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Separations, Volume 10, Issue 12 (December 2023) – 24 articles

Cover Story (view full-size image): Textile white mud is a typical industrial waste generated during the alkali weight-reduction process in printing and plant dyeing, which is mainly composed of 1,4-dicarboxybenzene (BDC). Based on a “waste-control-by-waste” strategy, this work is dedicated to upcycling textile white mud by separating BDC and fabricating a metal organic framework-derived TiO2/porous carbon composite for electro-reductive remediation. The separated BDC from the white mud shows less crystallinity than the BDC chemicals, which endows the TiO2/porous carbon composite with more oxygen vacancies and a larger specific surface area, and thus, much a higher electro-reductive activity level for the typical halogenated antibiotic contaminants. View this paper
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24 pages, 7983 KiB  
Article
Breaking the Equilibrium and Improving the Yield of Schiff Base Reactions by Pervaporation: Application to a Reaction Involving n-butylamine and Benzaldehyde
Separations 2023, 10(12), 602; https://doi.org/10.3390/separations10120602 - 18 Dec 2023
Viewed by 1056
Abstract
A comparative study of a Schiff base reaction involving benzaldehyde and n-butylamine was carried out to improve the yield of the resulting imine. This reaction was carried out at different temperatures without and with the elimination of the water produced during the [...] Read more.
A comparative study of a Schiff base reaction involving benzaldehyde and n-butylamine was carried out to improve the yield of the resulting imine. This reaction was carried out at different temperatures without and with the elimination of the water produced during the process by the pervaporation (PV) technique using a typical cylindrical cell. To reach this goal, different dense membranes made of crosslinked poly(vinyl alcohol) with different oxalic acid (crosslinker) contents were prepared by the solvent casting method. Different parameters influencing the performance of the membrane in the separation process including swellability, diffusivity, crosslinking density, and thermal properties were investigated. The total and partial cumulative transmembranar fluxes as well as the separation factor were studied and the separation process was monitored by HPLC analysis. The n-butyl-1-phenylmethanimine produced was characterized by FTIR and 1HNMR analyses. The results obtained were a clear improvement in the yield of the reaction. For example, the yield obtained from the Schiff base reaction occurring without assistance by PV varied from 58 to 84 wt% when the temperature changed from 5 to 45 °C. On the other hand, when the PV process was used to eliminate water from this reaction mixture, the yield went from 90.4 to 98.6% by weight in this same temperature order. The cumulative total and partial fluxes significantly decreased with time. On the other hand, the separation factor reached a maximum at about one hour at 5, 15, and 45 °C. At 25 °C, the maximum total flux was reached at about 2 h of the PV process. The best selectivity of the PVA-0.5 membrane with regard to water was obtained at 15 °C. It was also revealed from the results obtained that the cumulative total and partial flux decreased rapidly with time and the separation factor reached a maximum at one hour into the PV process, in which 1.51 × 104 was reached at 15 °C, 6.25 × 103 and 3.50 × 103 at one hour of the separation process, and 10.23 × 103 at 25 °C at 2 h of the water removal by PV. Full article
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15 pages, 1761 KiB  
Article
The Development and Validation of Simultaneous Multi-Component Quantitative Analysis via HPLC–PDA Detection of 12 Secondary Metabolites Isolated from Drynariae Rhizoma
Separations 2023, 10(12), 601; https://doi.org/10.3390/separations10120601 - 18 Dec 2023
Viewed by 1067
Abstract
Drynariae Rhizoma (DR) is a functional food and traditional medicine that has been widely used for bone and joint disorders for thousands of years. In this study, 14 compounds were isolated from DR, and their structures were identified using UPLC/QTOF–MS, UPLC–ESI/LTQ–Orbitrap–HRMS, and 2D [...] Read more.
Drynariae Rhizoma (DR) is a functional food and traditional medicine that has been widely used for bone and joint disorders for thousands of years. In this study, 14 compounds were isolated from DR, and their structures were identified using UPLC/QTOF–MS, UPLC–ESI/LTQ–Orbitrap–HRMS, and 2D NMR and compared with those obtained in previous studies. An HPLC–PDA multi-component simultaneous quantitative determination method was developed for 12 of the 14 DR-derived compounds, excluding compounds with a content <1.5 mg. The developed HPLC method was validated based on linearity (r2 ≥ 0.999), limit of detection (0.01–0.65 μg/mL), limit of quantification (0.04–1.97 μg/mL), intra-day precision and accuracy ranges (0.06–2.85% and 95.03–104.75%, respectively), and inter-day precision and accuracy ranges (0.24–2.83% and 95.75–105.75%, respectively). The developed analysis method improved the resolution of compounds 4 and 5. In addition, this is the first quantitative analysis of compounds 7, 8, and 11 and the first simultaneous quantitative analysis of 12 compounds, including compounds 4, 7, 8, 10, 11, and 14. This study developed a rapid, accurate, and economical HPLC method for performing the simultaneous quantitative analysis of 12 secondary metabolites isolated from DR. Full article
(This article belongs to the Special Issue Recent Advances and Trends in Dietary Supplement Analysis)
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12 pages, 486 KiB  
Review
Compositional Analysis of Metal(IV) Phosphate and Phosphonate Materials—Pitfalls and Best Practices
Separations 2023, 10(12), 600; https://doi.org/10.3390/separations10120600 - 18 Dec 2023
Viewed by 997
Abstract
Metal(IV) phosphate and phosphonates materials have increasingly found their applications in water purification, heterogeneous catalysis, drug delivery, and proton-exchange membrane fuel cells. The strong linkage between tetravalent metal cations and phosphate/phosphonate groups offers a unique bottom-up design platform, resulting in chemically stable inorganics [...] Read more.
Metal(IV) phosphate and phosphonates materials have increasingly found their applications in water purification, heterogeneous catalysis, drug delivery, and proton-exchange membrane fuel cells. The strong linkage between tetravalent metal cations and phosphate/phosphonate groups offers a unique bottom-up design platform, resulting in chemically stable inorganics or hybrids. Task-specific physiochemical functionalities could be deposited by modifying the phosphate/phosphonate groups before the material synthesis. The high reactivity between the metal centre and the phosphorus-containing linker, on the other hand, often leads to obtaining unordered materials (amorphous solids or coordination polymers). The chemical composition of the prepared materials is a key parameter in guiding the synthetic approach and in governing their performances. This narrative review focuses on critically summarising the traditional and advanced analytical methods for probing the composition of these materials. The reader is introduced to and guided on the advances and restrictions of different analysis techniques when probing metal(IV) phosphates/phosphonates. Both solution-based and solid-state spectroscopic techniques are covered with a focus on understanding the quantity and the linkage status of the phosphorus-containing moieties. These techniques include atomic spectroscopy, mass spectroscopy, nuclear magnetic resonance spectroscopy, X-ray-based methods, and neutron activation analysis. Full article
(This article belongs to the Section Materials in Separation Science)
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19 pages, 5159 KiB  
Article
Green and Fast Extraction of Chitin from Waste Shrimp Shells: Characterization and Application in the Removal of Congo Red Dye
Separations 2023, 10(12), 599; https://doi.org/10.3390/separations10120599 - 13 Dec 2023
Viewed by 1350
Abstract
Due to their detrimental and carcinogenic effects, synthetic organic dyes pose significant environmental and health risks. Consequently, addressing the bioremediation of industrial wastewater containing these organic dyes has become an urgent environmental concern. The adsorption using low-cost and green materials is one of [...] Read more.
Due to their detrimental and carcinogenic effects, synthetic organic dyes pose significant environmental and health risks. Consequently, addressing the bioremediation of industrial wastewater containing these organic dyes has become an urgent environmental concern. The adsorption using low-cost and green materials is one of the best alternative techniques for the removal of dyes. This study aims to investigate the use of chitin to eliminate Congo red (CR), an anionic dye, from wastewater. The chitin was produced from shrimp shell in a quick and environmentally friendly manner by utilizing a co-solvent (glycerol/citric acid (GLC)). The resulting adsorbent was characterized through various techniques, including X-ray diffraction (XRD), scanning electron microscopy (SEM), and FT-IR spectroscopy. The effectiveness of CR removal with chitin was studied with respect to contact time, adsorbent dose, initial pH, equilibrium isotherms, and kinetic and thermodynamic parameters. It was observed that variations in the dye concentration and pH significantly influenced the removal of CR with chitin. Under optimal operating conditions (pH = 7, contact time = 130 min, temperature = 50 °C), the adsorption capacity reached 29.69 ± 0.2 mg/g. The experimental data revealed that CR adsorption onto a chitin adsorbent is better represented by a Langmuir isotherm. Full article
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29 pages, 1092 KiB  
Review
Extraction and Analysis of Chemical Compositions of Natural Products and Plants
Separations 2023, 10(12), 598; https://doi.org/10.3390/separations10120598 - 09 Dec 2023
Cited by 1 | Viewed by 1533
Abstract
There are many types of natural plants in nature that contain a variety of effective and complex chemical components. These constituents can be categorized as organic acids, volatile oils, coumarins, steroids, glycosides, alkaloids, carbohydrates, phytochromes, etc., all of which play important roles in [...] Read more.
There are many types of natural plants in nature that contain a variety of effective and complex chemical components. These constituents can be categorized as organic acids, volatile oils, coumarins, steroids, glycosides, alkaloids, carbohydrates, phytochromes, etc., all of which play important roles in the fields of pharmaceuticals, food, nutraceuticals, and cosmetics. The study of extraction and chemical composition analysis of natural products is important for the discovery of these active ingredients and their precursors. Therefore, the aim of this article is to review the status of research on the extraction, separation and purification, and structural identification of natural products, to provide a reference for the study of natural products. Full article
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11 pages, 2374 KiB  
Article
Study on Enhancement of Denitrification Performance of Alcaligenes faecalis
Separations 2023, 10(12), 597; https://doi.org/10.3390/separations10120597 - 08 Dec 2023
Viewed by 1080
Abstract
Nitrogen pollution in water bodies presents a serious threat to ecosystems due to its role in eutrophication. In this study, the aerobic denitrifying bacterium Alcaligenes faecalis was used as a model microorganism to investigate the optimal operating conditions for nitrogen removal from nitrogen-containing [...] Read more.
Nitrogen pollution in water bodies presents a serious threat to ecosystems due to its role in eutrophication. In this study, the aerobic denitrifying bacterium Alcaligenes faecalis was used as a model microorganism to investigate the optimal operating conditions for nitrogen removal from nitrogen-containing wastewater by Alcaligenes faecalis under different aeration modes, microbial dosages and C/N ratios. The results showed that the optimal aeration mode for efficient bacterial denitrification was 10 min of aeration with a 30 min interval, and the total nitrogen removal reached 87.82%. At different bacterial doses, NO3–N was completely denitrified and NO2–N accumulation levels were reduced, all of which resulted in significant denitrification, and the final total nitrogen removal efficiencies reached 86.39–98.50%. With an increase in the C/N ratio, the pollutant removal performance of denitrifying bacteria increased. When the C/N ratio was 17, the final rates of NO3–N, TN and COD removal were 100%, 98.50% and 96.13%, respectively. At lower C/N ratios, the growth and metabolism of microorganisms were inhibited and fewer electron acceptors were available during the denitrification process, which seriously affected denitrification performance. In this study, the denitrification performance of aerobic denitrifying bacterium Alcaligenes faecalis was explored in experiments using changes in aeration mode, microbial dosage and C/N ratio, and the optimal operating conditions of Alcaligenes faecalis for treating nitrogenous wastewater were indicated. This provides technical support for Alcaligenes faecalis in improving the remediation effect of nitrogenous wastewater and provides a theoretical basis for further in-depth research on the performance of Alcaligenes faecalis in the future. Full article
(This article belongs to the Section Environmental Separations)
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17 pages, 1055 KiB  
Review
Research Progress on Extraction, Separation, and Purification Methods of Plant Essential Oils
Separations 2023, 10(12), 596; https://doi.org/10.3390/separations10120596 - 07 Dec 2023
Cited by 1 | Viewed by 1345
Abstract
Essential oils (EOs), also called liquid gold, are known for their wide range of applications and biological activities. The modern use of EOs has received increasing attention for more than 60 years. The precious EOs have been refined from plant raw materials using [...] Read more.
Essential oils (EOs), also called liquid gold, are known for their wide range of applications and biological activities. The modern use of EOs has received increasing attention for more than 60 years. The precious EOs have been refined from plant raw materials using a variety of methods. Since the extraction, separation, and purification methods determine the type, quantity, and stereochemical structure of EO molecules as well as the final yield and quality of EOs, the selection of an appropriate method is crucial. The traditional and emerging extraction methods (hydrodistillation, steam distillation, organic solvent extraction, etc.), as well as separation and purification methods (chromatography, macroporous resin, chemical reaction, etc.), of plant EOs and their main volatile compounds were shown. Our review focused on the principles, processes, characteristics, and applications of these methods, so as to better understand the preparation of pure plant EOs and further guide their large-scale use. Full article
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14 pages, 5148 KiB  
Article
The Effect of Paraburkholderia on the Nutrients in Eutrophic Lakes
Separations 2023, 10(12), 595; https://doi.org/10.3390/separations10120595 - 06 Dec 2023
Cited by 1 | Viewed by 1137
Abstract
Cyanobacterial blooms in freshwater bodies are mainly attributed to the excess loading of nutrients. The microbes in sediments may affect nutrient migration and transformation during the growth of cyanobacteria. This study focused on the role of Paraburkholderia disturbance in affecting the sediment nutrient [...] Read more.
Cyanobacterial blooms in freshwater bodies are mainly attributed to the excess loading of nutrients. The microbes in sediments may affect nutrient migration and transformation during the growth of cyanobacteria. This study focused on the role of Paraburkholderia disturbance in affecting the sediment nutrient conditions and further contributing to cyanobacterial community succession in Meiliang Bay, Lake Taihu. The dissolving phosphorus and fixing nitrogen of Paraburkholderia with different concentration and characteristic capabilities, as well as the impact on nutrients (nitrogen (N), phosphorus (P), iron (Fe), etc.) in eutrophic lakes were determined. The results indicated that the various forms of phosphorus in the sediments showed total phosphorus (TP) > inorganic phosphorus (IP) > iron/aluminum-bound phosphate (NaOH-P) > algal-available phosphorus (AAP) > organic phosphorus (OP) > calcium-bound phosphate (HCl-P). Additionally, it was observed that with higher values of Paraburkholderia (OD600), the higher the corresponding risk of endogenous nutrient release from the sediments into the overlying water (but more is not always better), especially for the solubilization of HCl-P. The diffusion fluxes of TP, total nitrogen (TN) and Fe at the sediment–water interface (SWI) were all positive in the bacteria only experiment, with maximum values of 0.64, 15.0 and 5.02 mg/(m2d), respectively. Additionally, it was interesting that Paraburkholderia were able to produce organic acids, causing a decrease in pH. Furthermore, glucose levels can seriously affect water quality, especially the reduction in dissolved oxygen (DO) (down to 0.01 mg/L), leading to a series of side effects that have a huge impact on cyanobacterial community succession. These results provide a theoretical basis for the microbial ecological factors in eutrophic lakes. Full article
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25 pages, 5194 KiB  
Article
Multi-Dimensional Liquid Chromatography of Pulse Triacylglycerols with Triple Parallel Mass Spectrometry
Separations 2023, 10(12), 594; https://doi.org/10.3390/separations10120594 - 05 Dec 2023
Viewed by 1214
Abstract
We analyzed ten pulses (the dried seeds of legumes), i.e., baby lima beans, black beans, black-eyed peas, butter beans, cranberry beans, garbanzo beans, green split peas, lentils, navy beans, and pinto beans, using three-dimensional liquid chromatography (3D-LC) with parallel second dimensions, LC × [...] Read more.
We analyzed ten pulses (the dried seeds of legumes), i.e., baby lima beans, black beans, black-eyed peas, butter beans, cranberry beans, garbanzo beans, green split peas, lentils, navy beans, and pinto beans, using three-dimensional liquid chromatography (3D-LC) with parallel second dimensions, LC × (LC + LC). We combined non-aqueous reversed-phase (NARP) chromatography as the first dimension separation, 1D, with argentation UHPLC for separation based on degree and location of unsaturation in the first second dimension, 2D(1), and multi-cycle NARP-UHPLC in the second second dimension, 2D(2). Pulses contained 1.9% to 2.7% lipids, except garbanzo beans, which contained 6.2% lipids. High-resolution, accurate-mass (HRAM) orbitrap mass spectrometry (MS) was used to perform lipidomic analysis of the 2D(2) and percent relative quantification, showing that the most abundant average triacylglycerol (TAG) molecular species across all pulses were PLL at 10.67% and PLLn at 10.45%. Common beans (Phaseolus vulgaris) were clustered together using principal component analysis (PCA), showing the highest levels of linolenic acid, C18:3, in molecular species such as PLnLn, LLnLn, and OLLn, with palmitic (P), C16:0, linoleic (L), 18:2, linolenic (Ln), 18:3, and oleic (O), 18:1, FAs. Calibration curves derived from interweaved sets of regioisomer standards allowed the absolute quantification of 1,2- and 1,3-regioisomers for a subset of TAGs. Full article
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16 pages, 1569 KiB  
Review
Recent Advances in the Effects of Biochar on Constructed Wetlands: Treatment Performance and Microorganisms
Separations 2023, 10(12), 593; https://doi.org/10.3390/separations10120593 - 04 Dec 2023
Viewed by 1202
Abstract
Constructed wetlands (CWs) are a kind of green environmental protection technology, which are widely used in sewage treatment. Traditional CWs are faced with the problem of a low treatment effect of high-concentration sewage. In recent years, biochar, as a new type of adsorption [...] Read more.
Constructed wetlands (CWs) are a kind of green environmental protection technology, which are widely used in sewage treatment. Traditional CWs are faced with the problem of a low treatment effect of high-concentration sewage. In recent years, biochar, as a new type of adsorption material, has been used in CWs because of its advantages of large specific surface area, strong adsorption capacity, and wide material sources. This paper systematically summarized the characteristics of biochar and the preparation of biochar by studying the changes in microorganisms added to CWs and compared the effects of different treatment methods coupled with biochar on the treatment performance of CWs. The effects of biochar coupled with CWs on enzyme activity, functional genes, metabolites, and microbial communities were investigated. This review summarizes how different preparation methods affect the properties of biochar and how these biochar properties cause changes in the microorganisms added to CWs. It provides a new theoretical basis for the treatment of pollutants in CWs. Full article
(This article belongs to the Special Issue Separation Technology in Bioprocess for Environmental Remediation)
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12 pages, 6404 KiB  
Review
Self-Driven Sustainable Oil Separation from Water Surfaces by Biomimetic Adsorbing and Transporting Materials
Separations 2023, 10(12), 592; https://doi.org/10.3390/separations10120592 - 04 Dec 2023
Viewed by 1572
Abstract
Oil films on water are an increasingly major contamination problem worldwide. In 2020, we published a novel adsorption and transportation technology for oil–water separation based on biological role models like the floating fern Salvinia. This application provides an unexpected ability for the [...] Read more.
Oil films on water are an increasingly major contamination problem worldwide. In 2020, we published a novel adsorption and transportation technology for oil–water separation based on biological role models like the floating fern Salvinia. This application provides an unexpected ability for the fast and efficient removal of oil films, particularly in ecologically important freshwater biota. A single small Bionic Oil Adsorber (BOA) with 1 m2 functional textile can collect up to 4 L of oil per hour, which equals about 100 m2 of oil film from a water surface into a collecting vessel. This is a safe, fast, and sustainable solution for the ubiquitous contaminations of, e.g., fuel oil in freshwater environments. Here, we present updated, new experimental data, and a review of the literature published since. Full article
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18 pages, 3402 KiB  
Review
Resource and Energy Utilization of Swine Wastewater Treatment: Recent Progress and Future Directions
Separations 2023, 10(12), 591; https://doi.org/10.3390/separations10120591 - 03 Dec 2023
Viewed by 1618
Abstract
Livestock and poultry farming, as a crucial component of agricultural production, poses a substantial threat to the ecological environment due to the discharge of wastewater. In recent years, researchers have proposed various resource treatment technologies for livestock and poultry breeding wastewater. However, a [...] Read more.
Livestock and poultry farming, as a crucial component of agricultural production, poses a substantial threat to the ecological environment due to the discharge of wastewater. In recent years, researchers have proposed various resource treatment technologies for livestock and poultry breeding wastewater. However, a comprehensive discussion regarding the limitations and avenues for optimizing resource utilization technologies for livestock and poultry farming wastewater treatment is notably absent in existing literature. This paper takes swine wastewater as an illustrative case and undertakes a review of the advantages, disadvantages, and optimization directions of resource treatment technologies, including physical and chemical technology, microbial metabolism, microbial electrochemistry, constructed wetlands, and microalgae-based techniques. Based on mass balance, the recovery rates of various treatment technologies are estimated, and it was found that microbial electrochemistry and constructed wetland techniques may become the mainstream for resource utilization in the future. Furthermore, this paper emphasizes that in addition to resource efficiency, the optimization of resource utilization technologies for swine wastewater should also focus on the following aspects: (1) striking a balance between environmental impact and economic benefits; (2) reducing the cost of resource and energy utilization; and (3) safeguarding environmental and ecological security. Full article
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15 pages, 2691 KiB  
Article
Study on Selective Adsorption Behavior and Mechanism of Quartz and Magnesite with a New Biodegradable Collector
Separations 2023, 10(12), 590; https://doi.org/10.3390/separations10120590 - 01 Dec 2023
Viewed by 1172
Abstract
Research on the efficient flotation desilication of low-grade magnesite is of great significance for the sustainable development of magnesium resources. Traditional collectors usually have some disadvantages, such as poor selectivity, severe environmental pollution, and weak water solubility. To strengthen the desilication flotation process [...] Read more.
Research on the efficient flotation desilication of low-grade magnesite is of great significance for the sustainable development of magnesium resources. Traditional collectors usually have some disadvantages, such as poor selectivity, severe environmental pollution, and weak water solubility. To strengthen the desilication flotation process of magnesite ore, the biodegradable surfactant, cocamidopropyl amine oxide (CPAO), was first utilized as the collector for the separation of the magnesite and quartz. The selective adsorption behavior and mechanism of the quartz and magnesite with the CPAO as the collector were studied through the micro-flotation experiments of the single mineral and the artificially mixed mineral, contact angle and atomic force microscopy (AFM) measurements, fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) analyses. The flotation results indicated that the CPAO showed good selectivity and could effectively separate magnesite and quartz. When the concentration of the CPAO was 10.0 mg/L in the natural pulp pH (about 7.2), the concentrates with 97.67% MgO recovery and 45.62% MgO grade were obtained. The contact angle and AFM measurements indicated that the CPAO could selectively adsorb on the quartz surface rather than the magnesite surface to improve the interface difference between them, especially its surface hydrophobicity. The results of the FTIR and XPS analyses indicated that the CPAO is selectively adsorbed on the surface of the quartz, mainly through electrostatic interaction and hydrogen bonding. In conclusion, the CPAO had good selectivity and great potential as an effective collector in the reverse flotation desilication progress of magnesite. Full article
(This article belongs to the Section Analysis of Energies)
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14 pages, 3213 KiB  
Article
Qualitative/Quantitative Analysis of Alcohol and Licit/Illicit Drugs on Post-Mortem Biological Samples from Road Traffic Deaths
Separations 2023, 10(12), 589; https://doi.org/10.3390/separations10120589 - 01 Dec 2023
Viewed by 1072
Abstract
Alcohol and drug abuse is a major contributory factor of all road deaths in Europe. The aim of this study is to investigate the prevalence of alcohol and licit/illicit drug intake among victims of road accidents in Campania region (Italy). A retrospective analysis [...] Read more.
Alcohol and drug abuse is a major contributory factor of all road deaths in Europe. The aim of this study is to investigate the prevalence of alcohol and licit/illicit drug intake among victims of road accidents in Campania region (Italy). A retrospective analysis of road traffic deaths from 2013 to 2022 in Campania was performed. The toxicological results from fluid samples collected at autopsy were reviewed. In total, 228 road deaths occurred, mostly during nights and weekends. A total of 106 victims tested positive for alcohol and/or drugs, among which 39 (36.8%) tested positive for alcohol only, 27 (25.5%) for alcohol and drugs in association; and 40 (37.7%) for licit/illicit drugs only, either individually or in combination. Polydrug intake has been found in 21 victims, and nine in combination with alcohol. The most detected drugs were cocaine and Δ9THC, followed by benzodiazepines. Blood alcohol concentration (BAC) > 1.5 g/L was found in most alcohol positives, both alone and in association with drugs. Despite the penalties for driving under the influence of alcohol (DUI) and drugs (DUID), no decrease in the number of alcohol and/or drugs related fatal road accidents has been observed. DUI and/or DUID cases were approximately one third of the entire sample study. Full article
(This article belongs to the Section Forensics/Toxins)
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14 pages, 1959 KiB  
Article
Comprehensive Chemical Characterization of Qingkailing Capsules by Ultra-High-Performance Liquid Chromatography Combined with Fourier Transform Ion Cyclotron Resonance Mass Spectrometry
by and
Separations 2023, 10(12), 588; https://doi.org/10.3390/separations10120588 - 01 Dec 2023
Viewed by 1061
Abstract
Qingkailing capsules are a classic traditional Chinese medicine prescription with remarkable clinical effects for the treatment of fevers. However, the chemical components of Qingkailing capsules are still unclear. To obtain and characterize the chemical profile of Qingkailing capsules, the present study applied a [...] Read more.
Qingkailing capsules are a classic traditional Chinese medicine prescription with remarkable clinical effects for the treatment of fevers. However, the chemical components of Qingkailing capsules are still unclear. To obtain and characterize the chemical profile of Qingkailing capsules, the present study applied a rapid, accurate, and sensitive method using ultra-high-performance liquid chromatography combined with Fourier transform ion cyclotron resonance mass spectrometry (UHPLC-FT-ICR-MS) to perform a comprehensive chemical characterization of Qingkailing capsules. Leveraging the high separation speed and good separation of UHPLC, the accurate mass data (within 5 ppm) and fragment ions, a total of 276 compounds, including 67 flavonoids and their glycosides, 52 organic acids, 75 terpenoids, 23 steroids, 22 phenylpropanoids, and 37 other compounds, were unambiguously or tentatively identified. This comprehensive analysis of the chemical components of Qingkailing capsules contributes to the quality evaluation and provides a scientific and reasonable basis for further study of prototype components and metabolites in vivo and pharmacological research, ultimately facilitating the advancement of Qingkailing capsules for further development and the therapeutic use of Qingkailing capsules in clinical applications. Full article
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27 pages, 388 KiB  
Review
Valorization of Olive Leaves through Polyphenol Recovery Using Innovative Pretreatments and Extraction Techniques: An Updated Review
Separations 2023, 10(12), 587; https://doi.org/10.3390/separations10120587 - 29 Nov 2023
Viewed by 1591
Abstract
Olive leaves are naturally generated as a by-product during olive harvesting and olive oil production. Usually discarded with no specific use, they are a valuable source of bioactive compounds that should not be overlooked. Their valorization must therefore be achieved through the recovery [...] Read more.
Olive leaves are naturally generated as a by-product during olive harvesting and olive oil production. Usually discarded with no specific use, they are a valuable source of bioactive compounds that should not be overlooked. Their valorization must therefore be achieved through the recovery of their polyphenols using an ecological strategy. Conventional extraction is commonly known as an energy- and solvent-consuming process, whereas emerging and innovative extraction technologies, such as ultrasound-assisted extraction (UAE), microwave-assisted extraction (MAE), pulsed-electric-field-assisted extraction (PEF), high-voltage-electric-discharge-assisted extraction (HVED), supercritical fluid extraction (SFE), infrared-assisted extraction (IAE), and “Intensification of Vaporization by Decompression to the Vacuum” (IVDV), are considered more sustainable and environmentally friendly. The aim of this review is to provide a comprehensive and updated overview of the valorization of olive leaves through both pretreatment and extraction techniques via an analysis of the recovered polyphenols and their potential applications. Full article
11 pages, 2825 KiB  
Article
Improving the Efficiency of Cement Mortar to Immobilize Sulfate in Industrial Wastewater Using Different Nanoparticles
Separations 2023, 10(12), 586; https://doi.org/10.3390/separations10120586 - 28 Nov 2023
Viewed by 1209
Abstract
The disposal of industrial wastewater (IWW) discharged from factories is a significant topic in the environment field, and the use of cement-based materials is a useful way to treat materials with unexpected ions. In this work, IWW with abundant SO42− collected [...] Read more.
The disposal of industrial wastewater (IWW) discharged from factories is a significant topic in the environment field, and the use of cement-based materials is a useful way to treat materials with unexpected ions. In this work, IWW with abundant SO42− collected from a factory was utilized to prepare cement mortar (IWWCM), and three kinds of nanomaterials (NMs), including nano-SiO2 (NS), nano-CaCO3 (NC), and nano-metakaolin (NMK), were used to improve the performance of IWWCM. The compressive strengths, hydration degree, hydration products, and micropore structure of the specimens were investigated. The test results showed that IWW reduced the strength of the specimens, and the use of NMs could compensate for this strength reduction. To be specific, the 28-day strength of the freshwater (FW) mixed specimen was 44.6 MPa, and the use of IWW decreased this value to 41.8 MPa. However, the strengths of the specimens with NMs were all higher than 50 MPa, indicating the advantage of NMs for the strengths of the IWWCMs. Moreover, the IWWCM showed a lower hydration degree with a poor pore structure, whereas the use of NMs in IWWCMs refined these properties, explaining the strength increase in the specimens. The results of the SO42− content measurements also showed that the use of NMs could improve the SO42− binding ratio, which is conducive to relieving the pressure of IWW disposal for industrial factories. Full article
(This article belongs to the Section Environmental Separations)
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11 pages, 1223 KiB  
Article
Impact of the Smoking Process on Biogenic Amine Levels in Traditional Dry-Cured Chorizo
Separations 2023, 10(12), 585; https://doi.org/10.3390/separations10120585 - 27 Nov 2023
Viewed by 1056
Abstract
This study aimed to investigate the influence of various production stages on the quality and spoilage conditions of traditionally dry-cured chorizo. To accomplish this, we employed an experimental design that examined three key production parameters: the batch, the filling stage, and the food [...] Read more.
This study aimed to investigate the influence of various production stages on the quality and spoilage conditions of traditionally dry-cured chorizo. To accomplish this, we employed an experimental design that examined three key production parameters: the batch, the filling stage, and the food smoking process. The study was conducted in collaboration with a local producer who adheres to traditional curing methods utilizing oak wood smoke and heat. Biogenic amine levels were closely monitored throughout the process. This involved their extraction and derivatization through the salting-out technique, followed by identification and quantification using LC-ESI/MSn and HPLC-DAD, respectively. The findings suggest that both raw materials and the production process are well controlled during the filling stage. However, it became evident that the 14-day oak wood smoking period had a significant impact on biogenic amine formation, whose total mean values increased from 126 to 1385 mg kg−1, particularly with respect to putrescine (PUT), cadaverine (CAD), and tyramine (TYR), although these levels remained below the oral toxicity limit (2000 mg kg−1). Consequently, the concentration of these compounds can influence the quality and safety of traditionally dry-cured chorizos. Therefore, the combined levels of PUT, CAD, and TYR can serve as a valuable quality indicator for these products. Full article
(This article belongs to the Section Analysis of Food and Beverages)
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21 pages, 8564 KiB  
Article
Using Kerosene as an Auxiliary Collector to Recover Gold from Refractory Gold Ore Based on Mineralogical Characteristics
Separations 2023, 10(12), 584; https://doi.org/10.3390/separations10120584 - 25 Nov 2023
Viewed by 1237
Abstract
Carbon–arsenic-bearing gold ore is a typical complex refractory gold resource. Traditionally, xanthate was often used as a flotation agent to separate gold minerals. But, in this paper, in order to reduce the cost of the agent, kerosene was used as an auxiliary collector, [...] Read more.
Carbon–arsenic-bearing gold ore is a typical complex refractory gold resource. Traditionally, xanthate was often used as a flotation agent to separate gold minerals. But, in this paper, in order to reduce the cost of the agent, kerosene was used as an auxiliary collector, and the gold grade and recovery rate were increased by about 10 g/t and 5.5%, respectively. Through process mineralogy studies of the raw ore, it was found that the ore has an Au grade of 5.68 g/t, most of which is surrounded by sulfide ore, accounting for 79.46%. The main minerals are pyrite, arsenopyrite, and quartz, etc. Their content, shape, particle size distribution, and occurrence state were obtained via microscopic observation and statistical analysis. According to the results of process mineralogy, various flotation conditions were tested, including grinding fineness, kerosene dosage, collector dosage, foaming agent dosage, and the slurry pH value. The optimal chemical system and the process flow of “two roughing, three cleaning and two scavenging” were finally determined, and the concentrate product with a gold grade of 42.83 g/t and recovery of 91.02% was obtained, which verified the feasibility of the kerosene-assisted xanthate flotation of refractory gold. Full article
(This article belongs to the Section Purification Technology)
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17 pages, 5313 KiB  
Review
Pros and Cons of Separation, Fractionation and Cleanup for Enhancement of the Quantitative Analysis of Bitumen-Derived Organics in Process-Affected Waters—A Review
Separations 2023, 10(12), 583; https://doi.org/10.3390/separations10120583 - 24 Nov 2023
Viewed by 1177
Abstract
Oil sands process-affected water (OSPW) contains a diverse mixture of inorganic and organic compounds. Naphthenic acids (NAs) are a subset of the organic naphthenic acid fraction compounds (NAFCs) and are a major contributor of toxicity to aquatic species. Thousands of unique chemical formulae [...] Read more.
Oil sands process-affected water (OSPW) contains a diverse mixture of inorganic and organic compounds. Naphthenic acids (NAs) are a subset of the organic naphthenic acid fraction compounds (NAFCs) and are a major contributor of toxicity to aquatic species. Thousands of unique chemical formulae are measured in OSPW by accurate mass spectrometry and high-resolution mass spectrometry (MS) analysis of NAFCs. As no commercial reference standard is available to cover the range of compounds present in NAFCs, quantitation may best be referred to as “semi-quantitative” and is based on the responses of one or more model compounds. Negative mode electrospray ionization (ESI-) is often used for NAFC measurement but is prone to ion suppression in complex matrices. This review discusses aspects of off-line sample preparation techniques and liquid chromatography (LC) separations to help reduce ion suppression effects and improve the comparability of both inter-laboratory and intra-laboratory results. Alternative approaches to the analytical parameters discussed include extraction solvents, salt content of samples, extraction pH, off-line sample cleanup, on-line LC chromatography, calibration standards, MS ionization modes, NAFC compound classes, MS mass resolution, and the use of internal standards. Full article
(This article belongs to the Topic Advances in Spectroscopic and Chromatographic Techniques)
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20 pages, 4316 KiB  
Article
Synthesis of Carboxymethylcellulose–Acrylamide–Montmorillonite Composite Hydrogels for Wastewater Purification
Separations 2023, 10(12), 582; https://doi.org/10.3390/separations10120582 - 23 Nov 2023
Viewed by 1192
Abstract
The three-dimensional network and ample pore structure of novel hydrogel materials enable outstanding adsorption performance for pollutants such as methylene blue (MB) and Cr6+ ions in wastewater. In order to develop an environmentally friendly hydrogel with high adsorption performance and low cost, [...] Read more.
The three-dimensional network and ample pore structure of novel hydrogel materials enable outstanding adsorption performance for pollutants such as methylene blue (MB) and Cr6+ ions in wastewater. In order to develop an environmentally friendly hydrogel with high adsorption performance and low cost, a type of carboxymethyl cellulose (CMC) composite hydrogel was synthesised with montmorillonite (MMT) via chain radical polymerization, which gives it great potential for application in the field of wastewater purification. A series of hydrogel samples were characterised through SEM, FTIR and nitrogen porosimetry analysis, indicating the successful intercalation of MMT nanosheets into the hydrogel crosslinking network. The mass ratio of CMC to MMT, the amounts of adsorbent, the initial concentration of wastes, pH, and the adsorption temperature were investigated and optimised for hydrogel adsorption performance. When the initial concentration of MB is 60 mg/L, pH is 7, the dosage of MB is 0.5 g/L, and the adsorption temperature is 30 °C, the hydrogel sample the highest adsorption capability for MB removal, with an adsorption amount of 112.9 mg/g. When the initial concentration of Cr6+ is 10 mg/L with a pH of 7, the highest adsorption capacity of the hydrogel for Cr6+ removal is 1.35 mg/g. The fitting results of the isothermal models, the kinetic models, internal particle diffusion models and the thermodynamics of the experimental data of the adsorbate adsorption process show that the adsorption of MB by hydrogel is a spontaneous segmented process of multi-layer physical and chemical adsorption. Additionally, the adsorption of Cr6+ ions by hydrogel is a spontaneous segmented process of multi-layer physical adsorption. Full article
(This article belongs to the Section Materials in Separation Science)
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12 pages, 2571 KiB  
Article
Rational Fabrication of Benzene-Linked Porous Polymers for Selective CO2 Capture
Separations 2023, 10(12), 581; https://doi.org/10.3390/separations10120581 - 23 Nov 2023
Viewed by 1214
Abstract
Various porous polymer materials have been prepared for the separation of CO2 from mixed gases. However, complex processes, expensive monomers, and costly catalysts are commonly used for their synthesis, making the adsorbents difficult to achieve in industrial applications. Herein, we developed a [...] Read more.
Various porous polymer materials have been prepared for the separation of CO2 from mixed gases. However, complex processes, expensive monomers, and costly catalysts are commonly used for their synthesis, making the adsorbents difficult to achieve in industrial applications. Herein, we developed a strategy to fabricate a series of benzene rings containing porous polymer materials (B-PPMs) via a facile condensation reaction of two inexpensive monomers, namely tetraphenylsilane and 1,4-bis(bromomethyl)benzene. The B-PPMs are verified to have accessible surface areas, large pore volumes, and appreciate pore sizes via a series of characterizations. The B-PPM-2 exhibits the best CO2 adsorption amount of 67 cm3·g−1 at 273 K and 1 bar, while the CO2/N2 selectivity can reach 64.5 and 51.9 at 273 K and 298 K, respectively. Furthermore, the adsorbent B-PPM-2 can be completely regenerated after five cycles of breakthrough experiments under mild conditions, which may provide promising candidates for selective capture of CO2 from mixtures. Full article
(This article belongs to the Special Issue Carbon Capture, Separation and Utilization)
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15 pages, 4074 KiB  
Article
Upcycling Textile White Mud to Fabricate MIL-125-Derived Amorphous TiO2@C: Effective Electrocatalyst for Cathodic Reduction of Antibiotics
Separations 2023, 10(12), 580; https://doi.org/10.3390/separations10120580 - 23 Nov 2023
Viewed by 1097
Abstract
Cathodic reduction is a green and promising remediation strategy for reducing the antibacterial activity of antibiotic contaminants and increasing their biodegradability. However, the lack of cost-effective electrocatalysts has restricted its application. In this study, we upcycled textile white mud by separating 1,4-dicarboxybenzene (BDC) [...] Read more.
Cathodic reduction is a green and promising remediation strategy for reducing the antibacterial activity of antibiotic contaminants and increasing their biodegradability. However, the lack of cost-effective electrocatalysts has restricted its application. In this study, we upcycled textile white mud by separating 1,4-dicarboxybenzene (BDC) and fabricating MIL-125(Ti)-derived amorphous TiO2@C (TiO2@C-W) as a functional electrocatalyst. The separated BDC from white mud shows lower crystallinity than BDC chemicals, but the resulting TiO2@C-W features a much higher degree of oxygen vacancies and a 25-fold higher specific surface area than that of TiO2@C derived from BDC chemicals. With florfenicol (FLO) as a probe, TiO2@C-W exhibits similar cathodic reductive activity (0.017 min−1) as commercial Pd(3 wt.%)/C (0.018 min−1) does, which was 1.4 and 3.7 times higher than that of oxygen vacancy-engineered TiO2 and TiO2@C, respectively. The as-fabricated TiO2@C-W could not easily remove FLO via the oxygen reduction reaction-based pathway with the applied bias for cathodic reduction. Though the activity of TiO2@C-W undergoes a slight decline with continuous running, more than 80% of 20 mg L−1 FLO can still be reduced in the eighth run. Water chemistry studies suggest that a lower initial solution pH boosts the cathodic reduction process, while common co-existing anions such as Cl, NO3, HCO3, and SO32− show a limited negative impact. Finally, TiO2@C-W shows reductive activity against several representative antibiotics, including nitrofurazone, metronidazole, and levofloxacin, clarifying its potential scope of application for antibiotics (e.g., molecules with structures like furan rings, nitro groups, and halogens). This study couples the upcycling of textile white mud with the remediation of antibiotics by developing functional electrocatalysts, and offers new insights for converting wastes from the printing and dyeing industry into value-added products. Full article
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19 pages, 7107 KiB  
Article
Experimental Investigations of the Detachment of Different Particle Structures from a Magnetizable Fiber in the Gas Phase
Separations 2023, 10(12), 579; https://doi.org/10.3390/separations10120579 - 22 Nov 2023
Viewed by 1046
Abstract
A current subject of research is the application of magnetic effects for the detachment of accumulated particles of fibrous collectors in gas particle separation. Initial studies have already shown the magnetically induced detachment behavior of a compact particle structure after a single deflection [...] Read more.
A current subject of research is the application of magnetic effects for the detachment of accumulated particles of fibrous collectors in gas particle separation. Initial studies have already shown the magnetically induced detachment behavior of a compact particle structure after a single deflection from a single fiber. In this study, the detachment behavior of particle structures with different morphologies from a single fiber is investigated as a function of the particle loading stage on the fiber, the external magnetic flux density, the inflow velocity and the number of regenerations of the fiber for a certain parameter range. Diffusive and more compact particle structures with non-magnetic properties are deposited on the magnetizable single fiber. By applying an external magnetic field, the fiber is magnetized and experiences a torsional moment. The deposited particle structures on the fiber are detached by the acceleration forces. The detachment of the particle structures is observed using a high-speed camera and the image sequences are analyzed. By determining the projection area before and after the fiber deflection, a degree of regeneration is calculated. With magnetic-induced regeneration, high degrees of regeneration close to 100% can be achieved. Repetitive fiber deflections improve the detachment of the particle structures. The magnetic-induced regeneration is suitable for applications where flow reversal is not possible and can be performed either online or offline. Due to the gentle regeneration, fewer emissions are produced on the clean gas side than, for example, with jet pulse cleaning. It makes it easier to achieve emission limits and simplifies product recovery. Full article
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