Separations

13 pages, 7158 KB

Open AccessEditor’s ChoiceArticle

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

Cited by 1 | Viewed by 1691

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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22 pages, 5183 KB

Open AccessEditor’s ChoiceArticle

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

Cited by 1 | Viewed by 682

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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20 pages, 1941 KB

Open AccessEditor’s ChoiceArticle

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 1773

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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15 pages, 2706 KB

Open AccessEditor’s ChoiceArticle

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 1378

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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26 pages, 1584 KB

Open AccessEditor’s ChoiceReview

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

Cited by 1 | Viewed by 1645

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

Open AccessEditor’s ChoiceArticle

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

Cited by 1 | Viewed by 993

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

Open AccessEditor’s ChoiceArticle

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 757

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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15 pages, 1611 KB

Open AccessEditor’s ChoiceArticle

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 753

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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19 pages, 656 KB

Open AccessEditor’s ChoiceReview

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

Cited by 6 | Viewed by 2315

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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17 pages, 855 KB

Open AccessEditor’s ChoiceArticle

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 1206

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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21 pages, 1076 KB

Open AccessEditor’s ChoiceReview

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

Cited by 4 | Viewed by 2376

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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16 pages, 2516 KB

Open AccessEditor’s ChoiceArticle

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

Cited by 2 | Viewed by 774

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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18 pages, 1697 KB

Open AccessEditor’s ChoiceArticle

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

Cited by 2 | Viewed by 2975

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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19 pages, 2470 KB

Open AccessEditor’s ChoiceArticle

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

Cited by 2 | Viewed by 1329

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, 2757 KB

Open AccessEditor’s ChoiceArticle

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 1128

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

Open AccessEditor’s ChoiceArticle

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 1123

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

Open AccessEditor’s ChoiceArticle

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 688

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 ρ_G.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 ρ_G.drag prediction model is 10%, the confidence degree is 90.00%. Based on the particle segregation model and the ρ_G.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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12 pages, 3718 KB

Open AccessEditor’s ChoiceArticle

Recovery of Fe, Pb and Zn from Blast Furnace Gas Ash by Intensive Calcination and Magnetic Separation Techniques

by Chunqing Gao, Huifen Yang, Jian Xu and Mingyu Sai

Separations 2026, 13(1), 10; https://doi.org/10.3390/separations13010010 - 25 Dec 2025

Viewed by 670

Abstract

Intensive calcination, selection and metallurgical joint comprehensive utilization of solid waste blast furnace gas ash generated by a Chinese iron and steel plant. The main valuable elements in the gas ash are Fe, Pb, Zn, and C, with contents of 22.46%, 3.22%, 10.57%, [...] Read more.

Intensive calcination, selection and metallurgical joint comprehensive utilization of solid waste blast furnace gas ash generated by a Chinese iron and steel plant. The main valuable elements in the gas ash are Fe, Pb, Zn, and C, with contents of 22.46%, 3.22%, 10.57%, and 27.02%, respectively. The iron minerals are mainly magnetite and hematite/limonite. Lead exists primarily in the form of lead vanadate and basic lead chloride. Zinc is associated with oxygen, sulfur, and iron in the form of zinc ferrite crystals. The effects of calcination temperature, calcination time, and reducing agent dosage on gasification and reduction indices were investigated. Results showed that using a gasification and reduction calcination–magnetic separation process with weak magnetism, at a calcination temperature of 1150 °C, with 20% anthracite as the reducing agent and a calcination time of 2 h, the volatilization rates of lead and zinc reached 96.70% and 98.26%, respectively. When the roasted ore was ground to a particle size of D₉₀ = 0.085 mm, high-quality iron concentrate with 65.61% iron grade and low lead and zinc contents of 0.08% and 0.17% was obtained, meeting the quality requirements for iron concentrate. The tailings from iron selection can be used as additives in cement and other construction materials. This integrated process combining pyrometallurgy and mineral processing enables the efficient and comprehensive utilization of blast furnace gas dust. Full article

(This article belongs to the Special Issue Advances in Novel Beneficiation Technology of Critical Minerals)

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19 pages, 3540 KB

Open AccessEditor’s ChoiceArticle

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 934

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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20 pages, 2917 KB

Open AccessEditor’s ChoiceArticle

Volatile Organic Compound Profiling of Traditional Multi-Herbal Prescriptions for Chemical Differentiation and Ethnopharmacological Insights

by Sumin Seo, Unyong Kim, Jiyu Kim, Chohee Jeong and Sang Beom Han

Separations 2026, 13(1), 8; https://doi.org/10.3390/separations13010008 - 24 Dec 2025

Viewed by 1174

Abstract

Traditional herbal prescriptions composed of multiple botanicals remain central to ethnopharmacological practice; however, their chemical basis and classification remain poorly understood. Non-volatile compound analyses of herbal medicines are well established, but comparative studies focusing on volatile organic compounds (VOCs) across multi-herbal prescriptions are [...] Read more.

Traditional herbal prescriptions composed of multiple botanicals remain central to ethnopharmacological practice; however, their chemical basis and classification remain poorly understood. Non-volatile compound analyses of herbal medicines are well established, but comparative studies focusing on volatile organic compounds (VOCs) across multi-herbal prescriptions are scarce. To enhance the chemical understanding of traditional formulations and clarify prescription-level characteristics, this study applied headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME–GC–MS) to characterize VOC-based chemical signatures in 30 prescriptions composed of 76 herbal ingredients. Multivariate analyses such as principal component analysis, partial least squares discriminant analysis (PLS-DA), and orthogonal PLS-DA (OPLS-DA) enabled systematic differentiation of various prescriptions and identified 25 discriminant VOCs, 9 of which were common among multiple therapeutic categories. These shared compounds, such as 5-hydroxymethylfurfural (5-HMF) and 4H-pyran-4-one derivatives, reflect recurrent chemical patterns associated with broad-spectrum applications, whereas category-specific volatiles (including isopsoralen, senkyunolide, and fenipentol) delineated therapeutic boundaries, even among prescriptions with overlapping botanicals. Capturing both shared and distinct volatile signatures clarified ambiguous boundaries between categories such as cold, inflammation, or diabetes versus kidney disorder prescriptions, thereby linking chemical patterns with ethnopharmacological indications. Together, these findings highlight VOC profiling as a valuable diagnostic and interpretive tool that bridges traditional categorization systems with modern chemical analysis, offering a robust framework for future pharmacological and mechanistic investigations. Such an approach not only substantiates traditional categorization but also provides a practical basis for quality control and pharmacological evaluation of multi-herbal formulations. Full article

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

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18 pages, 3471 KB

Open AccessEditor’s ChoiceArticle

Conceptual Design and Optimization of Reactive Distillation-Based Processes for the Separation of Methanol/Methyl Acetate/Ethyl Acetate with an Ethyl Acetate-Rich Feed Composition

by Cong Jing, Liangxiao Wei, Wei Xiang and Keyan Liu

Separations 2026, 13(1), 7; https://doi.org/10.3390/separations13010007 - 24 Dec 2025

Viewed by 1557

Abstract

Industrial effluents often contain azeotropic mixtures that are difficult to separate by conventional distillation. An illustrative case is the methanol/methyl acetate/ethyl acetate (MA/ME/EA) mixture. To address these challenges, this work studies the conceptual design and optimization of the reactive distillation-based hybrid processes for [...] Read more.

Industrial effluents often contain azeotropic mixtures that are difficult to separate by conventional distillation. An illustrative case is the methanol/methyl acetate/ethyl acetate (MA/ME/EA) mixture. To address these challenges, this work studies the conceptual design and optimization of the reactive distillation-based hybrid processes for separating the MA/ME/EA mixture with an EA-rich feed composition (0.25/0.20/0.55 mol fraction). An improved triple-column extractive–reactive distillation with a side-draw product (TCERD-SP) and its heat-integrated variant (TCERD-SP-HI) have been developed. In the TCERD-SP process, EA is strategically withdrawn as a side product, reconfiguring the extractive column into integrated pre-separation and entrainer-recovery sections, thereby reducing entrainer and energy demands. A four-step process design methodology is applied, including thermodynamics analysis, conceptual design, rigorous optimization via Aspen Plus integrated with the genetic algorithm to minimize total annual cost (TAC), and comparative evaluation of economic and environmental performance. The results show that the basic double-column pre-separation-reactive distillation (DCPSRD) process, optimal for a previous feed composition, exhibits unsatisfactory TAC performance for this EA-rich feed composition. Among the configurations studied, the TCERD-SP process exhibits superior performance, saving TAC by 8.4% and 14.4% compared to the TCERD and DCPSRD processes, respectively. In addition, based on the advantage of convenient heat integration between the side reboiler and the reactive distillation column condenser, the heat-integrated TCERD-SP-HI process achieves a further 10.7% TAC reduction. Thus, for this EA-rich feed examined in this work, the TCERD-SP and TCERD-SP-HI processes are demonstrated as effective solutions for recovering these valuable chemicals. Full article

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

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22 pages, 2056 KB

Open AccessEditor’s ChoiceArticle

Valorization of Lemon, Apple, and Tangerine Peels and Onion Skins–Artificial Neural Networks Approach

by Biljana Lončar, Aleksandra Cvetanović Kljakić, Jelena Arsenijević, Mirjana Petronijević, Sanja Panić, Svetlana Đogo Mračević and Slavica Ražić

Separations 2026, 13(1), 9; https://doi.org/10.3390/separations13010009 - 24 Dec 2025

Cited by 2 | Viewed by 1293

Abstract

This study focuses on the optimization of modern extraction techniques for selected by-product materials, including apple, lemon, and tangerine peels, and onion skins, using artificial neural network (ANN) models. The extraction methods included ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) with water as [...] Read more.

This study focuses on the optimization of modern extraction techniques for selected by-product materials, including apple, lemon, and tangerine peels, and onion skins, using artificial neural network (ANN) models. The extraction methods included ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) with water as the extractant, as well as maceration (MAC) with natural deep eutectic solvents (NADES). Key parameters, such as total phenolic content (TPC), total flavonoid content (TFC), and antioxidant activities, including reducing power (EC₅₀) and free radical scavenging capacity (IC₅₀), were evaluated to compare the efficiency of each method. Among the techniques, UAE outperformed both MAE and MAC in extracting bioactive compounds, especially from onion skins and tangerine peels, as reflected in the highest TPC, TFC, and antioxidant activity. UAE of onion skins showed the best performance, yielding the highest TPC (5.735 ± 0.558 mg CAE/g) and TFC (1.973 ± 0.112 mg RE/g), along with the strongest antioxidant activity (EC₅₀ = 0.549 ± 0.076 mg/mL; IC₅₀ = 0.108 ± 0.049 mg/mL). Tangerine peel extracts obtained by UAE also exhibited high phenolic content (TPC up to 5.399 ± 0.325 mg CAE/g) and strong radical scavenging activity (IC₅₀ 0.118 ± 0.099 mg/mL). ANN models using multilayer perceptron architectures with high coefficients of determination (r² > 0.96) were developed to predict and optimize the extraction results. Sensitivity and error analyses confirmed the robustness of the models and emphasized the influence of the extraction technique and by-product type on the antioxidant parameters. Principal component and cluster analyses showed clear grouping patterns by extraction method, with UAE and MAE showing similar performance profiles. Overall, these results underline the potential of UAE- and ANN-based modeling for the optimal utilization of agricultural by-products. Full article

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24 pages, 3841 KB

Open AccessEditor’s ChoiceReview

The Neglected Dimension in Pesticide Residues: Emerging Green and Enantioselective Strategies for the Analysis and Removal of Chiral Pesticides

by Binbin Liu, Ziyan Gong and Haixiang Gao

Separations 2026, 13(1), 4; https://doi.org/10.3390/separations13010004 - 23 Dec 2025

Cited by 1 | Viewed by 1558

Abstract

Chirality remains the most neglected axis of pesticide residue science. Many active ingredients are sold as racemates although their enantiomers differ in potency, persistence, transport, and toxicology; as a result, total concentration is a poor surrogate for risk. This review synthesizes green and [...] Read more.

Chirality remains the most neglected axis of pesticide residue science. Many active ingredients are sold as racemates although their enantiomers differ in potency, persistence, transport, and toxicology; as a result, total concentration is a poor surrogate for risk. This review synthesizes green and enantioselective strategies spanning the full analytical–remediation continuum. We survey solvent-minimized sample preparation approaches (SPME/TF-SPME, FPSE, µSPE, DLLME with DES/NADES), MS-compatible chiral separations (immobilized polysaccharide CSPs in LC and SFC, cyclodextrin-based selectors in GC, CE/CEC), and HRMS-enabled confirmation and suspect screening. Complex matrices (e.g., fermented beverages such as wine and high-sugar products) are critically discussed, together with practical matrix-tolerant workflows and the complementary role of chiral GC for hydrophobic residues. We then examine emerging enantioselective materials—MIPs, MOFs/COFs, and cyclodextrin-based sorbents—for extraction and preconcentration and evaluate stereoselective removal via adsorption, biodegradation, and chiral photocatalysis. Finally, we propose toxicity-weighted enantiomeric fraction (EF) metrics for decision-making, outline EF-aware green treatment strategies, and identify metrological and regulatory priorities (CRMs, ring trial protocols, FAIR data). Our thesis is simple: to reduce hazards efficiently and sustainably, laboratories and practitioners must measure—and manage—pesticide residues in the chiral dimension. Full article

(This article belongs to the Special Issue New Techniques for Extraction and Removal of Pesticide Residues)

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17 pages, 1418 KB

Open AccessEditor’s ChoiceArticle

Sustainable Luffa cylindrica Bio-Sponge Immobilized with Trichoderma koningiopsis UFPIT07 for Efficient Azo Dye Removal from Textile Effluents

by Paulo Henrique Silva de França Dias, Raphael Luiz Andrade Silva, Anna Gabrielly Duarte Neves, André Filipe Marinho de Andrade, Kethylen Barbara Barbosa Cardoso, Maria Eduarda Luiz Coelho de Miranda, Daniel Charles dos Santos Macêdo, Luiz Henrique Svintiskas Lino, Márcia Nieves Carneiro da Cunha, Alice Maria Gonçalves Santos, Marcos Antônio Barbosa de Lima, Thiago Pajeú Nascimento, Ana Lúcia Figueiredo Porto and Romero Marcos Pedrosa Brandão Costa

Separations 2026, 13(1), 1; https://doi.org/10.3390/separations13010001 - 19 Dec 2025

Viewed by 1096

Abstract

The contamination of water bodies by industrial dyes is a critical environmental challenge due to the toxicity and persistence of these compounds in aquatic ecosystems. This study evaluated the efficiency of Trichoderma koningiopsis immobilized on Luffa cylindrica matrices for the decolorization of the [...] Read more.

The contamination of water bodies by industrial dyes is a critical environmental challenge due to the toxicity and persistence of these compounds in aquatic ecosystems. This study evaluated the efficiency of Trichoderma koningiopsis immobilized on Luffa cylindrica matrices for the decolorization of the azo dye Direct Black 22 (DB22), proposing a biotechnological approach for wastewater treatment. The fungus was cultivated and immobilized on matrices characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). Experiments under different temperature, pH, and initial dye concentration conditions demonstrated that the immobilized system achieved up to 96% decolorization within 24 h under optimized conditions of 50 °C and pH 4, significantly outperforming the free fungus. The Luffa cylindrica matrix provided mechanical stability and a larger contact area for DB22 decolorization. Thus, the immobilized Trichoderma koningiopsis system on Luffa cylindrica stands out as a sustainable, cost-effective, and efficient alternative for dye removal from textile effluents, contributing to safer and more effective environmental practices. Full article

(This article belongs to the Section Advanced Separation Science in Biomedical Research and Clinical Applications)

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24 pages, 15014 KB

Open AccessEditor’s ChoiceArticle

Effect of Spiral Guide Groove Structure on Flow Field and Separation Performance of Cyclone Clarifiers

by Yulong Zhang, Kaiwei Guo, Qiang Liu, Lanyue Jiang, Anjun Li and Peikun Liu

Separations 2026, 13(1), 2; https://doi.org/10.3390/separations13010002 - 19 Dec 2025

Viewed by 1288

Abstract

This paper addresses the problem of high fine particle content in the overflow and insufficient separation efficiency of traditional cyclone clarifiers. A cyclone clarifier with a spiral guide groove is proposed. A comparative numerical simulation analyzes the flow field characteristics and separation performance [...] Read more.

This paper addresses the problem of high fine particle content in the overflow and insufficient separation efficiency of traditional cyclone clarifiers. A cyclone clarifier with a spiral guide groove is proposed. A comparative numerical simulation analyzes the flow field characteristics and separation performance inside traditional and spiral guide groove cyclone clarifiers. Comparing the flow fields shows that the spiral guide groove increases tangential velocity at the inlet, centrifugal force increases, axial velocity decreases, separation time increases, and separation efficiency improves. The spiral guide groove forces the fluid to follow an optimized path. It reduces circulating flows and vortices. The flow field becomes more uniform and stable. In the cone-plate region, streamlines are dense and axial velocity is low. This favors particle settling. In the underflow region, turbulent kinetic energy and the interaction between inner and outer vortices decrease. This reduces the number of particles entering the overflow pipe with the inner vortex. Compared to the traditional cyclone clarifier, the spiral guide groove cyclone clarifier effectively improves particle removal efficiency. The removal efficiency increases by 6.8%. The improvement effect varies for different particle sizes. The removal efficiency improvement is greatest for 15–20 μm particles. It effectively improves the water quality of the overflow outlet. Full article

(This article belongs to the Topic Advances in Separation Engineering)

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21 pages, 1620 KB

Open AccessEditor’s ChoiceArticle

Investigation of the Performance and Mechanism of CO₂ Capture Using Novel MEA/Polyamine/Sulfolane Biphasic Absorbents

by Guangjie Chen, Guangying Chen, Li Sze Lai, Zhiwei Zhang, Xiaodi Chen and Yun Hin Taufiq-Yap

Separations 2025, 12(12), 342; https://doi.org/10.3390/separations12120342 - 18 Dec 2025

Cited by 1 | Viewed by 1135

Abstract

Mixed amine/sulfolane (TMS) biphasic solutions have gained attention for their adjustable structure–activity relationships and lower regeneration energy. In this study, monoethanolamine (MEA) is employed as the main absorbent and polyamine as the co-absorbent, which are subsequently mixed with the phase separation promoter sulfolane [...] Read more.

Mixed amine/sulfolane (TMS) biphasic solutions have gained attention for their adjustable structure–activity relationships and lower regeneration energy. In this study, monoethanolamine (MEA) is employed as the main absorbent and polyamine as the co-absorbent, which are subsequently mixed with the phase separation promoter sulfolane (TMS) to form ternary biphasic solvent systems. Polyamine co-absorbents include 3-Dimethylaminopropylamine (DMAPA), 3-Diethylaminopropylamine (DEAPA), and Diethylenetriamine (DETA). Phase separation, absorption, and desorption performances were systematically studied. Reaction and phase separation mechanisms were elucidated through ¹³C nuclear magnetic resonance (NMR) spectroscopy. The overall mass transfer coefficients (K_G) were measured using a wetted wall column (WWC). Variations in the amine-to-sulfolane concentration ratio showed minimal impact on phase volume, while temperature and solvent composition significantly influenced phase separation behavior. All three solvents exhibited superior CO₂ capture performance, with CO₂ loadings in the rich phases ranging from 4.09 to 4.71 mol/L and over 96.82% of CO₂ concentrated in them, cyclic capacities reached or exceeded 3 mol/L, and regeneration energy consumption was 29.63–55.51% lower than 5 M MEA. ¹³C NMR analysis indicated that multiple N atoms in polyamines promoted the formation of additional ionic species during CO₂ absorption, thereby enhancing phase separation completeness. Furthermore, K_G values for the ternary systems exceeded that of conventional MEA, with the MEA/DEAPA/TMS system exhibiting a 1.7-fold increase. These findings demonstrated the industrial potential of MEA/polyamine/TMS biphasic solvents for efficient CO₂ capture. Full article

(This article belongs to the Topic Carbon Capture Science and Technology (CCST), 2nd Edition)

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16 pages, 1535 KB

Open AccessEditor’s ChoiceArticle

Determination of Dextromethorphan and Dextrorphan in Urine Using Bar Adsorptive Microextraction Followed by Gas Chromatography–Mass Spectrometry Analysis

by Marisa H. Maria, Margarida Fonseca, Alexandre Quintas and Nuno R. Neng

Separations 2025, 12(12), 341; https://doi.org/10.3390/separations12120341 - 16 Dec 2025

Viewed by 2315

Abstract

Over the past few years, the misuse of medications has progressively increased, posing a significant public health concern. This study proposed the development and validation of an alternative and greener analytical method for the determination of dextromethorphan (DXM) and its major metabolite, dextrorphan [...] Read more.

Over the past few years, the misuse of medications has progressively increased, posing a significant public health concern. This study proposed the development and validation of an alternative and greener analytical method for the determination of dextromethorphan (DXM) and its major metabolite, dextrorphan (DXO), in urine matrices using bar adsorptive microextraction (BAμE), followed by gas chromatography–mass spectrometry (GC-MS) analysis. Under optimized experimental conditions, average recoveries of 96.3% and 80.4% were achieved for DXM and DXO, respectively. The analytical limits obtained were 0.016 μg/mL for the limit of detection and 0.054 μg/mL for the limit of quantification. The working range was from 0.06 μg/mL to 2.0 μg/mL, with linearity for both compounds by determination coefficients (r² > 0.99) and the goodness-of-fit and lack-of-fit tests. Intra-day precision and trueness yielded values below 8.77% and 16.28%, respectively, for both compounds. Inter-day precision and trueness values were below 7.67% and 9.73%, respectively. The application to 26 urine samples allowed the quantification of both compounds, with concentrations ranging from 0.06 to 3.21 μg/mL for DXM and 0.06 to 8.88 μg/mL for DXO. The method proved to be effective, selective, sensitive, simple, and cost-effective in the detection and quantification of DXM and DXO, reinforcing its applicability and feasibility in various laboratory contexts. Full article

(This article belongs to the Special Issue Separation Techniques on a Miniaturized Scale)

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15 pages, 1179 KB

Open AccessEditor’s ChoiceArticle

Development and Validation of a Stability-Indicating RP-HPLC Method for Bexagliflozin and Structural Elucidation of a Novel Acidic Degradation Product

by Hadeel Alhourani, Nafisah Al-Rifai and Anas Alshishani

Separations 2025, 12(12), 340; https://doi.org/10.3390/separations12120340 - 15 Dec 2025

Cited by 1 | Viewed by 1678

Abstract

A robust and stability-indicating Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) method was developed and validated for the quantitative determination of bexagliflozin and its related impurities in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH Q2(R1)) [...] Read more.

A robust and stability-indicating Reverse Phase-High Performance Liquid Chromatography (RP-HPLC) method was developed and validated for the quantitative determination of bexagliflozin and its related impurities in accordance with the International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use (ICH Q2(R1)) guidelines. Chromatographic separation was achieved on a C18 column using a mobile phase of methanol and ammonium acetate buffer (pH 4.2) in a 60:40 (v/v) ratio, with a flow rate of 1.0 mL·min⁻¹ and UV detection at 220 nm. The method was validated for linearity, sensitivity (LOD and LOQ), precision, robustness, and system suitability, all within acceptable limits for low-concentration analysis. Excellent linearity (r² > 0.999) and precision (%RSD 0.3–4.4%) confirmed its reliability for stability assessment. The assay was performed at 100 µg·mL⁻¹, where all validation parameters showed %RSD values ≤ 2%, demonstrating high precision and robustness. Forced degradation studies under acidic, basic, oxidative, photolytic, and thermal conditions revealed a major degradation product formed under acidic stress. This product was isolated and structurally characterized using LC–MS, ¹H NMR, and ¹³C NMR, and is reported here for the first time. The proposed RP-HPLC method proved to be specific, precise, and reliable for the determination of bexagliflozin and its related impurities, making it suitable for routine stability testing, quality control, and pharmaceutical development applications. Full article

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27 pages, 3231 KB

Open AccessEditor’s ChoiceReview

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

by Athina Papadopoulou, Vasiliki Boti and Christina Nannou

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

Cited by 4 | Viewed by 2580

Abstract

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

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

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

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43 pages, 1255 KB

Open AccessEditor’s ChoiceReview

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

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

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

Cited by 8 | Viewed by 1876

Abstract

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

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

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

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14 pages, 1618 KB

Open AccessEditor’s ChoiceArticle

Fast Analytical Separation of Selected Agricultural Pesticides Using Supercritical Fluid Chromatography

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

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

Cited by 1 | Viewed by 1037

Abstract

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

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

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

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13 pages, 1304 KB

Open AccessEditor’s ChoiceArticle

Anticoagulant Potential of the Isolate with Green Solvents from Prosthechea karwinskii

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

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

Viewed by 769

Abstract

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

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

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

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14 pages, 1523 KB

Open AccessEditor’s ChoiceArticle

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

by Yuxin Bian, Honggen Wu and Wenlong Li

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

Viewed by 897

Abstract

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

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

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

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14 pages, 1584 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 3 | Viewed by 1268

Abstract

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

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

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

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20 pages, 1458 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 1 | Viewed by 1578

Abstract

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

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

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

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17 pages, 3037 KB

Open AccessEditor’s ChoiceArticle

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

by Aleksandras Chlebnikovas

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

Cited by 3 | Viewed by 1378

Abstract

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

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

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

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20 pages, 7539 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Viewed by 1251

Abstract

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

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

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

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17 pages, 1552 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 2 | Viewed by 1204

Abstract

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

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

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

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16 pages, 3577 KB

Open AccessEditor’s ChoiceArticle

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

by Bartłomiej Zieniuk and Dorota Kowalska

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

Cited by 1 | Viewed by 1184

Abstract

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

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

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

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14 pages, 1186 KB

Open AccessEditor’s ChoiceArticle

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

by Unai Duoandicoechea and Natalia Villota

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

Cited by 3 | Viewed by 1904

Abstract

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

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

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

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18 pages, 1969 KB

Open AccessEditor’s ChoiceReview

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

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

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

Cited by 2 | Viewed by 1572

Abstract

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

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

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

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20 pages, 1440 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 2 | Viewed by 2518

Abstract

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

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

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

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14 pages, 2341 KB

Open AccessEditor’s ChoiceArticle

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

by Daniela Angelova, Vesislava Toteva and Georgi Georgiev

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

Viewed by 1766

Abstract

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

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

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

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22 pages, 3564 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 1 | Viewed by 1194

Abstract

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

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

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

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18 pages, 2919 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 2 | Viewed by 3032

Abstract

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

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

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

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24 pages, 1470 KB

Open AccessEditor’s ChoiceReview

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

by Pedro Dinis, Eugenia Gallardo and Cláudia Margalho

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

Viewed by 3186

Abstract

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

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

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

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26 pages, 13045 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 1 | Viewed by 1072

Abstract

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

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

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

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12 pages, 1446 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Cited by 4 | Viewed by 1320

Abstract

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

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

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19 pages, 13378 KB

Open AccessEditor’s ChoiceArticle

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

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

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

Viewed by 1087

Abstract

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

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

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

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14 pages, 4696 KB

Open AccessEditor’s ChoiceArticle

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

by Na Huang, Shengwen Chen and Wanhe Du

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

Cited by 1 | Viewed by 1315

Abstract

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

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

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