Article
Analysis of Occurrence of Deep Coalbed Methane and Its “Desorption–Diffusion–Seepage” Process
by Bingwen Zhang, Tao Jiang, Li Niu, Sha Li and Shu Tao
Separations 2026, 13(1), 19; https://doi.org/10.3390/separations13010019 - 30 Dec 2025
Viewed by 239
Abstract
China has abundant deep coalbed methane (CBM) resources; however, high temperature, stress, and reservoir pressure complicate the gas adsorption–desorption–diffusion–seepage processes, severely restricting the development of deep CBM. Through experimental research on adsorption, desorption, diffusion, and seepage behaviors of various coal samples, the control [...] Read more.
China has abundant deep coalbed methane (CBM) resources; however, high temperature, stress, and reservoir pressure complicate the gas adsorption–desorption–diffusion–seepage processes, severely restricting the development of deep CBM. Through experimental research on adsorption, desorption, diffusion, and seepage behaviors of various coal samples, the control mechanisms of deep coal reservoir properties on CBM production in the Linxing–Shenfu region have been revealed. The results indicate that CBM adsorption and desorption characteristics are jointly controlled by coal rank, ash yield, temperature. and pressure. Among the above conditions, coal rank and pressure exhibit positive effects, while ash yield and temperature show inhibitory effects. Analysis of desorption efficiency based on the Langmuir model further identifies sensitive desorption and rapid desorption stages as key phases for enhancing productivity. Moreover, the gas diffusion mechanism is dynamically evolving, with Knudsen diffusion and Fick diffusion being the main modes during high ground pressure stages, gradually transitioning to the coexistence of Knudsen, transition, and Fick diffusions as pressure decreases. Concurrently, gas–water seepage experiments demonstrate that increasing temperature will reduce the irreducible water saturation and enhance the relative permeability of the gas. Since irreducible water saturation is negatively correlated with relative permeability of gas, the relative permeability of the gas phase, cross-point saturation, and the range of the two-phase co-seepage zone all significantly increases with the increase in temperature. The findings systematically elucidate the regulatory mechanisms of deep coal reservoir properties in the process of “adsorption–desorption–diffusion–seepage,” providing critical theoretical support for optimizing development strategies and enhancing the efficiency of deep CBM development. Full article
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21 pages, 1076 KB  
Review
Advances in Biochar-Assisted Anaerobic Digestion: Effects on Process Stability, Methanogenic Pathways, and Digestate Properties
by Anita S. Leovac Maćerak, Dragana S. Žmukić, Nataša S. Duduković, Nataša S. Slijepčević, Aleksandra Z. Kulić Mandić, Dragana D. Tomašević Pilipović and Đurđa V. Kerkez
Separations 2026, 13(1), 18; https://doi.org/10.3390/separations13010018 - 30 Dec 2025
Viewed by 409
Abstract
Sludge, a by-product of wastewater treatment, contains harmful components that negatively impact the environment. One of the most ecologically viable and cost-effective methods for sludge treatment is anaerobic digestion, which produces biogas and stabilized digestate that can be applied to agricultural land. However, [...] Read more.
Sludge, a by-product of wastewater treatment, contains harmful components that negatively impact the environment. One of the most ecologically viable and cost-effective methods for sludge treatment is anaerobic digestion, which produces biogas and stabilized digestate that can be applied to agricultural land. However, anaerobic digestion has certain limitations that reduce biogas yield. To address these issues, various improvement methods have been developed, including the addition of biochar. Biochar, a carbon-rich biomass, enhances the decomposition of organic matter, reduces ammonia toxicity, and supports the growth of methanogenic archaea. Additionally, biochar improves the quality of the resulting digestate, making it more suitable for agricultural use and plant growth. This sustainable approach to sludge management not only benefits the wastewater sector, but also contributes to the energy and agricultural industries. Full article
(This article belongs to the Special Issue Engineering the Loop: Advancing Wastewater Treatment and Sludge Valorization Through Innovative Separation Materials)
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17 pages, 855 KB  
Article
Evaluation of Retention Mechanisms of Polar Compounds on Polar Stationary Phases Based on Type C Silica
by Minzhu Zou and Yong Guo
Separations 2026, 13(1), 17; https://doi.org/10.3390/separations13010017 - 30 Dec 2025
Viewed by 340
Abstract
Polar compounds can be separated on polar stationary phases attached on the surface of silica hydride (Type C silica). Although aqueous normal phase (ANP) chromatography has been used to denote this mode of separation, there have been no detailed studies on the retention [...] Read more.
Polar compounds can be separated on polar stationary phases attached on the surface of silica hydride (Type C silica). Although aqueous normal phase (ANP) chromatography has been used to denote this mode of separation, there have been no detailed studies on the retention mechanisms. We have applied the quantitative assessment methodology to investigate the retention mechanisms of polar compounds on the silica-hydride-based polar phases using a widely used hybrid silica-based amide phase for comparison. The study results indicate that the silica-hydride-based polar phases are not fundamentally different from the hybrid silica-based phase in terms of the adsorbed water layer and the retention mechanisms for polar compounds. Similar forces governing the retention in HILIC (i.e., partitioning, adsorption, and electrostatic interactions) are sufficient to describe the retention mechanisms of polar compounds on the silica-hydride-based polar phases. However, some small differences in selectivity are observed between the silica-hydride-based and hybrid silica-based phases. Full article
(This article belongs to the Collection State of the Art in Separation Science)
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19 pages, 2470 KB  
Article
Quantifying the Molecular Structural Effects on the Reaction Kinetics and Equilibrium Between Organic Amines and CO2: Insights from Theoretical Calculations
by Yupeng Cui, Qiyue Zhao, Yousheng Zhou, Chuanlei Liu and Hui Sun
Separations 2026, 13(1), 16; https://doi.org/10.3390/separations13010016 - 29 Dec 2025
Viewed by 320
Abstract
Understanding how molecular structure governs the reactivity of organic amines with CO2 is essential for the rational design of next-generation carbon-capture solvents. In this work, three representative series of amines, including linear aliphatic, cyclic aliphatic, and aromatic, were systematically conducted with substituents [...] Read more.
Understanding how molecular structure governs the reactivity of organic amines with CO2 is essential for the rational design of next-generation carbon-capture solvents. In this work, three representative series of amines, including linear aliphatic, cyclic aliphatic, and aromatic, were systematically conducted with substituents at different positions, and their reaction rate constants and equilibrium constants with CO2 were calculated using transition state theory. A suite of electronic-structure and steric descriptors, including ALIE, Hirshfeld charge, Fukui functions, and ESP-derived parameters, was developed to quantify structure–reactivity relationships. Linear aliphatic amines were found to be most sensitive to steric hindrance, while cyclic and aromatic amines were predominantly governed by inductive and conjugation effects. Key descriptors such as N_ALIE and q(N) showed strong correlations with both kinetic and thermodynamic parameters, enabling quantitative interpretation of substituent effects. Notably, a positive linear correlation between ln(k) and ln(K) was observed across all amine classes, revealing an intrinsic coupling between reaction rate and equilibrium. These findings deepen the mechanistic understanding of CO2–amine chemistry and provide a theoretical foundation for the targeted design and optimization of high-performance CO2-capture solvents. Full article
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18 pages, 1697 KB  
Article
Effects of pH and Salts on the Aggregation State of Semaglutide and Membrane Filtration Performance
by Lei Duan, Yu Yang, Hao Wu, Xuehuan Ding and Min Jiang
Separations 2026, 13(1), 15; https://doi.org/10.3390/separations13010015 - 29 Dec 2025
Viewed by 382
Abstract
The hydrophobic region of semaglutide makes it prone to aggregation in aqueous solution, which leads to serious interception in microfiltration. The influences of pH and low concentrations of salts (NaCl, CH3COONa, Na2SO4 and (NH4)2SO [...] Read more.
The hydrophobic region of semaglutide makes it prone to aggregation in aqueous solution, which leads to serious interception in microfiltration. The influences of pH and low concentrations of salts (NaCl, CH3COONa, Na2SO4 and (NH4)2SO4) on the particle size and zeta potential of semaglutide aggregates were studied in this work. The results showed pH could change the zeta potential on the semaglutide surface, but the impact on semaglutide dispersion was limited. When salts were introduced into aqueous solution, NaCl had a more significant dispersion effect on semaglutide than other salts. Under pH 2.5 or pH 8.0 conditions, the addition of 0.01 mol/L NaCl reduced the average particle size of semaglutide aggregates to below 70 nm. The permeability of semaglutide in microfiltration increased from 60% to 86% under optimized conditions with the PES membrane (0.22 μm), and the adsorption loss also reduced 40%. In addition, this study compared the HPLC detection precision of semaglutide samples prefiltered with different microfiltration filters. Some semaglutide was intercepted by various microfiltration filters, resulting in serious detection errors. When semaglutide was dissolved in the aqueous solution containing 0.01 mol/L NaCl with pH 2.5, the detection error was controlled within 1%. Full article
(This article belongs to the Section Separation Engineering)
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18 pages, 2757 KB  
Article
Heat Transfer Model for Traditional Chinese Medicine Extraction and Its Application in Laboratory and Industrial Equipment
by Gelin Wu, Feng Ding, Xinyan Zhao, Zhenfeng Wu, Xingchu Gong and Na Wan
Separations 2026, 13(1), 14; https://doi.org/10.3390/separations13010014 - 28 Dec 2025
Viewed by 443
Abstract
A semi-empirical lumped parameter model for the extraction process of traditional Chinese medicine based on thermal equilibrium was established in this work. In this model, the effect of heat dissipation was considered. Differential equations was solved using numerical methods. Key model parameters such [...] Read more.
A semi-empirical lumped parameter model for the extraction process of traditional Chinese medicine based on thermal equilibrium was established in this work. In this model, the effect of heat dissipation was considered. Differential equations was solved using numerical methods. Key model parameters such as the overall heat transfer coefficient and heat dissipation coefficient were obtained by fitting measured data. In the laboratory scale, Ginkgo biloba leaves were used as the liquid-solid extraction object to systematically investigate the effects of liquid-to-solid ratio, extraction temperature, solvent ratio, and slice particle size on the temperature changes during the extraction process. The average determination coefficient (R2) of the model fitting was 0.9955, and the R2 value for the prediction group was 0.9950. In the laboratory scale, extraction experiments of Xiaochaihu Decoction were conducted, and the performance of the model was verified. Furthermore, the model was applied to the mixed decoction process of five medicinal materials (Bupleurum, Glycyrrhiza, Scutellaria, Codonopsis, and Jujube) in industrial-scale for the production of Xiaochaihu capsules. The temperature change curves of three extraction tanks were all fitting well. The fitting results indicated abnormal heat transfer performance in Tank No. 1, providing a prompt for equipment maintenance and process optimization for the enterprise. A feasible method for temperature calculation and abnormal identification in the industrial process of traditional Chinese medicine extraction was provided in this work. Full article
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13 pages, 1607 KB  
Article
Characterization of Impurity Profile of Dimercaptosuccinate Using High-Performance Liquid Chromatography and Mass Spectrometry
by Jing Yao, Xiaofang Lian, Limin Zuo, Yongsheng Gu, Bingyu Yang, Yechun Zhang, Mingzhe Xu and Xiaodan Qiu
Separations 2026, 13(1), 13; https://doi.org/10.3390/separations13010013 - 27 Dec 2025
Viewed by 236
Abstract
As one of the key components in technetium-labeled radiopharmaceuticals, the quality of the dimercaptosuccinate (DMSA) plays a critical role in determining the safety and efficacy of the final drug product. However, due to its high polarity and susceptibility to oxidation, comprehensive characterization of [...] Read more.
As one of the key components in technetium-labeled radiopharmaceuticals, the quality of the dimercaptosuccinate (DMSA) plays a critical role in determining the safety and efficacy of the final drug product. However, due to its high polarity and susceptibility to oxidation, comprehensive characterization of the impurity profile of DMSA remains challenging. In this study, high-performance liquid chromatography and mass spectrometry were employed to achieve a systematic and thorough analysis of DMSA-related impurities. First, an HPLC-UV method was developed to enable baseline separation of DMSA and its impurities. Subsequently, a two-dimensional liquid chromatography–tandem mass spectrometry (2D-LC-MS/MS) approach was applied to identify six structurally diverse impurities present in DMSA. The developed HPLC method was rigorously validated and demonstrated to be sensitive, robust, and suitable for the accurate quantification and detection of trace impurities. Using the validated method, DMSA raw materials sourced from multiple manufacturers were analyzed, revealing significant variability in their impurity profiles. These findings underscore the importance of stringent quality control measures for DMSA in radiopharmaceutical manufacturing. This work not only establishes a reliable analytical framework for impurity profiling and structural elucidation of DMSA but also provides valuable insights for the development of quality control strategies and process optimization of radiopharmaceuticals. Full article
(This article belongs to the Section Chromatographic Separations)
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17 pages, 3548 KB  
Article
Study on Separation Density of Feeding Group Particle in the Gas–Solid Separation Fluidized Bed
by Xuchen Fan, Yuping Fu, Yongliang He, Liying Sun and Yijiang Li
Separations 2026, 13(1), 12; https://doi.org/10.3390/separations13010012 - 26 Dec 2025
Viewed by 240
Abstract
Gas–solid separation fluidized bed is an efficient coal cleaning and separation technology, and this technology has been extensively used in coal separation. The separation of the feeding coal particles in the fluidized bed is generally carried out in the form of particle groups, [...] Read more.
Gas–solid separation fluidized bed is an efficient coal cleaning and separation technology, and this technology has been extensively used in coal separation. The separation of the feeding coal particles in the fluidized bed is generally carried out in the form of particle groups, hence, a systematic examination of stratification as well as diffusion of the feeding particle group in the gas–solid separation fluidized bed is required. Simulated particles are used in this study and the technique that combines both theoretical calculation and an experimental method is used to investigate the effect of the inherent properties of the feeding particle group, bed characteristics, and operating parameters on the variation in voidage and air drag force in the separation process. According to the correlation between the separation density of the single-component particle group and the voidage of the gas–solid separation fluidized bed, the ρG.drag (change in separation density brought about by the upward airflow drag force during particle group fluidized bed separation) prediction model of the single-component spherical feeding particle group in the gas–solid separation fluidized bed is developed with the correction of voidage. When the prediction error of the ρG.drag prediction model is 10%, the confidence degree is 90.00%. Based on the particle segregation model and the ρG.drag prediction model, the separation density prediction model for the single-component spherical feeding particle group in the gas–solid separation fluidized bed is proposed. On this basis, the separation density prediction model for the single-component non-spherical feeding particle group in the gas–solid separation fluidized bed is further introduced. The separation density prediction model provides critical guidance for optimizing the gas–solid fluidized bed separation process. Full article
(This article belongs to the Special Issue Research Progress of Gas–Solid Fluidized Dry Separation)
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19 pages, 3540 KB  
Article
Uncarbonized Bovine Bone/MOF Composite as a Hybrid Green Material for CO and CO2 Selective Adsorption
by Helen Paola Toledo-Jaldin, Alien Blanco-Flores, Marquidia Pacheco, Ricardo Valdivia-Barrientos and Joel Pacheco
Separations 2026, 13(1), 11; https://doi.org/10.3390/separations13010011 - 25 Dec 2025
Viewed by 386
Abstract
This work aims to adsorb CO and CO2 using a low-cost biogenic waste (bone) as a platform for the in situ growth of HKUST-1, employing two methodologies. The synthesized composite materials, BMOF2 and BMOF3, exhibited functional, textural, and structural characteristics that [...] Read more.
This work aims to adsorb CO and CO2 using a low-cost biogenic waste (bone) as a platform for the in situ growth of HKUST-1, employing two methodologies. The synthesized composite materials, BMOF2 and BMOF3, exhibited functional, textural, and structural characteristics that were modulated by the MOF growth pathway. SEM, RXD, FTIR, XPS, and the N2 adsorption–desorption isotherm confirmed the growth of HKUST-1. Both methodologies yield the same MOF, but differ in surface area and shape. The relative and total coverage percentages were determined, as well as the apparent selectivity at a fixed time, establishing direct correlations between the structural and textural differences in the materials and their dynamic performance in the presence of both gases. Although the adsorption capacities obtained do not exceed those of other MOFs, the results from BMOF2 and BMOF3 demonstrate that the efficiency of an adsorbent depends not only on its capacity but also on its technological feasibility, including rapid processing and high capacities. The combination of abundant availability, a simple, sustainable, and reproducible synthetic route, and competitive performance makes these compounds viable alternatives for large-scale applications. Incorporating HKUTS-1 into bone as a functional material is a promising approach to developing new compounds for gas capture in the treatment of gas streams. Full article
(This article belongs to the Special Issue Separation and Remediation of Environmental Pollutants Using Functional Materials)
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