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Volume 11
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Separations, Volume 11, Issue 11 (November 2024) – 28 articles

Cover Story (view full-size image): Effervescence-assisted microextraction is a method that is based on the use of weak acids and carbonate salts to generate CO2 bubbles in water to disperse a sorbent medium into an aqueous solution and facilitate the extraction of analytes. Although the main role of effervescence is the dispersion and mixing of the sorbent, several experimental factors are also affected, which play a pivotal role in the extraction efficiency. These include the pH of the solution, the ionic strength and the extraction time. This work assesses for the first time the influence of effervescence on these parameters and tries to elucidate general guidelines on how to select the effervescence reagents that provide a comprise between the efficient dispersion of the sorbent medium and the experimental conditions that maximize the extraction efficiency. View this paper
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17 pages, 3383 KiB  
Article
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
Viewed by 519
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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10 pages, 4038 KiB  
Article
In Situ Synthesis of Hypercrosslinked Polymer as Stationary Phase for Capillary Gas Chromatography
by Yan Wu, Chaofan Song, Guanwen Huang, Kaicheng Wu, Yinghong Zhao, Ailin Ning, Wenlanqi Du and Jia Jia
Separations 2024, 11(11), 329; https://doi.org/10.3390/separations11110329 - 18 Nov 2024
Viewed by 519
Abstract
Hypercrosslinked polymers (HCPs) constructed by the Friedel–Crafts alkylation reaction of aromatic compounds have emerged as a new class of porous materials with unique merit. Herein, a HCP named HCP-TPB was coated onto a capillary column through in situ synthesis. The prepared column exhibited [...] Read more.
Hypercrosslinked polymers (HCPs) constructed by the Friedel–Crafts alkylation reaction of aromatic compounds have emerged as a new class of porous materials with unique merit. Herein, a HCP named HCP-TPB was coated onto a capillary column through in situ synthesis. The prepared column exhibited a nonpolar nature, and the column efficiency for n-dodecane was 3003 plates m−1. Moreover, the relative standard deviations of retention time and peak area for six replicate injections of the C3–C6 were lower than 0.1% and 1.5%, respectively. The results of this study showed that it is very promising to utilize HCPs as stationary phases for the separation of C3–C6. Full article
(This article belongs to the Topic Advances in Separation Engineering)
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13 pages, 1000 KiB  
Article
The Development of a High-Throughput Homonuclear Decoupling HSQC NMR Platform for the Determination of 10 Sex Hormones in Animal-Source Food and Medicines
by Bing Wang, Qing-Zhi Liu, Jing-Ya Yang, Yu-Jie Du, Nai-Shuo Liu, Wei-Liang Cui, Man Yuan, Yong Zhang, Jing-Qi Wang, Dong-Liang Wang and Shu-Qi Wang
Separations 2024, 11(11), 328; https://doi.org/10.3390/separations11110328 - 18 Nov 2024
Viewed by 521
Abstract
Owing to their endocrine disruption effect, the hormone levels in animal-source food and medicines need to be efficiently and accurately quantified by a reliable analytical method. In the current study, by using a homonuclear decoupling and heteronuclear single quantum correlation (HSQC) experiment, coupled [...] Read more.
Owing to their endocrine disruption effect, the hormone levels in animal-source food and medicines need to be efficiently and accurately quantified by a reliable analytical method. In the current study, by using a homonuclear decoupling and heteronuclear single quantum correlation (HSQC) experiment, coupled with non-uniform sampling (NUS) that was used to shorten the experimental time, we developed a method to quantify 10 hormone residues in animal-source products. This method was validated following the guidelines of USP–NF 2022. The application of the homonuclear decoupling (HD) technique to conventional HSQC yielded 2D spectra that exhibited excellent signal separation and specificity. For all the tested hormones, good linearity with correlation coefficients of more than 0.99 was observed in the linear range of 0.2–6 mg/0.6 mL. Satisfactory precision and recoveries of spiked animal samples were also obtained. Finally, the method was applied in residue determination of 10 hormones in real animal-source samples at the ug/g level. Full article
(This article belongs to the Section Chromatographic Separations)
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10 pages, 4825 KiB  
Article
Aniline-p-Phenylenediamine Copolymer for Removal of Hexavalent Chromium from Wastewater
by Yifeng Li, Jingyue Chen, Xiwei Tan, Han Lou and Hongbo Gu
Separations 2024, 11(11), 327; https://doi.org/10.3390/separations11110327 - 14 Nov 2024
Viewed by 723
Abstract
Hexavalent chromium, one of the heavy metal pollutants in water, harms the ecological environment and human health. In this work, an aniline-p-phenylenediamine copolymer has been prepared by chemical oxidative polymerization to remove the hexavalent chromium (Cr(VI)) from wastewater. The results show [...] Read more.
Hexavalent chromium, one of the heavy metal pollutants in water, harms the ecological environment and human health. In this work, an aniline-p-phenylenediamine copolymer has been prepared by chemical oxidative polymerization to remove the hexavalent chromium (Cr(VI)) from wastewater. The results show that when the initial Cr(VI) concentration is 1.5 mg·L−1, the removal percentage (RP%) of Cr(VI) could reach 94.84% after 180 s of treatment. The RP% of Cr(VI) increases with the dosage of copolymers and decreases with an increase in the initial Cr(VI) concentration. Additionally, the RP% of Cr(VI) removal reaches a maximum of 97.70% with a pH value of 1.0. The Cr(VI) removal kinetics of the copolymers follows a pseudo-first-order chemical reaction model. The X-ray photoelectron spectroscopy (XPS) results demonstrate that the Cr(VI) removal mechanism by the aniline-p-phenylenediamine copolymer is a redox reaction. The positive value of ΔH° and negative value of ΔG° affirm that the Cr(VI) removal process by aniline-p-phenylenediamine copolymer is endothermic, thermodynamically achievable, and spontaneous. Full article
(This article belongs to the Collection Recent Advances in Environmental Separations Analysis)
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15 pages, 3259 KiB  
Article
Structure and Activity of β-Oligosaccharides Obtained from Lentinus edodes (Shiitake)
by Wei Jia, Wenhan Wang, Yanzhen Yu, Huimin Wang, Hongtao Zhang, Peng Liu, Meiyan Zhang, Qiaozhen Li, Henan Zhang, Huaxiang Li and Jingsong Zhang
Separations 2024, 11(11), 326; https://doi.org/10.3390/separations11110326 - 14 Nov 2024
Viewed by 408
Abstract
The structure and characteristics of LEOPs, β-oligosaccharides from the fruiting body of Lentinus edodes obtained via acid degradation and gel permeation chromatography, were investigated. We performed high-performance liquid chromatography, infrared spectroscopy, methylation analysis, nuclear magnetic resonance, and correlated activity experiments, including antioxidant, immunomodulatory, [...] Read more.
The structure and characteristics of LEOPs, β-oligosaccharides from the fruiting body of Lentinus edodes obtained via acid degradation and gel permeation chromatography, were investigated. We performed high-performance liquid chromatography, infrared spectroscopy, methylation analysis, nuclear magnetic resonance, and correlated activity experiments, including antioxidant, immunomodulatory, and liver injury protection to gain insights. LEOPs comprised an oligosaccharide (Mw 2445 Da) based on six β-1, 3-D-glucose residues as the main chain and six β-1, 6-D-glucose residues as the side chain. Surface plasmon resonance analysis indicated that LEOPs directly bound to dectin-1, which facilitated their immunoenhancing activity via downstream NF-κB activation. The results implied that LEOPs may be the active unit of the shiitake β-glucan. The determination of LEOPs structure was performed to reveal the anti-tumor effect and immune-regulatory function of shiitake β-glucan on a molecular level to provide a basis. Full article
(This article belongs to the Special Issue Research Progress for Isolation of Plant Active Compounds)
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11 pages, 8089 KiB  
Article
Copper–Chitosan-Modified Magnetic Textile as a Peroxidase-Mimetic Catalyst for Dye Removal
by Ivo Safarik, Jitka Prochazkova and Kristyna Zelena Pospiskova
Separations 2024, 11(11), 325; https://doi.org/10.3390/separations11110325 - 10 Nov 2024
Viewed by 470
Abstract
Copper chitosan attached to a magnetic synthetic nonwoven textile was manufactured using a simple, rapid, and green procedure employing chitosan dissolved in diluted acetic acid and treatment with copper sulfate solution. The prepared copper–chitosan-modified textile exhibited peroxidase-mimetic activity which was subsequently used for [...] Read more.
Copper chitosan attached to a magnetic synthetic nonwoven textile was manufactured using a simple, rapid, and green procedure employing chitosan dissolved in diluted acetic acid and treatment with copper sulfate solution. The prepared copper–chitosan-modified textile exhibited peroxidase-mimetic activity which was subsequently used for the degradation (decolorization) of important organic dyes, namely methylene blue, Congo red, and Bismarck brown Y, in the presence of hydrogen peroxide. After 5 h of treatment at 22 °C, 87.5%, 79.5%, and 87.7% dye removal were observed for methylene blue, Congo red, and Bismarck brown Y, respectively. The textile bound catalyst can be easily recovered from the reaction mixture after the process is completed. Full article
(This article belongs to the Special Issue Application of Advanced Materials and Technologies in the Separation and Adsorption)
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25 pages, 6867 KiB  
Article
Mineral Heterostructures for Simultaneous Removal of Lead and Arsenic Ions
by Tijana Spasojević, Mirjana Ćujić, Vesna Marjanović, Zlate Veličković, Maja Kokunešoski, Aleksandra Perić Grujić and Maja Đolić
Separations 2024, 11(11), 324; https://doi.org/10.3390/separations11110324 - 9 Nov 2024
Viewed by 538
Abstract
This study focuses on Pb2+ and As(V) adsorption on mineral heterostructures based on a mixture of Si, Fe, and Ti oxides (MOHs). Various techniques were performed to analyze the morphological and structural properties of the synthesized metal oxide samples. In addition to [...] Read more.
This study focuses on Pb2+ and As(V) adsorption on mineral heterostructures based on a mixture of Si, Fe, and Ti oxides (MOHs). Various techniques were performed to analyze the morphological and structural properties of the synthesized metal oxide samples. In addition to the experimental optimization of the parameters determined by the response surface method (RSM), the effects of pH, adsorbent dosage, temperature, and contact duration on the batch and column system adsorption efficiency of single-component and simultaneous lead and arsenate removal were tested. The pseudo-second-order kinetic model and Weber–Morris model were more relevant to the adsorption on the metal(loid)s. The adsorption of Pb2+ was related to the Langmuir isotherm model, while the adsorption of As(V) was fitted to the Freundlich isotherm model. The thermodynamic parameters indicate the spontaneity of the adsorption process with a low endothermic character. The MOHs were more effective in removing Pb2+ and As(V) in the multi-component system (87.7 and 46.1%, respectively) than in the single-component system (56.3 and 23.4%, respectively). This study demonstrates that mineral heterostructures can be effectively used to remove cations and anions from water systems, and due to their fast kinetics, they can be applied to the needs of rapid interventions after pollution. Full article
(This article belongs to the Special Issue Materials from Biomass and Waste for Adsorption Applications)
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13 pages, 1988 KiB  
Article
Extraction and Counter-Current Separation of Phenylpropanoid Glycosides from Pedicularis oederi Vahl by Deep Eutectic Solvent
by Yao Wang, Jun Dai, Xiaoting Zhang, Yuhan Wang, Fangfang He, Lu Liang, Duojie Longzhu and Denglang Zou
Separations 2024, 11(11), 323; https://doi.org/10.3390/separations11110323 - 8 Nov 2024
Viewed by 530
Abstract
Deep eutectic solvents (DESs) are mixtures of organic compounds displaying excellent solvent properties while keeping an ecofriendly character. In this study, DESs have been applied to the extraction of phenylpropanoid glycosides from Pedicularis oederi Vahl, successively separated by means of counter-current chromatography. Firstly, [...] Read more.
Deep eutectic solvents (DESs) are mixtures of organic compounds displaying excellent solvent properties while keeping an ecofriendly character. In this study, DESs have been applied to the extraction of phenylpropanoid glycosides from Pedicularis oederi Vahl, successively separated by means of counter-current chromatography. Firstly, the ultrasonic-assisted extraction conditions were optimized by response surface methodology, and the results showed phenylpropanoid glycosides could be well extracted under the optimized extraction conditions with deep eutectic solvents. Then, the sample was separated by counter-current chromatography using ethyl acetate/aqueous solution of choline chloride and glycerol (6:6, v/v) as the solvent system. In about 360 min, four phenylpropanoid glycosides, including 31.6 mg of echinacoside, 65.3 mg of Jionoside A1, 28.9 mg of Forsythoside B, 74.1 mg of verbascoside, and 21.2 mg of kaempferol-3-O-rutinoside were obtained from about 900 mg of the sample. It revealed deep eutectic solvents could be well employed as a green solvent for the extraction and counter-current separation of natural products. Full article
(This article belongs to the Special Issue Green Separation and Purification Technology)
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18 pages, 4538 KiB  
Article
Antimicrobial Profiling of Piper betle L. and Piper nigrum L. Against Methicillin-Resistant Staphylococcus aureus (MRSA): Integrative Analysis of Bioactive Compounds Based on FT-IR, GC-MS, and Molecular Docking Studies
by Budiman Yasir, Suwahyuni Mus, Sitti Rahimah, Rein Mostatian Tandiongan, Kasandra Putri Klara, Nurul Afrida, Nur Rezky Khairun Nisaa, Risna Risna, Agum Wahyudha Jur, Gemini Alam and Abdul Rohman
Separations 2024, 11(11), 322; https://doi.org/10.3390/separations11110322 - 8 Nov 2024
Viewed by 904
Abstract
This study explored the antimicrobial potential of Piper betle L. (PBL) and Piper nigrum L. (PNL) extracts against MRSA. Plant parts including stem, leaf, and fruit were extracted using aquadest, methanol, and hexane, resulting in 18 distinct extracts. FT-IR combined with cluster analysis [...] Read more.
This study explored the antimicrobial potential of Piper betle L. (PBL) and Piper nigrum L. (PNL) extracts against MRSA. Plant parts including stem, leaf, and fruit were extracted using aquadest, methanol, and hexane, resulting in 18 distinct extracts. FT-IR combined with cluster analysis (CA) categorized the extracts, and anti-MRSA activity was assessed through the paper disk diffusion method. The most potent extracts were further analyzed using GC-MS to identify bioactive compounds. Additionally, molecular docking studies were conducted for MRSA protein targets (4DKI, 6H5O, and 4CJN). The hexane extract of PNL and the aqueous extract of PBL fruit showed the strongest inhibitory effects. GC-MS identified piperine (14.22%) and diisooctyl phthalate (14.67%) as major compounds, with piperolein B, piperanine, β-caryophyllene oxide, and α-caryophylladienol as minor compounds in the hexane extract of PNL, while hydroxychavicol (81.89%) and chavibetol (12.01%) were predominant in the aquadest extract of PBL. Molecular docking revealed that piperolein B and piperine had strong binding affinities to MRSA proteins 4DKI, 6H5O, and 4CJN, comparable to ciprofloxacin. In conclusion, this study confirms the potential of PBL and PNL as sources of novel anti-MRSA agents, supporting further research to develop new therapies. Full article
(This article belongs to the Special Issue Green Extraction Processes to Recover Natural Bioactive Compounds from Food By-Products)
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17 pages, 3919 KiB  
Article
Fatty Acid Profiling in Greek Wines by Liquid Chromatography–High-Resolution Mass Spectrometry (LC-HRMS)
by Maroula G. Kokotou
Separations 2024, 11(11), 321; https://doi.org/10.3390/separations11110321 - 6 Nov 2024
Viewed by 446
Abstract
In recent years, the interest in lipids present in wines has increased, because these natural components, even at low or very low concentrations, play an important role in wine evolution and quality and contribute substantially to the taste and mouthfeel of wines. Herein, [...] Read more.
In recent years, the interest in lipids present in wines has increased, because these natural components, even at low or very low concentrations, play an important role in wine evolution and quality and contribute substantially to the taste and mouthfeel of wines. Herein, we present a liquid chromatography–high-resolution mass spectrometry (LC-HRMS) method for the profiling of free fatty acids (FFAs) in wines. The method is fast and allows the simultaneous determination of twenty-seven saturated and unsaturated FFAs in wine samples, avoiding any prior derivatization step. After validation, a variety of white and rose commercial wine samples from the Greek market, either sparkling or non-sparkling, were analyzed by the present method. The majority of wine FFAs are saturated long aliphatic, in particular palmitic (C16:0) and stearic (C18:0) acids, followed by myristic (C14:0) and pentadecanoic (C15:0) acids, while oleic (C18:1), palmitoleic (C16:1) and linoleic (C18:2) acids were quantified among the unsaturated FAs. The medium-chain C6:0 and the unsaturated C16:1 and C18:2 acids were found at higher concentrations in rose wines compared to white. Full article
(This article belongs to the Special Issue Isolation and Identification of Biologically Active Natural Compounds)
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35 pages, 1639 KiB  
Review
Removal of Inorganic Pollutants and Recovery of Nutrients from Wastewater Using Electrocoagulation: A Review
by Mohamed Ammar, Ezz Yousef, Sherif Ashraf and Jonas Baltrusaitis
Separations 2024, 11(11), 320; https://doi.org/10.3390/separations11110320 - 5 Nov 2024
Viewed by 597
Abstract
Water pollution is a major concern due to its detrimental effects on the environment and public health. The particular danger of inorganic pollutants arises from their persistent toxicity and inability to biodegrade. Recently, electrocoagulation (EC) has been demonstrated as an alternative sustainable approach [...] Read more.
Water pollution is a major concern due to its detrimental effects on the environment and public health. The particular danger of inorganic pollutants arises from their persistent toxicity and inability to biodegrade. Recently, electrocoagulation (EC) has been demonstrated as an alternative sustainable approach to purifying wastewater due to the increasingly strict pollution prevention rules. In particular, EC has been used to remove inorganic pollutants, such as Cr, Zn, Pb, or As. EC has emerged as a sustainable tool for resource recovery of some inorganic pollutants such as N and P that, when recovered, have value as plant nutrients and are critical in a circular economy. These recovered materials can be obtained from diverse agricultural drainage water and recycled as fertilizers. In this work, a state-of-the-art technique is reviewed describing the advances in contaminant removal and nutrient recovery using EC through an in-depth discussion of the factors influencing the contaminant removal process, including operating pH, time, power, and concentration. Furthermore, limitations of the EC technology are reviewed, including the high-power consumption, fast deterioration of the sacrificial electrodes, and the types of contaminants that could not be efficiently removed. Finally, new emerging constructs in EC process optimization parameters are presented. Full article
(This article belongs to the Collection Recent Advances in Environmental Separations Analysis)
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14 pages, 653 KiB  
Article
Phytochemical Study of the Plant Centaurea bruguieriana (DC.) Hand.-Mazz. subsp. belangeriana (DC.) Bornm. of the Family Asteraceae
by Kyriakos Michail Dimitriadis, Olga Tsiftsoglou, Dimitra Hadjipavlou-Litina, Mohammad Arfan and Diamanto Lazari
Separations 2024, 11(11), 319; https://doi.org/10.3390/separations11110319 - 4 Nov 2024
Viewed by 546
Abstract
The aim of this study is to isolate and identify the secondary metabolites of the aerial part of the plant Centaurea bruguieriana (DC.) Hand. -Mazz. subsp. belangeriana (DC.) Bornm. (Centaurea phyllocephala) (Asteraceae), and to study the biological activities of the extracts [...] Read more.
The aim of this study is to isolate and identify the secondary metabolites of the aerial part of the plant Centaurea bruguieriana (DC.) Hand. -Mazz. subsp. belangeriana (DC.) Bornm. (Centaurea phyllocephala) (Asteraceae), and to study the biological activities of the extracts and isolated compounds with in vitro tests. With the use of chromatography and spectroscopy we identified three elemanolides: 8α-O-(3,4-dihydroxy-2-methylenebutanoyloxy) dehydromelitensine (1), 8α-O-(3-hydroxy-4-acetoxy-2-methylene-butanoyloxy) dehydromelitensine (2) and methyl 6α,8α,15-trihydroxyelema-1,3,11(13)-trien-12-oate (3); two germacranolides: cnicin (4) and 4′-O-acetylcnicin (5); one eudesmanolide: malacitanolide (6); five flavonoids: cirsilineol (7), eupatorine (8), 5-hydroxy, 6,7,3′,4′-tetramethoxy-flavone (9), 3,4′,5,7-tetrahydroxy-6-methoxyflavone 3-O-β-D-glucopyranoside (10) and astragalin (11); and also p-OH-benzoic acid (12) and 3-hydroxy-2-methyl-butyrolactone (13). All the isolated compounds were evaluated in silico with the use of molinspiration, while the crude extract, the organic phase B and compounds 2, 4, 5 and 6 were tested as antioxidants and anti-inflammatories for the inhibition of lipid hyperoxide and the inhibition of lipoxygenase. Full article
(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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13 pages, 742 KiB  
Article
Nationwide Surveillance and Cumulative Risk Assessment of Pesticide Residues in Egyptian Vegetables: Results from 2018 to 2021
by Farag Malhat, Ayman Saber, El-Sayed Saber, Shokr Abel Salam Shokr and Mohammed Abdel-Megeed
Separations 2024, 11(11), 318; https://doi.org/10.3390/separations11110318 - 4 Nov 2024
Viewed by 1079
Abstract
Pesticide residues in food are a global concern due to their potential impacts on human health and the environment. This study investigates pesticide residues in vegetables commonly consumed in Egypt, utilizing advanced analytical techniques such as Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) and Gas [...] Read more.
Pesticide residues in food are a global concern due to their potential impacts on human health and the environment. This study investigates pesticide residues in vegetables commonly consumed in Egypt, utilizing advanced analytical techniques such as Liquid Chromatography–Tandem Mass Spectrometry (LC-MS/MS) and Gas Chromatography–Tandem Mass Spectrometry (GC-MS/MS). A total of 4200 vegetable samples, including cucumber, squash, eggplant, okra, peas, onion, green onion, parsley, lettuce, and cantaloupe, were collected from 20 markets across different Egyptian governorates between 2018 and 2021. The analysis revealed that 42% of the samples contained pesticide residues, with only 13% of the analyzed samples exceeding the maximum residue limits (MRLs) established by Codex/EU-MRL standards. Despite this, the estimated daily intake (EDI) of the detected pesticides did not surpass acceptable daily intake (ADI) limits, suggesting no immediate chronic health risks to consumers. These findings highlight Egypt’s ongoing commitment to food safety, while also underscoring the importance of continuous monitoring and the promotion of sustainable agricultural practices to ensure the long-term safety and quality of the food supply. Full article
(This article belongs to the Special Issue Chemical and Contaminant Residue Analysis via Chromatography)
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17 pages, 5104 KiB  
Article
QuEChERS-Based Method for the Determination of Fipronil in Protein Baits and Vespa velutina Larvae by HPLC-DAD and GC-MS
by Omaira de la Hera, Aritza Izaguirre, Arrate Rivas and Rosa María Alonso
Separations 2024, 11(11), 317; https://doi.org/10.3390/separations11110317 - 3 Nov 2024
Viewed by 803
Abstract
Protein baits containing fipronil as a biocide have shown their effectivity as a control method for Vespa velutina nigrithorax (Lepeletier, 1836) in apiaries. This biocide is not selective for Vespa velutina, so it is important to use the minimum dose to inactivate [...] Read more.
Protein baits containing fipronil as a biocide have shown their effectivity as a control method for Vespa velutina nigrithorax (Lepeletier, 1836) in apiaries. This biocide is not selective for Vespa velutina, so it is important to use the minimum dose to inactivate a nest. Therefore, the aim of this work was the development of analytical methods for the determination of fipronil in protein baits for quality control purposes and in larvae of Vespa velutina to determine the biocide content after protein bait ingestion and to acquire knowledge on fipronil metabolism in larvae. For this purpose, a Quechers-based HPLC-PDA method was developed and validated for the determination of fipronil in both matrixes. Furthermore, a GC-MS method was developed for the analysis of fipronil and its metabolites in dead Vespa velutina larvae fed with a mash containing 0.01% fipronil. Quechers-based HPLC-DAD allowed for the determination of the fipronil content in baits. Fipronil and the metabolites fipronil sulfone and fipronil sulfide were identified by GC-MS in extracts of larvae fed with a protein mash containing 0.01% fipronil. The transformation of fipronil into fipronil sulfone inside the larvae and the high toxicity of this metabolite open the possibility to produce protein baits with lower biocide concentrations. Full article
(This article belongs to the Section Chromatographic Separations)
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14 pages, 5840 KiB  
Article
Isolation, Purification, and Antioxidant Activity of Polyphenols from Cynanchum auriculatum Royle ex Wight
by Mustapha Muhammad Nasiru, Yue-E Sun, Lingyun Zhao, Taing Bunhok, Chuon Mony Roth, Sun Sovath, Hay Pharith, Weidong Wang and Chunyang Li
Separations 2024, 11(11), 316; https://doi.org/10.3390/separations11110316 - 1 Nov 2024
Viewed by 568
Abstract
Cynanchum auriculatum Royle ex Wight (CA) is a traditional medicinal and edible plant in China. This study aimed to isolate and characterize the phenolic compounds of C. auriculatum to identify its main antioxidant constituents. Polyphenols were extracted using an ultrasound-assisted ethanol extraction method, [...] Read more.
Cynanchum auriculatum Royle ex Wight (CA) is a traditional medicinal and edible plant in China. This study aimed to isolate and characterize the phenolic compounds of C. auriculatum to identify its main antioxidant constituents. Polyphenols were extracted using an ultrasound-assisted ethanol extraction method, followed by partitioning with ethyl acetate. The ethyl acetate extract was then purified through thin-layer chromatography, silica gel column chromatography, and reverse-phase silica gel column chromatography. Three monomeric compounds—cynandione A (I), 2,5-dihydroxyacetophenone (II), and radix piperacanthone (III)—were identified through their physical and chemical properties, UV and IR spectra, and liquid chromatography–mass spectrometry (LC-MS/MS). Vitamin C (VC) and 2,4-dihydroxyacetophenone were used as controls to evaluate the antioxidant potential of the two most abundant monomers. Antioxidant assays demonstrated that 2,5-dihydroxyacetophenone and cynandione A exhibited strong antioxidant activity at lower concentrations, whereas 2,4-dihydroxyacetophenone showed significantly weaker activity. Furthermore, cynandione A displayed superior cellular antioxidant activity compared to 2,5-dihydroxyacetophenone, indicating its potential as a promising bioactive compound. In conclusion, this study provides valuable insights into the phenolic composition of C. auriculatum and highlights cynandione A as a key antioxidant, paving the way for future research on its therapeutic applications. Full article
(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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13 pages, 4888 KiB  
Article
A Revisit to Effervescence-Assisted Microextraction of Non-Polar Organic Compounds Using Hydrophobic Magnetic Nanoparticles—Application to the Determination of UV Filters in Natural Waters
by Efthymia Toti, Vasiliki Gouma, Vasiliki I. Karagianni and Dimosthenis L. Giokas
Separations 2024, 11(11), 315; https://doi.org/10.3390/separations11110315 - 1 Nov 2024
Viewed by 765
Abstract
In this work, we revisited the method of effervescence-assisted microextraction, aiming to assess the effects of the process of effervescence on the extraction efficiency of organic compounds. We used a magnetic nano-sorbent material composed of stearic acid-coated cobalt-ferrite magnetic nanoparticles as an adsorbent [...] Read more.
In this work, we revisited the method of effervescence-assisted microextraction, aiming to assess the effects of the process of effervescence on the extraction efficiency of organic compounds. We used a magnetic nano-sorbent material composed of stearic acid-coated cobalt-ferrite magnetic nanoparticles as an adsorbent and dispersed it in water using 12 combinations of acid and base mixtures at two different mass ratios. The solution pH, the ionic strength, and the duration of effervescence were calculated and correlated to the extraction efficiency of nonpolar UV filters from aqueous samples as model organic compounds. Our findings provide a general perspective into the influence of the process of effervescence on extraction efficiency. Based on these findings, we developed and optimized a new analytical method for extracting UV filters from water samples using HPLC-UV as a detector. Under the optimum experimental conditions (0.2 g fumaric acid/0.1 g Na2CO3, 50 mg of magnetic nanoparticles and methanol as an elution solvent assisted by vortex agitation for 5 min) the method was found to afford good linearity in the calibration curves expanding by two orders of magnitude, satisfactory reproducibility and repeatability (1.8–11.1%), and high recoveries (78.4–127.1%). This research provides a new perspective on the influence of the process of effervescence on the extraction efficiency of nonpolar organic compounds and introduces a new method for extracting UV filters from aqueous media. Full article
(This article belongs to the Section Environmental Separations)
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8 pages, 1250 KiB  
Communication
Deep Eutectic Solvents as Candidates for Lithium Isotope Enrichment
by Jesse E. Smith, Kori D. McDonald, Dale A. Hitchcock and Brenda L. Garcia-Diaz
Separations 2024, 11(11), 314; https://doi.org/10.3390/separations11110314 - 1 Nov 2024
Viewed by 614
Abstract
Nuclear fusion is a phenomenon that is well known within the nuclear physics community as a viable option for alternative energy as many natural gases and fossil fuels are phased out of commercial use. Deuterium and tritium fusion reactions are currently the leading [...] Read more.
Nuclear fusion is a phenomenon that is well known within the nuclear physics community as a viable option for alternative energy as many natural gases and fossil fuels are phased out of commercial use. Deuterium and tritium fusion reactions are currently the leading candidates for nuclear fusion, with a major limiting factor being a means to produce tritium on an industrial scale. Lithium-6 is a well-known isotope that can produce tritium and helium following a fission reaction with a neutron. Unfortunately, the lithium-6 enrichment methods are limited to the COLEX process, which leaves behind an alarming amount of mercury waste as a potential environmental contaminant. Deep eutectic solvents are believed to be a potential alternative to lithium isotope separations due to the ease of generation, in addition to the minimum environmental waste generated when these solvents are employed. Previous studies have suggested that deep eutectic solvents are capable of separating lithium isotopes by utilizing a 2-thenoyltrifluoroacetone and trioctylphosphine oxide system that can biphasically react with a buffered solution containing lithium chloride. This system displays a separation factor of 1.068, which when compared to the 1.054 separation within the COLEX process, makes it a potential candidate for lithium-6/7 separation. Within this study, we investigate this system in comparison to two newly synthesized deep eutectic solvents and find that within these acetylacetone-based systems, little isotopic separation is observed. We investigate these systems both experimentally and computationally, showing the different lithium cation affinities, in addition to proposing how the electron-donating or -withdrawing nature can influence these systems. Full article
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6 pages, 405 KiB  
Communication
The Volatolome of Chromhidrosis
by Mila Radan and Anđela Plavčić
Separations 2024, 11(11), 313; https://doi.org/10.3390/separations11110313 - 1 Nov 2024
Viewed by 538
Abstract
This study investigates the volatolome in an individual with chromhidrosis, utilizing solid-phase microextraction (SPME) and pentane extraction, followed by gas chromatography–mass spectrometry (GC-MS), to identify key volatile organic compounds (VOCs). A total of 31 compounds were identified, including aldehydes, fatty acid esters, and [...] Read more.
This study investigates the volatolome in an individual with chromhidrosis, utilizing solid-phase microextraction (SPME) and pentane extraction, followed by gas chromatography–mass spectrometry (GC-MS), to identify key volatile organic compounds (VOCs). A total of 31 compounds were identified, including aldehydes, fatty acid esters, and benzoic acid derivatives. SPME was more effective in capturing highly volatile compounds, while pentane extraction primarily isolated lipophilic substances such as squalene and cholesterol. The findings suggest that lipid peroxidation and metabolic dysregulation contribute to the formation of lipofuscin, the pigment responsible for colored sweat. Additionally, the detection of 9-octadecenamide and benzoic acid derivatives highlights the role of oxidative processes in chromhidrosis. Full article
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12 pages, 3222 KiB  
Article
Study on an Integrated Water Treatment System by Simultaneously Coupling Granular Activated Carbon (GAC) and Powdered Carbon with Ultrafiltration
by Yi Wang, Sijia Yu and Weiwei Cai
Separations 2024, 11(11), 312; https://doi.org/10.3390/separations11110312 - 30 Oct 2024
Viewed by 505
Abstract
The process of using powdered activated carbon (PAC) in conjunction with ultrafiltration (UF) has been widely adopted for the treatment of various types of water and wastewater. However, during the application of this integrated PAC-UF process, PAC tends to adhere significantly to the [...] Read more.
The process of using powdered activated carbon (PAC) in conjunction with ultrafiltration (UF) has been widely adopted for the treatment of various types of water and wastewater. However, during the application of this integrated PAC-UF process, PAC tends to adhere significantly to the surface of the UF membrane, which exacerbates membrane fouling. To tackle this issue, this study proposed an innovative water treatment approach that simultaneously integrated granular activated carbon (GAC) and PAC/biochar with UF. In this setup, PAC/biochar was intended to enhance water quality, while the fluidized GAC particles were aimed at reducing membrane fouling and the deposition of PAC/biochar on the membrane surface. We systematically analyzed the operational performance of the integrated systems concerning fouling formation, PAC/biochar attachment, effluent quality, and foulant components. The results indicate that both PAC and biochar effectively improved effluent quality in terms of chemical oxygen demand (COD) and hardness, although they significantly deposited on the membrane surface during operation. Notably, PAC was more prone to attach to the membrane than biochar, and the fouling in biochar-UF systems was primarily attributed to the attachment of organic foulants rather than biochar itself. By combining with GAC, up to 46.01% of membrane fouling and 96.11% of PAC/biochar attachment were mitigated due to the strong mechanical action of the fluidized GAC particles. Importantly, the inclusion of fluidized GAC did not significantly affect effluent quality. Consequently, the GAC-PAC/biochar systems proposed in this study demonstrated dual benefits of improving effluent quality and ensuring stable operation, thereby providing a viable solution for efficient and sustainable water treatment. Full article
(This article belongs to the Special Issue Advanced Research in Desalination)
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11 pages, 2496 KiB  
Article
Exploration of the Functional Constituents of the Substrate of Flammulina velutipes
by Ruixiang Jiang, Renqing Zheng, Bin Yuan, Bo Li, Yiyong Chen and Yongbiao Zheng
Separations 2024, 11(11), 311; https://doi.org/10.3390/separations11110311 - 28 Oct 2024
Viewed by 571
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 ( [...] Read more.
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. Full article
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18 pages, 5440 KiB  
Article
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
Viewed by 555
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Materials from Biomass and Waste for Adsorption Applications)
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11 pages, 2615 KiB  
Article
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
Viewed by 591
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Green and Efficient Separation and Extraction of Salt Lake Resources)
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15 pages, 2432 KiB  
Article
Utilizing Zn(Cu/Cr)Al-Layered Double Hydroxide-Based Photocatalysts for Effective Photodegradation of Environmental Pollutants
by 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
Viewed by 992
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Application of Advanced Oxidation Technology in Wastewater Purification)
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14 pages, 2303 KiB  
Article
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
Viewed by 522
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Development of Materials for Separation and Analysis Applications)
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12 pages, 1622 KiB  
Article
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
Viewed by 603
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 [...] Read more.
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. Full article
(This article belongs to the Special Issue Separation Techniques in Drug Analysis)
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13 pages, 3856 KiB  
Article
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
Viewed by 553
Abstract
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 [...] Read more.
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. Full article
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14 pages, 1096 KiB  
Article
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
Viewed by 755
Abstract
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 [...] Read more.
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”. Full article
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22 pages, 4818 KiB  
Article
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
Viewed by 696
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 [...] Read more.
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%. Full article
(This article belongs to the Section Separation Engineering)
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