Separations

20 pages, 1963 KiB

Open AccessArticle

MEMS-Based Micropacked Thermal Desorption GC/PID for In-Field Volatile Organic Compound Profiling from Hot Mix Asphalt

by Stefano Dugheri, Giovanni Cappelli, Riccardo Gori, Stefano Zampolli, Niccolò Fanfani, Ettore Guerriero, Donato Squillaci, Ilaria Rapi, Lorenzo Venturini, Alexander Pittella, Chiara Vita, Fabio Cioni, Domenico Cipriano, Mieczyslaw Sajewicz, Ivan Elmi, Luca Masini, Simone De Sio, Antonio Baldassarre, Veronica Traversini and Nicola Mucci

Separations 2025, 12(5), 133; https://doi.org/10.3390/separations12050133 - 19 May 2025

Abstract

Background: In response to the growing demand for the real-time, in-field characterization of odorous anthropogenic emissions, this study develops and uses a MEMS-based micropacked thermal desorption Gas Chromatography system coupled with a PhotoIonization Detector (GC/PID) for Hot Mix Asphalt (HMA) plant emissions. Methods: [...] Read more.

Background: In response to the growing demand for the real-time, in-field characterization of odorous anthropogenic emissions, this study develops and uses a MEMS-based micropacked thermal desorption Gas Chromatography system coupled with a PhotoIonization Detector (GC/PID) for Hot Mix Asphalt (HMA) plant emissions. Methods: The innovative portable device, Pyxis GC, enables the high-sensitivity profiling of Volatile Organic Compounds (VOCs), particularly aldehydes and ketones, with sub-ppb detection limits using ambient air as the carrier gas. A comprehensive experimental design optimized the preconcentration parameters, resulting in an efficient, green analytical method evaluated via the Green Analytical Procedure Index (GAPI). Sorbent comparison showed quinoxaline-bridged cavitands outperform the conventional materials. Results and conclusions: The method was successfully deployed on site for source-specific sampling at an HMA plant, generating robust emission fingerprints. To assess environmental impact, a Generalized Additive Model (GAM) was developed, incorporating the process temperature and Sum of Odour Activity Values (SOAV) to predict odour concentrations. The model revealed a significant non-linear influence of temperature on emissions and validated its predictive capability despite the limited sample size. This integrated analytical–statistical approach demonstrates the utility of MEMS technology for real-time air quality assessment and odour dispersion modelling, offering a powerful tool for environmental monitoring and regulatory compliance. Full article

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

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14 pages, 1459 KiB

Open AccessArticle

Rapid Determination of Nimesulide by Capillary Zone Electrophoresis in Various Pharmaceutical Formulations

by Claudia Vinci Ho and Jiří Pazourek

Separations 2025, 12(5), 132; https://doi.org/10.3390/separations12050132 - 19 May 2025

Abstract

Nimesulide is a popular non-steroidal anti-inflammatory drug (NSAID) and a cyclooxygenase-2 inhibitor available in more than 50 countries worldwide. A rapid and simple method for nimesulide determination is presented. Experimental parameters based on a previously published work were revised and adopted into a [...] Read more.

Nimesulide is a popular non-steroidal anti-inflammatory drug (NSAID) and a cyclooxygenase-2 inhibitor available in more than 50 countries worldwide. A rapid and simple method for nimesulide determination is presented. Experimental parameters based on a previously published work were revised and adopted into a method with significantly better performance: pH was shifted from 8.10 to 9.25, borate background electrolyte concentration from 10 to 60 mM—resulting in a run time less than 4 min, and number of theoretical plates greater than 100,000. The method was validated and applied for the determination of nimesulide in three formulations with the active substance of nimesulide: tablets, gel, and powder (in sachets for oral suspension). Also, the tablets were tested for uniformity of content of single-dose preparations according to Ph. Eur. Full article

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

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13 pages, 5373 KiB

Open AccessArticle

Surface Properties of NaCl and KCl in a Potassium−Sodium-Saturated System with Low-Natrium Salt

by Yanfang Ma, Shouyan Huang, Xin Liu, Xujie Shi, Yongsheng Du and Haining Liu

Separations 2025, 12(5), 131; https://doi.org/10.3390/separations12050131 - 16 May 2025

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Abstract

With the continuous development of the potash industry in salt lakes, the preparation of low-natrium salt for the green and environmentally friendly utilization of potassium and sodium resources in salt lakes has become a research hotspot. The primary method involves obtaining potassium brine [...] Read more.

With the continuous development of the potash industry in salt lakes, the preparation of low-natrium salt for the green and environmentally friendly utilization of potassium and sodium resources in salt lakes has become a research hotspot. The primary method involves obtaining potassium brine from salt-lake brine through evaporation and then subjecting this mineral to transformation crystallization to obtain low-natrium salt crystals. In the crystallization vessel, a potassium−sodium-saturated solution is introduced, followed by the addition of an appropriate amount of water and solid magnesium chloride. After a thorough reaction, the solid−liquid separation yields the target product of low-natrium salt. Subsequently, the surface properties of KCl and NaCl crystals were calculated using first-principles methods. The research findings revealed that potassium chloride crystals, when they contained defects, readily adsorbed Na⁺ and NaCl. In a sodium−potassium-saturated system, KCl and NaCl easily formed heterojunctions, leading to embedded crystallization as the Mg²⁺ concentration increased in this saturated system. Feed rate and residence time directly affect the purity of low-natrium salt. A low-natrium salt meeting the requirements can be obtained after a residence time of more than 80 min under the following conditions. Full article

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

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35 pages, 8311 KiB

Open AccessReview

Efficient Exploitation of Lepidolite Resources: A Review on Beneficiation Techniques, Extraction Methods, and Synergistic Optimization

by Jiangang Ku, Xiao Shi, Qian Wang, Hanyu Lin, Hongliang Shang and Zhengchang Shen

Separations 2025, 12(5), 130; https://doi.org/10.3390/separations12050130 - 16 May 2025

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Abstract

Lithium is a critical mineral resource. With the development of high-end manufacturing industry, the demand for high-performance lithium-containing chemical raw materials continues to grow. At present, lithium needs to be acquired from a large amount of lepidolite ore, constrained by the existing lithium [...] Read more.

Lithium is a critical mineral resource. With the development of high-end manufacturing industry, the demand for high-performance lithium-containing chemical raw materials continues to grow. At present, lithium needs to be acquired from a large amount of lepidolite ore, constrained by the existing lithium resource supply limitation quandary, and the industry urgently needs to develop more efficient beneficiation and extraction methods for lepidolite. Findings have suggested mixed collectors (e.g., DDA/SDBS) achieve a 4.99% Li₂O grade and 98% recovery at neutral pH, reducing reagent use by 20–30%. Microwave-assisted roasting boosts Li recovery to 95.9% and cuts energy use by 26.9%. Bioleaching with Acidithiobacillus ferrooxidans (A.F.) and rhamnolipid releases 6.8 mg/L Li with a lower environmental impact. Sulfuric acid baking recovers Li (97.1%), Rb (96.0%), and Cs (95.1%) efficiently. Despite challenges in fine-particle recovery and reagent costs, integrated strategies like nanobubble flotation, green collectors, and AI optimization offer sustainable, high-efficiency extraction. This work provides insights for advancing lepidolite processing, balancing economics and environmental stewardship. Full article

(This article belongs to the Special Issue Mineral Processing and Separation: Research, Innovation and Production)

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20 pages, 4911 KiB

Open AccessArticle

Tannic Acid/Lysozyme-Assembled Loose Nanofiltration Membrane with Outstanding Antifouling Properties for Efficient Dye/Salt Separation

by Jianmao Yang, Xuzhao Yan, Shuai Liu, Mengchen Shi, Ying Huang, Fang Li and Xiaofeng Fang

Separations 2025, 12(5), 129; https://doi.org/10.3390/separations12050129 - 16 May 2025

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Abstract

Precise separation and antifouling capabilities are critical for the application of membrane separation technology. In this work, we developed a multiplayer layer-by-layer assembly strategy to sequentially deposit tannic acid (TA) and lysozyme (Lys) onto polyethersulfone/iron (PES/Fe) ultrafiltration membrane substrates, enabling the simple and [...] Read more.

Precise separation and antifouling capabilities are critical for the application of membrane separation technology. In this work, we developed a multiplayer layer-by-layer assembly strategy to sequentially deposit tannic acid (TA) and lysozyme (Lys) onto polyethersulfone/iron (PES/Fe) ultrafiltration membrane substrates, enabling the simple and efficient fabrication of a biofouling-resistant loose nanofiltration (LNF) membrane with superior dye/salt separation performance. This approach fully leverages the multifunctionality of TA by exploiting its coordination with Fe³⁺ and non-covalent interactions with Lys. The obtained PES/Fe-TA-Lys LNF membrane exhibits a pure water flux of 57.5 L·m⁻²·h⁻¹, along with exceptional dye rejection rates (98.3% for Congo Red (CR), 99.2% for Methyl Blue (MB), 98.4% for Eriochrome Black T (EBT), and 67.6% for Acid Orange 74 (AO74)) while maintaining minimal salt retention (8.2% for Na₂SO₄, 4.3% for MgSO₄, 3.5% for NaCl, and 2.4% for MgCl₂). The PES/Fe-TA-Lys LNF membrane also displays outstanding antifouling performance against bovine serum albumin (BSA), humic acid (HA), and CR, along with strong biofouling resistance against Escherichia coli (E. coli) and Pseudomonas aeruginosa (P. aeruginosa) via synergistic anti-adhesion and biofilm inhibiting effects. This work presents a novel and scalable approach to fabricating biofouling-resistant LNF membranes, offering great potential for dye/salt separation in textile wastewater treatment. Full article

(This article belongs to the Special Issue Advanced Functional Materials for Wastewater Treatment and Purification)

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20 pages, 5360 KiB

Open AccessArticle

Highly Efficient Removal of Cadmium from Wastewater Using Eco-Friendly and Cost-Effective Amorphous Silicoaluminophosphates as Adsorbent Particles

by Hamza Annath, Oluwafikayo Jaiyeola and Chirangano Mangwandi

Separations 2025, 12(5), 128; https://doi.org/10.3390/separations12050128 - 16 May 2025

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Abstract

This article presents a study on the development of amorphous aluminophosphate (Am-AlP) and silico-aluminophosphate (Am-SiAlP) materials for the removal of cadmium (Cd) from wastewater. Cadmium is a toxic heavy metal that poses significant environmental and health risks, and its removal from water sources [...] Read more.

This article presents a study on the development of amorphous aluminophosphate (Am-AlP) and silico-aluminophosphate (Am-SiAlP) materials for the removal of cadmium (Cd) from wastewater. Cadmium is a toxic heavy metal that poses significant environmental and health risks, and its removal from water sources is crucial. This study explores the synthesis of these materials, focusing on the impact of silicon content on their adsorption properties. The materials were characterized using various techniques, including FTIR, XRD, TGA, and BET analysis, which revealed that the incorporation of silicon increased the surface area and porosity of the adsorbents, enhancing their cadmium removal efficiency. The Am-SiAlP (7.5) sample, with a 7.5 mol% Si content, showed the highest adsorption capacity (52.63 mg g⁻¹) and removal efficiency (93%). Kinetic studies revealed that over 90% of cadmium was removed within the first 30 min, indicating rapid adsorption capabilities. The adsorption process was found to follow a pseudo-second-order kinetic model, indicating chemisorption as the rate-limiting step. The Langmuir isotherm model best described the adsorption, suggesting monolayer adsorption of cadmium on the adsorbent surface. This study also investigated the effect of interfering ions, showing that while the presence of other ions slightly reduced the adsorption efficiency, the Am-SiAlP (7.5) material still performed well. This research concludes that Am-SiAlP materials, particularly Am-SiAlP (7.5), are promising adsorbents for cadmium removal due to their high efficiency, cost-effectiveness, and environmental friendliness. Full article

(This article belongs to the Special Issue Adsorption/Degradation Methods for Water and Wastewater Treatment)

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13 pages, 2347 KiB

Open AccessArticle

Development and Optimization of a Gas Chromatography–Mass Spectrometry Analytical Method for Detecting Sulfolane and Benzene Toluene, Ethylbenzene, and Xylenes in Water Samples

by Merrik Kobarfard, Alexander Sweett, Jennie Hansson, Beth Parker and Tadeusz Górecki

Separations 2025, 12(5), 127; https://doi.org/10.3390/separations12050127 - 15 May 2025

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Abstract

Sulfolane, an organic solvent widely used in the petrochemical industry, has raised concerns due to its potential health risks and environmental mobility. Toxicological studies suggest that it may negatively affect human and ecological health, highlighting the need for risk assessments. Alongside sulfolane, BTEX [...] Read more.

Sulfolane, an organic solvent widely used in the petrochemical industry, has raised concerns due to its potential health risks and environmental mobility. Toxicological studies suggest that it may negatively affect human and ecological health, highlighting the need for risk assessments. Alongside sulfolane, BTEX compounds (benzene, toluene, ethylbenzene, and xylenes) are commonly present in petrochemical operations, and their migration may be influenced by sulfolane. This study developed a gas chromatography–mass spectrometry (GC-MS) method for simultaneous analyses of sulfolane and BTEX in water. The sample preparation was designed for simplicity to allow for easy implementation without specialized equipment. The method was characterized, validated, and its ruggedness was tested through experimental design. The method was then applied to evaluate the stability of water samples under various storage conditions, and to analyze 97 real water samples collected from a contaminated site in Alberta, Canada. The results identified 17 samples with sulfolane concentrations exceeding the maximum limits for aquatic life preservation, and three samples with detectable toluene levels. These findings highlight the need for further research to better understand contamination profiles and assess associated risks. Full article

(This article belongs to the Special Issue Separation and Speciation of Emerging Pollutants in Soil and Groundwater)

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19 pages, 2378 KiB

Open AccessArticle

Simulation of Water Vapor Sorption Profiles on Activated Carbons in the Context of the Nuclear Industry

by Felipe Cabral Borges Martins, Mouheb Chebbi, Céline Monsanglant-Louvet, Bénoit Marcillaud and Audrey Roynette

Separations 2025, 12(5), 126; https://doi.org/10.3390/separations12050126 - 14 May 2025

Viewed by 149

Abstract

Activated carbons (ACs) are employed in the nuclear industry to mitigate the emission of potential radioactive iodine species. Their retention performances towards iodine are mainly dependent on the relative humidity due to the competitive effect induced by adsorbed water molecules. Thus, this work [...] Read more.

Activated carbons (ACs) are employed in the nuclear industry to mitigate the emission of potential radioactive iodine species. Their retention performances towards iodine are mainly dependent on the relative humidity due to the competitive effect induced by adsorbed water molecules. Thus, this work will focus on the prediction of AC behavior toward the capture of water vapor to better assess the poisoning effect on radiotoxic iodine removal. For the first time, H₂O breakthrough curves (BTCs) on nuclear grade ACs are predicted through a specific methodology based on the combination of transport phenomena with adsorption kinetics and equilibrium. Three ACs, similar to those deployed in the nuclear context, are considered within the present study. Our model is based on the Linear Driving Force Model (LDF), governed by an intraparticle diffusion mechanism, notably surface and Knudsen diffusions. In addition, the type V isotherms obtained for H₂O and the investigated carbon supports were described through the Klotz equation, taking into account the formation and progressive growth of H₂O clusters within the internal porosity. This methodology allowed us to successfully simulate the H₂O adsorption by a non-impregnated AC, where only physisorption phenomena are involved. In addition, promising results were highlighted when extrapolating to the two other impregnated ACs (AC 5KI and AC Nuclear). Full article

(This article belongs to the Section Separation Engineering)

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21 pages, 2983 KiB

Open AccessArticle

Impact of Hydrogen Peroxide Concentration on Diclofenac Degradation by UV/H₂O₂: Kinetic Modeling for Water Treatment Applications

by Natalia Villota, Unai Duoandicoechea, Begoña Echevarria and Ana María de Luis

Separations 2025, 12(5), 125; https://doi.org/10.3390/separations12050125 - 14 May 2025

Viewed by 123

Abstract

This study researches the impact of diclofenac (DCF) oxidation via UV/H₂O₂ on water quality, focusing on aromaticity and color changes. The process effectively degrades DCF and its intermediates through hydroxyl radical attack on the aromatic structure, leading to the formation [...] Read more.

This study researches the impact of diclofenac (DCF) oxidation via UV/H₂O₂ on water quality, focusing on aromaticity and color changes. The process effectively degrades DCF and its intermediates through hydroxyl radical attack on the aromatic structure, leading to the formation of oxidized by-products. Initially, chromophoric compounds such as quinones and conjugated intermediates cause a yellow coloration, which diminishes as mineralization progresses. Turbidity remains below 1 NTU, aligning with European water quality standards. Aromaticity initially increases due to the stable intermediates (e.g., catechols and hydroquinones) but decreases as advanced oxidation cleaves aromatic rings. Kinetic modeling shows that DCF degradation follows first-order kinetics, while aromatic intermediates degrade via fractional-order kinetics (~0.3), indicating a non-linear relationship with concentration. The formation of chromophore compounds follows first-order kinetics, whereas their degradation transitions to zero-order kinetics when hydroxyl radicals are abundant. The study highlights the environmental relevance of these transformations, as aromatic intermediates like anilines and phenols, which contribute to water toxicity, are ultimately converted into less hazardous compounds (e.g., carboxylic acids and inorganic ions). Experimental validation confirms that degradation kinetics depend on hydrogen peroxide concentration, underscoring the potential of UV/H₂O₂ for water purification and pollutant removal. Full article

(This article belongs to the Special Issue Adsorption/Degradation Methods for Water and Wastewater Treatment)

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24 pages, 1664 KiB

Open AccessReview

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

by Attilio Naccarato, Rosangela Elliani and Antonio Tagarelli

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

Viewed by 169

Abstract

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

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

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

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15 pages, 6357 KiB

Open AccessArticle

Study on Floatation Separation of Molybdenite and Talc Based on Crystal Surface Anisotropy

by Qidong Zhang, Xiaoli Li, Zhifang Hu, Bowen Gao and Chen Liu

Separations 2025, 12(5), 123; https://doi.org/10.3390/separations12050123 - 13 May 2025

Viewed by 107

Abstract

Talcose molybdenite resources are abundant but resource utilization is low. The floatation separation of molybdenite (MoS₂) and talc is challenging due to their similar natural hydrophobicity and layered structures. This study investigates the surface properties and interaction mechanisms between these minerals [...] Read more.

Talcose molybdenite resources are abundant but resource utilization is low. The floatation separation of molybdenite (MoS₂) and talc is challenging due to their similar natural hydrophobicity and layered structures. This study investigates the surface properties and interaction mechanisms between these minerals to improve their separation efficiency. Density functional theory (DFT) calculations confirm that the basal planes of both minerals are hydrophobic, while their edge surfaces are hydrophilic. Atomic force microscopy (AFM) and DLVO theory reveal that molybdenite and talc particles aggregate in neutral/acidic conditions but disperse in alkaline solutions due to altered surface forces. Floatation experiments demonstrate that pulp pH is the key controlling factor—alkaline conditions (pH > 10) effectively reduce hetero-aggregation, enabling selective molybdenite recovery. These findings provide critical insights into optimizing floatation processes for talcose molybdenite ores, enhancing resource utilization. Full article

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

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11 pages, 1447 KiB

Open AccessArticle

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

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

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

Viewed by 183

Abstract

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

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

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

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14 pages, 1954 KiB

Open AccessArticle

Sunflower Seed Oil Enriched with Compounds from the Turmeric Rhizome: Extraction, Characterization and Cell Viability

by Késia Corsato de Oliveira Segantini, Oscar de Oliveira Santos Junior, Vitor Augusto Dos Santos Garcia, Djéssica Tatiane Raspe and Camila da Silva

Separations 2025, 12(5), 121; https://doi.org/10.3390/separations12050121 - 11 May 2025

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Abstract

The present work aimed to obtain and characterize sunflower seed oil (SO) enriched with compounds from turmeric rhizome (TR). For this purpose, the enriched oil was obtained from two strategies: extraction of the compounds from TR using SO as solvent (ESO) and simultaneous [...] Read more.

The present work aimed to obtain and characterize sunflower seed oil (SO) enriched with compounds from turmeric rhizome (TR). For this purpose, the enriched oil was obtained from two strategies: extraction of the compounds from TR using SO as solvent (ESO) and simultaneous extraction of SO and TR compounds using ethyl acetate as solvent (ESOS). In these strategies, the effect of time (15 and 30 min) and temperature (60 and 70 °C) on the enrichment in relation to the curcuminoids content was determined. Evaluation of phytochemicals such as total phenolic compounds (TPCs), phenolic compound profile and fatty-acid profile and bioactivity by antioxidant potential (AP) was carriedoutin the enriched oils and in the SO;mean while, oxidative stability and cytotoxicity were evaluated using HaCaT (human immortalized keratinocyte) cells. From the results obtained, higher contents of curcuminoids (510 mg/100 g oil) were observed in the oil obtained from simultaneous extraction (ESOS) in a shorter time and lower temperature (15 min and 60 °C), and similar behavior was found for the content of phenolic compounds and antioxidant potential. The profile of phenolic compounds revealed the presence of phenolic acids, curcuminoids and terpenes in the composition of the enriched oils, which increased oxidative stability. The oils obtained did not show any cytotoxic effect against the cells tested, confirmed by the high survival rate (>88%) after 48 h of exposure. Full article

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

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16 pages, 2101 KiB

Open AccessArticle

Simultaneous Determination and Quantification of NineNitrosamine Impurities in Semi-Solid Forms Using a GC–MS/MS Method

by Namjin Lee, Hyejin Go and Young-joon Park

Separations 2025, 12(5), 120; https://doi.org/10.3390/separations12050120 - 11 May 2025

Viewed by 193

Abstract

Many studies are being conducted on the detection of nitrosamine impurities in solid formulations. However, research on semi-solid formulations such as gels, ointments and creams is not common. In particular, excipients used to increase viscosity and add fragrance can significantly impact the sample [...] Read more.

Many studies are being conducted on the detection of nitrosamine impurities in solid formulations. However, research on semi-solid formulations such as gels, ointments and creams is not common. In particular, excipients used to increase viscosity and add fragrance can significantly impact the sample preparation. Volatile compounds derived from natural fragrances are composed of a wide variety of complex components, making them very difficult to handle and completely separate from the analytes. Due to the complex composition of these formulations, an analytical method was developed to accurately separate and analyze nine nitrosamine impurities (NDMA, NDEA, NMEA, NDPA, NDBA, NPIP, NMOR, DIPNA and EIPNA) simultaneously. To overcome challenges in the sample preparation of excipients with physical and chemical properties, the sample was prepared using solvents such as methanol, hexane, water and dichloromethane. The target analytes were extracted with dichloromethane for the final preparation for GC–MS/MS and the optimal conditions were established. While multiple GC columns were tested, peak overlapping interferences were observed, leading to the use of a 60m-long column to overcome peak overlap. The GC–MS/MS condition was set for optimal performance and ionization energy, with parameters adjusted for each analyte. The developed method was validated in accordance with guidelines to ensure its reliability and suitability. As a result, all nine nitrosamine impurities were simultaneously analyzed, confirming excellent performance. The sample preparation method and procedure, column specification and GC–MS/MS conditions have the potential to be adapted not only for semi-solid formulations of pharmaceuticals and cosmetics but also for other formulations such as solid and liquid samples, rendering them suitable for the analysis of nitrosamine impurities. Full article

(This article belongs to the Special Issue Analysis and Bioanalysis of Pharmaceuticals: Sample Preparation and Chromatography)

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17 pages, 2794 KiB

Open AccessArticle

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

by Kiana Modaresahmadi, Amid P. Khodadoust and James Wescott

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

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Abstract

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

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

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16 pages, 3021 KiB

Open AccessArticle

Repurposing Portable Gas Chromatograph–Mass Spectrometers for Detecting Volatile Organic Compound Biomarkers in Urine Headspace

by Mark Woollam, Serenidy Eckerle, Eray Schulz, Sahanaa Nishkaran, Sara Button and Mangilal Agarwal

Separations 2025, 12(5), 118; https://doi.org/10.3390/separations12050118 - 7 May 2025

Viewed by 586

Abstract

Volatile organic compounds (VOCs) in urine headspace are potential biomarkers for different medical conditions, as canines can detect human diseases simply by smelling VOCs. Because dogs can detect disease-specific VOCs, gas chromatography–mass spectrometry (GC–MS) systems may be able to differentiate medical conditions with [...] Read more.

Volatile organic compounds (VOCs) in urine headspace are potential biomarkers for different medical conditions, as canines can detect human diseases simply by smelling VOCs. Because dogs can detect disease-specific VOCs, gas chromatography–mass spectrometry (GC–MS) systems may be able to differentiate medical conditions with enhanced accuracy and precision, given they have unprecedented efficiency in separating, quantifying, and identifying VOCs in urine. Advancements in instrumentation have permitted the development of portable GC–MS systems that analyze VOCs at the point of care, but these are designed for environmental monitoring, emergency response, and manufacturing/processing. The purpose of this study is to repurpose the HAPSITE^® ER portable GC–MS for identifying urinary VOC biomarkers. Method development focused on optimizing sample preparation, off-column conditions, and instrumental parameters that may affect performance. Once standardized, the method was used to analyze a urine standard (n = 10) to characterize intra-day reproducibility. To characterize inter-day performance, n = 3 samples each from three volunteers (and the standard) were analyzed each day for a total of four days (n = 48 samples). Results showed the method could detect VOC signals with adequate reproducibility and distinguish VOC profiles from different volunteers with 100% accuracy. Full article

(This article belongs to the Special Issue Chromatographic Analysis of Biomarkers)

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25 pages, 5272 KiB

Open AccessArticle

Synthesis of Magnetic Iron Oxide Heat-Activated Termite Mound Composite for Adsorption of Basic Blue 41 Dye from Textile Wastewater: Characterization and Box–Behnken Optimization

by Amare Melaku, Esayas Alemayehu, Abebe Worku and Bernd Lennartz

Separations 2025, 12(5), 117; https://doi.org/10.3390/separations12050117 - 6 May 2025

Viewed by 141

Abstract

The discharge of textile effluents containing dyes poses severe environmental risks. This study aimed to develop a

m a g n e t i c i r o n o x i d e

–HTM (magnetite–heat-activated termite mound) composite via the [...] Read more.

The discharge of textile effluents containing dyes poses severe environmental risks. This study aimed to develop a

m a g n e t i c i r o n o x i d e

–HTM (magnetite–heat-activated termite mound) composite via the coprecipitation method for the adsorption of Basic Blue 41 (BB41) dye from textile wastewater under batch conditions. The

m a g n e t i c i r o n o x i d e

–HTM composite was characterized using BET (surface area), XRD (crystalline structure), FTIR (functional groups), and SEM (microstructure) analyses, confirming the successful synthesis of

m a g n e t i c i r o n o x i d e

–HTM. Comprising 80% HTM by mass, the composite demonstrates economic viability. Using batch experiments and a Box–Behnken design, the adsorption performance of

m a g n e t i c i r o n o x i d e

–HTM for BB41 dye removal from aqueous solutions was evaluated. Optimization of the sorption process revealed that a dosage of 2.6 g/L, a contact time of 47.5 min, a temperature of 60 °C, and an initial dye concentration of 100 mg/L resulted in a BB41 dye removal efficiency of 98%. Additionally,

m a g n e t i c

–HTM effectively removed BB41 dye from real wastewater samples, achieving a removal efficiency exceeding 80%, highlighting the improved sorption properties of the modified termite mound. The spent

m a g n e t i c

–HTM was easily separated from the treated solution using an external magnet and successfully recovered. Its reusability demonstrated a dye removal efficiency of 78% after four cycles, without compromising its magnetic properties. Overall, the magnetically separable

m a g n e t i c i r o n o x i d e

–HTM composite shows significant potential for the treatment of textile wastewater. Full article

(This article belongs to the Section Purification Technology)

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22 pages, 2918 KiB

Open AccessArticle

Comparative Evaluation of UV-C-Activated Peroxide and Peroxydisulfate for Degradation of a Selected Herbicide

by Jelena Mitrović, Miljana Radović Vučić, Miloš Kostić, Milica Petrović, Nena Velinov, Slobodan Najdanović and Aleksandar Bojić

Separations 2025, 12(5), 116; https://doi.org/10.3390/separations12050116 - 3 May 2025

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Abstract

Extensive utilization of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has resulted in contamination of the aquatic environment; this situation requires effective treatment technology. Ultraviolet-based advanced oxidation processes (UV-AOPs) are widely employed for the removal of organic contaminants from water. This study’s aim was to [...] Read more.

Extensive utilization of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) has resulted in contamination of the aquatic environment; this situation requires effective treatment technology. Ultraviolet-based advanced oxidation processes (UV-AOPs) are widely employed for the removal of organic contaminants from water. This study’s aim was to compare the degradation of the pesticide 2,4-D in UV-C-activated peroxide and peroxydisulfate systems. UV-C irradiation alone exhibited a negligible effect on pesticide degradation, whereas the addition of oxidants significantly enhanced the degradation efficiency relative to 2,4-D. Complete pesticide removal was achieved after 15 min of UV/H₂O₂ treatment, while twice as much time was required with the UV/S₂O₈²⁻ process. COD decreased by 74% and 28% for UV-C-activated peroxide and peroxydisulfate, respectively. Both investigated systems demonstrated good performance for 2,4-D dechlorination. Pesticide degradation rates increased with increasing dosages of the applied oxidants. Acidic conditions were more favorable for degradation of 2,4-D, compared to neutral and basic conditions, for both systems studied. The degradation efficiency relative to 2,4-D decreased in the presence of HA, Cl⁻ and HCO₃⁻ in water matrices. The predominant radical for the UV-C-activated peroxydisulfate was determined to be a sulfate radical. These findings are of fundamental and practical significance in understanding UV-C-activated 2,4-D degradation, paving the way for the selection of preferred processes for the optimal removal of pesticides from various aqueous matrices. Full article

(This article belongs to the Special Issue Adsorption/Degradation Methods for Water and Wastewater Treatment)

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20 pages, 4455 KiB

Open AccessArticle

Chemical Composition, Chemometric Analysis, and Sensory Profile of Santolina chamaecyparissus L. (Asteraceae) Essential Oil: Insights from a Case Study in Serbia and Literature-Based Review

by Biljana Lončar, Mirjana Cvetković, Milica Rat, Jovana Stanković Jeremić, Jelena Filipović, Lato Pezo and Milica Aćimović

Separations 2025, 12(5), 115; https://doi.org/10.3390/separations12050115 - 2 May 2025

Viewed by 193

Abstract

The flowers of Santolina chamaecyparissus have a distinct aroma and taste, with a wide range of applications in medicine, food, and packaging. Its essential oil offers numerous health benefits, including antioxidant, hepatoprotective, anticancer, antidiabetic, spasmolytic, anti-inflammatory, immunomodulatory, antimicrobial, and antiparasitic properties. Additionally, it [...] Read more.

The flowers of Santolina chamaecyparissus have a distinct aroma and taste, with a wide range of applications in medicine, food, and packaging. Its essential oil offers numerous health benefits, including antioxidant, hepatoprotective, anticancer, antidiabetic, spasmolytic, anti-inflammatory, immunomodulatory, antimicrobial, and antiparasitic properties. Additionally, it is used as a flavoring agent in food and beverages and as a natural preservative in edible coatings for food packaging. This study investigates the chemical composition and sensory properties of the S. chamaecyparissus essential oil from Serbia, obtained via hydrodistillation, and includes a literature-based analysis of the existing profiles. Gas Chromatography–Mass Spectrometry (GC–MS) was employed for identifying the essential oil composition, while chemometric techniques like the genetic algorithm (GA), quantitative structure–retention relationship (QSRR) analysis, artificial neural network (ANN), and molecular descriptors were applied to ensure accurate and reliable results for authenticating the oil. Among the 47 identified compounds, oxygenated monoterpenes, especially artemisia ketone (36.11%), and oxygenated sesquiterpenes, notably vulgarone B (22.13%), were the primary constituents. Chemometric analysis proved effective in predicting the oil’s composition, and sensory evaluation revealed a herbal aroma with earthy, woody, and camphoraceous notes. A literature review highlighted the variability in oil composition due to geographical, environmental, and extraction factors, underscoring its chemical diversity, bioactivity, and potential applications. Full article

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17 pages, 2019 KiB

Open AccessArticle

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

by Christiana Mantzourani and Maroula G. Kokotou

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

Viewed by 468

Abstract

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

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

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

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19 pages, 3465 KiB

Open AccessArticle

Metabolic Profiling and Pharmacokinetics Characterization of Yinhua Pinggan Granules with High-Performance Liquid Chromatography Combined with High-Resolution Mass Spectrometry

by Ningning Gu, Haofang Wan, Imranjan Yalkun, Yu He, Yihang Lu, Chang Li and Haitong Wan

Separations 2025, 12(5), 113; https://doi.org/10.3390/separations12050113 - 28 Apr 2025

Viewed by 201

Abstract

Yinhua Pinggan Granules (YPG) is a patented traditional Chinese medicine (TCM) compound prescription, with wide clinical application against cold, cough, and relevant diseases. However, the chemical profiles of YPG in vivo are still unknown, hindering further pharmacological and quality control (QC) researches. This [...] Read more.

Yinhua Pinggan Granules (YPG) is a patented traditional Chinese medicine (TCM) compound prescription, with wide clinical application against cold, cough, and relevant diseases. However, the chemical profiles of YPG in vivo are still unknown, hindering further pharmacological and quality control (QC) researches. This study presents an ultra-high-performance liquid chromatography coupled with high-resolution orbitrap mass spectrometry (UHPLC-MS)-based method. Using the Compound Discoverer platform and a self-built ‘in-house’ compound database, the metabolic profiles and pharmacokinetics characters of YPG were investigated. Consequently, a total of 230 compounds (including 39 prototype components and 191 metabolites) were tentatively identified, in which the parent compounds were mainly flavonoids, alkaloids, and terpenoids, and the main metabolic pathways of metabolites include hydration, dehydration, and oxidation. The serum concentration of seven major representative compounds, including quinic acid, chlorogenic acid, amygdalin, 3′-methoxypuerarin, puerarin, glycyrrhizic acid, and polydatin, were also measured, to elucidate their pharmacokinetics behaviors in vivo. The pharmacokinetic study showed that the seven representative compounds were quantified in rat plasma within 5 min post-administration, with T_max of less than 2 h, followed by a gradual decline in concentration over a 10 h period. The method demonstrated excellent linearity (R² > 0.998), precision, and recovery (RSD < 15%). As the first systematic characterization of YPG’ s in vivo components and metabolites using UHPLC-MS, this study may contribute to comprehensively elucidate the metabolic profiles of the major components in YPG, and provide a critical foundation for further investigation on the QC and bioactivity research of YPG. Full article

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

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14 pages, 3695 KiB

Open AccessArticle

Synergistic Effects of SDS and Non-Ionic Surfactants on Ceramic Membrane Cleaning Performance Under Acidic Conditions

by Yang Deng, Mengkui Tian, Hai Liu, Yan An, Mingkun Wu and Hongpeng Lu

Separations 2025, 12(5), 112; https://doi.org/10.3390/separations12050112 - 28 Apr 2025

Viewed by 234

Abstract

To reinforce the cleaning agent’s wetting and cleaning capabilities on ceramic microfiltration membranes in acidic environments, the wetting properties of sodium dodecyl sulfate (SDS) in combination with multiple nonionic surfactants were examined in a systematic manner. The research findings suggested that there was [...] Read more.

To reinforce the cleaning agent’s wetting and cleaning capabilities on ceramic microfiltration membranes in acidic environments, the wetting properties of sodium dodecyl sulfate (SDS) in combination with multiple nonionic surfactants were examined in a systematic manner. The research findings suggested that there was a potential synergistic effect among SDS, isooctyl alcohol polyoxyethylene ether (JFC), and fatty alcohol polyoxyethylene ether (AEO-7). Moreover, atomic force microscopy (AFM) and infrared spectroscopy were utilized to assess the pre- and post-cleaning contamination levels. The research findings also demonstrated that using a compound cleaning agent conspicuously regenerated the structure and elevated the hydrophilicity of the ceramic membrane surface. The synergistic mechanism between JFC and SDS can be explained by the fact that the inclusion of JFC can lessen the electrostatic repulsion between the ionic groups of SDS and heighten their hydrogen bonding effect, which in turn enhances the dispersion of contaminants and lowers the surface tension of composite solution. Full article

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13 pages, 3847 KiB

Open AccessArticle

Construction of Z-Scheme Heterojunction BiOCl/Bi₂WO₆ for Visible-Light Photocatalytic Degradation of Tetracycline Hydrochloride

by Hetian Zhang, Zengying Zhu, Yajie Huang, Jiaxing Yu and Ming Li

Separations 2025, 12(5), 111; https://doi.org/10.3390/separations12050111 - 28 Apr 2025

Viewed by 236

Abstract

Tetracycline hydrochloride pollution poses a serious environmental threat; however, it is difficult to deal with by conventional methods. In this study, the Z-scheme BiOCl/Bi₂WO₆ composite was hydrothermally synthesized and evaluated for its ability to decompose tetracycline hydrochloride under visible light. [...] Read more.

Tetracycline hydrochloride pollution poses a serious environmental threat; however, it is difficult to deal with by conventional methods. In this study, the Z-scheme BiOCl/Bi₂WO₆ composite was hydrothermally synthesized and evaluated for its ability to decompose tetracycline hydrochloride under visible light. The composite material was systematically characterized by XRD, SEM, TEM/HRTEM, XPS, FTIR, BET, PL, UV-Vis DRS, and EPR to analyze its structure, morphology, and optical/electrochemical properties. Characterization revealed that the composite featured a flower-ball structure with broader light absorption and higher solar energy efficiency. A narrow bandgap further facilitated charge separation, boosting photocatalytic performance. Among the synthesized materials, the 20% BiOCl/Bi₂WO₆ composite exhibited the best performance, removing 94% of tetracycline hydrochloride in 60 min, which was 5.2 times and 1.4 times higher than pure BiOCl and Bi₂WO₆, respectively. The rate constant was 10.8 times and 2.5 times higher than that of pure BiOCl and Bi₂WO₆. After five cycles, it maintained the 88.7% removal rate, with X-ray diffraction analysis confirming its structural stability and well mechanical properties. Electron paramagnetic resonance and radical scavenging experiments identified photogenerated holes (h⁺) and superoxide radicals (·O₂⁻) as the primary active species. This work highlights the fact that the prepared Z-scheme BiOCl/Bi₂WO₆ composite exhibited excellent photocatalytic performance in the degradation of tetracycline hydrochloride, demonstrating promising potential for practical applications. Full article

(This article belongs to the Special Issue Photocatalytic Degradation of Organic Pollutant in Wastewater)

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15 pages, 3815 KiB

Open AccessArticle

Study of Bacterial Elution from High-Efficiency Glass Fiber Filters

by Le Rong, Yun Liang, Zhaoqian Li, Desheng Wang, Hao Wang, Lingyun Wang and Min Tang

Separations 2025, 12(5), 110; https://doi.org/10.3390/separations12050110 - 25 Apr 2025

Viewed by 185

Abstract

Antibacterial filter materials have been effectively utilized for controlling biological contaminants and purifying indoor air, with the market for such materials experiencing continuous expansion. Currently, textile antibacterial testing standards are widely adopted to evaluate the antimicrobial efficacy of filter materials, yet no dedicated [...] Read more.

Antibacterial filter materials have been effectively utilized for controlling biological contaminants and purifying indoor air, with the market for such materials experiencing continuous expansion. Currently, textile antibacterial testing standards are widely adopted to evaluate the antimicrobial efficacy of filter materials, yet no dedicated assessment protocols specifically tailored for filtration media have been established. This study aims to investigate the applicability of textile antibacterial testing methods to high-efficiency glass fiber filter materials (filtration efficiency > 99.9%), as well as to explore the factors that affect the rate of bacterial elution from high-efficiency glass fiber filter materials. By referencing the textile antibacterial testing standard (absorption method), significant discrepancies in bacterial recovery counts were observed between the high-efficiency glass fiber materials and the various textile control samples, with the former exhibiting a markedly lower recovery rate (approximately 10%). Pore structure and wettability analyses revealed the underlying causes of these differences. To ensure the accuracy of the antibacterial evaluation results, the effects of oscillation elution parameters (time and intensity) and material incubation conditions (duration, sealing and humidity) on bacterial recovery rates in glass fiber filter materials were systematically investigated to optimize the elution methodology. The results indicate that specimen type, size, elution method, incubation duration (4 h or 24 h), sealing conditions, and environmental humidity (10% or 30%, 60% and 95% RH) collectively influence bacterial recovery efficiency. The highest recovery efficiency (55%) was achieved when the filter materials were incubated in a sealed environment with humidity maintained at ≥60% RH. These findings emphasize the critical need to establish clear and specialized antibacterial performance testing standards for filter materials. The study provides essential guidance for developing material-specific evaluation protocols to ensure a reliable and standardized assessment of antimicrobial efficacy in high-efficiency filtration systems. Full article

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14 pages, 680 KiB

Open AccessArticle

Ultrasound-Assisted Extraction of Phenolic Compounds and Flavonoids from Banana Inflorescence and Characterization of Its Fibrous Residue

by Fábio Dias Bertoco Júnior, Érica Marusa Pergo Coelho, Mirian Cristina Feiten and Beatriz Cervejeira Bolanho Barros

Separations 2025, 12(5), 109; https://doi.org/10.3390/separations12050109 - 25 Apr 2025

Viewed by 297

Abstract

The banana inflorescence (BI) is a rich source of antioxidants and dietary fiber, making it a valuable by-product of banana harvesting. This study aimed to maximize the ultrasound-assisted extraction (UAE) of antioxidant compounds from BI and analyze the residue’s composition and functional properties. [...] Read more.

The banana inflorescence (BI) is a rich source of antioxidants and dietary fiber, making it a valuable by-product of banana harvesting. This study aimed to maximize the ultrasound-assisted extraction (UAE) of antioxidant compounds from BI and analyze the residue’s composition and functional properties. The Box–Behnken Design was applied to test different ultrasound powers, temperatures, and sample-to-solvent ratios on the total phenolic content (TPC) and total flavonoid content (TFC). The UAE conducted at 350 W, 55 °C, 1:30 (g/mL) ratio for 30 min resulted in the highest TPC (1637.12 mg/100 g) and TFC (22.97 mg/100 g). Isovanillin, caffeine, naringin, sinapaldehyde, nicotinic acid, quinic acid, malic acid, and fumaric acids were reported for the first time for BI. The extract obtained by UAE showed a higher content of these compounds and higher antioxidant activity than that obtained through conventional extraction (orbital shaking). The residue obtained after UAE presented dietary fiber as the main component (71.91 g/100 g) and a higher oil absorption index (5.78 g/g) than untreated BI. Therefore, BI is a source of bioactive compounds, and both the extract and residue can be used in the pharmaceutical, food, and cosmetic industries, enabling the productive sector to move closer to the circular economy. Full article

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

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14 pages, 1759 KiB

Open AccessArticle

Electrochemical Precipitation of Struvite from Wastewater: A Sustainable Approach for Nitrogen Recovery

by Rúbia Mores, Anildo Cunha Junior, Fabiane Goldschmidt Antes, Marco Di Luccio, Carolina E. Demaman Oro, Marcus V. Tres, Clarice Steffens, Juliana Steffens, Airton Kunz and Rogério Marcos Dallago

Separations 2025, 12(5), 108; https://doi.org/10.3390/separations12050108 - 25 Apr 2025

Viewed by 268

Abstract

This study evaluates the feasibility of nitrogen recovery from wastewater via electrochemical methods as an alternative nutrient source for agricultural applications. Ammonium nitrogen (NH₄⁺-N) and phosphate (PO₄³⁻-P) contamination poses significant environmental risks and challenges water resource management [...] Read more.

This study evaluates the feasibility of nitrogen recovery from wastewater via electrochemical methods as an alternative nutrient source for agricultural applications. Ammonium nitrogen (NH₄⁺-N) and phosphate (PO₄³⁻-P) contamination poses significant environmental risks and challenges water resource management globally. The electrochemical precipitation of struvite (MgNH₄PO₄·6H₂O) offers a promising solution for nutrient recovery, with potential applications as a slow-release fertilizer. Experimental results demonstrate that increased current density (from 2.5 to 7.5 mA/cm²) and reduced electrode distance (1 cm) significantly enhance NH₄⁺ and PO₄³⁻ consumption and struvite precipitation. Increasing the amperage from 2.5 to 7.5 mA·cm⁻² at a 1 cm electrode distance raised the ammoniacal nitrogen incorporation from 1.59 to 5.34 g/100 g, signifying greater struvite production. The Mg and P concentrations were 15.44 and 12.60 g/100 g, respectively, for this higher amperage, although lower than the concentrations seen with 2.5 mA·cm⁻² (22.16 and 14.52 g/100 g). The majority of Mg (60%) and P (93.6%) were, however, incorporated within struvite. Additionally, this study reveals that Mg is primarily incorporated as struvite when using higher current densities, while lower current densities yield greater Mg incorporation in non-struvite forms, such as magnesium carbonate. Findings suggest that optimizing current density and electrode distance can improve nitrogen and phosphorus recovery efficiencies, making electrochemical struvite production a viable, sustainable approach for nutrient recycling. This method not only reduces dependence on synthetic fertilizers but also supports sustainable agricultural practices by transforming wastewater contaminants into valuable resources. Full article

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

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17 pages, 3618 KiB

Open AccessArticle

Polymer-Coated Nickel Nanoparticles for CO₂ Capture in Seawater

by Abhishek, Abhishek Ratanpara, Adib Mahmoodi Nasrabadi and Myeongsub Kim

Separations 2025, 12(5), 107; https://doi.org/10.3390/separations12050107 - 24 Apr 2025

Viewed by 372

Abstract

Carbon capture and storage (CCS) technologies are employed to mitigate global warming by removing carbon from the atmosphere. To enhance carbon capture efficiency, nanoparticles have gained considerable attention as catalysts due to their large surface area, tunable properties, regeneration, and enhanced reactivity. However, [...] Read more.

Carbon capture and storage (CCS) technologies are employed to mitigate global warming by removing carbon from the atmosphere. To enhance carbon capture efficiency, nanoparticles have gained considerable attention as catalysts due to their large surface area, tunable properties, regeneration, and enhanced reactivity. However, it poses some challenges, such as nanoparticle aggregation and reduced effectiveness in sustainable solvents like seawater. To address these limitations and promote an environmentally sustainable method for carbon capture, this study evaluates the CO₂ capture efficiency of seawater using nickel nanoparticles (NiNPs) coated with polyvinylpyrrolidone (PVP) as a catalyst. We examined the time-dependent size variations of CO₂ bubbles in a flow-focusing microchannel using high-speed bubble-based microfluidics, directly associated with transitory CO₂ dissolution into the surrounding solution. We hypothesized that smaller polymer-coated NiNPs, due to their higher surface-to-volume ratio, can enhance CO₂ solubility and capture rates under identical environmental conditions. To verify this, polymer-coated NiNPs of three different sizes—5 nm, 10 nm, and 20 nm—were synthesized and tested. The experiments revealed that 5 nm NiNPs achieved a CO₂ dissolution rate of 77%, in contrast to 71% for 10 nm and 43% for 20 nm particles. These findings validate the hypothesis, demonstrating that smaller nanoparticles facilitate more effective CO₂ capture using equivalent material quantities, thereby potentially improving the overall efficiency of CO₂ reduction. This innovative approach contributes to advancing NiNP-based catalysts for saltwater-based CO₂ capture. Full article

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

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15 pages, 2586 KiB

Open AccessArticle

Enhanced Selective Separation of Pu(IV) and U(VI) Using Novel Diethylene Glycolamide Ligand

by Xiaoyun Guo, Junli Wang, Yao Liu, Haojun Zhao, Hui Wang, Wentao Wang, Baole Li and Taihong Yan

Separations 2025, 12(5), 106; https://doi.org/10.3390/separations12050106 - 23 Apr 2025

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Abstract

Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a [...] Read more.

Developing a new efficient separation ligand based on the “CHON” principle to address the limitations of phosphorus containing extractants in nuclear fuel reprocessing can help further simplify the process flow and reduce the amount of secondary waste. Building upon this critical need, a novel ligand was developed through a strategic application of the Hard and Soft Acids and Bases (HSAB) theory, integrating a soft donor nitrogen atom into the linear architecture of bis-diglycolamide. This groundbreaking ligand, named N,N′-bis[2-(2-(N,N-dioctylcarbamoyl)ethoxy)ethylacetamido]-N″-diethylenetriamine (TOMDEA-BisDGA), has demonstrated remarkable potential in the extraction of Pu(IV). The study unveils that the ligand demonstrates remarkable selectivity and separation efficiency towards Pu(IV) ions while maintaining an exceptionally low extraction capacity for U(VI) across a wide acidity spectrum of 0.1~6 mol/L. To explain the structure properties of complex formed by the ligand and Pu(IV), a systematic analysis was performed, including slope analysis, proton nuclear magnetic resonance (NMR) titration, and Fourier-transform infrared (FT-IR) spectroscopy. This study explores the coordination and separation behavior of diglycolamide ligands with actinide. This work is expected to provide important information and theoretical bases upon which advanced design and optimization of ligands for high-performance processes for the separation of plutonium might be carried out. Such findings will contribute to the understanding of actinide chemistry and further the design of improved separation methods for nuclear applications. Full article

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6 pages, 761 KiB

Open AccessTechnical Note

Optimizing Liquid Electron Ionization Interface to Boost LC-MS Instrumental Efficiency

by Tommaso Grazioso, Genny Grasselli, Adriana Arigò, Giorgio Famiglini and Achille Cappiello

Separations 2025, 12(5), 105; https://doi.org/10.3390/separations12050105 - 23 Apr 2025

Viewed by 226

Abstract

Liquid Electron Ionization (LEI) is a powerful and robust interface for the qualitative and quantitative analysis of medium-low-molecular-weight compounds, including numerous environmental pollutants and toxicological substances. Although the robustness and performance of this interface have already been demonstrated, research on its optimization can [...] Read more.

Liquid Electron Ionization (LEI) is a powerful and robust interface for the qualitative and quantitative analysis of medium-low-molecular-weight compounds, including numerous environmental pollutants and toxicological substances. Although the robustness and performance of this interface have already been demonstrated, research on its optimization can still improve instrumental performance in terms of detectability. In this study, different setups of the interface’s vaporization micro-channel (VMC) made using different capillaries and various sizes were tested to evaluate the correspondent instrumental performance. The results show that a new combination of capillaries in the interface set up significantly improves instrumental detectability, reaching LOD values almost five times lower than those of the previous setup. Full article

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13 pages, 2822 KiB

Open AccessArticle

A Two-Dimensional Thiotitanate Ion Exchanger with High Cs⁺ Removal Performance

by Chang Wei, Shaoqing Jia, Yingying Zhao, Jiating Liu, Haiyan Sun, Meiling Feng and Xiaoying Huang

Separations 2025, 12(5), 104; https://doi.org/10.3390/separations12050104 - 22 Apr 2025

Viewed by 221

Abstract

¹³⁷Cs is a persistent β/γ-emitter (t_1/2 = 30.1 years) generated from ²³⁵U and ²³⁹Pu fission. It is a critical challenge to efficiently capture ¹³⁷Cs⁺ for nuclear waste management due to its high solubility, [...] Read more.

¹³⁷Cs is a persistent β/γ-emitter (t_1/2 = 30.1 years) generated from ²³⁵U and ²³⁹Pu fission. It is a critical challenge to efficiently capture ¹³⁷Cs⁺ for nuclear waste management due to its high solubility, environmental mobility, and propensity for biological accumulation. Herein, we prepare a two-dimensional (2D) thiotitanate Rb_0.32TiS₂·0.75H₂O (denoted Rb-TiS₂) using a special molten salt synthesis method, “Mg + RbCl”. Rb-TiS₂ can selectively capture Cs⁺ from aqueous solutions. Its structure features a flexible anionic thiotitanate layer with Rb⁺ as counter ions located at the interlayer spaces. As an ion exchanger, it possesses high adsorption capacity (q_m^Cs = 232.70 mg·g⁻¹), rapid kinetics (the removal rate R > 72% within 10 min), and a wide pH tolerance range (pH = 4–12) for Cs⁺ adsorption. Through a single-crystal X-ray structural analysis, we elucidated the mechanism of Cs⁺ capture, revealing the ion exchange pathways between Cs⁺ and Rb⁺ in Rb-TiS₂. This work not only provides an important reference for the synthesis of transition metal sulfides with alkali metal cations but also proves the application prospect of transition metal sulfides in radionuclide remediation. Full article

(This article belongs to the Special Issue Separation Technology for Metal Extraction and Removal)

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Separations, Volume 12, Issue 5 (May 2025) – 31 articles

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