Application of Liquid-Liquid Extraction for N-terminal Myristoylation Proteomics.

Proteins can be modified by lipids in various ways, for example, by myristoylation, palmitoylation, farnesylation, and geranylgeranylation-these processes are collectively referred to as lipidation. Current chemical proteomics using alkyne lipids has enabled the identification of lipidated protein candidates but does not identify endogenous lipidation sites and is not readily applicable to in vivo systems. Here, we introduce a proteomic methodology for global analysis of endogenous protein N-terminal myristoylation sites that combines liquid-liquid extraction of hydrophobic lipidated peptides with liquid chromatography-tandem mass spectrometry using a gradient program of acetonitrile in the high concentration range. We applied this method to explore myristoylation sites in HeLa cells and identified a total of 75 protein N-terminal myristoylation sites, which is more than the number of high-confidence myristoylated proteins identified by myristic acid analog-based chemical proteomics. Isolation of myristoylated peptides from HeLa digests prepared with different proteases enabled the identification of different myristoylated sites, extending the coverage of N-myristoylome. Finally, we analyzed in vivo myristoylation sites in mouse tissues and found that the lipidation profile is tissue-specific. This simple method (not requiring chemical labeling or affinity purification) should be a promising tool for global profiling of protein N-terminal myristoylation.

Chalcogen Bonding in Selective Recognition and Liquid-Liquid Extraction of Perrhenate.

Efficient recognition and extraction of hazardous anionic pollutants from water medium is of great significance for environmental concerns, representing a challenging area of research in supramolecular chemistry. In this study, we present, for the first time, a comprehensive demonstration of the ability of chalcogen bonding (ChB) to recognize and remove the ReO4 - from 100 % water medium. The anion recognition ability is well elucidated through solution phase NMR and ITC studies, which clearly reveal the selective binding of ReO4 - over other oxo-anions. Moreover, the selenoimidazolium scaffold effectively engages in Se•••O ChB interaction with ReO4 - as confirmed by X-ray crystal structure and XPS analysis. More importantly, the binding of ReO4 - with different prolongations of the σ-holes, along with Se•••Se chalcogen bonding interactions, lead to the formation of a 1D supramolecular assembly. Eventually, ChB receptor Se4Me-Br exhibits ~62 % ReO4 - extraction efficiency through precipitation as the extraction method. Furthermore, in efforts to enhance efficiency, a hydrophobic ChB receptor Se4Do-PF6 has been prepared, achieving an efficiency of up to ~93 % at a very low concentration (~5 ppm) by liquid-liquid extraction.

Recovery of Rare Earth Elements from Acid Mine Drainage with Supported Liquid Membranes: Impacts of Feedstock Composition for Extraction Performance.

Acid mine drainage (AMD) from inactive coal mines can be enriched in rare earth elements (REEs) and has gained much attention as an alternative source for these technology-critical metals. However, AMD is a relatively low-grade REE resource in which the abundance of impurities and the composition variability of the feedstock create major uncertainties for the performance of REE extraction technologies. This study sought to identify AMD feedstock variables that influence the extraction efficiency of REEs by supported liquid membranes (SLMs). SLM separation is a process involving a hydrophobic membrane embedded with an extracting solvent that facilitates the selective extraction of REE ions. The major aims were to (1) assess the effectiveness of SLM-based REE separation from several AMD samples representing a spectrum of aqueous composition, (2) determine the effects of AMD storage and holding time on extraction performance, and (3) assess the impact of AMD pretreatment (e.g., filtration and pH adjustment) on REE recovery. The results showed that relative extraction fluxes of REE correlated with AMD characteristics such as pH and major ions such as Fe, Ca, and Mn. The purity of the acid strippant product, expressed as the REE dry weight content, depended on the initial REE concentrations in the AMD source rather than the flux of individual REEs across the membrane. For AMD samples stored for 3 months prior to extraction, REE recovery by SLM separations was substantially decreased if oxidation of Fe(II) to Fe(III) was observed during sample storage. Pretreatment of AMD feedstocks by pH adjustment did not substantially improve the separation performance. Overall, this study establishes primary water quality parameters of AMD that influence the SLM separation flux and product purity. Such insights contribute to a mechanistic understanding of critical metals extractions by SLM for complex and nontraditional feedstocks such as AMD wastes.

Polar licit and illicit ingredients in dietary supplements: chemometric optimization of extraction and HILIC-MS/MS analysis.

Many dietary supplements claim the ability to enhance sports performance and to improve the fitness of the consumers. Occasionally, along with legal ingredients, illicit compounds may be added without being labelled, leading to unintended doping. Hence, the aim of this study was to develop an analytical method to determine a set of 12 polar (logDpH=7 from -2.0 to +0.3) compounds including diuretics, stimulants, ß2-agonists, methylxanthines, and sweeteners. Hydrophilic interaction liquid chromatography was chosen as separation strategy, coupled with tandem mass spectrometry. The instrumental method was optimized using a two-step design of experiments (DoE). Firstly, a Plackett-Burman (PB) DoE was performed to identify the more influencing variables affecting peak areas and chromatographic resolution among temperature, water percentage in the mobile phase, and flow rate, as well as type and concentration of buffers. Secondly, a D-optimal DoE was set, considering only the most significant variables from the PB-DoE results, achieving a deeper understanding of the retention mechanism. Sample processing by salt-assisted liquid-liquid extraction was studied through DoE as well, and the whole method showed recoveries in the range 40-107% and procedural precision ≤11% for all analytes. Finally, it was applied to real samples, in which the four methylxanthines and two artificial sweeteners were detected and quantified in the range of 0.02-192 mg g-1. These values were compared to the quantities declared on the DS labels, when possible. Furthermore, a sequence of MS/MS scans allowed detection of a signal in one of the samples, structurally similar to the ß2-agonist clenbuterol.

Biomonitoring urinary organophosphorus flame retardant metabolites by liquid-liquid extraction and ultra-high performance liquid chromatography-tandem mass spectrometry and their association with oxidative stress.

Organophosphate flame retardants (OPFRs) are widely used as substitutes for traditional brominated flame retardants, necessitating a reliable and sensitive method for biomonitoring their urinary metabolites to assess human exposure. This study conducted biomonitoring of 10 metabolites of OPFRs in 152 adults and assessed their association with oxidative stress biomarkers 8-hydroxydeoxyguanosine and 8-hydroxyguanosine. Urinary metabolites of OPFRs were released via enzymatic deconjugation. The addition of sodium chloride to the urine samples increases the ionic strength, inducing a salting-out effect that reduces the solubility of these compounds, thereby facilitating their extraction with a mixture of ethyl acetate and acetonitrile. Then, the metabolites of OPFRs were quantified by ultra-high performance liquid chromatography-tandem mass spectrometry, and we validated the method for linear range, precision, matrix effect, and method detection limit. The detection limit of the metabolites of OPFRs ranged from 0.01 to 0.2 µg/L, and these metabolites were detected with high frequencies ranging from 25.0 to 98.68% in the urine samples. The concentration of bis (2-chloroethyl) phosphate was significantly higher in males than in females, with the geometric mean concentration of 0.88 µg/L for males and 0.53 µg/L for females, respectively. Spearman correlation analysis revealed weak but statistically significant positive correlations among the urinary metabolites. Bayesian kernel machine regression analysis showed a significant positive association between elevated urinary concentrations of metabolites of OPFRs and increased oxidative stress levels. Di-n-butyl phosphate was identified as the metabolite that significantly contributed to the elevated level of 8-hydroxyguanosine.

Enantioselective liquid-liquid extraction of 2-cyclohexylmandelic acid enantiomers using chiral ionic liquids.

Obtaining optically pure compounds in an eco-friendly and cost-efficient manner plays an important role in human health and pharmaceutical industry. Racemic separation using multistage stereoselective liquid-liquid extraction has become one of the most practical and effective approach to access homochiral enantiomers. Currently, chiral ionic liquids (CILs) with structural designability have become a promising chiral additive and enable them as adjustable candidates for racemic separation. Herein, a high-effective stereoselective liquid-liquid extraction process composed of imidazolium cations and amino acid-derived anions as the chiral additive was established for racemic 2-cyclohexylmandelic acid (CHMA) separation. We have systematically investigated the choice of organic solvent, concentration of CIL, extraction temperature, and the pH of aqueous phase. For three-stage stereoselective extraction, the maximum enantiomeric excess (e.e.) for CHMA was reached up to 40.6%. Furthermore, the mechanism of steric effect and stereoselective capacity between the CILs and racemic CHMA was discussed and simulated. We envision that the work will facilitate the development of CILs in multistage liquid-liquid extraction and promote the large-scale production of optically pure enantiomers.

Deep eutectic solvent-based pressurized liquid extraction combined with dispersive liquid-liquid microextraction of organophosphorus pesticide residues in egg powder prior to high-performance liquid chromatography analysis.

Herein, a deep eutectic solvent (DES)-based miniaturized pressurized liquid extraction in combination with DES-based dispersive liquid-liquid microextraction (DLLME) was developed for the extraction of organophosphorus pesticides (parathion-methyl, triazophos, parathion, diazinon, and phoxim) from egg powder samples prior to their analysis by a high-performance liquid chromatography-diode array detector. In this work, first, the analytes' extraction was done by a pressurized liquid phase extraction for effective extraction of the analytes from the solid matrix, and then they were concentrated on a DLLME for more concentration of the analytes to reach low limits of detections. The use of DESs was done in both steps to omit the use of toxic organic solvents. Satisfactory results including high extraction recoveries (74-90%), great repeatability (relative standard deviations equal or less than 4.3% and 5.3% for intra- and inter-day precisions), and low limits of detection (0.11-0.29 ng/g) and quantification (0.38-0.98 ng/g) were attained under the optimum conditions. Lastly, the suggested approach was utilized for the determination of the studied pesticides in various egg powder samples marketed in Tabriz, Iran.

Characterizing lipid constituents of B. moojeni snake venom: a comparative approach for chemical and biological investigations.

Snake venoms are complex mixtures majorly composed of proteins with well-studied biological effects. However, the exploration of non-protein components, especially lipids, remains limited despite their potential for discovering bioactive molecules. This study compares three liquid-liquid lipid extraction methods for both chemical and biological analyses of Bothrops moojeni snake venom. The methods evaluated include the Bligh and Dyer method (methanol, chloroform, water), considered standard; the Acunha method, a modification of the Bligh and Dyer protocol; and the Matyash method (MTBE/methanol/water), featuring an organic phase less dense than the aqueous phase. Lipidomic analysis using liquid chromatography with high-resolution mass spectrometry (LC-HRMS) system revealed comparable values of lipid constituents' peak intensity across different extraction methods. Our results show that all methods effectively extracted a similar quantity of lipid species, yielding approximately 17-18 subclasses per method. However, the Matyash and Acunha methods exhibited notably higher proportions of biologically active lipids compared to the Bligh and Dyer method, particularly in extracting lipid species crucial for cellular structure and function, such as sphingomyelins and phosphatidylinositol-phosphate. In conclusion, when selecting a lipid extraction method, it is essential to consider the study's objectives. For a biological approach, it is crucial to evaluate not only the total quantity of extracted lipids but also their quality and biological activity. The Matyash and Acunha methods show promise in this regard, potentially offering a superior option for extracting biologically active lipids compared to the Bligh and Dyer method.

Integrated Process for Schizochytrium Oil Extraction, Enzymatic Modification of Lipids and Concentration of DHA Fatty Acid Esters Using Alternative Methodologies.

Marine microalgae Schizochytrium sp. have a high content of docosahexaenoic acid (DHA), an omega-3 fatty acid that is attracting interest since it prevents certain neurodegenerative diseases. The obtention of a bioactive and purified DHA fatty acid ester using a whole-integrated process in which renewable sources and alternative methodologies are employed is the aim of this study. For this reason, lyophilized Schizochytrium biomass was used as an alternative to fish oil, and advanced extraction techniques as well as enzymatic modification were studied. Microalgal oil extraction was optimized via a surface-response method using pressurized liquid extraction (PLE) obtaining high oil yields (29.06 ± 0.12%) with a high concentration of DHA (51.15 ± 0.72%). Then, the enzymatic modification of Schizochytrium oil was developed by ethanolysis using immobilized Candida antarctica B lipase (Novozym® 435) at two reaction temperatures and different enzymatic loads. The best condition (40 °C and 200 mg of lipase) produced the highest yield of fatty acid ethyl ester (FAEE) (100%) after 8 h of a reaction attaining a cost-effective and alternative process. Finally, an enriched and purified fraction containing DHA-FAEE was obtained using open-column chromatography with a remarkably high concentration of 93.2 ± 1.3% DHA. The purified and bioactive molecules obtained in this study can be used as nutraceutical and active pharmaceutical intermediates of marine origin.

An analytical method using salting-out assisted liquid-liquid extraction to quantify ceftriaxone from micro volumes of human serum.

Ceftriaxone (CTRX) is a commonly used cephalosporin antibiotic. It is suggested that monitoring plasma/serum concentrations is helpful for its safe use. This study aimed to develop and validate an analytical method for measuring CTRX concentrations in human serum according to International Conference on Harmonization guideline M10. Ten microliters of serum sample was purified using a salting-out assisted liquid-liquid extraction procedure with magnesium sulfate. The upper layer was then diluted threefold and analyzed using a liquid chromatography-tandem mass spectrometry-based method with a total run time of 12 min. The linear calibration curve was obtained over the concentration range 5-500 µg/ml. The within-run accuracy varied from 0.2 to 6.5%, and the precision was ≤8.0%. The between-run accuracy and precision ranged from 0.7% to 5.6% and ≤6.4%, respectively. Significant carryover was resolved by injecting four blanks after high-concentration CTRX samples. The recovery rates from spiked serum at low and high concentrations were 44.4 and 43.4%, respectively. Other factors, including selectivity, matrix effects, stability, dilution integrity and reinjection reproducibility also met the acceptance criteria. Serum concentrations in 14 samples obtained from two participants receiving 2 g/day of CTRX were successfully determined using this method.

Liquid chromatography-tandem mass spectrometry determination of bumetanide in human plasma and application to a clinical pharmacokinetic study.

Determining a drug's bioavailability and bioequivalence is important for developing and approving a drug product. The procedure supports applications for generic drug products and novel therapeutic substances, makes important decisions regarding safety and efficacy, and measures a drug's concentration in biological matrices. This study aimed to develop and validate a specific, simple, sensitive, and accurate method using liquid chromatography-tandem mass spectrometry (LC-MS) for measuring bumetanide (BUM) in human plasma. Chromatographic separation was achieved using a Hypurity C18 column (4.6 × 50 mm, 5 µm) under isocratic conditions, and LC-MS detected positive ionization acquisition modes. Protonated precursor to product ion transitions were observed at m/z 365.08 → 240.10 and 370.04 → 244.52 for BUM and internal standard, respectively. The linear range of BUM in plasma samples was 3.490-401.192 ng/mL. The inter-precision value ranged from 1.76% to 4.75%. The inter-accuracy value ranged from 96.46% to 99.95%. The method was adequately validated per the U.S. Food and Drug Administration guidelines, and the results were within permissible bounds. The Cmax and Tmax values were ~53.097 ± 13.537 ng/mL and 1.25 (0.67-5.00) h, respectively. The new approach showed satisfactory results for studying BUM in human plasma with potential use in pharmacokinetic and bioequivalence investigations.

Tetraselmis chuii Edible Microalga as a New Source of Neuroprotective Compounds Obtained Using Fast Biosolvent Extraction.

Tetraselmis chuii is an EFSA-approved novel food and dietary supplement with increasing use in nutraceutical production worldwide. This study investigated the neuroprotective potential of bioactive compounds extracted from T. chuii using green biobased solvents (ethyl acetate, AcOEt, and cyclopentyl methyl ether, CPME) under pressurized liquid extraction (PLE) conditions and supercritical fluid extraction (SFE). Response surface optimization was used to study the effect of temperature and solvent composition on the neuroprotective properties of the PLE extracts, including anticholinergic activity, reactive oxygen/nitrogen species (ROS/RNS) scavenging capacity, and anti-inflammatory activity. Optimized extraction conditions of 40 °C and 34.9% AcOEt in CPME resulted in extracts with high anticholinergic and ROS/RNS scavenging capacity, while operation at 180 °C and 54.1% AcOEt in CPME yielded extracts with potent anti-inflammatory properties using only 20 min. Chemical characterization revealed the presence of carotenoids (neoxanthin, violaxanthin, zeaxanthin, α- and ß-carotene) known for their anti-cholinesterase, antioxidant, and anti-inflammatory potential. The extracts also exhibited high levels of omega-3 polyunsaturated fatty acids (PUFAs) with a favorable ω-3/ω-6 ratio (>7), contributing to their neuroprotective and anti-inflammatory effects. Furthermore, the extracts were found to be safe to use, as cytotoxicity assays showed no observed toxicity in HK-2 and THP-1 cell lines at or below a concentration of 40 µg mL-1. These results highlight the neuroprotective potential of Tetraselmis chuii extracts, making them valuable in the field of nutraceutical production and emphasize the interest of studying new green solvents as alternatives to conventional toxic solvents.

Advanced Extraction Techniques Combined with Natural Deep Eutectic Solvents for Extracting Phenolic Compounds from Pomegranate (Punica granatum L.) Peels.

Pomegranate (Punica granatum L.) peel is a potential source of bioactive phenolic compounds such as ellagic acid and α- and ß-punicalagin. This work explores the efficiency of natural deep eutectic solvents combined with ultrasound-assisted extraction (UAE) and pressurized liquid extraction (PLE) for their extraction. Five NaDESs were evaluated by employing UAE (25 °C, for 50 min) to determine their total phenolic content (Folin-Ciocalteu assay) and ellagic acid and α- and ß-punicalagin contents (high-performance liquid chromatography (HPLC-DAD)). The NaDES composed of choline chloride (ChCl) and glycerol (Gly) (1:2, molar ratio) was the most efficient in the UAE when compared with the rest of the NaDESs and water extracts. Therefore, ChCl:Gly was further evaluated using PLE at different temperatures (40, 80, 120 and 160 °C). The PLE-NaDES extract obtained at 80 °C for 20 min at 1500 psi exhibited the highest contents of ellagic acid and α- and ß-punicalagin compared to the rest of the temperatures and PLE-water extracts obtained under the same extraction conditions. Combining UAE or PLE with a NaDES emerges as a sustainable alternative for extracting ellagic acid and α- and ß-punicalagin from pomegranate peel.

Optimization of Pressurized Liquid Extraction (PLE) Parameters for Extraction of Bioactive Compounds from Moringa oleifera Leaves and Bioactivity Assessment.

Moringa oleifera leaves are rich sources of bioactive compounds with potential health benefits, including antioxidants and anti-inflammatory agents. Pressurized liquid extraction (PLE) stands out as a promising technique for effectively extracting valuable compounds from natural sources. In this study, we aimed to optimize PLE parameters, such as temperature, extraction duration, and pressure, to maximize bioactive compound (polyphenols, flavonoids, and ascorbic acid) yield from M. oleifera leaves and evaluate their antioxidant and anti-inflammatory activities. According to the outcomes of this research, the maximum achieved total polyphenol content was 24.10 mg gallic acid equivalents (GAE)/g of dry weight (dw), and the total flavonoid content was increased up to 19.89 mg rutin equivalents (RtE)/g dw. Moreover, after HPLC-DAD analysis, neochlorogenic and chlorogenic acids, catechin and epicatechin, rutin, and narirutin were identified and quantified. As far as the optimum ascorbic acid content is concerned, it was found to be 4.77 mg/g dw. The antioxidant activity was evaluated by three different methods: ferric reducing antioxidant power (FRAP), the DPPH method, and the anti-hydrogen peroxide activity (AHPA) method, resulting in 124.29 µmol ascorbic acid equivalent (AAE)/g dw, 131.28 µmol AAE/g dw, and 229.38 µmol AAE/g dw values, respectively. Lastly, the albumin denaturation inhibition was found to be 37.54%. These findings underscore the potential of PLE as an efficient extraction method for preparing extracts from M. oleifera leaves with the maximum content of bioactive compounds.

Eco-friendly solvent-based liquid-liquid extraction of phenolic acids from winery wastewater streams.

This study proposes liquid-liquid extraction (LLE) for the recovery of phenolic acids from winery wastewater replacing common volatile organic compounds (VOCs) with environmentally friendly solvents. On one hand, terpenes (α-pinene and p-cymene) and terpenoids (eucalyptol and linalool) were selected as green solvents and compared to common VOCs (ethyl acetate or 1-butanol). On the other hand, gallic acid (GA), vanillic acid (VA), syringic acid (SA) and caffeic acid (CA) were selected as phenolic acids to be recovered. The extraction performance was evaluated under different operation conditions: solvent-to-feed ratio, initial concentration of phenolic acids and temperature. This work also evaluated the back-extraction whole process global recovery and solvent regeneration, by means of aqueous NaOH solution. Eucalyptol has shown the highest overall global extraction performance (21.07 % for GA, 93.21 % for VA, 78.79 % for SA, and 80.57 % for CA) and lower water solubility compared to the best performing VOC solvent (1-butanol). Therefore, eucalyptol can be a potential eco-friendly solvent to replace VOCs for sustainable phenolic acid recovery from winery wastewater. Finally, to ensure a clean water stream after the LLE, the traces of solvent were completely removed by electrooxidation with boron-doped diamond anode at a current density of 422.54 A/m2.

Development of complete hydrometallurgical processes for gold recovery from ICs and CPUs using ionic liquids.

Integrated circuits (ICs) and central processing units (CPUs), essential components of electrical and electronic equipment (EEE), are complex composite materials rich in recyclable high-value strategic and critical metals, with many in concentrations higher than in their natural ores. With gold the most valuable metal present, increase in demand for gold for EEE and its limited availability have led to a steep rise in the market price of gold, making gold recycling a high priority to meet demand. To overcome the limitations associated with conventional technologies for recycling e-waste, the use of greener technologies (ionic liquids (ILs) as leaching agents), offers greater potential for the recovery of gold from e-waste components. While previous studies have demonstrated the efficiency and feasibility of using ILs for gold recovery, these works predominantly concentrate on the extraction stage and often utilise simulated solutions, lacking the implementation of a complete process validated with real samples to effectively assess its overall effectiveness. In this work, a simulated Model Test System was used to determine the optimal leaching and extraction conditions before application to real samples. With copper being the most abundant metal in the e-waste fractions, to access the gold necessitated a two-stage pre-treatment (nitric acid leaching followed by aqua regia leaching) to ensure complete removal of copper and deliver a gold-enriched leach liquor. Gold extraction from the leach liquor was achieved by liquid-liquid extraction using Cyphos 101 (0.1 M in toluene with an O:A = 1:1, 20 °C, 150 rpm, and 15 min) and as a second process by sorption extraction with loaded resins (Amberlite XAD-7 with 300 mg of Cyphos 101/g of resins at 20 °C, 150 rpm and 3 h). In both processes, complete stripping and desorption of gold was achieved (0.5 M thiourea in 0.5 M HCl) and gold recovered, as nanoparticles of purity ≥95%, via a reduction step using a sodium borohydride solution (0.1 M NaBH4 in 0.1 M NaOH). These two hydrometallurgical processes developed can achieve overall efficiencies of ≥95% for gold recovery from real e-waste components, permit the reuse of the IL and resins up to five consecutive times, and offer a promising approach for recovery from any e-waste stream rich in gold.

Quantification of Trimethylamine-N-Oxide and Trimethylamine in Fish Oils for Human Consumption.

Supplementing fish oil is one of the strategies to reduce the risk of cardiovascular disease, the leading cause of death around the world. Contradictorily, fish oil may also contain trimethylamine-N-oxide, a recently emerged risk factor for cardiovascular disease, as well as one of its precursors, trimethylamine. A method suitable for routine quantification of trimethylamine-N-oxide and trimethylamine in fish oil with a quick and easy liquid extraction without derivatization has been developed. Liquid chromatography with tandem mass spectrometry detection was employed along with a zwitterionic hydrophilic interaction liquid chromatography column and a gradient elution with eluents containing 50 mmol/L of ammonium formate. An internal standard (triethylamine) was used for quantification by mass spectrometry with an external calibration. The assay proved high linearity in the ranges of 10 to 100 ng/mL and 100 to 1000 ng/mL for trimethylamine-N-oxide and trimethylamine, respectively. The lowest limit of quantification was determined to be 100 µg/kg for trimethylamine and 10 µg/kg for trimethylamine-N-oxide, with the limit of detection at 5 µg/kg and 0.25 µg/kg, respectively. Accuracy ranged from 106-119%. Precision was below 7% the relative standard deviation for both analytes. The method was successfully applied for the determination of trimethylamine-N-oxide and trimethylamine contents in nine commercially available liquid fish oils and three commercially available fish oil capsules, showing that trimethylamine and trimethylamine-N-oxide are not present in highly refined fish oils.

Selective Solid-Liquid Extraction of Lithium Cation Using Tripodal Sulfate-Binding Receptors Driven by Electrostatic Interactions.

Owing to the important role of and increasing demand for lithium resources, lithium extraction is crucial. The use of molecular extractants is a promising strategy for selective lithium recovery, in which the interaction between lithium and the designed extractant can be manipulated at the molecular level. Herein, we demonstrate that anion receptors of tripodal hexaureas can selectively extract Li2SO4 solids into water containing DMSO (0.8% water) compared to other alkali metal sulfates. The hexaurea receptor with terminal hexyl chains displays the best Li+ extraction selectivity at 2-fold over Na+ and 12.5-fold over K+. The driving force underpinning selective lithium extraction is due to the combined interactions of Li+-SO42- electrostatics and the ion-dipole interaction of the lithium-receptor (carbonyl groups and N atoms); the latter was found to be cation size dependent, as supported by computational calculations. This work indicates that anion binding receptors could drive selective cation extraction, thus providing new insights into the design of receptors for ion recognition and separation.

Influence of Diluent on Extraction Parameters of Systems for Separation Am(III) and Ln(III) Based on 1,10-Phenanthroline-2,9-Diamide.

A systematic study of extraction systems for the separation of f-elements using the tetradentate N,O-donor diamide of 1,10-phenanthroline-2,9-dicarboxylic acid (L) in various molecular and ionic solvents was performed. It was demonstrated that the nature of a diluent has a significant impact on solvent extraction of Am(III) and Ln(III) and the stoichiometry of formed complexes with f-elements. The mechanism of complexation and forms of complexes in different diluents were investigated by radiometric methods, UV-vis titration, and XRD.

Extraction of Pyrrole from Its Mixture with n-Hexadecane Using Protic Ionic Liquids.

The removal of nitrogen compounds from fuel via the conventional method, which is hydrodenitrogenation, is costly and involves catalysts and energy-intensive conditions (600 K and 300 atm). Recently, ionic liquids (ILs) have emerged as a promising alternative solvent for the denitrogenation of fuel oil. However, certain ILs are expensive and challenging to synthesize, prompting the exploration of protic ionic liquid (PIL) substitutes, which offer similar advantages to ILs. This study utilized the conductor-like screening model for real solvents (COSMO-RS) to predict the phase equilibria for three PILs-triethylammonium p-toluenesulfonate (TEA-TSA), triethylammonium salicylate (TEA-SA) and triethylammonium benzoate (TEA-BZ)-which were subsequently validated through experimental investigations. Liquid-liquid extraction experiments were conducted at 298 K and 1 atm, with pyrrole (serving as the model nitrogen compound) concentrations in n-hexadecane (representing the model fuel) ranging from 10 to 50 wt%. Additionally, the NRTL model effectively correlated the experimental tie lines. The obtained data indicated that TEA-TSA exhibited superior selectivity and distribution ratio compared to TEA-SA and TEA-BZ. All the ternary systems tested displayed positive slopes, suggesting a higher affinity of nitrogen compounds for the PIL. Supporting this observation, interaction energy (ΔE) and excess enthalpy (HE) were employed. The predicted outcomes revealed that TEA-TSA had high ΔE, and all PILs exhibited negative values of HE. The HE calculation underscored the significance of strong hydrogen bond interactions between pyrrole and the PIL for successful extraction.