Journal Description
Separations
Separations
- formerly Chromatography - is an international, peer-reviewed, open access journal on separation and purification science and technology in all areas of chemical, biological, physical science, and separation performance published monthly online by MDPI. The Central European Group of Separation Sciences (CEGSS) is affiliated with Separations and their members receive discounts on the article processing charges.
- Open Access— free for readers, with article processing charges (APC) paid by authors or their institutions.
- High Visibility: indexed within Scopus, SCIE (Web of Science), CAPlus / SciFinder, and other databases.
- Rapid Publication: manuscripts are peer-reviewed and a first decision is provided to authors approximately 12.4 days after submission; acceptance to publication is undertaken in 2.8 days (median values for papers published in this journal in the first half of 2024).
- Recognition of Reviewers: reviewers who provide timely, thorough peer-review reports receive vouchers entitling them to a discount on the APC of their next publication in any MDPI journal, in appreciation of the work done.
- Companion journal: Purification.
Impact Factor:
2.5 (2023);
5-Year Impact Factor:
2.6 (2023)
Latest Articles
Exploration of the Functional Constituents of the Substrate of Flammulina velutipes
Separations 2024, 11(11), 311; https://doi.org/10.3390/separations11110311 - 28 Oct 2024
Abstract
After harvesting, the substrate of Flammulina velutipes (SFV) is repurposed for uses such as feed, fuel, and culture medium. This study identified four phenolic acids and one flavonoid from the SFV for the first time using solvent extraction and chromatography: ferulic acid (
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After harvesting, the substrate of Flammulina velutipes (SFV) is repurposed for uses such as feed, fuel, and culture medium. This study identified four phenolic acids and one flavonoid from the SFV for the first time using solvent extraction and chromatography: ferulic acid (1), ρ-coumaric acid (2), vanillic acid (3), 3-methoxygallic acid (4), and tricin (5). They showed significant activity in the DPPH scavenging test with concentrations determined by HPLC as follows: ferulic acid (218.88 mg/kg), ρ-coumaric acid (157.31 mg/kg), vanillic acid (281.54 mg/kg), 3-methoxygallic acid (33.85 mg/kg), and tricin (713.42 mg/kg). These findings indicate that the SFV is a valuable source of bioactive compounds for medicinal and health-promoting applications.
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Open AccessArticle
Eco-Friendly Green Approach to the Biosorption of Hazardous Dyes from Aqueous Solution on Ragweed (Ambrosia artemisiifolia) Biomass
by
Natalija Nedić, Tamara Tadić, Bojana Marković, Aleksandra Nastasović, Aleksandar Popović and Sandra Bulatović
Separations 2024, 11(11), 310; https://doi.org/10.3390/separations11110310 - 28 Oct 2024
Abstract
The presented research includes the preparation, characterization, and implementation of magnetic biosorbent (Fe3O4/RWB), obtained from ragweed (Ambrosia artemisiifolia) biomass. Fe3O4/RWB was examined for the removal of a hazardous dye, malachite green (MG), from
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The presented research includes the preparation, characterization, and implementation of magnetic biosorbent (Fe3O4/RWB), obtained from ragweed (Ambrosia artemisiifolia) biomass. Fe3O4/RWB was examined for the removal of a hazardous dye, malachite green (MG), from an aqueous solution in a batch system. The effects of the experimental parameters—initial dye concentration (10–300 mg/L), contact time (0–120 min), biosorbent dose (1–5 g/L), initial pH (2–10), ionic strength (0–1 mol/L), and temperature (298–318 K) on dye biosorption—were studied. The results showed that increases in biosorbent dose, contact time, and initial pH led to an increase in biosorption efficiency, while the increase in initial dye concentration, the ionic strength, and temperature had the opposite effect. The biosorption kinetics for MG on Fe3O4/RWB were analyzed with pseudo-first-order, pseudo-second-order, and Elovich kinetic models, while the Langmuir, Freundlich and Temkin isotherm models were used for equilibrium data analysis. It was observed that the MG biosorption followed the pseudo-second-order kinetic model, whereas the Langmuir model was the best fit for the equilibrium biosorption data of MG, with a Qmax of 34.1 mg/g. the desorption of MG from Fe3O4/RWB indicated reusability in five adsorption/desorption cycles, good performance, and potential in practical applications.
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(This article belongs to the Special Issue Materials from Biomass and Waste for Adsorption Applications)
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Open AccessArticle
Solid–Liquid Phase Equilibria of the Aqueous Quaternary System Rb+, Cs+, Mg2+//SO42− - H2O at T = 323.2 K
by
Zhangfa Yu, Ying Zeng, Xuequn Li, Hongbo Sun, Longgang Li, Wanghai He, Peijun Chen and Xudong Yu
Separations 2024, 11(11), 309; https://doi.org/10.3390/separations11110309 - 27 Oct 2024
Abstract
Sulfate-type salt lakes constitute over half of the total salt lakes in China and are rich in rare elements, such as rubidium and cesium. However, the complex interactions between ions make the separation and extraction process quite challenging. To address this, phase equilibrium
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Sulfate-type salt lakes constitute over half of the total salt lakes in China and are rich in rare elements, such as rubidium and cesium. However, the complex interactions between ions make the separation and extraction process quite challenging. To address this, phase equilibrium studies were conducted on the sulfate system containing rubidium, cesium, and magnesium. Specifically, the phase equilibria of the aqueous quaternary system Rb+, Cs+, Mg2+//SO42− - H2O at 323.2 K were investigated using the isothermal dissolution method. The solubility, density, and refractive index of the system were experimentally measured. The results indicate that the system at 323.2 K belongs to a complex type with the formation of one solid solution (Rb, Cs)2SO4 and two double salts (Rb2SO4·MgSO4·6H2O, Cs2SO4·MgSO4·6H2O). The corresponding phase diagram consists of four quaternary invariant points, nine univariate curves, and six crystallization regions. Among these, the crystalline region for Cs2SO4·MgSO4·6H2O is the largest, while that for the single salt Cs2SO4 is the smallest. Moreover, the crystalline regions for the double salt and solid solutions are significantly larger than those for the single salt, highlighting the difficulty in separation of valuable single salts. A comparison of multi-temperature phase diagrams from 298.2 K to 323.2 K reveals that the crystalline form of MgSO4 changes from MgSO4·7H2O (298.2 K) to MgSO4·6H2O (323.2 K). As the temperature increases, the phase regions for Rb2SO4, Cs2SO4, (Rb, Cs)2SO4, and Cs2SO4·MgSO4·6H2O expand, while the phase region of Rb2SO4·MgSO4·6H2O contracts, indicating that the single salts (Rb2SO4, Cs2SO4) are more readily precipitated at higher temperature, which provides theoretical guidance for the future production and separation of Rb, Cs, and Mg from sulfate-type salt lakes.
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(This article belongs to the Special Issue Green and Efficient Separation and Extraction of Salt Lake Resources)
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Utilizing Zn(Cu/Cr)Al-Layered Double Hydroxide-Based Photocatalysts for Effective Photodegradation of Environmental Pollutants
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Vesna Despotović, Milica Hadnađev-Kostić, Tatjana Vulić, Szabolcs Bognár, Đurđica Karanović, Nataša Tot and Daniela Šojić Merkulov
Separations 2024, 11(11), 308; https://doi.org/10.3390/separations11110308 - 27 Oct 2024
Abstract
Layered double hydroxides (LDHs) and their derived mixed oxides are emerging as a promising class of biocompatible inorganic lamellar nanomaterials. The detailed structure and textural characteristics of the synthesized LDH-based materials were examined using X-ray diffraction, Fourier transform infrared spectroscopy, and N2
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Layered double hydroxides (LDHs) and their derived mixed oxides are emerging as a promising class of biocompatible inorganic lamellar nanomaterials. The detailed structure and textural characteristics of the synthesized LDH-based materials were examined using X-ray diffraction, Fourier transform infrared spectroscopy, and N2 adsorption/desorption isotherm. This study explored the removal efficiency of pharmaceutical tolperisone hydrochloride (TLP), as well as the herbicides quinmerac (QUI) and clomazone (CLO) from water, using dried and calcined LDH-based photocatalysts under simulated solar irradiation and UV irradiation. A higher removal efficiency was observed using UV irradiation, for all substrates. The most effective removal was achieved using ZnAl photocatalysts thermally treated at 100 °C (ZnAl 100) and 500 °C (ZnAl 500). The highest removal rates were observed in the TLP/ZnAl 100 and QUI/ZnAl 100 systems, achieving ~79% and ~86% removal after 75 min of treatment under UV. In contrast, the CLO/ZnAl 100 and CLO/ZnAl 500 systems achieved ~47% removal of CLO. Furthermore, this study investigated the role of reactive species to elucidate the mechanisms of photodegradation under UV. It was found that in the degradation of TLP and QUI in the presence of ZnAl 100 and ZnAl 500, the superoxide anion radical played the most important role.
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(This article belongs to the Special Issue Application of Advanced Oxidation Technology in Wastewater Purification)
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Open AccessArticle
The Development and Evaluation of Biosorbent Composite Spheres for the Adsorption and Quantification of Copper
by
Irma Pérez-Silva, María Elena Páez-Hernández, Francisco Javier Martínez-Flores, Jesús Andrés Tavizón-Pozos and Giaan Arturo Álvarez Romero
Separations 2024, 11(11), 307; https://doi.org/10.3390/separations11110307 - 26 Oct 2024
Abstract
Separation techniques are employed to treat and preconcentrate samples. Preconcentration commonly employs adsorption due to the wide range of sorbents available. The biosorbent composite has emerged as a highly effective alternative, primarily due to its selectivity for active sites and its impressive adsorption
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Separation techniques are employed to treat and preconcentrate samples. Preconcentration commonly employs adsorption due to the wide range of sorbents available. The biosorbent composite has emerged as a highly effective alternative, primarily due to its selectivity for active sites and its impressive adsorption capability. This study aimed to assess and create a spherical biosorbent composite using cellulose acetate and avocado seed. The purpose of this work was to use a biosorbent composite for copper adsorption by flame atomic absorption spectrometry. The copper adsorption follows the Langmuir isotherm, which indicates that it occurs in a monolayer and is homogeneous. Additionally, the adsorption nature is favorable according to the RL factor. The highest capacity for copper adsorption is 0.121 mg g−1. The report describes the methodology and validation process for quantifying copper. The findings demonstrate that the composite biosorbent enables accurate preconcentration and quantification of copper found in decongestants.
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(This article belongs to the Special Issue Development of Materials for Separation and Analysis Applications)
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Investigation of Metoprolol Concentrations in Plasma Using Automated Sample Preparation and LC-MS/MS Detection
by
Ionel-Bogdan Cioroiu, Mona-Elisabeta Dobrin, Marius Niculaua, Constantin-Bogdan Nechita and Valeriu V. Cotea
Separations 2024, 11(11), 306; https://doi.org/10.3390/separations11110306 - 24 Oct 2024
Abstract
Metoprolol (MTP), a selective beta-1 adrenergic blocker, is commonly administered in the form of succinate or tartrate salts, depending on the pharmaceutical formulation. It is typically prescribed in oral forms as either immediate-release or extended-release tablets. This study describes a chromatographic method using
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Metoprolol (MTP), a selective beta-1 adrenergic blocker, is commonly administered in the form of succinate or tartrate salts, depending on the pharmaceutical formulation. It is typically prescribed in oral forms as either immediate-release or extended-release tablets. This study describes a chromatographic method using automated sample clean-up and elution via a reversed-phase mechanism. A TurboFlow approach was applied with a Cyclone P column, and the elution was performed isocratically using a mobile phase of water and acetonitrile (0.1% v/v formic acid) within 4.5 min. Quantification of MTP was achieved using triple quadrupole mass spectrometry, with the transition m/z 268.1 → m/z 130.96 for metoprolol, while bisoprolol fumarate, the internal standard, was detected at m/z 326.3 → m/z 116.2. The method was validated according to bioequivalence guidelines. Selectivity was assessed by checking for potential interferences from blank samples or related compounds formed during sample preparation. Precision and accuracy were evaluated both within and between runs, with a maximum coefficient of variation (CV%) of 10.28 and a maximum relative error (ER%) of 5.38. Linearity was demonstrated over the range of 5 ng/L to 1000 ng/L, with a lower limit of quantification at 0.042 ng/L, made possible by injecting larger sample volumes. A matrix effect of 89% was considered acceptable when compared to standard solutions. Plasma concentrations of MTP were monitored in patients administered either 50 mg or 100 mg doses. For the 50 mg dose, plasma levels reached up to 34 μg/L, while the 100 mg dose produced concentrations ranging from 3.56 to 50.81 μg/L. Although the higher dose generally resulted in elevated plasma levels, significant variability was observed. A strong correlation (r = 0.992) was found between the administered dose and plasma concentration, though variations in absorption rates and patient demographics likely contributed to the observed variability. This method provides a reliable analytical approach suitable for pharmacokinetic and clinical studies involving metoprolol.
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(This article belongs to the Special Issue Separation Techniques in Drug Analysis)
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Decoration of Pt–Ni Alloy on Molten Salt Etched Halloysite Nanotubes for Enhanced Catalytic Reduction of 4-Nitrophenol
by
Jingmin Duan, Yafei Zhao, Zhuhe Zhai, Shengqiang Chen and Bing Zhang
Separations 2024, 11(11), 305; https://doi.org/10.3390/separations11110305 - 24 Oct 2024
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Efficient and low-cost nanocatalysts are extremely desirable for the catalytic reduction of 4-nitrophenol (4-NP). A smaller nanocatalyst particle size and stronger support effect can significantly enhance the catalytic performance. Naturally occurring halloysite nanotubes (HNTs) are promising alternative supports for fine metal nanoparticles, but
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Efficient and low-cost nanocatalysts are extremely desirable for the catalytic reduction of 4-nitrophenol (4-NP). A smaller nanocatalyst particle size and stronger support effect can significantly enhance the catalytic performance. Naturally occurring halloysite nanotubes (HNTs) are promising alternative supports for fine metal nanoparticles, but the smooth surface and single type of functional groups on HNTs are usually unfavorable for the anchoring of metal ions. Herein, we modified HNTs using a mild and controllable molten salt etching method to create a rough surface (rHNTs), followed by loading Pt–Ni alloys to prepare Pt–Ni/rHNTs for the catalytic reduction of 4-NP. The results demonstrate that ultrafine Pt–Ni alloy nanoparticles with a diameter of 1.60 nm are uniformly dispersed on the rough surface of rHNTs. The particle size and catalytic performance can be tuned by adjusting the loading amount of Pt–Ni. The optimized Pt–Ni/rHNT (1 wt %) nanocatalyst reveals the smallest Pt–Ni particle size and the highest catalytic rate of 0.1953 min−1, which exceeds many Pt–Ni-based catalysts in previous reports. This work offers an ingenious idea for the mild surface modification of HNTs and a brilliant perspective for the rational design of inexpensive 4-NP reduction nanocatalysts.
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Open AccessArticle
Identification of Ginseng Radix et Rhizoma, Panacis Quinquefolii Radix, Notoginseng Radix et Rhizoma, and Platycodonis Radix Based on UHPLC-QTOF-MS and “Matrix Characteristics”
by
Jiating Zhang, Fangliang He, Xianrui Wang, Wenguang Jing, Minghua Li, Xiaohan Guo, Xianlong Cheng, Fudong An and Feng Wei
Separations 2024, 11(11), 304; https://doi.org/10.3390/separations11110304 - 23 Oct 2024
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Ginseng Radix et Rhizoma (GRR), Panacis Quinquefolii Radix (PQR), Notoginseng radix et rhizoma (NRR) and Platycodonis Radix (PR) are often confused in the material market because of similar appearances and characteristics. Moreover, chemical identification methods tend to characterize the whole herb with regard
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Ginseng Radix et Rhizoma (GRR), Panacis Quinquefolii Radix (PQR), Notoginseng radix et rhizoma (NRR) and Platycodonis Radix (PR) are often confused in the material market because of similar appearances and characteristics. Moreover, chemical identification methods tend to characterize the whole herb with regard to a single or a few components, which is an inaccurate representation and does not demonstrate the effective utilization of unknown components, and the result is unconvincing. In order to strengthen quality control, improve identification efficiency, and realize digital identification at the individual level of traditional Chinese medicine (TCM), we have put forward the “matrix characteristics” of TCM, combined with a UHPLC-QTOF-MS analysis to explore and realize the digital identification of GRR, PQR, NRR, and PR. The mass spectrometry was quantized to extract common data from different batches of the same TCMs as their matrix characteristics, and the matching credibility (M) was given by matching the “matrix characteristics” with unknown Chinese medicines. The results show that within a reasonable parameter threshold range, the M of four TCMs was higher than 92.00% compared with their own “matrix characteristics”, which was significantly higher than the M ranked second. Furthermore, the digital identification of four TCMs can be successfully realized based on the UHPLC-QTOF-MS analysis and “matrix characteristics”. This has important reference significance for developing the digital identification of GRR at an individual level based on UPLC-QTOF-MS and “matrix characteristics”.
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Open AccessArticle
Experimental Analysis of the Supercritical CO2-Based Circulation Type for the Remediation of Kilogram-Scale Soil Samples from Metal Ions
by
Wentao Wu, Lin Chen, Deqing Mei, Yuki Kanda and Atsuki Komiya
Separations 2024, 11(11), 303; https://doi.org/10.3390/separations11110303 - 22 Oct 2024
Abstract
Supercritical carbon dioxide (sCO2) has been proposed as one new alternative separation medium for soil remediation due to its preferrable dissolution properties and environmentally friendly nature. This study is focused on the effects of operation parameters, such as separation pressure, temperature
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Supercritical carbon dioxide (sCO2) has been proposed as one new alternative separation medium for soil remediation due to its preferrable dissolution properties and environmentally friendly nature. This study is focused on the effects of operation parameters, such as separation pressure, temperature and processing time, on the extraction efficiency of inorganic contaminants (chromium; arsenic) from soil samples by using the newly established kilogram-scale prototype. The prototype system was operated with Cyanex 302 as a chelating agent and methanol as a co-solvent. The extraction efficiency (EE) of chromium (Cr) is experimentally identified to be 97.98% at 35 MPa and 75 °C (with 60 min processing time), while it is found to drop quickly at low temperature and pressure (only 40% under 20 MPa and 35 °C). The EE of arsenic (As) has been identified generally with high efficiency, over 95% for most cases. For chromium (Cr), 30 MPa and 55 °C or higher parameter ranges are recommended to maintain an efficiency over 90%.
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(This article belongs to the Section Separation Engineering)
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Presence of Soya in Industrial and Homemade Sausage Production in Kosovo and Its Reflection on Fatty Acid Profile
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Dafina Mehmetukaj, Xhavit Bytyçi, Armend Cana, Vlora Gashi-Zogëjani, Malbora Shandro-Zeqiri, Drita Bajraktari, Dean Jankuloski and Zehra Hajrulai-Musliu
Separations 2024, 11(10), 302; https://doi.org/10.3390/separations11100302 - 21 Oct 2024
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In the present study, we investigated to what extent soybean was used in industrial and homemade sausage produced in Kosovo, as well as its potential impact on the fatty acid profile. In total, 63 samples, 42 industrial and 21 traditional sausages, were collected
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In the present study, we investigated to what extent soybean was used in industrial and homemade sausage produced in Kosovo, as well as its potential impact on the fatty acid profile. In total, 63 samples, 42 industrial and 21 traditional sausages, were collected either from the market or the production site. All samples were tested by means of real-time PCR for the detection and quantification of soy content, as well as the GC-FID to determine the potential reflection in the fatty acid profile. The presence of soy DNA was detected in 54 out of 63 samples. In total, 41 out of 42 industrial sausage samples were positive for soy DNA, with an average ct value of 22.60 and a standard deviation (SD) of 4.28, whereas 13 out of 21 traditional sausage samples were positive for soy DNA, with a mean ct value of 23.36 and a standard deviation (SD) of 4.56. There was a statistically significant difference in means between industrial sausage and traditional sausage, with p ≤ 0.001 based on CT values (ANOVA test). We investigated the correlation between ct values in real-time PCR for soy DNA with each fatty acid content. There is a moderate correlation of soy DNA ct values with C16:0 palmitin (decrease), C18:0 stearic acid (decrease), C18:1 oleic acid (increase), and overall saturated fatty acids (decrease). With the exception of C14:0 Myristin, C18:1 oleic, and C20:0 Arachin acids and monosaturated fats, the ANOVA test reveals a significant difference in means between groups for the majority of the fatty acids between industrial sausages and traditional sausages. The current study demonstrates that the fatty acid composition of sausages is influenced by the amount of soy present in them. The extent to which other components affect the fatty acid profile is unknown. However, an increase in oleic acid and a decrease in stearic and overall saturated fatty acids are expected.
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Open AccessArticle
A Hollow Hemispherical Mixed Matrix Lithium Adsorbent with High Interfacial Interaction for Lithium Recovery from Brine
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Yuyang Feng, Yifei Zhang, Lin Wang, Shiqiang Wang, Lina Xu, Senjian Han and Tianlong Deng
Separations 2024, 11(10), 301; https://doi.org/10.3390/separations11100301 - 19 Oct 2024
Abstract
Mixed matrix lithium adsorbents have attracted much interest for lithium recovery from brine. However, the absence of an interfacial interaction between the inorganic lithium-ion sieves (LISs) and the organic polymer matrix resulted in the poor structural stability and attenuated lithium adsorption efficiency. Here,
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Mixed matrix lithium adsorbents have attracted much interest for lithium recovery from brine. However, the absence of an interfacial interaction between the inorganic lithium-ion sieves (LISs) and the organic polymer matrix resulted in the poor structural stability and attenuated lithium adsorption efficiency. Here, a novel hollow hemispherical mixed matrix lithium adsorbent (H-LIS) with high interfacial compatibility was constructed based on mussel-bioinspired surface chemistry using a solvent evaporation induced phase transition method. The effects of types of functional modifiers, LIS loading amount, adsorption temperature and pH on their structural stability and lithium adsorption performance were systematically investigated. The optimized H-LIS adsorbent with the LIS loading amount of 50 wt.% possessed the structural merit that the LIS functionally modified by dopamine exposed on both the inner and outer surfaces of the hollow hemispheres. At the best adsorption pH of 12.0, it showed a comparable lithium adsorption capacity of 25.68 mg·g−1 to the powdery LIS within 4 h, favorable adsorption selectivity of Mg/Li and good reusability that could maintain over 90% of lithium adsorption capacity after the LiCl adsorption—0.25 M HCl pickling-DI water cleaning cycling processes for three times. The interfacial interaction mechanism of H-LIS for lithium adsorption was innovatively explored via advanced microcalorimetry technology. It suggested the nature of the Li+ adsorption process was exothermic and dopamine modification could reduce the activation energy for lithium adsorption from 15.68 kJ·mol−1 to 13.83 kJ·mol−1 and trigger a faster response to Li+ by strengthening the Li+-H+ exchange rate, which established the thermodynamic relationship between the structure and Li+ adsorption performance of H-LIS. This work will provide a technical support for the structural regulation of functional materials for lithium extraction from brine.
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(This article belongs to the Section Separation Engineering)
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Retention Mechanisms of Basic Compounds in Liquid Chromatography with Sodium Dodecyl Sulfate and 1-Hexyl-3-Methylimidazolium Chloride as Mobile Phase Reagents in Two C18 Columns
by
Carlos Josué Tereba-Mamani, Maria Celia Garcia-Alvarez-Coque and María José Ruiz-Ángel
Separations 2024, 11(10), 300; https://doi.org/10.3390/separations11100300 - 19 Oct 2024
Abstract
Reversed-phase liquid chromatography (RPLC) relies on a non-polar stationary phase and a more polar hydro-organic mobile phase, where compound retention is primarily governed by hydrophobicity, with more hydrophobic compounds being retained longer. The introduction of secondary equilibria in the chromatographic system through additives,
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Reversed-phase liquid chromatography (RPLC) relies on a non-polar stationary phase and a more polar hydro-organic mobile phase, where compound retention is primarily governed by hydrophobicity, with more hydrophobic compounds being retained longer. The introduction of secondary equilibria in the chromatographic system through additives, such as anionic surfactants and ionic liquids (ILs), was proposed to mitigate ionic interactions between positively charged analytes and the anionic free silanol groups in non-endcapped stationary phases, thereby preventing increased retention and peak tailing. Additionally, the combined hydrophobic and ionic interactions between cationic analytes and the ions in these additives was demonstrated to create mixed retention mechanisms that influence retention and selectivity. In this regard, this study investigates aqueous chromatographic systems incorporating both the anionic surfactant sodium dodecyl sulfate (SDS) and the IL 1-hexyl-3-methylimidazolium chloride as mobile phase reagents. This combination of reagents modulates the retention, eliminating the need for organic solvents and resulting in highly sustainable HPLC procedures. The chromatographic behavior was assessed using two different C18 columns (Zorbax Eclipse and XTerra-MS). The strength of solute interactions was estimated by calculating equilibrium parameters and the contributions of hydrophobic and ionic interactions through simple mathematical models. Focusing on the retention of six basic drugs (β-adrenoceptor antagonists), the study highlighted the significant role of ionic interactions. The results demonstrate the feasibility of using aqueous systems combining SDS and an IL for the efficient separation of moderately polar basic compounds without the use of organic solvents.
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(This article belongs to the Section Chromatographic Separations)
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Research Progress on Physical and Chemical Remediation Methods for the Removal of Cadmium from Soil
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Yonglin Mu, Chunhui Zhang, Yiyun Li, Weilong Zhou, Yanxin Li, Guifeng Zhao and Peidong Su
Separations 2024, 11(10), 299; https://doi.org/10.3390/separations11100299 - 17 Oct 2024
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Soil cadmium contamination is a global environmental issue, threatening ecosystem health and human safety. Common remediation strategies, including phytoremediation and soil replacement, are typically hampered by their lengthy processes or high costs. The aim of this review is to explore and evaluate innovative
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Soil cadmium contamination is a global environmental issue, threatening ecosystem health and human safety. Common remediation strategies, including phytoremediation and soil replacement, are typically hampered by their lengthy processes or high costs. The aim of this review is to explore and evaluate innovative physical and chemical remediation techniques to address cadmium pollution effectively. This review focuses on three promising approaches: the co-application of phosphate fertilizers and sepiolite, CaAl-layered double hydroxide (LDH) immobilization, and hydrochar treatments. The primary methodologies involved evaluating the adsorption capacity, ion exchange mechanisms, and remediation efficiency under varying environmental conditions. Results indicate that these techniques significantly enhance cadmium immobilization, with the co-application of phosphate fertilizers and sepiolite demonstrating up to 72.6% removal of HCl-extractable cadmium. The review concludes that these techniques offer superior cost-effectiveness and scalability for large-scale applications and recommends future research to optimize amendment formulations and develop renewable adsorbents to further improve sustainability.
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Treatment and Recycling of Tungsten Beneficiation Wastewater: A Review
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Wenxia Zhu, Jianhua Kang, Danxian Zhang, Wei Sun, Zhiyong Gao, Haisheng Han and Runqing Liu
Separations 2024, 11(10), 298; https://doi.org/10.3390/separations11100298 - 16 Oct 2024
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The large amount of wastewater containing various pollutants generated during the tungsten beneficiation process has become a bottleneck for the sustainable development of tungsten mining enterprises. Typical pollutants mainly include suspended solids (SSs), silicate ions, metal ions, and residual organic reagents. The direct
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The large amount of wastewater containing various pollutants generated during the tungsten beneficiation process has become a bottleneck for the sustainable development of tungsten mining enterprises. Typical pollutants mainly include suspended solids (SSs), silicate ions, metal ions, and residual organic reagents. The direct discharge of untreated tungsten beneficiation wastewater can cause serious harm to the ecological environment, while recycling can significantly affect flotation indicators. In this paper, the sources and characteristics of typical pollutants were analyzed, and various purification techniques were outlined, including coagulation, adsorption, chemical precipitation, oxidation, and biological treatment methods. Among these techniques, coagulation is particularly effective for the removal of SSs, while adsorption and chemical precipitation are recommended for the removal of soluble ions. For residual organic reagents, oxidation methods have demonstrated high treatment efficiencies. The mainstream methods for wastewater recycling were summarized, including centralized recycling, as well as internal recycling at certain stages. For tungsten beneficiation such a complex process, where the quality of wastewater varies greatly between different stages, it is suitable to recycle the wastewater after appropriate treatment at a specific stage. Furthermore, this study provided a perspective on the future directions of tungsten beneficiation wastewater treatment, serving as a reference for related research and industrial practices.
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Study on Phosphorus Variability Characteristics and Response Mechanism of Microbial Community during Sediment Resuspension Process
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Bo Zhang, Yujia Liu, Haoran Yang, Peng Ji and Yunyan Guo
Separations 2024, 11(10), 297; https://doi.org/10.3390/separations11100297 - 14 Oct 2024
Abstract
Submerged plants and related disturbances can affect both the phosphorus (P) release and the microbial communities in sediments. In this study, a sediment resuspension system was constructed, and P variability characteristics influenced by Vallisneria natans (V. natans) and the response mechanism
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Submerged plants and related disturbances can affect both the phosphorus (P) release and the microbial communities in sediments. In this study, a sediment resuspension system was constructed, and P variability characteristics influenced by Vallisneria natans (V. natans) and the response mechanism of the microbial community were studied. The results indicated that the total phosphorus (TP) content increased from 678.875 to 1019.133 mg/kg and from 1126.017 to 1280.679 mg/kg in sediments and suspended solids (SSs) during the sediment resuspension process, respectively. Organic P (OP) increased by 127.344 mg/kg and 302.448 mg/kg in sediments and SSs after the disturbance, respectively. The microbial communities in the sediments and the leaves of V. natans had higher Chao values after the disturbance, while Shannon values decreased after the disturbance compared to the control in SSs. Proteobacteria had the highest abundance with the value of 51.1% after the disturbance in the sediments and SSs, and the abundance values of Proteobacteria in rhizomes and leaves of V. natans could reach 73.2% on average. Chloroflexi, Acidobacteria, and Firmicutes were also the main phyla in the sediment resuspension system. Sodium hydroxide extractable P (NaOH-P) in sediments could reduce the bioavailability of this P fraction under disturbance conditions. The decrease in the abundance of Bacteroidetes and Nitrospirae indicated that they were more sensitive to the disturbance, and the rotational speed changed the survival conditions for the Bacteroidetes and Nitrospirae. The response mechanism of microbial community during the sediment resuspension process could reflect the influence of the microbial community on the changing characteristics of P and could provide a theoretical foundation for P control at the micro level.
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(This article belongs to the Special Issue Advanced Functional Materials for Wastewater Treatment and Purification)
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Comparison and Optimization of Three Extraction Methods for Epimedium polysaccharides
by
Cheng Liu, Fangyuan Gong, Yijia Chen, Zhengwei Xiong, Cun Wang, Jiepei Li and Jin Guo
Separations 2024, 11(10), 296; https://doi.org/10.3390/separations11100296 - 14 Oct 2024
Abstract
Epimedium is used in traditional Chinese medicine. Epimedium polysaccharides have a variety of physiological properties. This study compared three different processes for the extraction of polysaccharides from Epimedium spp., including ultrasonic, aqueous enzymatic, and microwave extraction, to optimize the extraction conditions and determine
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Epimedium is used in traditional Chinese medicine. Epimedium polysaccharides have a variety of physiological properties. This study compared three different processes for the extraction of polysaccharides from Epimedium spp., including ultrasonic, aqueous enzymatic, and microwave extraction, to optimize the extraction conditions and determine the optimal extraction method. The optimal parameters for each method were analyzed. The results showed that the optimal process for ultrasonic extraction was an ultrasonic power of 250 W, an extraction time of 60 min, a temperature of 50 °C, and a solid–liquid ratio of 1:35. The optimal conditions for the aqueous enzymatic method were a papain concentration of 70 U/mL, extraction time of 70 min, a temperature of 50 °C, and a material-to-liquid ratio of 1:30, while those for microwave extraction were a microwave power of 650 W, an extraction time of 50 min, a temperature of 40 °C, and a material-to-liquid ratio of 1:25. The polysaccharide yields were 4.85%, 4.72%, and 3.98% for the three methods, respectively, indicating that ultrasonic extraction resulted in the highest yield of polysaccharides from Epimedium brevicornum. After purification with DEAE-cellulose, the polysaccharide yields were 4.13%, 3.67%, and 3.12%, respectively. A comprehensive comparison demonstrated the superiority of the ultrasonic extraction method in terms of both extraction yield and purification efficiency. Characterization of the extracted Epimedium polysaccharides showed the presence of five monosaccharides, i.e., glucose, galactose, mannose, galacturonic acid, and rhamnose, and a number average molecular weight Mn of 1.65 × 105 Da and weight average molecular weight Mw of 6.61 × 105 Da. These results provide a scientific basis for the in-depth study and application of Epimedium polysaccharides.
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(This article belongs to the Special Issue Separation and Purification of Functional Components of Foods and Herbs)
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Supercritical Extraction of Ylang Ylang (Cananga odorata) Essential Oil at the Near-Critical Region
by
Rodney Mahabir, Sharad Maharaj, Marian J. Watson, David R. McGaw and Cian Coonai
Separations 2024, 11(10), 295; https://doi.org/10.3390/separations11100295 - 13 Oct 2024
Abstract
The flowers of the ylang ylang tree contain an essential oil which is utilized in high-quality perfumes. The traditional mode of extraction is by steam distillation but it has been shown that the more modern supercritical fluid extraction (SFE) using carbon dioxide has
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The flowers of the ylang ylang tree contain an essential oil which is utilized in high-quality perfumes. The traditional mode of extraction is by steam distillation but it has been shown that the more modern supercritical fluid extraction (SFE) using carbon dioxide has potential for replacing steam distillation. This technology, however, generally operates under high pressures, up to 500 bar. The work described in this paper examines the possibility of using carbon dioxide at much lower pressures, close to the critical point, i.e., 75 bar and 30 °C. Two series of experiments were therefore carried out under such conditions, the first using carbon dioxide alone and the second utilizing ethanol as a co-solvent, the conditions being chosen by applying the Design of Experiments (DOE) technique over ranges of pressure from 80 to 120 bar and temperatures from 35 to 50 °C. Extraction curves are presented which show the rates of extraction to be significantly increased by the use of the co-solvent, with the measured values being 0.74% to 0.97% with no co-solvent addition, increasing to 0.92% to 1.16% with co-solvent addition. These rates are, however, lower than the rates previously reported at higher pressures, i.e., 0.9 to 1.8%. Better quality oils are, however, produced compared to those at higher pressures, with the major components being benzene benzoate, benzene salicylate, cubebene, and benzyl acetate. It is recommended that an economic study be carried out to evaluate whether it is feasible to utilize this process commercially.
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(This article belongs to the Special Issue Extraction and Analysis of Chemical Composition from Natural Products and Metabolites)
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Heavy Metal Removal from Water Using Graphene Oxide in Magnetic-Assisted Adsorption Systems: Characterization, Adsorption Properties, and Modelling
by
A. P. Melchor-Durán, M. R. Moreno-Virgen, A. Bonilla-Petriciolet, H. E. Reynel-Ávila, E. Lucio Ortiz and O. F. González-Vázquez
Separations 2024, 11(10), 294; https://doi.org/10.3390/separations11100294 - 12 Oct 2024
Abstract
This study investigated the adsorption properties of graphene oxide in a magnetic-assisted adsorber for the depollution of water containing heavy metals. Two samples of graphene oxide with different surface chemistry were synthetized and assessed using the magnetic-assisted adsorption systems. One graphene oxide sample
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This study investigated the adsorption properties of graphene oxide in a magnetic-assisted adsorber for the depollution of water containing heavy metals. Two samples of graphene oxide with different surface chemistry were synthetized and assessed using the magnetic-assisted adsorption systems. One graphene oxide sample exhibited a dual magnetic behavior presenting both diamagnetic and ferromagnetic phases, while the other graphene oxide was diamagnetic. The adsorption properties of these graphene oxide samples for removing Pb2+ and Cu2+ were tested and compared with and without a magnetic field exposure. The results showed that the Pb2+ removal increased using both graphene oxide samples in the magnetic-assisted configuration, while Cu2+ adsorption was less sensitive to the application of the magnetic field. A monolayer model was used to simulate all the heavy metal adsorption isotherms quantified experimentally. It was concluded that the adsorption mechanism designed to remove Pb2+ and Cu2+ using tested graphene oxide samples was mainly multi-ionic where two metallic cations could interact with one active site (i.e., oxygenated functional groups) from the adsorbent surface. The oxygenated surface functionalities of graphene oxide samples played a relevant role in determining the impact of magnetic field exposure on the heavy metal removal efficacy. Magnetic-assisted adsorption using graphene oxide is an interesting alternative to reduce the concentration of Pb2+ in polluted effluents, and it can also be applied to improve the performance of adsorbents with a limited concentration of oxygenated functional groups, which usually show poor removal of challenging water pollutants such as toxic heavy metals.
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(This article belongs to the Special Issue Adsorption Process in Chemical Engineering)
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Quantitation of Copper Tripeptide in Cosmetics via Fabric Phase Sorptive Extraction Combined with Zwitterionic Hydrophilic Interaction Liquid Chromatography and UV/Vis Detection
by
Pantelitsa Pingou, Anthi Parla, Abuzar Kabir, Kenneth G. Furton, Victoria Samanidou, Spyridon Papageorgiou, Efthimios Tsirivas, Athanasia Varvaresou and Irene Panderi
Separations 2024, 11(10), 293; https://doi.org/10.3390/separations11100293 - 12 Oct 2024
Abstract
The increasing demand for effective cosmetics has driven the development of innovative analytical techniques to ensure product quality. This work presents the development and validation of a zwitterionic hydrophilic interaction liquid chromatography method, coupled with ultraviolet detection, for the quantification of copper tripeptide
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The increasing demand for effective cosmetics has driven the development of innovative analytical techniques to ensure product quality. This work presents the development and validation of a zwitterionic hydrophilic interaction liquid chromatography method, coupled with ultraviolet detection, for the quantification of copper tripeptide in cosmetics. A novel protocol for sample preparation was developed using fabric phase sorptive extraction to extract the targeted analyte from the complex cosmetic cream matrix, followed by chromatographic separation on a ZIC®-pHILIC analytical column. A thorough investigation of the chromatographic behavior of the copper tripeptide on the HILIC column was performed during method development. The mobile phase consisted of 133 mM ammonium formate (pH 9, adjusted with ammonium hydroxide) and acetonitrile at a 40:60 (v/v) ratio, with a flow rate of 0.2 mL/min. A design of experiments (DOE) approach allowed precise adjustments to various factors influencing the extraction process, leading to the optimization of the fabric phase sorptive extraction protocol for copper tripeptide analysis. The method demonstrated excellent linearity over a concentration range of 0.002 to 0.005% w/w for copper tripeptide, with a correlation coefficient exceeding 0.998. The limits of detection and quantitation were 5.3 × 10−4% w/w and 2.0 × 10−3% w/w, respectively. The selectivity of the method was verified through successful separation of copper tripeptide from other cream components within 10 min, establishing its suitability for high-throughput quality control of cosmetic formulations.
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(This article belongs to the Special Issue Analysis and Bioanalysis of Pharmaceuticals: Sample Preparation and Chromatography)
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Separation and Characterization of Wenjin Tongluo San Essential Oil with a Comprehensive Chromatographic Separation
by
Chaoyue Wang, Xionggao Han, Guanglei Zuo and Jinghui Feng
Separations 2024, 11(10), 292; https://doi.org/10.3390/separations11100292 - 11 Oct 2024
Abstract
The essential oil components of traditional Chinese medicine in-hospital preparation were complex, and one-dimensional chromatographic separation was difficult to completely separate them due to the limited peak capacity. This study was carried out to establish a comprehensive two-dimensional chromatographic separation and analysis method
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The essential oil components of traditional Chinese medicine in-hospital preparation were complex, and one-dimensional chromatographic separation was difficult to completely separate them due to the limited peak capacity. This study was carried out to establish a comprehensive two-dimensional chromatographic separation and analysis method based on countercurrent chromatography (CCC) and gas chromatography (GC). In this paper, we focused on the separation of the essential oil of the traditional Chinese medicine in-hospital preparation Wenjing Tongluo San by CCC × GC, and explored the orthogonality between the two chromatographic techniques to provide the new technical support for the screening of the active ingredients. A solvent system composed of n-hexane-ethyl acetate-methanol-water (9.5:0.5:8.5:1.5, v/v) was chosen for the first-dimensional CCC separation. All the fractions collected from CCC were transferred to GC for plotting two-dimensional contours map. The calculated capacity of the two-dimensional separation system exceeded 3000, which was 8 times more than that of the one-dimensional separation system. High orthogonality (r = 0.42) and spatial coverage factor (70.42%) were obtained. Meanwhile, all the fractions were identified by GC-MS. Our research provided a new methodology for separating essential oils in traditional Chinese medicine as well as an approach for evaluating the quality of traditional Chinese medicinal in-hospital preparation based on two-dimensional chromatographic fingerprints.
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(This article belongs to the Special Issue The 10th Anniversary of Separations: Advances in Separation and Analysis of Natural Products/Medicines)
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