Separations

15 pages, 2394 KiB

Open AccessEditor’s ChoiceArticle

Selective H₂ Evolution and CO₂ Absorption in Electrolysis of Ethanolamine Aqueous Solutions

by Satoshi Fukada, Ryosuke Sakai, Makoto Oya and Kazunari Katayama

Separations 2023, 10(11), 578; https://doi.org/10.3390/separations10110578 - 20 Nov 2023

Viewed by 1788

Selective H₂ evolution and CO₂ absorption in several ethanolamine aqueous solutions are comparatively investigated using a new electrolysis reactor. H₂ bubbles are generated from a cathode in any ethanolamine electrolyte, and its experimental gas evolution rates are correlated by Faraday’s [...] Read more.

Selective H₂ evolution and CO₂ absorption in several ethanolamine aqueous solutions are comparatively investigated using a new electrolysis reactor. H₂ bubbles are generated from a cathode in any ethanolamine electrolyte, and its experimental gas evolution rates are correlated by Faraday’s first rule. No or smaller amounts of CO₂ and N₂ bubbles than stoichiometric ones are generated on an anode through the reaction between hydroxide ions and ethanolamine ones. No CO or O₂ is observed in the system exhaust, and most of the CO₂, along with N_2, is still absorbed in ethanolamine aqueous solutions with the addition of KOH and/or HCOOH under high pH conditions. Variations of the concentrations of coexisting ions dissolved in the electrolytes of mono- or tri-ethanolamine (MEA or TEA) and ethylenediamine (EDA) solutions with CO₂ absorption are calculated using the equilibrium constants to relate the concentrations of solute ions. Electric resistivities of the ethanolamine aqueous solutions are correlated by the pH value and are analyzed in terms of equilibrium constants among the concentrations of coexisting ions. Conditions of the MEA electrolyte to achieve high-performance electrolysis is discussed for selective H₂ generation. Full article

(This article belongs to the Special Issue Advances in CO₂ Adsorptive Separation for CO₂ Capture)

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17 pages, 2240 KiB

Open AccessArticle

Optimization and Validation of Sensitive UPLC-PDA Method for Simultaneous Determination of Thymoquinone and Glibenclamide in SNEDDs Formulations Using Response Surface Methodology

by Doaa Hasan Alshora, Mohamed Abbas Ibrahim and Abdelrahman Y. Sherif

Separations 2023, 10(11), 577; https://doi.org/10.3390/separations10110577 - 19 Nov 2023

Cited by 4 | Viewed by 1739

Abstract

The development of analytical procedures capable of simultaneous determination of two or more drugs is in crucial demand due to the availability of different formulations that are composed of different APIs. The presented study aimed to optimize and validate a simple, accurate, and [...] Read more.

The development of analytical procedures capable of simultaneous determination of two or more drugs is in crucial demand due to the availability of different formulations that are composed of different APIs. The presented study aimed to optimize and validate a simple, accurate, and sensitive UPLC analytical method for the simultaneous determination of thymoquinone (TQ) and Glibenclamide (GB) using response surface methodology, and apply this method in pharmaceutical formulations. A 3² full design of experiment was utilized to study the impacts of the independent parameters (acetonitrile ACN concentration, A; and column temperature, B) on the drugs’ analytical attributes (viz, retention time, peak area, and peak asymmetry, in addition to the resolution between TQ and GB peaks). The results revealed that the independent parameters exhibited highly significant (p < 0.05) antagonistic effects on retention times for TQ and GB peaks, in addition to the agnostic effect on GB peak symmetry (p-value = 0.001). Moreover, antagonistic impacts (p < 0.05) on the resolution between TQ and GB peaks were found for both independent factors (A and B). The statistical software suggested 46.86% of ACN (A) and 38.80 °C for column temperature (B) for optimum analytical responses. The optimized green method was discovered to be acceptable in terms of selectivity, precision, accuracy, robustness, sensitivity, and specificity. Moreover, the optimized simultaneous method was successfully able to determine the contents of TQ and GB in self-nanoemulsifying drug delivery (SNEDD) formulation, in which the results showed that GB and TQ content within the prepared formulations were 1.54 ± 0.023 and 3.62 ± 0.031 mg/gm, respectively. In conclusion, the developed assay was efficient and valid in analyzing TQ and GB simultaneously in bulk and self-nanoemulsifying drug delivery system (SNEDDs) formulations. Full article

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12 pages, 2181 KiB

Open AccessArticle

Validation of a Liquid Chromatography Coupled to Mass Spectrometry Method for Glyphosate and Aminomethylphosphonic Acid in Urine for Human Biomonitoring Using Combined Hybrid Anion-Exchange and Hydrophilic Interaction Liquid Chromatography

by Elisa Polledri, Rosa Mercadante and Silvia Fustinoni

Separations 2023, 10(11), 576; https://doi.org/10.3390/separations10110576 - 19 Nov 2023

Cited by 2 | Viewed by 1824

Abstract

Glyphosate-based herbicides are the most widely used pesticides in the world; however, the toxicity of glyphosate (GlyP) toward humans, especially its carcinogenicity, is controversial. The aim of this work was to validate a rapid assay for measuring GlyP and its metabolite aminomethylphosphonic acid [...] Read more.

Glyphosate-based herbicides are the most widely used pesticides in the world; however, the toxicity of glyphosate (GlyP) toward humans, especially its carcinogenicity, is controversial. The aim of this work was to validate a rapid assay for measuring GlyP and its metabolite aminomethylphosphonic acid (AMPA) in urine for human biomonitoring. The analytes were purified via solid-phase extraction in the presence of isotopically labeled internal standards. An LC-MS/MS assay was developed using a column with a novel hybrid stationary phase combined with anion exchange and hydrophilic interaction liquid chromatography. Detection and quantification were performed using negative electrospray ionization in a hybrid triple quadrupole/linear ion trap mass spectrometer. The retention times for AMPA and GlyP were 1.44 and 7.24 min, respectively. Calibration curves showed a linear dynamic range of up to 40 µg/L, inter- and intra-run precisions <7.5%, and accuracies within 10% of the theoretical concentrations. The limits of quantification were 0.1 µg/L and 0.5 µg/L for GlyP and AMPA, respectively. The matrix effect bias was controlled using internal standards. Successful participation in external quality assurance exercises strengthens the validity of the method. The assay was applied to the measurement of GlyP and AMPA in the urine of 9 urban residents, 26 rural residents, and 12 agricultural workers; while AMPA was mostly not quantifiable, the median GlyP values were 0.1 and 0.34 µg/L in rural residents and workers, respectively. The assay is useful to assess GlyP and AMPA in human urine following different exposure scenarios. Full article

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26 pages, 1873 KiB

Open AccessArticle

Nutritional and Possible Pharmaceutical Aspects of Tree Exudates Eaten by Lemurs of Madagascar’s Dry Forests

by Jörg U. Ganzhorn, Yedidya R. Ratovonamana, Melina Rother, Peggy Giertz, Curswan A. Andrews, Sabine Baumann, Yvonne E.-M. B. Bohr, Peter M. Kappeler, B. Karina Montero, Andreas Pommerening-Röser, Ute Radespiel, S. Jacques Rakotondranary, Oliver Schülke, Kim J. E. Steffens, Sandra Thorén, Gabriele Timmermann and Irene Tomaschewski

Separations 2023, 10(11), 575; https://doi.org/10.3390/separations10110575 - 18 Nov 2023

Viewed by 1717

Abstract

Gums produced by trees after injuries are valuable food resources for several primate species. Yet, information on the chemical characteristics of gum is scant and inconsistent. We use gums consumed by lemurs (strepsirrhine primates of Madagascar) as an example to illustrate their possible [...] Read more.

Gums produced by trees after injuries are valuable food resources for several primate species. Yet, information on the chemical characteristics of gum is scant and inconsistent. We use gums consumed by lemurs (strepsirrhine primates of Madagascar) as an example to illustrate their possible nutritive and pharmaceutical properties. Exudates from 45 tree species of the dry forests of Madagascar contained 0.38–23.29% protein, 0.46–65.62% sugar, and 0.39–11.86 kJ/g of energy in dry matter. Exemplified by the lemur species Microcebus griseorufus, gum consumption increased with increasing sugar and energy content but was unrelated to protein. But lemurs also fed on gum with very low protein and energy content, suggesting that these exudates were consumed for other reasons. Disk diffusion tests with exudates from five out of 22 tree species consumed by lemurs showed antibacterial activity against Micrococcus spp. and/or Staphylococcus aureus. Exudates with antibacterial activity had lower protein, sugar, and energy contents than samples without antibacterial properties. GC-MS analyses revealed several components with antimicrobial effects that would have the potential for self-medication. This might explain the consumption of gum with very low nutritive value. Possible medicinal effects of tree exudates deserve further attention in view of their pharmaceutical applicability for animals and humans alike. Full article

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

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13 pages, 5573 KiB

Open AccessArticle

Mineralogical Characteristics of Baima Vanadium Titanomagnetite during Magnetic Separation Upgrading

by Xiang Zhong, Haoran Hu, Shuo Li, Jian Gao, Zhixin Shi and Fuxing Zhu

Separations 2023, 10(11), 574; https://doi.org/10.3390/separations10110574 - 17 Nov 2023

Viewed by 1933

Abstract

The Baima vanadium titanomagnetite deposit, located in the Panzhihua-Xichang (Panxi) metallogenic belt in China, is one of the super-large deposits in the region. The titanomagnetite upgrading process involves grinding the raw ore followed by magnetic separation. To determine the processing characteristics of the [...] Read more.

The Baima vanadium titanomagnetite deposit, located in the Panzhihua-Xichang (Panxi) metallogenic belt in China, is one of the super-large deposits in the region. The titanomagnetite upgrading process involves grinding the raw ore followed by magnetic separation. To determine the processing characteristics of the ore and assess the upgrading process, this study employs various methods and techniques, including the X-ray fluorescence spectrometer (XRF), chemical element analysis, the electron probe microanalyzer (EPMA), and the advanced mineral identification and characterization system (AMICS). The results show that the Fe grades in the upgraded raw ore, upgraded concentrate, and upgraded tailings are 55.68%, 57.89%, and 15.62%, respectively. After upgrading, the titanomagnetite content increased from 77.41% to 82.10%, and the Fe distribution in titanomagnetite also increased from 91.05% to 93.14%. In the upgraded raw ore, titanomagnetite particles followed a normal distribution, with 50.44% in the 38–74 μm range. In the upgraded concentrate, titanomagnetite was concentrated in the 19–38 μm range. Based on EPMA data, the theoretical Fe grade in titanomagnetite was calculated to be 65.08%, indicating the potential for further improvement through the upgrading process. This study elucidates the mineralogical characteristics during the vanadium titanomagnetite upgrading, providing a theoretical basis to further enhance the Fe recovery rate. Full article

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11 pages, 938 KiB

Open AccessArticle

Rapid Determination of Five Residual Solvents in Ursodeoxycholic Acid Raw Materials

by Ran Zhou, Jingyu He, Yi Shi, Xiaoying Gao, Fei Wang and Sijie Liu

Separations 2023, 10(11), 573; https://doi.org/10.3390/separations10110573 - 17 Nov 2023

Viewed by 1582

Abstract

The chromatographic conditions were optimized using headspace gas chromatography, and a simple and rapid method was established for the simultaneous determination of five residual solvents in ursodeoxycholic acid raw materials. The corresponding quality standards were revised. The research results demonstrate that by utilizing [...] Read more.

The chromatographic conditions were optimized using headspace gas chromatography, and a simple and rapid method was established for the simultaneous determination of five residual solvents in ursodeoxycholic acid raw materials. The corresponding quality standards were revised. The research results demonstrate that by utilizing a capillary column with a stationary phase consisting of 5% phenyl-95% dimethylpolysiloxane (HP-5, 30 m × 0.32 mm, film thickness 1.0 µm) and a flame ionization detector in conjunction with a headspace injection system and a programmed temperature ramping method, satisfactory analytical results can be achieved. The specific operating conditions are as follows: an initial column temperature of 45 °C, followed by a column temperature increase at a rate of 5 °C per minute up to 60 °C, then a further increase at a rate of 10 °C per minute up to 100 °C, and finally a rapid increase at a rate of 40 °C per minute up to 200 °C, where it is held for 10 min. Nitrogen is employed as the carrier gas at a flow rate of 1 mL/min with a split ratio of 14:1. The headspace vial temperature is maintained at 100 °C, with a sample equilibration time of 45 min. The concentration of methanol ranged from 0.06 mg/mL to 0.3 mg/mL, and the concentrations of acetone, tert-butanol, ethyl acetate, and triethylamine showed a good linear relationship with the peak area within the range of 0.1 mg/mL to 0.5 mg/mL (r = 0.999); The quantitation limits for methanol, acetone, tert-butanol, ethyl acetate, and triethylamine were 4.2, 0.9, 1.5, 1, and 0.1 μg/mL, respectively, with detection limits of 1.2, 0.25, 0.025, 0.3, and 0.025 μg/mL, respectively. The recovery rates of each solvent ranged from 92.9% to 106.0%, with RSD% (n = 9) less than 3.8%; the method exhibited good repeatability, with RSD% (n = 6) less than 2.5%. Furthermore, the robustness is good. The established method is simple, accurate, specific, and highly sensitive, and can be used for the simultaneous and rapid determination of five residual solvents in ursodeoxycholic acid raw materials. Full article

(This article belongs to the Special Issue Comprehensive Separations of Complex Mixtures by Gas Chromatography/Mass Spectrometry)

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20 pages, 2213 KiB

Open AccessReview

Liquid Nuclear Magnetic Resonance (NMR) Spectroscopy in Transition—From Structure Elucidation to Multi-Analysis Method

by Thomas Kuballa, Katja H. Kaltenbach, Jan Teipel and Dirk W. Lachenmeier

Separations 2023, 10(11), 572; https://doi.org/10.3390/separations10110572 - 16 Nov 2023

Cited by 1 | Viewed by 4368

Abstract

As early as 1946, Felix Bloch and Edward Mills Purcell detected nuclear magnetic resonance signals, earning themselves the Nobel Prize in 1952. The same year saw the launch of the first commercial nuclear magnetic resonance (NMR) spectrometer. Since then, NMR has experienced significant [...] Read more.

As early as 1946, Felix Bloch and Edward Mills Purcell detected nuclear magnetic resonance signals, earning themselves the Nobel Prize in 1952. The same year saw the launch of the first commercial nuclear magnetic resonance (NMR) spectrometer. Since then, NMR has experienced significant progress in various fields of application. While in the 1970s NMR spectroscopy was solely employed for determining the structure and purity of synthesis products in the chemical field, it gradually gained popularity in the medical field for the investigation and rendering of images of human organs. Since then, the technique has developed significantly in terms of stability, reproducibility, and sensitivity, thereby forming the foundation for high-resolution imaging, the automation or standardization of analytical procedures, and the application of chemometric methods, particularly in relation to identifying food adulteration. This review objectively assesses the current state of implementing liquid NMR in the food, cosmetics, and pharmaceutical industries. Liquid NMR has transitioned from a structural elucidation tool to a widely recognized, multi-analytical method that incorporates multivariate techniques. The illustrations and sources provided aim to enhance novice readers’ understanding of this topic. Full article

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21 pages, 5578 KiB

Open AccessArticle

Diffusion, Separation, and Buffering of Non-Steady-State VOCs Flow on Activated Carbon

by Tianzhe Shi, Tao Liu, Ning Qiang, Jiao He, Zhaohai Li, Yiqi Cao and Xianbin Shi

Separations 2023, 10(11), 571; https://doi.org/10.3390/separations10110571 - 16 Nov 2023

Cited by 1 | Viewed by 1640

Abstract

In this study, the diffusion, separation, and buffering of volatile organic compounds emitted in a non-steady state on activated carbon were studied. Ethanol and xylene, which have large differences in adsorption capacity and diffusion rate, were selected as the representative target pollutants of [...] Read more.

In this study, the diffusion, separation, and buffering of volatile organic compounds emitted in a non-steady state on activated carbon were studied. Ethanol and xylene, which have large differences in adsorption capacity and diffusion rate, were selected as the representative target pollutants of volatile organic compounds. In this paper, activated carbon with a certain intake concentration and adsorption equilibrium was chosen as the research object. The buffering effect of pulse load was studied. The buffering effect and influencing factors were analyzed. The Bangham equation proved to be a more effective tool in describing the dynamic processes of ethanol and xylene adsorption on activated carbon, indicating that pore diffusion was the rate-determining step in the adsorption process. R₃ emerged as a more suitable criterion for evaluating non-steady-state emissions. Factors such as pulse time and pulse multiplier were influenced by Empty Bed Contact Time (EBCT), which collaborated with EBCT to impact the buffering performance of activated carbon. An EBCT of 4 cm was identified as the optimal bed height, with R₃ reaching 1.48. Non-polar VOCs with chemically symmetric structures exhibited slower mass transfer rates compared to polar VOCs, resulting in larger adsorption capacities on activated carbon and better buffering performance. Full article

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18 pages, 5058 KiB

Open AccessArticle

Synthesis of Polyaluminum Chloride Coagulant from Waste Aluminum Foil and Utilization in Petroleum Wastewater Treatment

by Hanan H. Youssef, Sherif A. Younis, Esraa M. El-Fawal, Hager R. Ali, Yasser M. Moustafa and Gehad G. Mohamed

Separations 2023, 10(11), 570; https://doi.org/10.3390/separations10110570 - 15 Nov 2023

Cited by 3 | Viewed by 3151

Abstract

This work investigates the potential synthesis of cost-effective polyaluminum chloride (PACl) coagulant from waste household aluminum foil and utilization for treating petroleum wastewater (PWW), especially dissolved organic compounds (DOC, like octanol–water mixture) and nonsettleable suspended (NSS-kaolin) mineral particles. Based on the Standard Practice [...] Read more.

This work investigates the potential synthesis of cost-effective polyaluminum chloride (PACl) coagulant from waste household aluminum foil and utilization for treating petroleum wastewater (PWW), especially dissolved organic compounds (DOC, like octanol–water mixture) and nonsettleable suspended (NSS-kaolin) mineral particles. Based on the Standard Practice for Coagulation–Flocculation Jar Test, the efficiency of PACl for DOC and NSS removal was evaluated in relation to the effects of the operational parameters. The results demonstrated that the as-prepared PACl has an amorphous morphology with a Keggin-type e-Al13 molecular structure {Na[AlO₄(OH)₂₄(H₂O)]·xH₂O and good thermal stability up to 278 °C. PACl coagulant also exhibited a higher efficiency for NSS removal than DOC by around 1.5- to 1.9-fold under broad pH (5–7), while a higher acidic/alkaline pH disrupts the sweep floc formation. An increased PACl dosage (over 25 mg/L) also caused a decrease in the coagulation efficiency by 11.7% due to Al species’ transformation and pH depression (from 6.8 to 4.9) via increased PACl hydrolysis. With a fast rotating speed of 280 rpm for 2 min, the minimum dose of PACl (10–25 mg/L) can maximize the removal efficiency of NSS (~98%) and DOC (~69%) at pH 6.5 ± 0.5 and 35 °C after 30 min of settling time. Treating actual saline PWW samples (salinity up to 187.7 g/L) also verified the high efficacy of PACl coagulation performance in reducing the turbidity and dissolved hydrocarbons by more than 75.5% and 67.7%, respectively. These findings verify the techno-economic feasibility of the as-prepared PACl coagulant in treating PWW treatment at different salinity levels. Full article

(This article belongs to the Special Issue Advances in Materials for Separations: Energy and Environment)

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18 pages, 7130 KiB

Open AccessReview

Nanostructure-Based Oil–Water Separation: Mechanism and Status

by Bao Wang, Shaotong Feng, Caihua Wang, Xiaoyan Liu, Lei Chen and Dayun Yan

Separations 2023, 10(11), 569; https://doi.org/10.3390/separations10110569 - 15 Nov 2023

Cited by 5 | Viewed by 4387

Abstract

Flexible and effective methods for oil–water separation are crucial for reducing pollutant emissions and safeguarding water and fuel resources. In recent years, there has been growing interest in fundamental research and engineering applications related to water and fuel purification, especially oil–water separation. To [...] Read more.

Flexible and effective methods for oil–water separation are crucial for reducing pollutant emissions and safeguarding water and fuel resources. In recent years, there has been growing interest in fundamental research and engineering applications related to water and fuel purification, especially oil–water separation. To date, filter materials with special wetting characteristics have been widely used in oil–water separation. Nanostructured materials are one of the most attractive candidates for next-generation oil–water separation. This review systematically summarizes the mechanisms and current status of oil–water separation using nanostructured materials. Basically, this can be achieved by using nanostructured materials with specific wettability and nanostructures. Here, we provide a detailed discussion of two general approaches and their filtration mechanisms: (1) the selective filtration technique, based on specific surface wettability, which allows only oil or water to penetrate while blocking impurities; (2) the absorption technique, employing porous sponges, fibers, or aerogels, which selectively absorbs impure oil or water droplets. Furthermore, the main failure modes are discussed in this review. The purposes of this article are: (1) to summarize the methods of oil–water separation by nanotechnology; (2) to raise the level of environmental protection consciousness of water pollution by using nanotechnology; (3) to tease out the features of different approaches and provide a pivotal theoretical basis to optimize the performance of filtering materials. Several approaches for oil and water separation are compared. Furthermore, the principle and application scope of each method are introduced. Full article

(This article belongs to the Special Issue Advanced Oil–Water Separation Technology)

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17 pages, 6478 KiB

Open AccessArticle

Fenton Oxidation Combined with Iron–Carbon Micro-Electrolysis for Treating Leachate Generated from Thermally Treated Sludge

by Xiaoqing Dong, Hui Liu, Ji Li, Ruiqi Gan, Quanze Liu and Xiaolei Zhang

Separations 2023, 10(11), 568; https://doi.org/10.3390/separations10110568 - 14 Nov 2023

Cited by 1 | Viewed by 1714

Abstract

In this study, Iron–Carbon Micro-Electrolysis (ICME), Fenton oxidation, and their combination were investigated to treat the leachate obtained from a wastewater treatment plant located in southern China. The results show that the Fenton-ICME process was the most efficient one. After the leachate was [...] Read more.

In this study, Iron–Carbon Micro-Electrolysis (ICME), Fenton oxidation, and their combination were investigated to treat the leachate obtained from a wastewater treatment plant located in southern China. The results show that the Fenton-ICME process was the most efficient one. After the leachate was treated with the Fenton-ICME process, the COD concentration was reduced from the initial 35,772 mg/L to 13,522 mg/L, and the removal efficiency was up to 62.2%. In addition, the biological oxygen demand (BOD) to COD ratio increased by 40% at optimal conditions. This suggests that the biodegradability of the leachate has been increased, facilitating the biodegradation of the leachate after it is mixed with the raw wastewater. By studying the characteristic variation of the leachate treated with the Fenton-ICME process, it was found that the combined process mainly removes organic compounds such as aromatic compounds, ketones, and aldehydes. The separated sludge does not have a crystalline structure, and the iron in it mainly exists in the form of trivalent iron. It reveals that the Fenton-ICME process has great potential to be used as a pretreatment of leachate. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Materials in Separation Science')

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12 pages, 1713 KiB

Open AccessArticle

Simultaneous Quantification Method of Flavonoids in Jeju Native Citrus from Different Harvest Times Using a High-Performance Liquid Chromatography–Diode Array Detector (HPLC–DAD)

by Hyejin Hyeon, Ho Bong Hyun, Sung Chun Kim, Boram Go, Seon-A Yoon, Yong-Hwan Jung and Young-Min Ham

Separations 2023, 10(11), 567; https://doi.org/10.3390/separations10110567 - 11 Nov 2023

Cited by 1 | Viewed by 1682

Abstract

In Jeju-native Citrus, flavonoids are the main contributors to the various types of biological activity, such as antioxidant, antitumor, and anti-inflammatory activity. Thus, we developed simultaneous quantification methods for the analysis of ten bioactive flavonoids in Jeju Citrus fruits (Dangyuja, Gamja, Jigak, [...] Read more.

In Jeju-native Citrus, flavonoids are the main contributors to the various types of biological activity, such as antioxidant, antitumor, and anti-inflammatory activity. Thus, we developed simultaneous quantification methods for the analysis of ten bioactive flavonoids in Jeju Citrus fruits (Dangyuja, Gamja, Jigak, Sadugam, and Soyuja) harvested at six different time points using a high-performance liquid chromatography–diode array detector (HPLC-DAD). Separation was performed using a flow rate of 0.8 mL/min, a column temperature of 40 °C, a mobile phase buffer of 0.5% acetic acid, and a detection wavelength of 278 nm. The established analytical method showed good linearity (R² ≥ 0.9997), precision (inter-day < 0.599%, intra-day < 0.055%), and accuracy (recoveries 92.30–108.80%). The HPLC–DAD method was subsequently applied to analyze flavonoids in Citrus samples. Overall, the quantification results indicated that the compositions and content of flavonoids differed for each Citrus species. The harvesting period also influenced the changes in flavonoid content within each Citrus species. The analytical results with chemometrics revealed that higher flavonoid levels in early-harvested Citrus were derived from the improved fruit size and reduced flavonoid synthesis during maturation. This study provides a practical and reliable method for the analysis of ten flavonoids that can be further utilized in the quality assessment of Jeju Citrus. Full article

(This article belongs to the Special Issue Advanced Research on Plant-Based Food Extraction)

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16 pages, 3907 KiB

Open AccessEditor’s ChoiceArticle

Identifying the Early Post-Mortem VOC Profile from Cadavers in a Morgue Environment Using Comprehensive Two-Dimensional Gas Chromatography

by Darshil Patel, Rushali Dargan, Wesley S. Burr, Benoit Daoust and Shari Forbes

Separations 2023, 10(11), 566; https://doi.org/10.3390/separations10110566 - 10 Nov 2023

Cited by 1 | Viewed by 2798

Abstract

Understanding the VOC profile released during the early post-mortem period is essential for applications in training human remains detection dogs and urban search and rescue operations (USAR) to rapidly locate living and deceased victims. Human cadavers were sampled at the UQTR morgue within [...] Read more.

Understanding the VOC profile released during the early post-mortem period is essential for applications in training human remains detection dogs and urban search and rescue operations (USAR) to rapidly locate living and deceased victims. Human cadavers were sampled at the UQTR morgue within a 0–72 h post-mortem interval. VOC samples were collected from the headspace above the cadavers, using Tenax TA/Carbograph 5TD dual sorbent tubes, and analyzed using GC×GC-TOFMS. Multiple data processing steps, including peak table alignment and filtering, were undertaken using LECO ChromaToF and custom scripts in R programming language. This study identified 104 prevalent VOCs, some of which are linked to human decomposition, while others are connected to the persistence of living scent. Principal Component Analysis (PCA) further highlighted that VOC profiles can change dynamically over time, even in a controlled setting. The findings underscore the complexity and variability in VOC profiles during the early post-mortem period. This variability is influenced by multiple factors including the individual’s biological and physiological conditions. Despite the challenges in characterizing these profiles, the identified VOCs could potentially serve as markers in forensic applications. The study also highlights the need for additional research to build a dataset of VOCs for more robust forensic applications. Full article

(This article belongs to the Special Issue Chemical Separations in Criminalistics)

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26 pages, 2281 KiB

Open AccessReview

Advancements in Adsorption Techniques for Sustainable Water Purification: A Focus on Lead Removal

by Amal M. Badran, Uthumporn Utra, Nor Shariffa Yussof and Mohammed J. K. Bashir

Separations 2023, 10(11), 565; https://doi.org/10.3390/separations10110565 - 10 Nov 2023

Cited by 19 | Viewed by 7944

Abstract

The long-term sustainability of the global water supply, with a paramount emphasis on cleanliness and safety, stands as a formidable challenge in our modern era. In response to this pressing issue, adsorption techniques have emerged as pivotal and widely recognized solutions for the [...] Read more.

The long-term sustainability of the global water supply, with a paramount emphasis on cleanliness and safety, stands as a formidable challenge in our modern era. In response to this pressing issue, adsorption techniques have emerged as pivotal and widely recognized solutions for the removal of hazardous pollutants, with a particular emphasis on lead adsorption from wastewater. This comprehensive review explores the relentless advancements made in the adsorption domain, highlighting innovations using separation and purification techniques that surpass traditional metal oxide-based adsorbents. Of particular note is the growing exploration of alternative materials, such as starch, chitosan, nanoscale structures like zeolites and metal-organic frameworks, magnetic materials, and carbon-based substances for the development of inorganic adsorbents. These materials, with their remarkable capacity for nanoscale structural adjustment, possess extraordinary capabilities for effective contaminant removal, facilitating swift water purification. The literature survey for this review was conducted using the Google Scholar engine, with “adsorbents for lead remediation” as the starting keywords, resulting in approximately 6000 papers. The search was refined to focus on the last three years and specifically targeted review papers which are most relevant to lead remediation. More than 100 papers were analysed to investigate various techniques, surface modifications, and adsorbent materials for managing inorganic pollutants in water. This review also illuminates research limitations, with a specific focus on starch-based adsorbents in lead remediation. As we progress towards practical commercial applications, this review identifies challenges associated with the development of inorganic adsorbents and provides invaluable insights into future prospects. Surface modification emerges as a promising path, with the potential to substantially enhance adsorption capacity, potentially doubling or even quadrupling it. Moreover, the adsorbents demonstrate impressive regenerative capabilities, maintaining up to 90% regeneration efficiency after multiple cycles. In conclusion, starch-based adsorbents show considerable potential as effective agents for lead purification from aquatic environments. Nevertheless, the need for further research persists, emphasizing the optimization of the adsorption process and exploring the long-term stability of starch-based adsorbents in real-world scenarios. Full article

(This article belongs to the Collection Feature Paper Collection in Section 'Materials in Separation Science')

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14 pages, 2446 KiB

Open AccessArticle

Analysis of Polycyclic Aromatic Hydrocarbons Using Magnetic Three-Dimensional Graphene Solid-Phase Extraction Coupled with Gas Chromatography–Mass Spectrometry

by Hassan Sereshti, Mahsa Karimi, Sajad Karami, Shokouh Mahpishanian, Mehdi Esmaeili Bidhendi, Shahabaldin Rezania, Amin Mojiri, Hesam Kamyab and Hamid Rashidi Nodeh

Separations 2023, 10(11), 564; https://doi.org/10.3390/separations10110564 - 10 Nov 2023

Cited by 4 | Viewed by 1934

Abstract

In this study, a composite material consisting of three-dimensional graphene aerogel and iron oxide nanoparticles (3DG/Fe₃O₄) was created and utilized for the purpose of magnetic solid-phase extraction (MSPE) of thirteen polycyclic aromatic hydrocarbon (PAH) compounds via gas chromatography–mass spectrometry/selected [...] Read more.

In this study, a composite material consisting of three-dimensional graphene aerogel and iron oxide nanoparticles (3DG/Fe₃O₄) was created and utilized for the purpose of magnetic solid-phase extraction (MSPE) of thirteen polycyclic aromatic hydrocarbon (PAH) compounds via gas chromatography–mass spectrometry/selected ion monitoring (GC-MS/SIM) analysis. The synthesized adsorbent underwent a range of characterization techniques, including scanning electron microscopy, vibrating sample magnetometry, Raman spectroscopy, X-ray diffraction, Brunauer–Emmett–Teller, Fourier transform-infrared spectroscopy, and Barrett–Joyner–Halenda techniques, to examine its properties and morphology. The synthesized adsorbent integrates the benefits of superior adsorption capacity from modified graphene oxide (GO) with the magnetic separability of magnetite microparticles, resulting in a high adsorption capacity with easy separation from sample solutions. The efficiency of the proposed method was optimized and modeled using a central composite design (CCD), which considered the primary factors influencing it. The optimal conditions were obtained as the adsorbent dosage of 10 mg, the extraction time of 4 min, and the salt concentration of 3% w/v. The limit of detection for the target PAHs was established to range from 0.016 to 0.2 ng mL⁻¹ in optimal conditions, exhibiting a signal-to-noise ratio of 3. The linear dynamic range spanned from 5 to 100 ng mL⁻¹, with determination coefficients (R²) ranging from 0.9913 to 0.9997. The intra- and inter-day precisions were calculated as relative standard deviations (RSDs) equal to 3.9% and 4.7%, respectively. The proposed method was successfully applied to the determination of PAHs in water samples (tap, river, and rainwater), and recoveries in the range of 71–110% (RSDs < 5.2%, n = 3) were obtained. Full article

(This article belongs to the Section Environmental Separations)

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18 pages, 2636 KiB

Open AccessArticle

Enhancing Trace Metal Extraction from Wastewater: Magnetic Activated Carbon as a High-Performance Sorbent for Inductively Coupled Plasma Optical Emission Spectrometry Analysis

by Sergio J. Abellán-Martín, David Villalgordo-Hernández, Miguel Ángel Aguirre, Enrique V. Ramos-Fernández, Javier Narciso and Antonio Canals

Separations 2023, 10(11), 563; https://doi.org/10.3390/separations10110563 - 10 Nov 2023

Cited by 1 | Viewed by 2200

Abstract

A new fast, sensitive, and environmentally friendly analytical method has been developed for the simultaneous determination of Ba, Be, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn in wastewater samples using inductively coupled plasma optical emission spectroscopy (ICP OES). A preconcentration [...] Read more.

A new fast, sensitive, and environmentally friendly analytical method has been developed for the simultaneous determination of Ba, Be, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, and Zn in wastewater samples using inductively coupled plasma optical emission spectroscopy (ICP OES). A preconcentration step using a magnetic dispersive solid-phase extraction (MDSPE) technique with a new magnetic sorbent was performed. The new sorbent material was a carbon containing magnetic cobalt and nitrogen groups. This material was synthetized using controlled pyrolysis of a zeolitic imidazolate framework (i.e., ZIF-67). In order to optimize the experimental parameters that affect the MDSPE procedure, a multivariate optimization strategy, using Plackett–Burman and circumscribed central composite designs (CCD), was used. The method has been evaluated employing optimized experimental conditions (i.e., sample weight, 10 g; sample pH, 7.6; amount of sorbent, 10 mg; dispersive agent, vortex; complexing agent concentration, 0.5%; ionic concentration, 0%; eluent, HCl; eluent concentration, 0.5 M; eluent volume, 300 μL; elution time, 3 min and extraction time, 3 min) using external calibration. Limits of detection (LODs) in a range from 0.073 to 1.3 μg L⁻¹ were obtained, and the repeatability was evaluated at two different levels, resulting in relative standard deviations below 8% for both levels (n = 5). An increase in the sensitivity was observed due to the high enrichment factors (i.e., 3.2 to 13) obtained compared with direct ICP OES analysis. The method was also validated through carrying out recovery studies that employed a real wastewater sample and through the analysis of a certified reference material (ERM^®-CA713). The recovery values obtained with the real wastewater were between 94 and 108% and between 90 and 109% for the analysis of ERM^®-CA713, showing negligible matrix effects. Full article

(This article belongs to the Topic Analysis and Separations of Trace Elements in the Environment)

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17 pages, 8745 KiB

Open AccessArticle

A Study on the Removal Characteristics and Mechanism of Phosphorus from Simulated Wastewater Using a Novel Modified Red-Mud-Based Adsorption Material

by Wenbao Liu, Qin Zhang, Yanbai Shen, Weichao Li, Sikai Zhao, Qiang Zhao and Yiqun Zhang

Separations 2023, 10(11), 562; https://doi.org/10.3390/separations10110562 - 10 Nov 2023

Cited by 3 | Viewed by 1966

Abstract

In this work, a common third-generation environmentally friendly quaternary ammonium salt disinfectant, dimethyl dioctadecyl ammonium chloride (DDAC), was used as the modifier to achieve one-step rapid preparation of the modified red-mud-based adsorption material under the condition of microwave assistance, and applied it to [...] Read more.

In this work, a common third-generation environmentally friendly quaternary ammonium salt disinfectant, dimethyl dioctadecyl ammonium chloride (DDAC), was used as the modifier to achieve one-step rapid preparation of the modified red-mud-based adsorption material under the condition of microwave assistance, and applied it to the adsorption phosphorus in solutions. After the process of this modification, the structure of the red mud (RM) was not changed, and the DDAC modification could provide more adsorption active sites. The adsorption experiments indicated that the novel modified red mud (NMRM) exhibited a good adsorption performance for phosphorus. The adsorption capability of NMRM for phosphorus was significantly enhanced, and was about eight times higher than that of the initial RM. The kinetics model of the pseudo-second-order, which implied that phosphorus was chemically adsorbed on the surface of the NMRM, could accurately represent the adsorption procedure of NMRM. The adsorption equilibrium of NMRM could be better depicted using the isotherm model of Freundlich. It was speculated that the ion exchange might be responsible for the adsorption mechanism of NMRM for phosphorus. Thus, the NMRM is a potential material for the treatment of phosphorus-containing wastewater due to its outstanding adsorption capability. Full article

(This article belongs to the Section Analysis of Energies)

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19 pages, 3023 KiB

Open AccessArticle

Analysis of Kazakhstan Crude Oil Biomarkers by Gas Chromatography in Combination with Mass Spectrometry

by Mereke Alimzhanova and Bauyrzhan Abdykarimov

Separations 2023, 10(11), 561; https://doi.org/10.3390/separations10110561 - 9 Nov 2023

Cited by 2 | Viewed by 2699

Abstract

Kazakhstan ranks as the 12th largest oil producer globally and boasts a diverse range of crude oils. This research introduces a method for distinguishing between the different types of crude oils based on biomarker analysis of 28 crude oils from Western and Southern [...] Read more.

Kazakhstan ranks as the 12th largest oil producer globally and boasts a diverse range of crude oils. This research introduces a method for distinguishing between the different types of crude oils based on biomarker analysis of 28 crude oils from Western and Southern Kazakhstan using gas chromatography-mass spectrometry. Biomarkers serve as valuable tools, especially in forensic investigations of oil spills. These biomarkers effectively retain a significant portion of the original natural product’s carbon structure, providing crucial evidence regarding the origin and identity of the oils under examination. This study identifies a set of biomarkers, including pristine, phytane, n-C₁₇ and n-C₁₈ alkanes, hopanes, bisnorhopanes, iso-copalanes, pregnane, androstane, allopregnane, homopregnane, cholestane, and stigmastane. By examining ratios such as pristane/phytane, pristane/n-C₁₇ alkane, tricyclic/pentacyclic terpanes, and hopane, as well as the distribution of steranes, it was deduced that crude oils from West Kazakhstan exhibited resilience to biodegradation. These findings showed that gas chromatography-mass spectrometry is an effective method for oil biomarkers determination, especially because it provides efficient separation and identification. Additionally, this study delved into the origin conditions and maturity of these oils, contributing to a deeper understanding of their characteristics and analysis that is simple to use and available worldwide. Full article

(This article belongs to the Topic Oil, Gas and Water Separation Research)

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13 pages, 2628 KiB

Open AccessArticle

Effects of Rare Earth Doping on Structural and Electrocatalytic Properties of Nanostructured TiO₂ Nanotubes/SnO₂-Sb Electrode for Electrochemical Treatment of Industrial Wastewater

by Lisha Yang and Yanming Guo

Separations 2023, 10(11), 560; https://doi.org/10.3390/separations10110560 - 9 Nov 2023

Cited by 2 | Viewed by 1616

Abstract

The solvothermal synthesis technique was employed to successfully fabricate a series of rare earth doped SnO₂-Sb electrodes on the TNTs array substrate, serving as anode material for electrocatalytic degradation of phenol. The electrode doped with rare earth elements demonstrated superior electrocatalytic [...] Read more.

The solvothermal synthesis technique was employed to successfully fabricate a series of rare earth doped SnO₂-Sb electrodes on the TNTs array substrate, serving as anode material for electrocatalytic degradation of phenol. The electrode doped with rare earth elements demonstrated superior electrocatalytic activity and stability in comparison to the undoped electrode. The influence of adding rare earth elements (i.e., Gd and Nd) into the precursor solution on the structural and property of TNTs/SnO₂-Sb electrodes was studied in detail. The results obtained from SEM and XRD indicated that, compared to TNTs/SnO₂-Sb-Nd, TNTs/SnO₂-Sb-Gd exhibited a finer grain size due to the smaller ionic radius of the Gd element. This facilitated its incorporation into the SnO₂ lattice interior and inhibited grain growth, resulting in a significant decrease in particle size for exposing more active sites. The influence mechanism of rare earth doping on electrochemical activity was investigated through XPS, EPR, LSV, EIS and Hydroxyl radicals (•OH) generation tests. The results demonstrated that the enhanced electrocatalytic activity can be attributed to an increased generation of oxygen vacancies on the electrode surface, which act as active sites for enhancing the adsorption of oxygen species and promoting •OH generation. Full article

(This article belongs to the Special Issue Advanced Nitrogen Removal Process in Adsorption and Removal of Pollutants)

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18 pages, 15774 KiB

Open AccessArticle

Adsorption Properties and Mechanism of Copper Ions from Wastewater by Lessonia nigrescens and Lessonia nigrescens Residue

by Haoran Chen, Rui Zhang, Xiaohan Qu, Yuan Yuan, Bo Zhu, Shichao Zhao and Tengyao Jiang

Separations 2023, 10(11), 559; https://doi.org/10.3390/separations10110559 - 5 Nov 2023

Cited by 3 | Viewed by 2462

Abstract

Given the advantages of readily availability, low cost, convenient operation, and large adsorption capacity, brown seaweed has been studied extensively as a biosorbent for heavy metal remediation from aqueous media. Herein, raw Lessonia nigrescens and brown seaweed residue, a waste product from the [...] Read more.

Given the advantages of readily availability, low cost, convenient operation, and large adsorption capacity, brown seaweed has been studied extensively as a biosorbent for heavy metal remediation from aqueous media. Herein, raw Lessonia nigrescens and brown seaweed residue, a waste product from the manufacturing of alginate from L. nigrescens, were employed as low-cost and renewable adsorption materials for effective copper removal in wastewater streams. The influences of temperature, sample loadings, adsorption time, initial metal ion concentrations, and pH on the efficiency of the metal ions adsorption process were investigated. The thermodynamics and kinetics of Cu (II) adsorption for both the raw seaweed and seaweed residue were studied in order to determine the maximum removal efficiency and capacity. The characterization of the seaweed and seaweed residue before and after copper adsorption with SEM, FTIR, EDS, etc., coupled with the thermodynamics study, confirmed the ion exchange mechanism involved in the adsorption process. Under optimal conditions, the removal efficiencies were 75% and 71% for L. nigrescens and seaweed residue, respectively, and the adsorption capacities can reach 12.15 mg/g and 9.09 mg/g within 10 min for L. nigrescens and seaweed residue, respectively. The slight reduction in removal efficiency was because the active ion exchange sites were partially removed during the alginate extraction. The comparable metal ion removal efficiency between raw seaweed and seaweed residue suggesting the L. nigrescens residue is viable as bio-adsorbent and potential for industrial applications in adsorption process. The results provided a novel way to upgrade seaweed biomass in a biorefinery concept. Full article

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

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25 pages, 4971 KiB

Open AccessEditor’s ChoiceArticle

Evaluation of CO₂ Adsorption Parameters in Fluidised Zeolite 13X Beds Using Non-Linear Multivariate Optimisation

by Alessio Caravella, Giuseppe Prenesti, Salvatore De Luca, Maria Turano, Flaviano Testa and Rossella Girimonte

Separations 2023, 10(11), 558; https://doi.org/10.3390/separations10110558 - 3 Nov 2023

Cited by 1 | Viewed by 3061

Abstract

This work is part of a research project aimed at studying potential sorbents for CO₂ capture. The main parameters characterising the adsorption process of zeolite 13X were derived with the aim of overcoming the limits of experimental analysis and thus predicting the [...] Read more.

This work is part of a research project aimed at studying potential sorbents for CO₂ capture. The main parameters characterising the adsorption process of zeolite 13X were derived with the aim of overcoming the limits of experimental analysis and thus predicting the performances of the materials of interest. In particular, the main parameters that control the adsorption process of CO₂ in zeolite 13X were evaluated through parametric optimisation. This systematic procedure allows for the prediction of the performances of the materials at different operating conditions, identifying the most suitable ones for the case under consideration. Another important application lies in the possibility of a preliminary study of a potential process scale-up for future industrial use. The captured carbon dioxide can be stored or used as a reagent in the production of products with higher economic values, such as methanol, DME and others. Full article

(This article belongs to the Special Issue Advances in CO₂ Adsorptive Separation for CO₂ Capture)

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2 pages, 147 KiB

Open AccessEditorial

Separations—Scope Update

by Frank L. Dorman

Separations 2023, 10(11), 557; https://doi.org/10.3390/separations10110557 - 1 Nov 2023

Viewed by 1271

Abstract

The journal Separations (ISSN: 2297-8739) was launched in 2014 [...] Full article

14 pages, 1525 KiB

Open AccessArticle

Examination of Volatile Signatures of Fusarium Bulb Rot in Garlic Using Proton-Transfer-Reaction Time-of-Flight Mass Spectrometry and Solid-Phase Microextraction Gas Chromatography/Mass Spectrometry

by Alessandro Infantino, Cosimo Taiti, Alessandro Grottoli, Stefano Mancuso, Corrado Costa and Stefania Garzoli

Separations 2023, 10(11), 556; https://doi.org/10.3390/separations10110556 - 31 Oct 2023

Cited by 2 | Viewed by 1781

Abstract

Fusarium bulb rot, caused by Fusarium proliferatum, is a worldwide disease of garlic, both in the open field and during storage. Early diagnosis of the disease during storage is difficult due to the morphology of the bulbs and cloves. Volatile organic compounds [...] Read more.

Fusarium bulb rot, caused by Fusarium proliferatum, is a worldwide disease of garlic, both in the open field and during storage. Early diagnosis of the disease during storage is difficult due to the morphology of the bulbs and cloves. Volatile organic compounds (VOCs) are secondary metabolites produced by several microorganisms, including phytopathogenic fungi and bacteria. In recent years, the development of several techniques for the detection and characterization of VOCs has prompted their use, among others, as a diagnostic tool for the early and non-destructive analysis of many diseases of species of agricultural interest. In this paper, proton-transfer-reaction time-of-flight mass spectrometry (PTR-ToF-MS) and solid-phase microextraction gas chromatography/mass spectrometry (SPME-GC/MS) were successfully utilized to characterize the volatolome of commercial garlic cloves, artificially and naturally infected with F. proliferatum, for the early discrimination between diseased and healthy ones. A partial least squares discriminant analysis (PLSDA) and a principal component analysis (PCA) allowed for the separation of infected and healthy cloves and the identification of specific VOCs produced by the fungus during the infection. The results obtained in this work could be utilized for the development of simpler, more economical, and more portable devices for the early detection of infected garlic bulbs during storage. Full article

(This article belongs to the Special Issue Application of Chromatography in Analytical Chemistry)

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21 pages, 3743 KiB

Open AccessEditor’s ChoiceArticle

A Rule-Based Automated Chemical Recognition Algorithm for a Multi-Cell Multi-Detector Micro Gas Chromatograph

by Qu Xu, Yutao Qin and Yogesh B. Gianchandani

Separations 2023, 10(11), 555; https://doi.org/10.3390/separations10110555 - 31 Oct 2023

Cited by 1 | Viewed by 1801

Abstract

A chemical recognition algorithm is an integral part of any autonomous microscale gas chromatography (µGC) system for automated chemical analysis. For a multi-detector µGC system, the chemical analysis must account for the retention time of each chemical analyte as well as the relative [...] Read more.

A chemical recognition algorithm is an integral part of any autonomous microscale gas chromatography (µGC) system for automated chemical analysis. For a multi-detector µGC system, the chemical analysis must account for the retention time of each chemical analyte as well as the relative response of each detector to each analyte, i.e., the detector response pattern (DRP). In contrast to the common approaches of heuristically using principal component analysis and machine learning, this paper reports a rule-based automated chemical recognition algorithm for a multi-cell, multi-detector µGC system, in which the DRP is related to theoretical principles; consequently, this algorithm only requires a small amount of calibration data but not extensive training data. For processing both the retention time and the raw DRP, the algorithm applies rules based on expert knowledge to compare the detected peaks; these rules are located in a customized software library. Additionally, the algorithm provides special handling for chromatogram peaks with a small signal-to-noise ratio. It also provides separate special handling for asymmetrical peaks that may result from surface adsorptive analytes. This work also describes an experimental evaluation in which the algorithm used the relative response of two complementary types of capacitive detectors as well as a photoionization detector that were incorporated into the µGC system of interest. In these tests, which were performed on chromatograms with 21–31 peaks for each detector, the true positive rate was 96.3%, the true negative rate was 94.1%, the false positive rate was 5.9%, and the false negative rate was 3.7%. The results demonstrated that the algorithm can support µGC systems for automated chemical screening and early warning applications. Full article

(This article belongs to the Special Issue Development of Materials for Chromatographic Separation)

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21 pages, 4025 KiB

Open AccessArticle

Purification, Characterization, and Ferrous Oxidation Kinetics of Iron Oxidase from Acidithiobacillus ferridurans

by Yuandong Liu, Jiayu He, Xiangdong Shangguan, Run Liu, Xiaofeng Zeng, Wissal Belqadi, Kan Wang, Yan Tong, Runlan Yu, Weimin Zeng, Xueling Wu, Li Shen and Guanzhou Qiu

Separations 2023, 10(11), 554; https://doi.org/10.3390/separations10110554 - 31 Oct 2023

Viewed by 2093

Abstract

Iron oxidase was proposed to be the initial electron acceptor from the ferrous ion in the iron oxidation of the Acidithiobacillus genus for metal bioextraction; however, its most fundamental property of direct ferrous oxidation kinetics remains undetermined due to the confusion of reaction [...] Read more.

Iron oxidase was proposed to be the initial electron acceptor from the ferrous ion in the iron oxidation of the Acidithiobacillus genus for metal bioextraction; however, its most fundamental property of direct ferrous oxidation kinetics remains undetermined due to the confusion of reaction monitor method. Here, a recombinant iron oxidase from Acidithiobacillus ferridurans Riv11 was constructed, expressed, purified, characterized, and further used to investigate the kinetics and mechanism of ferrous oxidation. This protein is more stable in an acid solution than in a neutral solution. An infrared characteristic peak around 1050 cm⁻¹ of the [Fe₄S₄] cluster was identified. The [Fe₄S₄] cluster does not affect the secondary structure of protein, but plays an important role in the stability of protein and strongly absorbs the intrinsic fluorescence of protein, resulting in a great loss of the fluorescence emission. The protein has far more absorbance than those of the iron ions in solution in the visible region; therefore, the maximum difference absorbance around 500 nm between the oxidized and reduced states of protein can be used to monitor the reaction of ferrous oxidation. Accordingly, the kinetic rate constant of the reaction was determined. Bioinformatics analysis and molecular simulation further revealed the underlying molecular mechanism that ferrous ions approach the protein at the edge of a large hydrophobic surface patch nearest to the [Fe₄S₄] cluster from a direction far from all positively charged residues, which enough enables an efficient electron transfer. Full article

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13 pages, 2364 KiB

Open AccessArticle

Analysis of Volatile Components and Antibacterial Activity of Silver Wormwood Essential Oils from Different Habitats by E-Nose Combined with GC-MS

by Yiqin Yang, Dongyun Guo, Shujie Yang, Huiquan Hu, Xiaorong Luo and Na Wan

Separations 2023, 10(11), 553; https://doi.org/10.3390/separations10110553 - 31 Oct 2023

Cited by 1 | Viewed by 2057

Abstract

Electronic nose (E-nose) combined with gas chromatography–mass spectrometry (GC-MS) was used to analyze the volatile components of silver wormwood from different habitats, and the antibacterial activity of essential oils was also studied, to provide a scientific basis for quality control of silver wormwood [...] Read more.

Electronic nose (E-nose) combined with gas chromatography–mass spectrometry (GC-MS) was used to analyze the volatile components of silver wormwood from different habitats, and the antibacterial activity of essential oils was also studied, to provide a scientific basis for quality control of silver wormwood and rational utilization of their essential oils. In this study, the total content of essential oils in silver wormwood was determined by steam distillation; the volatile components were conducted in an overall analysis by E-nose combined with chemometrics; the volatile components were analyzed and identified by GC-MS; and two G-negative bacteria and one Gram-positive bacteria were used as test bacteria to determine the antibacterial activity of the essential oils from silver wormwood. The results showed that principal component analysis (PCA) and linear discriminant analysis (LDA) of E-nose could distinguish the essential oils of silver wormwood from different habitats, and the odor difference of essential oils was obvious. A total of 87 volatile components were identified by GC-MS, and there were significant differences in components and contents in silver wormwood from different habitats; PCA and hierarchical cluster analysis (HCA) could effectively distinguish silver wormwood from different habitats. The essential oils from silver wormwood from different habitats all had a certain inhibitory effect on Bacillus subtilis, Staphylococcus aureus, and Escherichia coli. Therefore, the combination of E-nose and GC-MS could quickly distinguish silver wormwood from different habitats and provide a reference for quality control, drug selection, and comprehensive utilization of silver wormwood. Full article

(This article belongs to the Special Issue Advances in the Chromatographic Separation and Analysis of Natural Products/Medicines)

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22 pages, 5351 KiB

Open AccessArticle

LC/MS-Based Profiling of Hedyotis aspera Whole-Plant Methanolic Extract and Evaluation of Its Nephroprotective Potential against Gentamicin-Induced Nephrotoxicity in Rats Supported by In Silico Studies

by Dsnbk Prasanth, Lingareddygari Siva Sanker Reddy, Tharani Dasari, Pamula Reddy Bhavanam, Sheikh F. Ahmad, Rahul Nalluri and Praveen Kumar Pasala

Separations 2023, 10(11), 552; https://doi.org/10.3390/separations10110552 - 30 Oct 2023

Cited by 2 | Viewed by 2293

Abstract

Many high-altitude plants, such as Hedyotis aspera, need to be explored for their possible medicinal value. The current study explored the protective effect of Hedyotis aspera methanolic extract whole plant (HAME) against gentamicin-induced nephrotoxicity in rats. It profiled their phytocontents using HPLC-QTOF-MS/MS [...] Read more.

Many high-altitude plants, such as Hedyotis aspera, need to be explored for their possible medicinal value. The current study explored the protective effect of Hedyotis aspera methanolic extract whole plant (HAME) against gentamicin-induced nephrotoxicity in rats. It profiled their phytocontents using HPLC-QTOF-MS/MS analytic methods. The LC-MS analysis of HAME revealed 27 compounds. Eight compounds followed Lipinski’s rule of five and were found to be potential TNF-α inhibitors with binding affinities of −6.9, −6.3, −6.3, and −6.3 Kcal/mol, such as 14,19-Dihydroaspidospermatine, coumeroic acid, lycocernuine and muzanzagenin. All potential compounds were found to be safe according to the ADMET analysis. The in vitro 2,2-diphenyl-1-picrlhydrazyl (DPPH) assay assessed the antioxidant activity. The nephroprotective activity was assessed in rats using a gentamicin-induced nephrotoxicity model. The in vivo analysis involved histological examination, tissue biochemical evaluation, including a kidney function test, catalase activity (CAT), reduced glutathione (GSH) levels, superoxide dismutase (SOD), and the inflammatory mediator TNF-α. Based on DPPH activity, HAME showed a scavenging activity IC₅₀ of 264.8 ± 1.2 µg/mL, while results were compared with a standard vitamin C IC₅₀ of 45 ± 0.45 µg/mL. Nephrotoxicity was successfully induced, as shown by elevated creatinine and uric acid levels, decreased kidney antioxidant levels, and increased TNF-α in gentamicin-treated rats. The HAME treatment significantly reduced serum creatinine and uric acid levels, increased GSH (p < 0.01 **), CAT (p < 0.01 **), and SOD (p < 0.001 ***), and decreased TNF-α (p < 0.001 ***) in nephrotoxic rats. The histopathological examination of the groups treated with HAME revealed a notable enhancement in the structural integrity of the kidneys as compared to the group exposed to gentamicin. Biochemical, histopathological, and phytochemical screening of HAME suggests that it has nephroprotective potential, owing to the presence of 14,19-Dihydroaspidospermatine, coumeroic acid, lycopene, and muzanzagenin. Full article

(This article belongs to the Special Issue Advanced Research on Extraction and Analysis of Plant Extracts)

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15 pages, 2776 KiB

Open AccessEditor’s ChoiceArticle

Application of Choline Chloride-Based Deep Eutectic Solvents in the Synthesis of Hydrazones

by Valentina Bušić, Sunčica Roca and Dajana Gašo-Sokač

Separations 2023, 10(11), 551; https://doi.org/10.3390/separations10110551 - 29 Oct 2023

Cited by 2 | Viewed by 2727

Abstract

The synthesis of 14 hydrazone compounds derived from pyridoxal, pyridine-4-carbaldehyde, and quinoline-2-carbaldehyde using two methods, conventional method in deep eutectic solvents (DESs) and effective combination of ultrasound and DESs, is presented in this paper. In addition, the possibility of using 12 choline chloride [...] Read more.

The synthesis of 14 hydrazone compounds derived from pyridoxal, pyridine-4-carbaldehyde, and quinoline-2-carbaldehyde using two methods, conventional method in deep eutectic solvents (DESs) and effective combination of ultrasound and DESs, is presented in this paper. In addition, the possibility of using 12 choline chloride (ChCl)-based DESs as an alternative to organic solvents was investigated. The results show that the application of ultrasound not only improves the reaction yield but also shortens the reaction time. The prepared compounds synthesized at room temperature were analyzed via NMR spectroscopy and MS spectrometry. The studies confirmed that the DESs ChCl:malonic, oxalic, levulinic, and trans-cinnamic acid can be excellent alternatives to classical organic solvents. By the combined use of DESs and the ultrasonic method, compound 11 was obtained in a nearly quantitative yield of 98% in DES ChCl:oxalic acid. The advantages of using DESs as reaction media are that they are biodegradable, nontoxic, recyclable, and can be easily prepared with inexpensive starting materials. The results of recycling DESs show that they can be used up to the fourth recycling cycle without significantly changing the reaction yield. Full article

(This article belongs to the Special Issue Application of Deep Eutectic Solvents in Green Separation Chemistry)

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14 pages, 4623 KiB

Open AccessArticle

Design Methodology for a Low-Shear Rotating Swirler

by Zheng Si, Yipeng Ji, Jiaqing Chen, Xiujun Wang, Hong Du, Jian Zhang, Hai Yu, Qiang Ren and Zhao Hua

Separations 2023, 10(11), 550; https://doi.org/10.3390/separations10110550 - 28 Oct 2023

Viewed by 1750

Abstract

The tubular dynamic hydrocyclone (TDH) holds great potential for the pre-deoiling of offshore oil platforms. However, the shear and turbulence in the flow field can cause the oil droplets, the dispersed phase in water, to break up when the swirling flow is produced [...] Read more.

The tubular dynamic hydrocyclone (TDH) holds great potential for the pre-deoiling of offshore oil platforms. However, the shear and turbulence in the flow field can cause the oil droplets, the dispersed phase in water, to break up when the swirling flow is produced by the swirler. A design method is proposed for the low-shear rotary swirler (LSRS) of TDH, the aim of which is to reduce the shear force and local turbulence during the fluid forming swirling flow. The blade setting angle of the LSRS is calculated based on the relative velocity vector between the fluid and the swirler. The distribution characteristics of the tangential velocity and turbulence in the TDH with LSRS are simulated by Computational Fluid Dynamics (CFD). The maximum stable droplet diameter is analyzed. The results show that the shear stress and turbulence energy dissipation rates are reduced by 74.6% and 68.5%, respectively, and that the stable droplet diameter is increased by more than 60%, compared to the conventional rotating swirler. In addition, a TDH prototype with LSRS was tested in an offshore oil field by continuous operation for more than 36 h. The average separation efficiency was 83%, and the average underflow oil concentration was 27 mg/L. The research also found that the drastic changes in the tangential velocity along the axial direction were critical to shear. Moreover, the results make up for the deficiency of the spatial variation of the tangential velocity in the dynamic cyclone separator. Full article

(This article belongs to the Special Issue Advanced Oil–Water Separation Technology)

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14 pages, 3024 KiB

Open AccessArticle

Genomic and Proteomic Analysis of Pseudomonas aeruginosa Isolated from Industrial Wastewater to Assess Its Resistance to Antibiotics

by Zongwu Wang, Wantao Tian, Siyuan Sun, Xing Chen and Haifeng Wang

Separations 2023, 10(11), 549; https://doi.org/10.3390/separations10110549 - 27 Oct 2023

Cited by 2 | Viewed by 1572

Abstract

Industrial wastewater usually contains a large amount of organic and inorganic pollutants, and many microorganisms. However, the types of microorganism present in industrial wastewater are still unclear. The aim of this study was to analyze the physicochemical properties and drug resistance of Pseudomonas [...] Read more.

Industrial wastewater usually contains a large amount of organic and inorganic pollutants, and many microorganisms. However, the types of microorganism present in industrial wastewater are still unclear. The aim of this study was to analyze the physicochemical properties and drug resistance of Pseudomonas aeruginosa isolated from industrial wastewater containing high concentrations of sulfate compounds. Pseudomonas aeruginosa was isolated from industrial wastewater from industrial produce with high concentrations of sulfate and phosphate, and mass spectrometry identification, gene identification, biochemical analysis and genomic and proteomic property identification were carried out. According to the results of matrix-assisted flight mass spectrometry and 16S rDNA sequencing, the isolated bacterium was identified as Pseudomonas aeruginosa, and was positive for reactions of ONPG, ACE, GLU, MNE, etc. Through growth experiments, it can be seen that Pseudomonas aeruginosa had a significant growth rate in the LB medium. Antibiotic sensitivity tests showed that Pseudomonas aeruginosa was susceptible to most antibiotics and moderately resistant to Polymyxin B and Polymyxin E. The drug resistance gene experiment showed that Pseudomonas aeruginosa had the gyrB gene related to antibiotic resistance. Proteomic analysis revealed that six proteins were involved in antibiotic resistance. This experiment isolated Pseudomonas aeruginosa from industrial produce wastewater containing high concentrations of sulfate and phosphate ions, providing a new perspective for further research on the characteristics and drug resistance of microorganisms in industrial wastewater and their potential functions when using them to deal with environmental pollution. Full article

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Separations, Volume 10, Issue 11 (November 2023) – 32 articles

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