Separations

21 pages, 34624 KiB

Open AccessFeature PaperArticle

Steam and Pressure Management for the Conversion of Steelworks Arising Gases to H₂ with CO₂ Capture by Stepwise Technology

by Francesco Sebastiani, Leonie Lucking, Marija Sarić, Jebin James, Jurriaan Boon, H. J. A. Eric van Dijk, Paul Cobden and Johannis A. Z. Pieterse

Separations 2022, 9(1), 20; https://doi.org/10.3390/separations9010020 - 17 Jan 2022

Cited by 4 | Viewed by 3023

Abstract

Steel production is a main source of CO₂ emissions globally. These emissions must be drastically reduced to meet climate change mitigation goals. STEPWISE is a Sorption Enhanced Reactive Process (SERP) technology that converts steel works arising gases to H₂ with simultaneous [...] Read more.

Steel production is a main source of CO₂ emissions globally. These emissions must be drastically reduced to meet climate change mitigation goals. STEPWISE is a Sorption Enhanced Reactive Process (SERP) technology that converts steel works arising gases to H₂ with simultaneous CO₂ capture. The main energy requirements of the process are the high- and low-pressure steam quantities that are needed to rinse and regenerate the adsorbent. In this simulation study, the separation performance of STEPWISE is evaluated over a range of steam and feed pressure inputs by searching those design points where CO₂ recovery and purity percentages are equalized. This method is used to facilitate the comparison of different operating regimes. Results highlight the importance of the rinse to purge ratio (R/P) as a design variable. A higher R/P ratio is demonstrated to maintain CO₂ recovery and purity of ~95.5%, while total steam consumption and feed carbon loading are reduced by 27% and 20%, respectively. This is achieved without changing other parameters, like cycle time. Additionally, it is demonstrated that the CO₂ capture performance can be maintained for varying feed pressure values by tuning the feed carbon loading. Future studies are recommended to focus on the expected role of the feed gas steam content on these findings. Full article

(This article belongs to the Special Issue Adsorption Based Reactive-Separation Processes)

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13 pages, 1110 KiB

Open AccessArticle

Distribution and Estrogenic Risk of Alkylphenolic Compounds, Hormones and Drugs Contained in Water and Natural Surface Sediments, Morelos, Mexico

by José Gustavo Ronderos-Lara, Hugo Saldarriaga-Noreña, Mario Alfonso Murillo-Tovar, Laura Alvarez, Josefina Vergara-Sánchez, Victor Barba and Jorge Antonio Guerrero-Alvarez

Separations 2022, 9(1), 19; https://doi.org/10.3390/separations9010019 - 16 Jan 2022

Cited by 9 | Viewed by 2733

Abstract

This study evaluated the distribution and potential estrogenic risk of the presence of bisphenol A (BPA), 4-nonylphenol (4NP), naproxen (NPX), ibuprofen (IBU), 17-β-estradiol (E₂) and 17-α-ethinylestradiol (EE2) in water and sediments of the Apatlaco river micro-basin (Morelos, Mexico). The concentration of [...] Read more.

This study evaluated the distribution and potential estrogenic risk of the presence of bisphenol A (BPA), 4-nonylphenol (4NP), naproxen (NPX), ibuprofen (IBU), 17-β-estradiol (E₂) and 17-α-ethinylestradiol (EE2) in water and sediments of the Apatlaco river micro-basin (Morelos, Mexico). The concentration of the determined compounds ranged between <LOD to 86.40 ng·L⁻¹ and <LOD to 3.97 ng g⁻¹ in water and sediments, respectively. The Log K_d distribution obtained (from 1.05 to 1.91 L Kg⁻¹) indicates that the compounds tend to be adsorbed in sediments, which is probably due to the hydrophobic interactions confirmed by the significant correlations determined mainly between the concentrations and parameters of total organic carbon (TOC), total suspended solids (TSS), biological oxygen demand (BOD₅) and chemical oxygen demand (COD). Of five sites analyzed, four presented estrogenic risk due to the analyzed endocrine-disrupting compounds (EEQE₂ > 1 ng·L⁻¹). Full article

(This article belongs to the Section Environmental Separations)

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33 pages, 2131 KiB

Open AccessReview

Novel Applications of Microextraction Techniques Focused on Biological and Forensic Analyses

by Cristian D’Ovidio, Martina Bonelli, Enrica Rosato, Angela Tartaglia, Halil İbrahim Ulusoy, Victoria Samanidou, Kenneth G. Furton, Abuzar Kabir, Imran Ali, Fabio Savini, Marcello Locatelli and Ugo de Grazia

Separations 2022, 9(1), 18; https://doi.org/10.3390/separations9010018 - 15 Jan 2022

Cited by 26 | Viewed by 5535

Abstract

In recent years, major attention has been focused on microextraction procedures that allow high recovery of target analytes, regardless of the complexity of the sample matrices. The most used techniques included liquid-liquid extraction (LLE), solid-phase extraction (SPE), solid-phase microextraction (SPME), dispersive liquid-liquid microextraction [...] Read more.

In recent years, major attention has been focused on microextraction procedures that allow high recovery of target analytes, regardless of the complexity of the sample matrices. The most used techniques included liquid-liquid extraction (LLE), solid-phase extraction (SPE), solid-phase microextraction (SPME), dispersive liquid-liquid microextraction (DLLME), microextraction by packed sorbent (MEPS), and fabric-phase sorptive extraction (FPSE). These techniques manifest a rapid development of sample preparation techniques in different fields, such as biological, environmental, food sciences, natural products, forensic medicine, and toxicology. In the biological and forensic fields, where a wide variety of drugs with different chemical properties are analyzed, the sample preparation is required to make the sample suitable for the instrumental analysis, which often includes gas chromatography (GC) and liquid chromatography (LC) coupled with mass detectors or tandem mass detectors (MS/MS). In this review, we have focused our attention on the biological and forensic application of these innovative procedures, highlighting the major advantages and results that have been accomplished in laboratory and clinical practice. Full article

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

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21 pages, 460 KiB

Open AccessReview

Hypericum spp.—An Overview of the Extraction Methods and Analysis of Compounds

by Valentin Ion, Irina Ielciu, Anca-Gabriela Cârje, Daniela Lucia Muntean, Gianina Crişan and Ramona Păltinean

Separations 2022, 9(1), 17; https://doi.org/10.3390/separations9010017 - 14 Jan 2022

Cited by 7 | Viewed by 5794

Abstract

The Hypericum genus contains one of the few genera of flowering plants that contains a species with authorization for marketing as a traditional medicine, H. perforatum. Due to the fact that this is a large genus, comprising numerous species, a large amount [...] Read more.

The Hypericum genus contains one of the few genera of flowering plants that contains a species with authorization for marketing as a traditional medicine, H. perforatum. Due to the fact that this is a large genus, comprising numerous species, a large amount of interest has been shown over the years in the study of its various pharmacological activities. The chemical composition of these species is quite similar, containing compounds belonging to the class of phloroglucinol derivatives, naphthodianthrones, phenols, flavonoids and essential oils. Taking all of this into consideration, the present study aims to offer an overview of the species of the genus from the point of view of their extraction techniques and analysis methods. An extensive study on the scientific literature was performed, and it revealed a wide range of solvents and extraction methods, among which ethanol and methanol, together with maceration and ultrasonication, are the most frequent. Regarding analysis methods, separation and spectral techniques are the most employed. Therefore, the present study provides necessary data for future studies on the species of the genus, offering a complete overview and a possible basis for their development. Full article

(This article belongs to the Special Issue Early Career Stars in Separation Analysis of Natural Products and Pharmaceuticals)

14 pages, 1996 KiB

Open AccessArticle

Targeted UHPLC-ESI-MS/MS Analysis of Selected Neurotransmitters, Tryptophan and Its Metabolite Kynurenine in Tau Transgenic Rat Brain Tissue: A Pivotal Study

by Juraj Piestansky, Andrea Forgacsova, Dominika Olesova, Jaroslav Galba, Peter Mikus, Petra Majerova and Andrej Kovac

Separations 2022, 9(1), 16; https://doi.org/10.3390/separations9010016 - 14 Jan 2022

Cited by 3 | Viewed by 3086

Abstract

Neurotransmitters (NT) are widely distributed in the central nervous system. These molecules are important for many physiological processes and the function of the immune system. Imbalance of NT are linked to numerous neurological disorders and diseases, including tauopathies. Here, a targeted approach based [...] Read more.

Neurotransmitters (NT) are widely distributed in the central nervous system. These molecules are important for many physiological processes and the function of the immune system. Imbalance of NT are linked to numerous neurological disorders and diseases, including tauopathies. Here, a targeted approach based on on-line combination of ultra-high performance liquid chromatography with tandem mass spectrometry was validated and applied to the quantitative analysis of nine NT (acetylcholine, choline, aspartic acid, asparagine, glutamic acid, glutamine, pyroglutamate, γ-aminobutyric acid, N-acetyl-L-aspartic acid), tryptophan and its metabolite kynurenine in brain tissue samples of a rat model for tauopathy. The applied analytical method was characterized by excellent validation parameters for all analytes, such as limits of detection in the range of 0.01–1.70 µg/mL, regression coefficients of the calibration curves ≥ 0.9946, intra-day and inter-day precision expressed as coefficient of variation in the range of 0.6–11.9% and 0.6–14.4%, and accuracy in the range of 87.6–107.1% and 87.2–119.6%. Our analytical approach led to the identification of increased levels of choline and γ-aminobutyric acid in pons, and elevated concentration levels of pyroglutamate in medulla oblongata. These findings indicate that NT could play a valuable role in the study and clarification of neuroinflammation and neurodegenerative diseases. Full article

(This article belongs to the Special Issue Chromatographic and Electrophoretic Methods in Current Biomedical Analysis)

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10 pages, 2442 KiB

Open AccessArticle

Sensitivity Increase in Headspace Analysis of Hydrocarbons in Water by Using Online Selective Elimination of Gas Extractant

by Oleg V. Rodinkov, Alexey Y. Pisarev, Leonid N. Moskvin, Aleksandra S. Bugaichenko and Pavel N. Nesterenko

Separations 2022, 9(1), 15; https://doi.org/10.3390/separations9010015 - 14 Jan 2022

Cited by 2 | Viewed by 2283

Abstract

In this study, a novel approach in headspace gas chromatographic analysis using the selective absorption of the gas extractant during concentration of the analytes was developed. The carbon dioxide used as the gas extractant was removed from the sample flow by passing it [...] Read more.

In this study, a novel approach in headspace gas chromatographic analysis using the selective absorption of the gas extractant during concentration of the analytes was developed. The carbon dioxide used as the gas extractant was removed from the sample flow by passing it through a column packed with microdispersed sodium hydroxide granules. The analytical capabilities of the suggested method were illustrated by the determination of aliphatic and aromatic hydrocarbons in water. We established that this method allows the preconcentration of analytes in the gas phase to be increased proportionally to the volume ratios of the gas extractant before and after absorption, while the analyte limits of detection decrease 30-fold. For example, benzene can be detected in water at a concentration of 0.5 μg/L. Full article

(This article belongs to the Section Environmental Separations)

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23 pages, 3780 KiB

Open AccessReview

State of the Art in Separation Processes for Alternative Working Fluids in Clean and Efficient Power Generation

by Odi Fawwaz Alrebei, Abdulkarem I. Amhamed, Muftah H. El-Naas, Mahmoud Hayajnh, Yasmeen A. Orabi, Ward Fawaz, Ahmad S. Al-tawaha and Agustin Valera Medina

Separations 2022, 9(1), 14; https://doi.org/10.3390/separations9010014 - 13 Jan 2022

Cited by 8 | Viewed by 3851

Abstract

Gas turbines must now comply with much stricter emission control regulations. In fact, to combat the greenhouse effect, regulatory authorities have drastically reduced allowable emission levels. For example, in less than 12 years, the United States’ Clean Air Act issued the New Source [...] Read more.

Gas turbines must now comply with much stricter emission control regulations. In fact, to combat the greenhouse effect, regulatory authorities have drastically reduced allowable emission levels. For example, in less than 12 years, the United States’ Clean Air Act issued the New Source Performance Standards (NSPS), which tightened the NOx emission margin of natural gas combustion (from 75 ppm to 10 ppm). On the other hand, despite those efforts, the high demand for energy produced by fossil-fueled gas turbines in power plants has resulted in dramatic increases in anthropogenic CO₂ and NO_x emitted by gas combustors. Most systems responsible for these undesirable emissions are directly linked to power generation, with gas turbines playing a pivotal role. Yet, gas turbines are still widely used in power plants and will continue to meet the growing demand. Therefore, sequestration and separation techniques such as Carbon Capture and Storage (CCS) and Air Separation Units (ASU) are essential to reduce CO₂ and NO_x emissions while allowing large amounts of power to be generated from these systems. This paper provides an in-depth examination of the current state of the art in alternative working fluids utilized in the power generation industry (i.e., gas turbines, combustion). In addition, this paper highlights the recent contribution of integrating separation techniques, such as air separation, steam methane reforming, and water-gas shifting, to the power generation industry to facilitate a continuous and adequate supply of alternative working fluids. Full article

(This article belongs to the Collection State of the Art in Separation Science)

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15 pages, 2298 KiB

Open AccessArticle

Detection of Escherichia coli by Combining an Affinity-Based Method with Contactless Atmospheric Pressure Ionization Mass Spectrometry

by Juli Novita Sari, Karthikeyan Kandasamy and Yu-Chie Chen

Separations 2022, 9(1), 13; https://doi.org/10.3390/separations9010013 - 11 Jan 2022

Cited by 4 | Viewed by 2683

Abstract

Escherichia coli are common pathogens, whereas E. coli O157:H7 is the most notorious E. coli strain, owing to its high virulence that can cause serious adverse effects and death. E. coli contains abundant peroxidases. Thus, the presence of E. coli can be determined [...] Read more.

Escherichia coli are common pathogens, whereas E. coli O157:H7 is the most notorious E. coli strain, owing to its high virulence that can cause serious adverse effects and death. E. coli contains abundant peroxidases. Thus, the presence of E. coli can be determined by mixing E. coli with its substrate such as 3,5,3′,5′ tetramethylbenzidines (TMB) for endogenous peroxidase reactions. Under the presence of a high concentration of E. coli, colorless TMB turned to bluish, owing to the generation of the complexity of TMB and its oxidized TMB. To further reduce the detectable cell concentration, we developed an affinity-based method combined with an endogenous peroxidase reaction and mass spectrometric detection to detect E. coli. Affinity probes (diameter: ~20 µm) modified with maltose were generated for the enrichment of E. coli from sample solutions. E. coli trapped by the affinity probes was reacted with TMB in the presence of hydrogen peroxide for endogenous peroxidase reactions. Contactless atmospheric pressure ionization mass spectrometry was used for the detection of the reaction product, oxidized TMB (TMB cationic radical), to indicate the presence of target bacteria. The results showed that the developed method can be used to rapidly determine the presence of E. coli from a sample solution based on the detection of the TMB cationic radicals. The lowest detectable concentration of our method against E. coli O157:H7 in buffers and in complex juice samples was as low as ~100 cfu mL⁻¹. Full article

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

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11 pages, 1665 KiB

Open AccessCommunication

Health Risk Assessment of Lead in Soils from an Historic Industrial Site in North-East England

by Renli Ma and John R. Dean

Separations 2022, 9(1), 12; https://doi.org/10.3390/separations9010012 - 11 Jan 2022

Cited by 2 | Viewed by 2646

Abstract

The former St. Antony’s Lead Works site, now the central part of an urban recreational park (Walker Riverside Park) in the east end of Newcastle upon Tyne (England, UK), has been assessed based on the Pb concentration in topsoil according to recently derived [...] Read more.

The former St. Antony’s Lead Works site, now the central part of an urban recreational park (Walker Riverside Park) in the east end of Newcastle upon Tyne (England, UK), has been assessed based on the Pb concentration in topsoil according to recently derived Category 4 Screening Level (C4SL) for public open space–park (POS_park, 1300 mg/kg). The site was divided into eight sampling areas following its physical layout. In total 79 soil samples were collected, characterised for acidity and organic matter content, and analysed by energy dispersive X-ray fluorescence (ED-XRF). The Pb levels in most of the samples, particularly those from the fringes of the site, are below the generic guideline value (down to 70 mg/kg). More than 16% of the samples from nearly all sampling areas, especially those sampling points around the former horizontal condenser flue and main chimney, contain levels of Pb significantly exceeding the limit (up to 206,000 mg/kg). No correlation is found between the Pb concentration in soil samples and their acidity (mostly neutral, pH 7.0 ± 0.5) or organic matter content (15.5 ± 4.1%). Using the Contaminated Land Exposure Assessment (CLEA) model (version 1.071), the site-specific risk assessment criteria (SSAC) for Lead (C4SL child), 2862 mg/kg, is obtained based on adjusted exposure frequency and occupancy period. Nearly 9% of the individual sample Pb concentrations (n = 79) across sample locations B, C, D and H are still above the specific value. Further statistical evaluation based on 95% upper confidence limit confirms that the site still represents a potential human health risk. This is because Pb concentrations, from two areas in the centre of the site (sample locations B and C), are greatly over the SSAC specific threshold (sample mean at location B is 12,350 mg/kg and at location C is 11,745 mg/kg). Full article

(This article belongs to the Section Environmental Separations)

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15 pages, 4076 KiB

Open AccessArticle

A Novel and Green Method for Turning Food Waste into Environmentally-Friendly Organic Deicing Salts: Enhanced VFA Production through AnMBR

by Qiuhong Xiang, Kunlun Yang, Ziwen Chen, Manman Li, Yuanqi Zhang, Xiaorui Wang, Yingying Jiang, Peng Gu and Hengfeng Miao

Separations 2022, 9(1), 11; https://doi.org/10.3390/separations9010011 - 6 Jan 2022

Cited by 2 | Viewed by 2844

Abstract

In order to improve the production efficiency of volatile fatty acids (VFAs) by anaerobic fermentation of food waste and reduce the cost for the production of organic deicing salt (ODS), ceramic microfiltration (MF) membrane separation was applied in the conventional food waste fermenter [...] Read more.

In order to improve the production efficiency of volatile fatty acids (VFAs) by anaerobic fermentation of food waste and reduce the cost for the production of organic deicing salt (ODS), ceramic microfiltration (MF) membrane separation was applied in the conventional food waste fermenter to build an anaerobic membrane bioreactor (AnMBR). Results showed that the maximum VFA concentration in AnMBR was up to 55.37 g/L. Due to the fact that the MF membrane could realize in situ separation of VFAs, the recovery of VFAs could reach 95.0%; 66.6% higher than that of traditional fermentation reactors. After the application of the MF membrane, more than 20.0% of soluble COD, 40.0% of proteins, and 50.0% of polysaccharides were retained and more than 90.0% of VFAs could be transferred in a timely fashion in the AnMBR system. In addition, the enrichment effect of the MF membrane enhanced enzymatic activities such as protease, α-Glucosidase and acetate kinase, and increased the abundance of some important bacteria for organic acid generation such as Amphibacter, Peptoniphilus and Halomonas, which made a significant contribution to the yield of VFAs. After concentration, evaporation and crystallization, the melting efficiency of obtained ODS can reach more than 90.0% in chloride salts, which was 112.0% of commercial calcium magnesium acetate (CMA). When compared to chloride salts and CMA, ODS was more environmentally-friendly as it can reduce the corrosion of carbon steel and concrete significantly. This study created a new way of converting food waste into a high-value organic deicing agent, realizing the resource utilization of solid waste and reducing the production cost of organic deicing agents. Full article

(This article belongs to the Section Environmental Separations)

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15 pages, 3174 KiB

Open AccessArticle

Low-Cost and Eco-Friendly Hydroxyapatite Nanoparticles Derived from Eggshell Waste for Cephalexin Removal

by Huda S. Alhasan, Nadiyah Alahmadi, Suhad A. Yasin, Mohammed Y. Khalaf and Gomaa A. M. Ali

Separations 2022, 9(1), 10; https://doi.org/10.3390/separations9010010 - 5 Jan 2022

Cited by 28 | Viewed by 5056

Abstract

This work describes the hydroxyapatite nanoparticle (HAP) preparation from eggshell waste and their application as an adsorbent for Cephalexin (Ceph) antibiotic removal from aqueous solutions. Chemical precipitation with phosphoric acid was used to evaluate the feasibility of calcium oxide for HAP preparation. The [...] Read more.

This work describes the hydroxyapatite nanoparticle (HAP) preparation from eggshell waste and their application as an adsorbent for Cephalexin (Ceph) antibiotic removal from aqueous solutions. Chemical precipitation with phosphoric acid was used to evaluate the feasibility of calcium oxide for HAP preparation. The structural properties of HAP were characterized by X-ray diffraction, which revealed the formation of the hydroxyapatite crystalline phase formation. In addition, transmitting electron spectroscopy showed an irregular shape with a variation in size. The impact of various experimental conditions on the removal efficiency such as the solution’s pH, contact time, HAP mass, solution temperature, and Ceph concentration were studied. Experimental data showed that HAP could remove most Ceph species from aqueous solutions within 1 h at pH = 7 with 70.70% adsorption efficiency utilizing 50 mg of the HAP. The removal process of Ceph species by HAP was kinetically investigated using various kinetic models, and the results showed the suitability of the pseudo-second-order kinetic model for the adsorption process description. Moreover, the removal process was thermodynamically investigated; the results showed that the removal was spontaneous endothermic and related to the randomness increase. The data confirmed that HAP had high efficiency in removing Ceph antibiotics from an aqueous solution. Full article

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11 pages, 1279 KiB

Open AccessArticle

Rapid and Simultaneous Determination of Free Aromatic Carboxylic Acids and Phenols in Commercial Juices by GC-MS after Ethyl Chloroformate Derivatization

by Alessio Incocciati, Elisa Di Fabio, Alberto Boffi, Alessandra Bonamore and Alberto Macone

Separations 2022, 9(1), 9; https://doi.org/10.3390/separations9010009 - 30 Dec 2021

Cited by 4 | Viewed by 3034

Abstract

Natural phenol and phenolic acids are widely distributed in the plant kingdom and the major dietary sources include fruits and beverages derived therefrom. Over the past decades, these compounds have been widely investigated for their beneficial effects on human health and, at the [...] Read more.

Natural phenol and phenolic acids are widely distributed in the plant kingdom and the major dietary sources include fruits and beverages derived therefrom. Over the past decades, these compounds have been widely investigated for their beneficial effects on human health and, at the same time, several analytical methods have been developed for their determination in these matrices. In the present paper, 19 different aromatic carboxylic acids and phenols were characterized by GC-MS using ethyl chloroformate as the derivatizing agent. This procedure occurs quickly at room temperature and takes place in aqueous media simultaneously with the extraction step in the presence of ethanol using pyridine as a catalyst. The analytical method herein developed and validated presents excellent linearity in a wide concentration range (25–3000 ng/mL), low LOQ (in the range 25–100 ng/mL) and LOD (in the range 12.5–50 ng/mL), and good accuracy and precision. As a proof of concept, ethyl chloroformate derivatization was successfully applied to the analysis of a selection of commercial fruit juices (berries, grape, apple, pomegranate) particularly rich in phenolic compounds. Some of these juices are made up of a single fruit, whereas others are blends of several fruits. Our results show that among the juices analyzed, those containing cranberry have a total concentration of the free aromatic carboxylic acids and phenols tested up to 15 times higher than other juices. Full article

(This article belongs to the Special Issue Food Quality and Safety: Advances in Analytical Methods and Applications)

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9 pages, 1526 KiB

Open AccessArticle

Determination of Ecdysterone in Dietary Supplements and Spinach by Ultra-High-Performance Liquid Chromatography-Tandem Mass Spectrometry

by Krzysztof Grucza, Mariola Wicka, Aleksandra Drapała and Dorota Kwiatkowska

Separations 2022, 9(1), 8; https://doi.org/10.3390/separations9010008 - 29 Dec 2021

Cited by 11 | Viewed by 4914

Abstract

Ecdysterone is a naturally occurring steroid hormone of the ecdysteroid class. This group is widely marketed to athletes in dietary supplements as a “natural anabolic agent”, advertised to increase strength and muscle mass during resistance training, reduce fatigue and ease recovery. The aim [...] Read more.

Ecdysterone is a naturally occurring steroid hormone of the ecdysteroid class. This group is widely marketed to athletes in dietary supplements as a “natural anabolic agent”, advertised to increase strength and muscle mass during resistance training, reduce fatigue and ease recovery. The aim of the study was to develop and validate a straightforward approach for identifying ecdysterone in dietary supplements by means of ultra-high-performance liquid chromatography–tandem mass spectrometry (UHPLC-MS/MS). Furthermore, due to the fact that ecdysterone is one of the compounds naturally occurring in spinach, the fit-for-purpose method for extraction and identification of ecdysterone in spinach is proposed. The validity of the developed method was confirmed with the use of a reference standard and the limit of detection (LOD) for ecdysterone was established at 1 mg/g supplement. The presence of ecdysterone was confirmed in all tested supplements at estimated concentrations ranging between 5 mg/g and 383 mg/g. Full article

(This article belongs to the Topic Application of Analytical Chemistry in Exercise Physiology and Pharmacology)

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17 pages, 5042 KiB

Open AccessArticle

Enantiomeric Separation and Molecular Modelling of Bioactive 4-Aryl-3,4-dihydropyrimidin-2(1H)-one Ester Derivatives on Teicoplanin-Based Chiral Stationary Phase

by Isabella Bolognino, Antonio Carrieri, Rosa Purgatorio, Marco Catto, Rocco Caliandro, Benedetta Carrozzini, Benny Danilo Belviso, Maria Majellaro, Eddy Sotelo, Saverio Cellamare and Cosimo Damiano Altomare

Separations 2022, 9(1), 7; https://doi.org/10.3390/separations9010007 - 28 Dec 2021

Cited by 4 | Viewed by 2119

Abstract

The enantiomeric separation of 15 racemic 4-aryl-3,4-dihydropyrimidin-2(1H)-one (DHP) alkoxycarbonyl esters, some of which proved to be highly active as A_2B adenosine receptor antagonists, was carried out by HPLC on Chirobiotic^TM TAG, a chiral stationary phase (CSP) bearing teicoplanin aglycone [...] Read more.

The enantiomeric separation of 15 racemic 4-aryl-3,4-dihydropyrimidin-2(1H)-one (DHP) alkoxycarbonyl esters, some of which proved to be highly active as A_2B adenosine receptor antagonists, was carried out by HPLC on Chirobiotic^TM TAG, a chiral stationary phase (CSP) bearing teicoplanin aglycone (TAG) as the chiral selector. The racemic compounds were separated under polar organic (PO) conditions. Preliminarily, the same selectands were investigated on three different Pirkle-type CSPs in normal-phase (NP) conditions. A baseline separation was successfully obtained on TAG-based CSPs for the majority of compounds, some of which achieved high enantioselectivity ratios (α > 2) in contrast with the smaller α values (1–1.5) and the lack of baseline resolution observed with the Pirkle-type CSPs. In particular, the racemic tetrazole-fused DHP ester derivatives, namely compounds 8 and 9, were separated on TAG-based HPLC columns with noteworthy α values (8.8 and 6.0, respectively), demonstrating the potential of the method for preparative purposes. A competition experiment, carried out with a racemic analyte (6) by adding N-acetyl-d-alanine (NADA) to the mobile phase, suggested that H-bonding interactions involved in the recognition of the natural dipeptide ligand d-Ala-d-Ala into the TAG cleft should be critical for enantioselective recognition of 4-aryl DHPs by TAG. The X-ray crystal structure of TAG was elucidated at a 0.77 Å resolution, whereas the calculation of molecular descriptors of size, polar, and H-bond interactions, were complemented with molecular docking and molecular dynamics calculations, shedding light on repulsive (steric effects) and attractive (H-bond—polar and apolar) interactions between 4-aryl DHP selectands and TAG chiral selectors. Full article

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

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17 pages, 2464 KiB

Open AccessArticle

Effect of Cone-Plate Clarifier Structure Parameters on Flocculation Efficiency

by Yulong Zhang, Peikun Liu, Linjing Xiao, Long Chang, Fangping Yan and Lanyue Jiang

Separations 2022, 9(1), 6; https://doi.org/10.3390/separations9010006 - 24 Dec 2021

Cited by 1 | Viewed by 2526

Abstract

In this study, a coal mine water flocculation system was established. A series of flocculation tests were carried out at different structural parameters (cylinder height, cone-plate insertion depth and cone-plate spacing) to better investigate the effect of the cone-plate clarifier on coal mine [...] Read more.

In this study, a coal mine water flocculation system was established. A series of flocculation tests were carried out at different structural parameters (cylinder height, cone-plate insertion depth and cone-plate spacing) to better investigate the effect of the cone-plate clarifier on coal mine water treatment performance. Sixteen sampling points were set up in the system for data monitoring to generate the required data. The cone-plate clarifier was divided into five zones for flocculation analysis. The increased cylinder height facilitated the flocculation of particles in the micro flocculation zone and the settling of particles in the settlement zone. The chemicals used are polyaluminum chloride (PACl), Fe₃O₄ and polyacrylamide (PAM), corresponding to doses of 60 mg/L, 40 mg/L and 6 mg/L, respectively. Insufficient insertion depth of the cone-plate will cause the small flocs that have not been fully flocculated to enter the exit pipe zone directly through the cone-plate, while too much insertion depth will cause the large floc in the settlement zone to re-enter the exit pipe zone. The flocculation effect of small flocs increased as the cone-plate spacing decreased, which is consistent with the shallow pool theory. When the cone plate spacing was too narrow, the amount of fluid was reduced and the increase in fluid velocity reduced the flocculation effect. Curve fitting was conducted for Suspended solids(SS) and turbidity removal efficiency under each structural parameter to derive the variation of SS and turbidity removal efficiency under different structural parameters. The regression models of SS and turbidity removal efficiency on the cylinder height, cone-plate insertion depth and cone-plate spacing were established based on the curve fitting results, and the regression models were verified to be well fitted based on the comparison of experimental results. Finally, the optimal values of SS and turbidity removal efficiency were found based on the regression model. The flow rate of the cone-plate clarifier is 0.6 m³/h. The SS removal efficiency reached 96.82% when the cylinder height was 708 mm, the cone-plate insertion depth was 367 mm and the cone-plate spacing was 26 mm. The turbidity removal efficiency reached 86.75% when the cylinder height was 709 mm, the cone-plate insertion depth was 369 mm and the cone-plate spacing was 26 mm. Full article

(This article belongs to the Special Issue Research on Separation Performance of Separator)

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17 pages, 3798 KiB

Open AccessArticle

DES Based Efficient Extraction Method for Bioactive Coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.

by Ting Wang and Qian Li

Separations 2022, 9(1), 5; https://doi.org/10.3390/separations9010005 - 23 Dec 2021

Cited by 5 | Viewed by 3493

Abstract

In this study, a simple and environmentally friendly method was developed for the extraction of seven active coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.(A. dahurica) based on deep eutectic solvents (DESs). Among the 16 [...] Read more.

In this study, a simple and environmentally friendly method was developed for the extraction of seven active coumarins from Angelica dahurica (Hoffm.) Benth. & Hook.f. ex Franch. & Sav.(A. dahurica) based on deep eutectic solvents (DESs). Among the 16 kinds of DES based on choline chloride, the DES system with the molar ratio of choline chloride, citric acid, and water as 1:1:2 had the best extraction effect. Ultrasonic-assisted response surface methodology (RSM) was used to investigate the optimal extraction scheme. The results showed that the optimal extraction conditions were a liquid–solid ratio of 10:1 (mL/g), an extraction time of 50 min, an extraction temperature of 59.85 °C, and a moisture content of 49.28%. Under these conditions, the extraction yield reached 1.18%. In addition, scanning electron microscopy (SEM) was used to observe the degree of powder fragmentation before and after extraction with different solvents. The cells of A. dahurica medicinal materials obtained by DES ultrasonic-assisted treatment were the most seriously broken, indicating that DES had the highest efficiency in the treatment of A. dahurica. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) DPPH radical scavenging model was used to evaluate the biological activity of DES extract. The results showed that DES extract had better scavenging ability of DPPH free radical. Therefore, DES is a green solvent suitable for extracting coumarin compounds of A. dahurica, with great potential to replace organic solvents. Full article

(This article belongs to the Special Issue Extraction and Analysis of Plant Active Ingredients)

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4 pages, 199 KiB

Open AccessEditorial

The Pivotal Role of Chemistry in Research and Development

by Victoria Samanidou, George Zachariadis, Michael A. Terzidis and Adamantini Paraskevopoulou

Separations 2022, 9(1), 4; https://doi.org/10.3390/separations9010004 - 23 Dec 2021

Cited by 1 | Viewed by 2609

Abstract

Undoubtedly, all pivotal advances in a great number of scientific fields rely on advances in chemistry. [...] Full article

(This article belongs to the Special Issue Research as Development Perspective 2019)

14 pages, 5807 KiB

Open AccessArticle

Simultaneous Determination of 16 Kinds of Synthetic Cathinones in Human Urine Using a Magnetic Nanoparticle Solid-Phase Extraction Combined with Gas Chromatography-Mass Spectrometry

by Dan Wang, Xueguo Chen, Zhu Ming, Limin Jiang and Yan Zhou

Separations 2022, 9(1), 3; https://doi.org/10.3390/separations9010003 - 23 Dec 2021

Cited by 7 | Viewed by 3319

Abstract

A specific and sensitive approach using magnetic nanoparticle solid-phase extraction combined with gas chromatography-mass spectrometry (GC-MS) was carried out and applied in the simultaneous determination of 16 kinds of synthetic cathinones in human urine. The functionalized extraction material (Fe₃O₄/NH [...] Read more.

A specific and sensitive approach using magnetic nanoparticle solid-phase extraction combined with gas chromatography-mass spectrometry (GC-MS) was carried out and applied in the simultaneous determination of 16 kinds of synthetic cathinones in human urine. The functionalized extraction material (Fe₃O₄/NH₂-MWCNTs) was synthesized and factors affecting the extraction efficiency were all tested. Under the optimized conditions of magnetic nanoparticle solid-phase extraction, the determination of synthetic cathinones in human urine was carried out with GC-MS. Good linear relationships of 16 kinds of synthetic cathinones were obtained in the range of 0.005–5.00 μg/mL with the correlation coefficients (r) ranging from 0.9901 to 0.9979, the limits of detection were in the range between 0.005 and 0.01 μg/mL, and the limits of quantitation were between 0.01 and 0.02 μg/mL. Furthermore, the average intra-day precisions were below 8.90%, the average inter-day precisions were less than 9.52%, and the average recoveries were between 87.03% and 99.13%, respectively. The results show the advantages of the approach in the determination of trace synthetic cathinones in complex matrixes, such as environmentally friendly, fast detection, high efficiency and sensitivity. The practical application indicated that this method could provide scientific basis for the determination of drugs of abuse in forensic laboratories. Full article

(This article belongs to the Section Forensics/Toxins)

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16 pages, 4574 KiB

Open AccessArticle

Cross-Linking Combined with Surfactant Bilayer Assembly Enhances the Hydrophilic and Antifouling Properties of PTFE Microfiltration Membranes

by Shijie Xu, Wenzhong Ma, Haicun Yang, Zheng Cao, Fanghong Gong and Chunlin Liu

Separations 2022, 9(1), 2; https://doi.org/10.3390/separations9010002 - 22 Dec 2021

Cited by 6 | Viewed by 3539

Abstract

The inherent strong hydrophobicity of Polytetrafluoroetylene (PTFE) microfiltration membranes results in low separation efficiency and easy contamination. In order to enhance its hydrophilic and antifouling properties, we first modified the PTFE microfiltration membrane by using Polyethylene glycol laurate (PEGML) for first layer deposition [...] Read more.

The inherent strong hydrophobicity of Polytetrafluoroetylene (PTFE) microfiltration membranes results in low separation efficiency and easy contamination. In order to enhance its hydrophilic and antifouling properties, we first modified the PTFE microfiltration membrane by using Polyethylene glycol laurate (PEGML) for first layer deposition and then used Polyvinyl alcohol (PVA)/citric acid (CA) cross-linked coatings for second layer deposition. The Scanning Electron Microscope (SEM) results showed that the fibers and nodes of the modified PTFE microfiltration membrane were coated with PVA/CA hydrophilic coating. FT-IR Spectromete and X-ray photoelectron spectrometer (XPS) analysis results confirmed that crosslinking of PVA and CA occurred and that PEGML and PVA/CA were successfully deposited onto the membrane surface. The modification conditions were optimized by hydrophilicity testing, and the best hydrophilicity of the modified membrane was achieved when the crosslinking content of PEGML was 2 g·L⁻¹, PVA was 5 g·L⁻¹, and CA was 2 g·L⁻¹. PTFE microfiltration membranes modified by the optimal conditions achieved a water flux of 396.9 L·m⁻²·h⁻¹ (three times that of the original membrane) at low operating pressures (0.05 MPa), and the contact angle decreased from 120° to 40°. Meanwhile, the modified PTFE microfiltration membrane has improved contamination resistance and good stability of the hydrophilic coating. Full article

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

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44 pages, 14112 KiB

Open AccessEditor’s ChoiceReview

Review of New Approaches for Fouling Mitigation in Membrane Separation Processes in Water Treatment Applications

by Mervette El Batouti, Nouf F. Alharby and Mahmoud M. Elewa

Separations 2022, 9(1), 1; https://doi.org/10.3390/separations9010001 - 21 Dec 2021

Cited by 69 | Viewed by 11327

Abstract

This review investigates antifouling agents used in the process of membrane separation (MS), in reverse osmosis (RO), ultrafiltration (UF), nanofiltration (NF), microfiltration (MF), membrane distillation (MD), and membrane bioreactors (MBR), and clarifies the fouling mechanism. Membrane fouling is an incomplete substance formed on [...] Read more.

This review investigates antifouling agents used in the process of membrane separation (MS), in reverse osmosis (RO), ultrafiltration (UF), nanofiltration (NF), microfiltration (MF), membrane distillation (MD), and membrane bioreactors (MBR), and clarifies the fouling mechanism. Membrane fouling is an incomplete substance formed on the membrane surface, which will quickly reduce the permeation flux and damage the membrane. Foulant is colloidal matter: organic matter (humic acid, protein, carbohydrate, nano/microplastics), inorganic matter (clay such as potassium montmorillonite, silica salt, metal oxide, etc.), and biological matter (viruses, bacteria and microorganisms adhering to the surface of the membrane in the case of nutrients) The stability and performance of the tested nanometric membranes, as well as the mitigation of pollution assisted by electricity and the cleaning and repair of membranes, are reported. Physical, chemical, physico-chemical, and biological methods for cleaning membranes. Biologically induced biofilm dispersion effectively controls fouling. Dynamic changes in membrane foulants during long-term operation are critical to the development and implementation of fouling control methods. Membrane fouling control strategies show that improving membrane performance is not only the end goal, but new ideas and new technologies for membrane cleaning and repair need to be explored and developed in order to develop future applications. Full article

(This article belongs to the Special Issue Advances in Novel Polymeric Membranes and Membrane Process)

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Separations, Volume 9, Issue 1 (January 2022) – 20 articles

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