Separations

10 pages, 2330 KiB

Open AccessArticle

The 288.2 K Isothermal Evaporation Experiment of Potassium Precipitation Brine in West Taijinair Salt Lake

by Yousheng Yang, Xiaowang Wu, Xudong Yu, Jiazheng Qin, Jianjun Su, Caixiong Quan and Pan Xu

Separations 2024, 11(12), 348; https://doi.org/10.3390/separations11120348 (registering DOI) - 9 Dec 2024

Abstract

Rubidium and cesium are important strategic resources, and West Taijinar Salt Lake is rich in rubidium and cesium reserves, while the concentration is low and the relationship with coexisting potassium and magnesium ions is complex. In order to understand the evaporative enrichment and [...] Read more.

Rubidium and cesium are important strategic resources, and West Taijinar Salt Lake is rich in rubidium and cesium reserves, while the concentration is low and the relationship with coexisting potassium and magnesium ions is complex. In order to understand the evaporative enrichment and salt precipitation patterns of rare elements such as lithium, rubidium, cesium, and boron of the brine after potassium precipitation in West Taijinar Salt Lake, the 288.2 K isothermal evaporation experiment was carried out. The experimental results show that during the evaporation process at 288.2 K, the following salts precipitate from the brine after potassium crystallization: halite (NaCl), bischofite (MgCl₂·6H₂O), carnallite (KCl·MgCl₂·6H₂O), hexahydrite (MgSO₄·6H₂O), epsomite (MgSO₄·7H₂O), boric acid (H₃BO₃), and lithium sulfate monohydrate (Li₂SO₄·H₂O). The concentrations of lithium and boron are significantly enriched, the content of Li⁺ was enriched from 1.7 g/L to 5.63 g/L, and the B₂O₃ content was enriched from 6.72 g/L to 50.78 g/L. The isomorphism phenomenon of Rb⁺, Cs⁺, and K⁺ makes Rb⁺ and Cs⁺ enter potassium ore to form solid solution-type carnallite ((K, Rb)MgCl₃·6H₂O, (K, Cs)MgCl₃·6H₂O)) and reduce the content of brine. This study provides data support for the development and comprehensive utilization of lithium, boron, rubidium, and cesium resources in West Taijinar Salt Lake. Full article

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

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10 pages, 859 KiB

Open AccessCommunication

Some Aspects of the Use of Carbon Dioxide as a Carrier and Makeup Gas in GC–FID Analysis

by Łukasz Dąbrowski

Separations 2024, 11(12), 347; https://doi.org/10.3390/separations11120347 - 8 Dec 2024

Abstract

The paper presents the possibility of using carbon dioxide as a carrier gas in capillary gas chromatography (with a stationary liquid phase) to analyze semi-volatile compounds (boiling points of up to 400 °C). Based on the experiments carried out for compounds from the [...] Read more.

The paper presents the possibility of using carbon dioxide as a carrier gas in capillary gas chromatography (with a stationary liquid phase) to analyze semi-volatile compounds (boiling points of up to 400 °C). Based on the experiments carried out for compounds from the group of organochlorine pesticides (OCPs), organophosphate pesticides (OPPs), polycyclic aromatic hydrocarbons (PAHs) and polychlorinated biphenyls (PCBs), the maximum volumetric flow rate (2.4 mL/min for CO₂) was determined, enabling the correct separation of the tested standard mixtures (except for two compounds from the OCP group: 4,4′-DDD and Endrin aldehyde and two other pairs of compounds with Rs slightly less than 1.5). Compared to using helium as a carrier gas (and makeup), carbon dioxide produces wider (about 1.6 times) and lower (about 1.8 times) peaks of analytes; these values can vary depending on the separation efficiency of the column. Carbon dioxide can also be effectively used as a makeup gas for the FID detector. The signal increase is comparable to that obtained with helium used as makeup (on average 40–50% depending on the carrier gas). When high sensitivity and high resolution are not required, CO₂ can be an alternative carrier and makeup gas to helium under the same flow conditions. The paper also describes practical aspects related to the implementation of CO₂ as a carrier and makeup gas in GC. Full article

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13 pages, 2164 KiB

Open AccessArticle

Eco-Friendly Capillary Electrophoresis Method for the Quantification of Apixaban in Oral Dosage Form

by Manoelly Oliveira Rocha, Amanda Mohr, Leandro Kolling, Marcia Messias da Silva, Jacqueline Arguello da Silva and Martin Steppe

Separations 2024, 11(12), 346; https://doi.org/10.3390/separations11120346 - 7 Dec 2024

Abstract

The present work describes, for the first time, an eco-friendly capillary zone electrophoresis (CZE) methodology for determining apixaban (APX), an oral anticoagulant. Separation was carried out using a fused silica capillary with an applied voltage of 20 kV and hydrodynamic injection for 5 [...] Read more.

The present work describes, for the first time, an eco-friendly capillary zone electrophoresis (CZE) methodology for determining apixaban (APX), an oral anticoagulant. Separation was carried out using a fused silica capillary with an applied voltage of 20 kV and hydrodynamic injection for 5 s at 50 mbar. The electrolyte system consisted of 50 mM sodium borate at pH 8.0. The method was validated as recommended by ICH, establishing selectivity, linearity, precision, accuracy, and robustness. The analytical procedure was linear in the range of 10–125 µg mL⁻¹ (r = 0.999). The limits of detection and quantification were determined to be 1.77 µg mL⁻¹ and 5.37 µg mL⁻¹, respectively. Precision was evaluated by relative standard deviation (RSD), with an intra-day RSD (n = 6) of 0.96% and an inter-day RSD (n = 18) of 4.42%. The average recovery rates for the pharmaceutical samples were excellent, ranging from 98.03% to 101.01%, with an RSD of 1.51%. Moreover, the green profile of the method was evaluated using the National Environmental Methods Index (NEMI), Analytical Eco-Scale, Green Analytical Procedure Index (GAPI), and Analytical GREEnness Metric (AGREE) assessment tools. The results suggest that the CZE method aligns with the principles of green chemistry, offering a greener alternative for the routine analysis of APX quality control. Also, the method presents a low-cost analysis, using fewer organic solvents and minimizing waste generation compared to techniques commonly used in routine analysis. Full article

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

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22 pages, 6605 KiB

Open AccessArticle

Technological Characterization of Cobalt and Nickel Ores from Greece for Metal Recovery

by Amina Eljoudiani, Carlos Hoffmann Sampaio, Josep Oliva, Moacir Medeiros Veras, Pura Alfonso, Hernan Anticoi, Stylianos Tampouris, Jose Luis Cortina and Percy Rodrigo Escalante

Separations 2024, 11(12), 345; https://doi.org/10.3390/separations11120345 - 6 Dec 2024

Abstract

Greece has mineral resources in which strategic elements such as nickel (Ni) and cobalt (Co) are present. In this study, characterizations of the metal concentrations of three laterite deposits, as well as minerals from a kiln originating from a mineral processing plant, were [...] Read more.

Greece has mineral resources in which strategic elements such as nickel (Ni) and cobalt (Co) are present. In this study, characterizations of the metal concentrations of three laterite deposits, as well as minerals from a kiln originating from a mineral processing plant, were carried out. The aim of this research was to integrate technological characterization data on the quantities of cobalt (Co) and nickel (Ni) present in the lateritic profiles of three mineral deposits from Greece and in kiln dust. The study was conducted at the Mineral Processing Laboratory of UPC/Bases Manresa. Aliquots were constituted for particle-size distribution tests by wet sieving followed by laser granulometry. Scanning electron microscopy (SEM) was used to determine the mineralogical compositions. Sink–float tests were conducted to estimate the particle liberation. Mineral liberation analysis (MLA) was performed to understand the liberation and the association of minerals in the samples. Full article

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

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11 pages, 3928 KiB

Open AccessArticle

Effective Removal of Sr²⁺ Ions by K₂SbPO₆/Polyacrylonitrile Composite Microspheres

by Shuangjiang Li, Jianghai He, Yanling Guo, Lu Yang, Haiyan Sun, Meiling Feng and Xiaoying Huang

Separations 2024, 11(12), 344; https://doi.org/10.3390/separations11120344 - 3 Dec 2024

Abstract

⁹⁰Sr is one of the highly radioactive and hazardous nuclides in nuclear waste liquids. The high water solubility and mobility of ⁹⁰Sr²⁺ ions make it difficult to effectively remove ⁹⁰Sr from the complex aqueous environment. Herein, K₂SbPO [...] Read more.

⁹⁰Sr is one of the highly radioactive and hazardous nuclides in nuclear waste liquids. The high water solubility and mobility of ⁹⁰Sr²⁺ ions make it difficult to effectively remove ⁹⁰Sr from the complex aqueous environment. Herein, K₂SbPO₆, a phosphatoantimonate ion exchange material with an excellent removal ability for Sr²⁺ ions, has been organically granulated with polyacrylonitrile (PAN) by an automated method to form K₂SbPO₆/PAN composite microspheres. The K₂SbPO₆/PAN microspheres with radiation resistance exhibit a high maximum adsorption capacity (q_m^Sr) of 131.15 mg g⁻¹ for Sr²⁺ ions and retain the high removal rate (R^Sr) in a wide pH range (pH = 3–12). It is important that K₂SbPO₆/PAN microspheres could efficiently treat Sr²⁺ ions solutions in a dynamic adsorption manner even at 970 bed volumes (R^Sr > 81%). This work paves the way for the preparation of low-cost ion exchange materials with the advantages of regular shape and easy operation by a simple and fast method and the practical application of powdered ion exchange materials. Full article

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

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19 pages, 4646 KiB

Open AccessArticle

Hazelnut Shells as a Tenable Biosorbent for Basic Red 18 Azo Dye Removal

by Naji Agilee, Tijana Spasojević, Milica Delić, Đorđe Ogrizović, Isabel R. Gria, Nevena Prlainović and Maja Đolić

Separations 2024, 11(12), 343; https://doi.org/10.3390/separations11120343 - 2 Dec 2024

Abstract

The increasing pollution from the textile industry, particularly organic azo dyes, presents a significant environmental challenge, necessitating the development of effective and sustainable treatment methods. This study investigates the adsorption potential of hazelnut shells (raw—RHSs; modified—MHSs) for the removal of organic azo dyes [...] Read more.

The increasing pollution from the textile industry, particularly organic azo dyes, presents a significant environmental challenge, necessitating the development of effective and sustainable treatment methods. This study investigates the adsorption potential of hazelnut shells (raw—RHSs; modified—MHSs) for the removal of organic azo dyes from aqueous solutions. As biomass, hazelnut shells are biodegradable and represent a sustainable alternative to synthetic adsorbents, thereby reducing the ecological footprint. Through a series of batch adsorption experiments, the influence of various parameters, including pH, contact time, concentration, and temperature, on adsorption capacity was examined. Characterization of the hazelnut shells was conducted using optical microscopy and ATR-FTIR, XRF, and XRD spectroscopy, confirming its suitability as a biosorbent. The analyzed isotherms showed that adsorption onto RHSs was best fitted by the Freundlich model, while adsorption onto MHSs was best fitted by the Temkin model. Kinetic studies demonstrated that the adsorption process is well described by the pseudo-second-order model, suggesting that chemical adsorption plays a significant role. The maximal adsorption capacity was 62.11 mg/g for RHSs and 80.65 mg/g for MHSs, highlighting the potential of hazelnut shells as an abundant, low-cost, and eco-friendly adsorbent. Furthermore, recycling studies indicated the feasibility of the adsorbent, underscoring its practical applicability in real scenarios. Full article

(This article belongs to the Special Issue Materials from Biomass and Waste for Adsorption Applications)

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44 pages, 489 KiB

Open AccessReview

Recent Developments (2020–23) on the Use of LC in the Determination of Food Contaminants

by A. P. Louppis and M. G. Kontominas

Separations 2024, 11(12), 342; https://doi.org/10.3390/separations11120342 - 28 Nov 2024

Abstract

Food quality and safety are critical public health concerns, with approximately 600 million people worldwide being affected by foodborne diseases each year due to contamination. These diseases not only lead to a notable number of deaths but also impose substantial economic burdens, especially [...] Read more.

Food quality and safety are critical public health concerns, with approximately 600 million people worldwide being affected by foodborne diseases each year due to contamination. These diseases not only lead to a notable number of deaths but also impose substantial economic burdens, especially in low- and middle-income countries. Given the severe health risks posed by food contaminants, developing advanced, sensitive analytical methods to detect such contaminants is essential. Contemporary food safety challenges include detecting contaminants at trace levels and managing cumulative risks from simultaneous exposure to multiple chemicals. Liquid chromatography, particularly in combination with high-resolution mass spectrometry (LC/MS), has proven indispensable for detecting key contaminants such as perfluoroalkyl and polyfluoroalkyl substances, polycyclic aromatic hydrocarbons, pesticides, veterinary residues, packaging-derived contaminants, mycotoxins, and pyrrolizidine alkaloids in various food matrices. The present article reviews recent studies on the subject published between 2020 and 2023. Full article

(This article belongs to the Collection Liquid Chromatography: Its Effectiveness in Food Safety)

17 pages, 4437 KiB

Open AccessArticle

Study on Separation Kinetics of Non-Spherical Single Feeding Particle in the Gas–Solid Separation Fluidized Bed

by Xuchen Fan, Yuping Fu, Yongliang He and Liying Sun

Separations 2024, 11(12), 341; https://doi.org/10.3390/separations11120341 - 28 Nov 2024

Abstract

Gas–solid separation fluidized bed is an efficient and clean coal separation technology with a good separation effect for coal particles. However, there is a lack of systematic research on the complex motion behavior of the feeding particles in gas–solid separation fluidized beds. In [...] Read more.

Gas–solid separation fluidized bed is an efficient and clean coal separation technology with a good separation effect for coal particles. However, there is a lack of systematic research on the complex motion behavior of the feeding particles in gas–solid separation fluidized beds. In this study, the separation kinetics of non-spherical single feeding particles in the fluidized bed are examined. The particle sphericity coefficient Φ is introduced to characterize the morphology of irregular coal particles, and the drag coefficient for the feeding particles is modified to verify the suitability of the non-spherical particle drag model for gas–solid fluidized bed separation. After optimization and correction, a ρ_S.sus (the bed density when single feeding particles are suspended in the gas–solid separation fluidized bed) prediction model is obtained. When the prediction accuracy of the ρ_S.sus prediction model is 90%, the confidence degree is 85.72%. This ρ_S.sus of the single non-spherical feeding particle prediction model highlights a direction for improving the separation effect, provides a theoretical basis for the industrialization of gas–solid fluidized bed, and promotes the process of dry fluidized separation. Full article

(This article belongs to the Special Issue Research Progress of Gas–Solid Fluidized Dry Separation)

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19 pages, 4118 KiB

Open AccessArticle

A Convenient and Efficient Strategy for Improving Separation Ability of Capillary Electrophoresis Through Tilting Capillary as Needed

by Wenhui Jia, Pingyi Zheng, Yuchen Cui, James J. Bao, Yanmei Xu and Youxin Li

Separations 2024, 11(12), 340; https://doi.org/10.3390/separations11120340 - 27 Nov 2024

Abstract

The effect of gravity based on the vector sum of gravity and buoyancy forces working spontaneously for all species was introduced into capillary electrophoresis (CE) as another important force which cooperated with electrophoretic flow and electro-osmotic flow. Their portion was adjusted by simply [...] Read more.

The effect of gravity based on the vector sum of gravity and buoyancy forces working spontaneously for all species was introduced into capillary electrophoresis (CE) as another important force which cooperated with electrophoretic flow and electro-osmotic flow. Their portion was adjusted by simply tilting the whole of the capillary at an angle during CE running. The related formula was proposed and verified through a series of experiments. After investigating the related parameters, results showed that the gravity effect was significantly affected by additives in the buffer, the length, and the inner diameter of the capillary, and the size of the sample molecule. This made the different ions with opposite or significantly different mobilities to be observed at a CE run. It significantly improved separation efficiencies of some small molecules, chiral compounds, macromolecules and cells when the tilt angles of the capillary were adjusted to a special range predicted through the fitting curve. In addition, micrometer level microspheres and cells were firstly separated by the new CE strategy and the resolutions were more than 1.0. After ingeniously designing the gradient of the tilting angle with time, we were able to further enhance the separation efficiency of the targets. For example, the resolution of lysozyme and ribonuclease A could be increased from 3.691 to 7.342. These indicated the huge potential of the new CE strategy and its gradient mode in separation. Full article

(This article belongs to the Special Issue Development and Applications of Chromatographic Materials and Analytical Methods)

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14 pages, 2204 KiB

Open AccessArticle

Qualitative and Quantitative Analysis Method of Recombinant Collagen in Complex Matrix Based on HPLC-MS/MS

by Jianping Gao, Liping Jia, Zhenhu Guo, Liming Xu, Daidi Fan and Guifeng Zhang

Separations 2024, 11(12), 339; https://doi.org/10.3390/separations11120339 - 26 Nov 2024

Abstract

The purpose of this study is to achieve the quantitative detection of recombinant type III collagen (rh-COL-III) in dressings with complex matrix. First of all, the marker peptide (GEAGIPGVPGAK) of rhCOL-III was identified with HPLC-MS/MS. Then, a qualitative and quantitative method based on [...] Read more.

The purpose of this study is to achieve the quantitative detection of recombinant type III collagen (rh-COL-III) in dressings with complex matrix. First of all, the marker peptide (GEAGIPGVPGAK) of rhCOL-III was identified with HPLC-MS/MS. Then, a qualitative and quantitative method based on marker peptides was established and validated. In order to obtain higher sensitivity, a pretreatment method of liquid, gel, and ointment dressings was optimized. The reference material for quantification was combined using rhCOL-III and blank matrix of each dressing. The results indicated that the relative standard deviation (RSD) of the quantitative method was 2.77%, and the RSD of intraday and interday precision was 2.76% and 2.31%, respectively. The spiking recovery rate was between 80% and 90%. The optimal pretreatment method was Tris-HCl solvent replacement. The optimal trypsin concentration for the dressing solution was 20 μg in 500 μL. The method of preparing standard substances with a blank matrix can effectively eliminate the influence of the matrix effect on the quantitative results. The average spiking recovery rates of 50 μg/mL, 100 μg/mL, and 200 μg/mL in three different dressings ranged from 80% to 120%. The quantitative detection of limit (LOD) of rhCOL-III was 1 ng/mL, 2 ng/g, and 1 ng/g in liquid, ointment, and gel dressings. Full article

(This article belongs to the Topic Application of Liquid Chromatography-Mass Spectrometry and Related Techniques)

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22 pages, 956 KiB

Open AccessArticle

Theory of Gas Purification by Liquid Absorber in Small Rotating Channels with Application to the Patented Rotational Absorber Device

by J. J. H. Brouwers

Separations 2024, 11(12), 338; https://doi.org/10.3390/separations11120338 - 26 Nov 2024

Abstract

A new design for absorbing vapour-phase impurities from gases is presented. It consists of small channels packed in a rotating vertical cylinder. Gas flows through the channels adjacent to a thin film of absorber liquid. The liquid film is pressed to the radially [...] Read more.

A new design for absorbing vapour-phase impurities from gases is presented. It consists of small channels packed in a rotating vertical cylinder. Gas flows through the channels adjacent to a thin film of absorber liquid. The liquid film is pressed to the radially outward side of each channel by the centrifugal force and flows downwards by gravity. Formulae are presented which describe the concentration distributions of gaseous impurities subject to absorption in gas and liquid. Results include expressions for laminar and turbulent diffusion coefficients to be used in mass balance equations. The role of rotation is quantified including the effect on wavy motion and enhanced diffusion in the liquid layer. Application in design is indicated for the case of separation of the greenhouse gas

C O_{2}

from flue gases of fossil fuel combustion processes. At other equal dimensions, the height of the Rotational Absorber Device is calculated to be 25 times shorter than the enormous heights of conventional tray and packed columns. Full article

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20 pages, 11422 KiB

Open AccessArticle

Modified Fly Ash as an Adsorbent for the Removal of Pharmaceutical Residues from Water

by Marija Vukčević, Dušan Trajković, Marina Maletić, Miljana Mirković, Aleksandra Perić Grujić and Dragana Živojinović

Separations 2024, 11(12), 337; https://doi.org/10.3390/separations11120337 - 26 Nov 2024

Abstract

In this work, different methods for fly ash modification were applied to obtain an adsorbent for the efficient removal of selected pharmaceuticals from a multiclass aqueous solution. Morphological and surface properties of the modified fly ash samples were analyzed by scanning electron microscopy, [...] Read more.

In this work, different methods for fly ash modification were applied to obtain an adsorbent for the efficient removal of selected pharmaceuticals from a multiclass aqueous solution. Morphological and surface properties of the modified fly ash samples were analyzed by scanning electron microscopy, X-ray fluorescence, X-ray diffraction, Fourier transform infrared spectroscopy, and point of zero charge, and the influence of the applied modifications was determined by comparison with the results obtained for unmodified fly ash. Experimental parameters of the adsorption of the pharmaceutical onto the modified fly ash were optimized, and special attention was paid to the influence of different parameters on the adsorption capacities. Multivariate methods of analysis, such as artificial neural networks, applied to the obtained results showed that the contact time, the initial concentration of the pharmaceutical solution, and the pH value had the strongest influence on the adsorption process. Fly ash modified with chitosan and magnetic iron oxide showed the best adsorption properties (removal efficiency above 80% for the majority of the selected pharmaceuticals), and artificial neural networks confirmed its susceptibility to the modeling process. Full article

(This article belongs to the Special Issue Materials from Biomass and Waste for Adsorption Applications)

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13 pages, 1187 KiB

Open AccessArticle

Body Volatilome Study Strategy for COVID-19 Biomarker Identification Considering Exogenous Parameters

by Elsa Boudard, Nabil Moumane, José Dugay, Jérôme Vial and Didier Thiébaut

Separations 2024, 11(12), 336; https://doi.org/10.3390/separations11120336 - 22 Nov 2024

Abstract

Since the 1950s, the screening of the body volatilome has proven to be a powerful tool for preventing diseases from spreading. Following the COVID-19 crisis, several studies began investigating the connection between viruses and the body volatilome, gradually identifying potential biomarkers, which varied [...] Read more.

Since the 1950s, the screening of the body volatilome has proven to be a powerful tool for preventing diseases from spreading. Following the COVID-19 crisis, several studies began investigating the connection between viruses and the body volatilome, gradually identifying potential biomarkers, which varied depending on the study. To try to elucidate potential sources of inconsistency in biomarker findings, we decided to set up a study taking into consideration the factors often overlooked in previous studies. The VOCs constituting the body volatilomes of 40 COVID-19 patients and 13 healthy subjects were sampled by using PowerSorb^® as the sorbent phase. Thermodesorption, followed by comprehensive two-dimensional gas chromatography combined with time-of-flight mass spectrometry (TD-GC×GC/TOF MS), was utilized for the analysis. A non-targeted biomarker research methodology compared Covid(+) and Covid(−) chromatograms, assessing statistical significance and peak area changes. Out of the 25 compounds highlighted, 13 associated with cosmetic products were excluded, and 8 linked to air pollution in urban settings were also excluded. Finally, after having quantitatively evaluated the potential sources of the compounds (cosmetic or environmental), 4 compounds remained and their relevance was assessed using ROC curves. Among them, hexanoic acid, 2-ethyl- identification was confirmed with standard and led to an area-under-the-curve value of 92%. More in-depth studies are needed to investigate the specificity of the biomarker in relation to COVID-19, but the strategy of this study shows how to avoid obtaining data that are biased by exogenous factors. Full article

(This article belongs to the Section Bioanalysis/Clinical Analysis)

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8 pages, 3294 KiB

Open AccessArticle

Aggregation-Dispersion Chromatography: Application of Elastin-like Polypeptides

by Han Bin Shin and Young Kee Chae

Separations 2024, 11(12), 335; https://doi.org/10.3390/separations11120335 - 21 Nov 2024

Abstract

Protein purification is a crucial step for various downstream applications like drug development, antibody preparation, and structure determination. The constant pursuit is for methods that are more efficient and cost-effective. We propose a novel approach using an elastin-like polypeptide (ELP) as an aggregation [...] Read more.

Protein purification is a crucial step for various downstream applications like drug development, antibody preparation, and structure determination. The constant pursuit is for methods that are more efficient and cost-effective. We propose a novel approach using an elastin-like polypeptide (ELP) as an aggregation core that serves as an anchor between the beads in a chromatography column. In this method, a chilled sample containing a [target protein type] fusion protein is loaded onto a pre-equilibrated IMAC (immobilized metal affinity chromatography) column with a low-salt buffer. The column is then washed with a warm buffer containing high salt to remove impurities. Here, the key step involves warming the column above the ELP’s transition temperature (Tt), which triggers its aggregation. This aggregation is expected to trap the target protein tightly between the beads. Subsequently, a harsh wash with high salt and high imidazole can be applied to remove even persistent contaminants, achieving high protein purity. Finally, the temperature is lowered, and a cold, low-salt buffer is introduced to reverse the aggregation and elute the purified target protein. This method has the potential to eliminate the need for sophisticated chromatography systems while still achieving high protein purity. Full article

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27 pages, 1465 KiB

Open AccessReview

Useful Extracts from Coffee By-Products: A Brief Review

by Krystyna Pyrzynska

Separations 2024, 11(12), 334; https://doi.org/10.3390/separations11120334 - 21 Nov 2024

Abstract

The waste materials generated from the processing of coffee cherries are still rich in several bioactive compounds. Several studies highlight coffee by-products as a valuable source for diverse applications, such as biofuels, biopolymers, biocomposites, and natural antioxidants in food, pharmaceuticals, and cosmetics. The [...] Read more.

The waste materials generated from the processing of coffee cherries are still rich in several bioactive compounds. Several studies highlight coffee by-products as a valuable source for diverse applications, such as biofuels, biopolymers, biocomposites, and natural antioxidants in food, pharmaceuticals, and cosmetics. The development of prospective strategies for the valorization of coffee wastes is a goal of a sustainable and circular bioeconomy, increasing the added value of these wastes and reducing environmental pollution. This brief overview describes the recently proposed procedures for the extraction and recovery of functional ingredients from the diversity of coffee by-products. The comparison between conventional and alternative extraction methods enables one to choose the most suitable techniques for valorizing a given coffee by-product. Full article

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

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19 pages, 6365 KiB

Open AccessArticle

Hierarchically Ordered Macroporous–Mesoporous (HOM-m) MgFe₂O₄/MgO for Highly Efficient Adsorption of Ce(III) and La(III): Experimental Study and DFT Calculation Analysis

by Lina Zhang, Jiarui Lu and Baixiong Liu

Separations 2024, 11(12), 333; https://doi.org/10.3390/separations11120333 - 21 Nov 2024

Abstract

This study employed a template method to prepare a highly ordered and interconnected porous HOM-m MgFe₂O₄/MgO rare earth ion-efficient adsorbent. The specific surface area of the adsorbent was as high as 130 m²/g, with saturation adsorption capacities [...] Read more.

This study employed a template method to prepare a highly ordered and interconnected porous HOM-m MgFe₂O₄/MgO rare earth ion-efficient adsorbent. The specific surface area of the adsorbent was as high as 130 m²/g, with saturation adsorption capacities for Ce(Ⅲ) and La(Ⅲ) of 5689.69 mg/g and 2123.50 mg/g, respectively. The adsorbent exhibited superparamagnetism with efficient and rapid separation from an aqueous solution using a magnet. The adsorption results indicated that the adsorption mechanism of HOM-m MgFe₂O₄/MgO towards Ce(III) and La(III) primarily involved the ion exchange and redox reactions between Mg(II) hydrolyzed from MgO and Ce(III)/La(Ⅲ), as well as the electrostatic attraction between MgFe₂O₄ and Ce(Ⅲ)/La(Ⅲ). Density functional theory (DFT) calculations revealed that the adsorption process was driven by the interaction of Ce(III) and La(III) ions with the surface oxygen atoms of MgFe₂O₄/MgO. Moreover, MgFe₂O₄/MgO showed a higher affinity and stronger adsorption effect towards Ce(III) than La(III). Adsorption cycling experiments demonstrated that even after three cycles, HOM-m MgFe₂O₄/MgO maintained good removal efficiency for Ce(III) and La(III). Therefore, this adsorbent shows promise as an effective material for removing Ce(III) and La(III) and has significant implications for the remediation of water resources in ion adsorption-type rare earth mining areas. Full article

(This article belongs to the Special Issue Recent Advances in Rare Earth Separation and Extraction)

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27 pages, 3104 KiB

Open AccessReview

Developments in the Dry Fractionation of Plant Components: A Review

by Ganapathy Subramanian Meenakshi Sundaram, Divyapratim Das, Tolu Emiola-Sadiq, Abdullah Sajeeb Khan, Lifeng Zhang and Venkatesh Meda

Separations 2024, 11(12), 332; https://doi.org/10.3390/separations11120332 - 21 Nov 2024

Abstract

Over the years, pulses and cereals have been identified as promising sources of plant proteins. The intensive production of these crops and concerns about food security and malnutrition worldwide have intensified research into their separation. While wet extraction remains the standard protein isolation [...] Read more.

Over the years, pulses and cereals have been identified as promising sources of plant proteins. The intensive production of these crops and concerns about food security and malnutrition worldwide have intensified research into their separation. While wet extraction remains the standard protein isolation method, the search for more sustainable extraction methods is still ongoing. Two dry fractionation techniques, air classification and tribo-electrostatic separation, have been discussed in this review. This review highlights the design aspects of air classifiers including the cut-off point and flow rate, and for electrostatic separators, factors such as charger materials, the nature of the flow in charger tubes, and the strength of the electric field potential have been discussed in detail. Our analysis revealed that cascading the two techniques should help enhance the concentration and purity of the separated fractions. While limitations such as low purity and low yield exist, current research studies are focused on overcoming such drawbacks. Dry fractionation exhibits potential as a sustainable processing method while also preserving the native functionality of the proteins, making it easier to incorporate the fractions in commercial scale processes. Full article

(This article belongs to the Special Issue Extraction, Purification and Application of Bioactive Compounds)

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14 pages, 3137 KiB

Open AccessArticle

Estimation of Bubble Size and Gas Dispersion Property in Column Flotation

by HyunSoo Kim and Chul-Hyun Park

Separations 2024, 11(12), 331; https://doi.org/10.3390/separations11120331 - 21 Nov 2024

Abstract

This study investigates bubble size measurements, bubble characteristics, and the relationship between key operating variables and gas dispersion properties in column flotation. As the frother concentration increased to 120 ppm, the bubble size distribution (BSD) transformed from bimodal to unimodal and achieved a [...] Read more.

This study investigates bubble size measurements, bubble characteristics, and the relationship between key operating variables and gas dispersion properties in column flotation. As the frother concentration increased to 120 ppm, the bubble size distribution (BSD) transformed from bimodal to unimodal and achieved a minimum bubble size of 0.62 mm. The critical coalescence concentration (CCC) was identified as 120 ppm. Gas velocity and wash water velocity significantly influenced bubble size, with gas holdup peaking at 27% at 1.08 cm/s a gas velocity. The bubble-rising velocity increased as the bubble size increased, indicating that the bubble size and bubble-rising velocity were proportional. The bubble surface area flux decreased linearly with increasing bubble size and was significantly affected by the gas velocity. A strong correlation (R² = 0.86) between measured and calculated bubble sizes was achieved, with an average size of 0.64 mm and an estimation error of ±13%. The study demonstrated that bubble size and distribution could be effectively controlled under specific operational conditions (J_g = 0.65–1.3 cm/s, J_W = 0.13–0.52 cm/s, frother = 30–120 ppm). These findings highlight the importance of optimizing key variables to enhance column stability, regime maintenance, and flotation performance. Full article

(This article belongs to the Special Issue Separation Techniques for Flotation and Recycling in Mineral Processing)

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17 pages, 3383 KiB

Open AccessArticle

Condensable Particulate Matter Removal and Its Mechanism by Phase Change Technology During Wet Desulfurization Process

by Hui Tong, Yun Xu, Qiangqiang Ren, Hao Wu, Linzhi Shen, Menglong Sun and Hongmin Yang

Separations 2024, 11(11), 330; https://doi.org/10.3390/separations11110330 - 18 Nov 2024

Abstract

Limestone-gypsum wet flue gas desulfurization (WFGD) played a key role in SOx removal and clean emissions. However, it would also affect the condensable particulate matter (CPM) removal and compositions. The effects of the WFGD system on the removal of CPM and the contents [...] Read more.

Limestone-gypsum wet flue gas desulfurization (WFGD) played a key role in SOx removal and clean emissions. However, it would also affect the condensable particulate matter (CPM) removal and compositions. The effects of the WFGD system on the removal of CPM and the contents of soluble ions in CPM were investigated in a spray desulfurization tower at varied conditions. The results indicate that the emission concentration of CPM decreased from 7.5 mg/Nm³ to 3.7 mg/Nm³ following the introduction of cold water spray and hot alkali droplet spray systems. This resulted in a CPM reduction rate of approximately 51%, reducing the percentage of CPM in total particulate matter and solving the problem of substandard particulate matter emission concentrations in some coal-fired power plants. The concentrations of NO₃⁻, SO₄²⁻, and Cl⁻ among the soluble ions decreased by 41–66.6%. As the liquid-to-gas ratio of the cold water spray and hot alkali droplet spray increased, CPM came into contact with more spray, which accelerated dissolution and chemical reactions. Consequently, the CPM emission concentration decreased by 17.4–19%. The liquid-to-gas ratio has a great effect on the ion concentrations of NO₃⁻, SO₄²⁻, Cl⁻ and NH₄⁺, with a decrease of 28–66%. The temperatures of the cold water spray and the hot alkali droplet spray primarily affect the ionic concentrations of SO₄²⁻ and Ca²⁺, leading to a decrease of 32.3–51%. When the SO₂ concentration increased from 0 mg/Nm³ to 1500 mg/Nm³, large amounts of SO₂ reacted with the desulfurization slurry to form new CPM and its precursors, the CPM emission concentration increased by 57–68.4%. This study addresses the issue of high Concentration of CPM emissions from coal-fired power plants in a straightforward and efficient manner, which is significant for enhancing the air quality and reducing hazy weather conditions. Also, it provides a theoretical basis and technical foundation for the efficient removal of CPM from actual coal-fired flue gas. Full article

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

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