Liquid-liquid Solvent Extraction Research Articles

Performance prediction of disc and doughnut extraction columns using bayes optimization algorithm-based machine learning models

Pulsed disk and doughnut column (PDDC) is widely applied in liquid-liquid solvent extraction. Due to a nonlinear and complex mechanism in PDDC, existing single empirical models often fail to predict the performance of different PDDCs. In this work, machine learning (ML) models such as random forest (RF), support vector machine (SVM), and artificial neural network (ANN) are developed to predict the PDDC's performance including dispersed-phase holdup (xd), drop size (d32), axial diffusion coefficient (Ec) and the height of mass transfer unit (Hoc). ML models were trained based on a comprehensive dataset and the results showed that the prediction performances of the ML models are better than the empirical correlations. The best average absolute relative error (AARE) and correlation coefficient (R2) of d32, xd, Ec and Hoc were 3.97% and 0.99, 10.16% and 0.955, 12.71% and 0.973, 13.44% and 0.982, respectively. RF and SVM exhibited the highest predictive accuracy. Furthermore, the feature importance was determined, which indicated the most significant features for d32, xd, Ec and Hoc were pulse intensity, the velocity of dispersed phase, the velocity of continuous phase and the properties of continuous phase, respectively. This study provided a new perspective to model and design PDDC.

Rapid and simultaneous determination of multiple endocrine-disrupting chemicals and their metabolites in human serum and urine samples

Bisphenols, parabens, and their metabolites are a group of chemical compounds with a wide range of polarities but similar chemical structures, which presents a challenge for the simultaneous determination of these compounds in complex biological samples. In this study, a rapid and sensitive method for simultaneous quantification of free bisphenol A (BPA), conjugated BPA, bisphenols, and parabens analogs was developed using solid-phase extraction (SPE) tandem liquid–liquid extraction (LLE). We compared the effects of different types of SPE cartridges, diluents, and LLE solvents on the analyte recovery. Utilizing the direct and indirect determination methods (enzyme hydrolysis), we confirmed the accuracy of the direct method for measuring BPA glucuronide and BPA disulfate. The method enabled the analysis of 24 endocrine-disrupting chemicals (EDCs) in one injection through UHPLC-MSMS measurements, with satisfactory recovery (mean: 91.8–98.6% for urine, 80.2%–96.8% for serum) and precision (RSD <15%). The LOD and LOQ values were 0.003 and 0.01 ng/mL for serum, and 0.002 and 0.006 ng/mL for urine samples, respectively. For real sample analysis, the median concentration of analytes in serum and urine samples ranged from 0.04 ng/mL (BPS) to 56.4 ng/mL (4-HB) and 0.11 ng/mL (BPA) to 136 ng/mL (4-HB), respectively. This method provides a new strategy to simultaneously identify compounds with a wide range of polarities from complicated biological matrices.

Optimization of a method to detect levothyroxine and related compounds in serum and urine by liquid chromatography coupled to triple quadrupole mass spectrometry

Thyroid hormones and their derivatives are structurally related to the non-essential amino acid tyrosine (4-hydroxyphenylalanine). However, there are physicochemical differences that make it difficult to apply an analytical method for their simultaneous detection. This work focused on the optimization of a method using liquid chromatography-electrospray ionization mass spectrometry to measure eight compounds related to levothyroxine (T4). In addition, the influence of the additives to the mobile phase, the solvents for liquid-liquid extraction and the influence of the hydrolysis of the conjugated analytes were studied.Optimization of MRM transitions and collision energy for analytes and capillary voltage, nebulizer gas pressure, nozzle voltage, sheath gas flow, sheath gas temperature, drying gas flow and drying gas temperature for ionization source was done. The recovery of analytes was studied using five solvents and six solvent systems to introduce them into the liquid-liquid extraction and matrix cleanup steps. Different additives to the mobile phase were evaluated as well as the effectiveness of enzymatic and chemical hydrolysis.The best MRM transitions and source parameters were settled in order to generate an optimized instrumental method. The addition of ammonium formate, ammonium fluoride, and acetic acid to the mobile phase showed no improvement in responses compared to classic 0.1% formic acid. The use of tert-butyl methyl ether: isopropanol (75: 25, V: V) showed a suitable recovery of analytes to perform a liquid-liquid extraction, and n-hexane might be an appropriate solvent if a cleanup step is needed. The stability of T3, T4 and thyronine, checked after the hydrolysis with extracts of E. coli and H. pomatia showed good results, contrary to chemical hydrolysis that showed a total degradation of T3 and T4.

Simultaneous determination of 46 semi-volatile organic compounds in water by liquid-liquid extraction-gas chromatography-mass spectrometry

半挥发性有机物主要包括多环芳烃类(PAHs)、邻苯二甲酸酯类(PAEs)、有机氯农药类(OCPs)和硝基苯类(NBs)等化合物,这些物质多具有致癌、致畸、致突变作用,以及内分泌干扰效应。因此,快速准确测定水中半挥发性有机物非常重要,目前国内尚无水中半挥发性有机物的检测标准。该研究从氮吹温度、水样pH值和萃取时间3个方面进行了优化,旨在建立一种液液萃取-气相色谱-质谱(LLE-GC-MS)同时测定水中46种半挥发性有机物的方法。结果表明:氮吹温度对46种半挥发性有机物的回收率影响不大,考虑回收率及浓缩效率,将氮吹温度设定为35 ℃;水样在中性环境下萃取效果好于碱性环境下的效果;萃取时间由7 min增加至10 min时,回收率也随之提高,但时间增加至15 min时,17种(占比37%)化合物回收率有所增加,29种(占比63%)化合物回收率则呈降低趋势。因此,将萃取时间设定为每次10 min。采用气相色谱-质谱仪进行检测,内标法定量。该方法在20.0~2000 μg/L范围内线性良好,相关系数(r 2)≥0.9916, 46种SVOCs检出限为0.28~16.55 ng/L,定量限为0.92~55.16 ng/L;在0.02、0.2、0.4 μg/L 3个加标水平下的平均回收率为63.6%~125%,相对标准偏差(n=6)为1.03%~17.0%。采用该方法检测了黄河流域济南段的27个地表水样品,检出的物质以PAEs和PAHs为主,2种OCPs在部分点位有检出,NBs均未检出。该方法操作简单,通用性强,准确度及精密度良好,检出限低,适用于地表水及地下水中46种半挥发性有机物的同时检测。

Miniaturized multiresidue method for the analysis of pesticides and persistent organic pollutants in non-target wildlife animal liver tissues using GC-MS/MS

In order to gain a better insight into pesticide and pollutant exposure of small (non-target) wildlife animals, a QuEChERS sample preparation method was first developed for 5 g liver tissues (e.g. hedgehog samples) and then downscaled for the analysis of 100 mg liver tissues (e.g. bat samples). The optimized (micro) QuEChERS methods used 1% acetic acid in acetonitrile as organic solvent for liquid-liquid extraction (LLE) and salting out was performed with anhydrous magnesium sulfate and sodium acetate (4:1). After a freezing-out step, sample clean-up was carried out with anhydrous magnesium sulfate, PSA, C18, and GCB (150:25:20:5). Overall, 209 pesticides and persistent organic pollutants (POPs) can be analysed within each sample with gas chromatography coupled to tandem mass spectrometry (GC-MS/MS). Both methods were validated with representative analytes according to the European Commission guideline SANTE/12682/2019. Limits of quantification were between 1 and 20 μg kg−1, and the methods proved to be linear up to 400 μg kg−1. Additionally, the analytes delivered satisfactory results regarding recovery and precision. As proof of concept, samples of six hedgehog livers were analysed with both methods to prove the accuracy of the micro QuEChERS method. Additionally, six livers of different bat species were analysed with the downscaled method. The newly developed micro QuEChERS method for multiresidue analysis requires only minute amounts of biomaterial and represents a sophisticated novel technique for determining the exposure of small wildlife animals to different contaminants.

Liquid-liquid extraction of Toluene from Heptane using [EMIM][NTF2] ionic liquid: Experimental and extensive thermodynamics study

The performance of the ionic liquid (1-ethyl-3methylimidazolium bis(trifluoromethylsulfonyl)imide, [EMIM][NTF2]) as a green, non-aqueous and hydrophobic solvent and sulfolane as a conventional solvent for liquid-liquid extraction of toluene from its mixture with heptane was investigated. The LLE phase behavior was predicted with the help of the UNIFAC as a predictive thermodynamic model. The interfacial tension of the studied systems was measured to investigate the effect of the dissolved toluene concentration on interfacial tension. It was revealed that the average selectivity of the systems with IL (316.752) is much higher than the systems containing sulfolane (18.661) under similar experimental conditions. For low mass fractions of toluene less than 0.4, the performance of the IL is better, whereas, for high toluene mass fraction more than 0.4, sulfolane exhibits superior performance.

Determination of trace uranium in thorium matrix by laser induced fluorimetry after separation of thorium by its fluoride precipitation using NH4HF2

Abstract Thorium, a major element in thorium matrix, quenches uranium fluorescence when it is present above the ratio (Th/U) of 2000 in conventional pellet fluorimetry determination of uranium. A single step ‘sample digestion cum thorium fluoride precipitation’ with NH4HF2 has been developed for separation of bulk thorium as hydrated thorium fluoride precipitates. Uranium in aqueous solution is extracted into ethyl acetate and stripped into pyrophosphate medium (pH ∼ 7), prior to its laser induced fluorimetry determination. Optimizations of certain parameters such as the effects of fluoride flux, mineral acid, temperature and time, stripping solution, diverse ions etc. are discussed in detail. The method has been validated by analyzing a set of synthetic mixtures and certified reference materials of rock samples such as SY-2, SY-3, GSP-2, NKT-1 and CG-2 doped with a large excess of thorium. This method has been applied for the determination of microgram to nanogram uranium in thorium rich rocks and synthetic nuclear grade ThO2 with high degree of accuracy and precision. This is the improvement of the existing method which involves two liquid-liquid solvent extraction separation of thorium and uranium using the chelating agent 2,3-dihydroxynaphthalene at the different pH, compared to one solvent extraction separation of uranium in the present method, because separation of thorium by precipitation as its fluoride has already been carried out during sample digestion step itself. The proposed method involving ammonium hydrogen fluoride in combination with laser induced fluorimetry is simple, rapid, cost effective and more eco-friendly.

Hydrophobic Deep Eutectic as a New Solvent for Liquid-Liquid Extraction and Its Potential Application in Ligandless Extraction of Cu (II)

Background: The cost-effective and environmentally benign solvent of hydrophobic deep eutectic (DES) was prepared for the removal of Cu (II) from aqueous solution. Hydrophobic DES has been gaining increasing attention from researchers for the replacement of hazardous solvent consumption in liquid-liquid extraction (LLE). Objectives: To synthesize the hydrophobic DES and optimize the parameters for ligandless LLE using DES, and LLE with DES-LIG, respectively. Materials and Methods: The fatty acid-based DES was prepared using a mixture of capric acid (C10) and lauric acid (C12) as a potential solvent for the extraction of Cu (II). The DES was characterized via FT-IR, NMR, and TGA. The removal percentage of Cu (II) was compared between ligandless LLE and other conventional LLE techniques. DES was used as the solvent in the ligandless LLE, while 1,10-phenanathroline ligand with DES (DES-LIG) was used in the conventional LLE techniques. The optimized parameters such as pH, initial concentration, and contact time for Cu (II) removal were studied and analyzed using atomic absorption spectroscopy (AAS). Results and Discussion: The ligandless LLE with DES demonstrated the highest removal percentage of Cu (II) at optimum conditions of pH 8, initial concentration of 80 μg mL-1, and contact time of 45 minutes. Conclusion: The removal of Cu (II) was more effective in ligandless LLE using DES.

Microvolume Screening of Extraction and Phase Behavior in a Liquid-Liquid Microsystem.

Spontaneous formation of a third immiscible phase during liquid-liquid solvent extraction presents an enormous technical challenge for industry. Insight from current empirical investigations is greatly limited by the lack of methodologies that simultaneously report the progress of the extraction, third-phase onset time, and chemical and physical nature. The microfluidic strategy presented here answers this challenge by supporting an optically transparent submicroliter organic-phase film in a micropillar array surrounded by the aqueous phase. To demonstrate, we used 1 M Cyanex 572 in Shellsol D70 (organic phase) to extract Yb3+ and Dy3+ from a pH 2 aqueous phase. Real-time optical tracking confirmed that the visual onset of third-phase formation is consistent with the cessation of extraction (at the loading limit). Spectroscopic analysis of the solid-like third phase was carried out successfully. The new analytical approach offers a step change in speed and efficiency for reagent development, process control, and fundamental studies of complex phase behavior in reactive multiphase systems.

Identification of Transient Receptor Potential Vanilloid 3 Antagonists from Achillea alpina L. and Separation by Liquid-Liquid-Refining Extraction and High-Speed Counter-Current Chromatography.

Bioassay-guided fractionation of the ethanol extract of whole herbs of Achillea alpina led to the isolation of isochlorogenic acids A and B as transient receptor potential vanilloid 3 (TRPV3) channel antagonists by using a calcium fluorescent assay. The structures were identified by spectroscopic analysis and the inhibitory activities of isochlorogenic acids A and B were confirmed by whole-cell patch clamp recordings of human embryonic kidney 293 (HEK293) cells expressing human TRPV3. Molecular docking results revealed that these two compounds reside in the same active pocket of human TRPV3 channel protein with lower binding energy than the agonist 2-aminoethoxydiphenyl borate (2-APB). High-speed counter-current chromatography (HSCCC) coupled with a liquid-liquid extraction approach was successfully established for the separation of isochlorogenic acids A and B from the whole herbs of A. alpina. Ethyl acetate and n-hexane-ethyl acetate-water (3:3:4 and 1:5:4, v/v/v) were selected as liquid-liquid extraction solvent systems to remove high- and low-polarity impurities in the mixture. Sixty g of ethanol extract was refined by solvent partition to yield 1.7 g of the enriched fraction, of which 480 mg in turn obtained 52.5 mg of isochlorogenic acid B (purity 98.3%) and 37.6 mg isochlorogenic acid A (purity 96.2%) after HSCCC with n-hexane-ethyl acetate-water containing 1% acetic acid (1:4:8, v/v/v).

Practical method for air sampling and analysis of some natural gas odorant

In this study, a method was presented for sampling and analysis of co-exposure to gas odorants such as methyl ethyl sulphide (MES), dimethyl sulphide (DMS) and tert-butyl mercaptane (TBM). An impregnated fibre glass with mercuric acetate was used for air sampling of odorants. In this study, odorant assessment was optimised with respect to the mercuric acetate, type of solution for odorant releasing and type of solvent for liquid-liquid extraction. Air sampling simulation was provided by standard preparation in tedlar bag. Odorants were analysed by gas chromatography equipped with mass spectrometry. Odorants released from 7% impregnated filters by 20% hydrochloric acid. MES, DMS and TBM were extracted by dichloroethane. Inter-day and intra-day coefficients variation was found to be lower than 11 by the recovery higher than 94%. According to the results of the recent study, a practical and reliable method was presented for air sampling and analysis of DMS, MES and TBM. [Received: October 8, 2019; Accepted: April 23, 2020]

Decomposition of deep eutectic solvents based on choline chloride and phenol in aqueous phase

Deep eutectic solvents (DESs) are compounds formed by donor and acceptor of hydrogen bond in a liquid state at ambient temperature. They are non-volatile, with high thermal stability and readily dissolve many organic and inorganic compounds. DESs based on choline chloride and phenol have recently appeared in analytical practice and have already found wide application in various fields. The numerous articles have been reported efficient liquid-liquid extraction using these DESs as extraction solvents. In this paper the process of liquid-liquid extraction using DESs based on choline chloride and phenol was investigated. It was established that the DES decomposition in aqueous phase takes place due to the dissociation of choline and phenol, which leads to the destruction of the hydrogen bond. In addition, with the addition of an aprotic solvent, tetrahydrofuran, the extraction of organic phase is observed. This phase was mistakenly used as DES, but in our study we showed that this phase consists of tetrahydrofuran, water and phenol, which is not the initial phase of DES. This phenomenon was investigated by gas chromatography with mass spectrometric detection and coulometric Karl-Fischer titration It was confirmed that these DESs cannot be considered as extraction solvents in liquid-liquid extraction from aqueous solutions. The main goal of the present work is to pay attention of researchers to a wrong conception in liquid-liquid extraction using DESs based on choline chloride and phenol to avoid mistakes in the future.

Deep insights into the solution and interface behaviors in heavy rare earth extraction: A molecular dynamics study

Heavy rare earth extraction (HRE) is a complex process involving extractant partition, complexation at metastable oil-water interface and cation separation from aqueous phase to organic phase. Beyond the coordination chemistry of the HRE extracted complex, the solution and interfacial behaviors can be crucial to extractant distribution, orientation and reactivity of ionic species for understanding and further improving the extraction performance. We report a molecular dynamics investigation on dilute and concentrated solutions of four acidic organophosphoric extractants (P507, P204, P227 and Cyanex272) in pure oil phase and oil-water biphasic systems for purpose of depicting solution and interface behaviors, which has been a cornerstone of chemistry in solvent extraction and separation. We can intuitively find that the single extractant promotes the interface movement. When the extractants get concentrated in organic phase, they diffuse and aggregate to dimers and trimers. In oil-water biphasic system, most of the extractants tend to migrate to the interface and remain an excess adsorption phenomenon, where –OH groups point towards water and are ready to capture an approaching HRE cation. Some important findings of different extractants are determined by theoretical simulation, such as interfacial activity, residual water number in equilibrated organic phase and capture time of HRE cation. These simulated quantitative features are in good agreement with the experiments of interfacial tension, phase separation and kinetic extraction. The results indicate the key role of the amphiphilic moiety, the oxygen atoms of P–O ester linkages and the hydrophobicity of P–C ester linkages of extractants in the HRE extraction process. This MD study could provide a straightforward approach to comprehensively evaluate and design the extractants for liquid-liquid solvent extraction in future.

Development and validation of a GC\u2013MS/MS method for the determination of 11 amphetamines and 34 synthetic cathinones in whole blood

PurposePsychoactive compounds that contain a phenylethylamine structure (such as amphetamine-type stimulants and synthetic cathinones) are one of the major classes of stimulants on the recreational drug market. Approximately 670 new psychoactive substances (NPS) are monitored only in Europe; however, new psychoactive compounds are being developed for illicit trade each year. In this context, the development of new analytical procedures for the determination of such compounds in biological specimens for forensic toxicology is of great importance.MethodsGas chromatography–tandem mass spectrometry (GC–MS/MS) technique was applied for analysis of amphetamines and synthetic cathinones. The volumes of 200 µL of each whole blood sample and 1 mL of liquid-liquid extraction solvent were used for extraction, followed by pentafluoropropionyl derivatization.ResultsA high-throughput, robust, rapid, and sensitive procedure involving a simple liquid-liquid extraction for the simultaneous determination of 45 amphetamine-type stimulants and synthetic cathinones in whole blood was developed. The assay was validated based on its recovery (83.2–106%), interday accuracy (89.0–108%), and interday precision (≤ 8.1%). In view of the low limits of detection (ranged between 0.02 and 0.72 ng/mL) and limits of quantification (1 and 2.5 ng/mL), the developed method can serve as a less expensive and more ecologically friendly alternative to the liquid chromatography–tandem mass spectrometric methods.ConclusionsTo the best of our knowledge, this is the first work presenting a GC–MS/MS method for the determination of NPS in blood samples. The presented procedure was applied to authentic samples from forensic cases, demonstrating its utility in the quantification of a wide number of psychoactive substances in routine toxicological analyses. The developed procedure can also be easily expanded to additional compounds.

Cytotoxic Properties of Damiana (Turnera diffusa) Extracts and Constituents and A Validated Quantitative UHPLC-DAD Assay.

In our continuing search for new cytotoxic agents, we assayed extracts, fractions, and pure compounds from damiana (Turnera diffusa) against multiple myeloma (NCI-H929, U266, and MM1S) cell lines. After a first liquid-liquid solvent extraction, the ethyl acetate layer of an acetone (70%) crude extract was identified as the most active fraction. Further separation of the active fraction led to the isolation of naringenin (1), three apigenin coumaroyl glucosides 2–4, and five flavone aglycones 5–9. Naringenin (1) and apigenin 7-O-(4″-O-p-E-coumaroyl)-glucoside (4) showed significant cytotoxic effects against the tested myeloma cell lines. Additionally, we established a validated ultra-high performance liquid chromatography diode array detector (UHPLC-DAD) method for the quantification of the isolated components in the herb and in traditional preparations of T. diffusa.

Process modelling, design and technoeconomic Liquid–Liquid Extraction (LLE) optimisation for comparative evaluation of batch vs. continuous pharmaceutical manufacturing of atropine

Continuous Pharmaceutical Manufacturing (CPM) can revolutionise industrial efficiency via potential operational and economic benefits over currently dominant batch methods. Process modelling and optimisation are valuable towards rapid design space evaluation and elucidation of optimal process design configurations, without expensive and time-consuming experimental campaigns. This paper pursues total cost minimisation via nonlinear optimisation of different separation design options for atropine, a product of great societal importance. The study considers a demonstrated continuous flow synthesis, presents reaction kinetic parameter estimation towards reactor design, and illustrates a comparative analysis of the subsequent batch vs. continuous liquid–liquid extraction (LLE) for product purification, using published partition coefficient data and UNIFAC-modelled ternary liquid–liquid equilibria. Original optimisation results show that toluene is the best continuous LLE solvent, attaining the lowest total costs at both plant capacities considered and the greatest total cost savings with respect to the batch LLE design for varying solvent recovery, at acceptable material efficiencies.

Extraction of Nicotine (3-(1-methyl-2-pyrrolidinyl) pyridine) from Tobacco Leaves Separated from Gold Live Classic Brand™ Cigarettes by Solvent Extraction Approach and Characterization via IR Analysis

Nicotine is obtained from the tobacco plant, Nicotiana tabacum L. This plant comes from the nightshade family which has other members including red peppers, eggplant, tomatoes and potatoes. In this study, Nicotine was extracted from tobacco leaves separated from Gold Live Classic BrandTM cigarettes using liquid-liquid solvent extraction method with ether by dissolving the leaves in NaOH solution. The percentage yield determined after the whole extraction method was 0.6%. Calculated percent recovery was 0.6 %, this percentage yield clarified that in this brand, very small nicotine is investigated, this deduces a significant loss of product throughout the procedure which are due to formation of emulsions and not due to washing thoroughly with ether to extract maximum yield, so repeated the process three times. In order to verify the nicotine, other physical properties were determined, MW;162.23g/mol, MP; -79oC, and BP; 246.8oC. While the [α]D of nicotine; -168.5o at the temperature of 293.15K was determined. Distinct peaks on the IR spectra indicated the bond frequencies of certain functional groups, which also confirm the nicotine.

Measurements of activity coefficients at infinite dilution for organic solutes in two quaternary ammonium-based ionic liquids [DDA][ClO4] and [DDA][BF4

The paper presents new data on the activity coefficient at infinite dilution (γ13∞) for 29 various organic solutes: alkanes, alkenes, al-kynes, cycloalkanes, alcohols, ethers, ketones and aromatic hydrocarbons in two quaternary-ammonium based ionic liquids (quat-based ILs): didecyldimethylammonium perchlorate [DDA][ClO4] and didecyldimethylammonium tetrafluoroborate [DDA][BF4]. The activity coefficient at infinite dilution and physicochemical properties of two mentioned ionic liquids, were determined by inverse gas chromatography at four different temperatures: 308K, 323K, 338K and 353K. Additionally, on the basis of the specific retention volume (Vg0) the Flory – Huggins interaction parameters (χ∞) were determined. In order to identify the fundamental interaction between solute and solvent inside the column, the partial molar excess enthalpies at infinite dilution (ΔH1E,∞) were calculated on the basis of experimental γ13∞ values. The selectivity (Sij∞) and capacity (kj∞) at infinite dilution for a few different separation problems: hexane/benzene, cyclohexane/benzene and hexane/tetrahydrofuran were calculated from the experimental γ13∞ values to evaluate the possible use of the ionic liquids studied as a new class of solvents in liquid-liquid extraction and in other extraction or microextraction methods. The values of the above-mentioned parameters were compared and discussed taking into regard the chemical structures of both quaternary ammonium-based ionic liquids, including the same cation and their interactions with the organic solute.

The role of solvent and neutral organophosphorus extractant structure in their organization and association

The choice of organic solvent is known to impact metal ion partitioning in solvent extraction systems, although an understanding based on molecular interactions has been largely qualitative. To provide a more quantitative and molecular scale understanding of extractant and solvent association in liquid-liquid solvent extraction systems, molecular dynamics studies of binary extractant/solvent systems are conducted for several organophosphorus solvating extractants across a range of organic solvents. Classical molecular dynamics potentials for the extractants are optimized in pure phase simulations. These potentials are then validated with binary extractant/solvent solutions by comparison to experimental data for percent volume change on mixing and mixing enthalpies. Trends in association free energy, mixing enthalpy and deviations from ideal mixing volume are reported for each extractant and solvent binary mixture. Contributions to those properties depending on extractant and solvent molecular structure are investigated, including the relative enthalpic favorability of extractant solutions in toluene, diethyl ether or n-hexane. Inclusion of the ether group in diethyl ether lowered the enthalpy of mixing to a similar degree as reducing the alkane solvent chain length from n-dodecane to n-hexane owing to dipole-dipole interactions with the “head” and “tail” regions of the extractant molecules, which depend on extractant alkyl chain length. Despite similar percent volume changes on mixing with n-hexane or diethyl ether, extractant/toluene mixtures were significantly more enthalpically favorable with an enthalpy of mixing minimum controlled by stoichiometry rather than volume fraction, as observed for alkane solvents.

Delignification from Geodae-Uksae1 using soda-pulping followed by evaluation on recycling of liquid-liquid extraction solvent

In this study, lignin, monomeric sugars, and organic acids are separated effectively from Geodae-Uksae1 (GU1, Miscanthus spp) using various processes such as soda-pulping, liquid-liquid extraction (LLE), and distillation. Soda-pulping is performed using a 1 L rocking reactor at a liquid-solid ratio of 8:1, temperature of 170 °C, H-factor of 900 (the H-factor is a function of time and temperature), and NaOH concentrations of 10 g kg−1, 40 g kg−1, and 80 g kg−1, the experiment condition for highest pulp and delignification yields is approximately 64.0% and 78.6% at 10 g kg−1 and 20 g kg−1 NaOH, respectively. The hydrolyzate derived using soda-pulping and acid hydrolysis carried out LLE with liquid-liquid solvents (LLESs) as tri-octyl phosphine oxide (TOPO) and tri-alkyl phosphine oxide (TAPO). Afterwards, the used LLESs in LLE process are performed on distillation process and reused at LLE process. These results showed that the extraction efficiency of acetic acid using TOPO and TAPO decreased to 33.1% 23.5% at the number of recycled tenth times, respectively. In addition, the extraction efficiency of acetic acid using TOPO and TAPO after washing with 40 g kg−1 NaOH solution are 66.31% and 67.99% at the number of recycled tenth times, respectively. Through recycling of LLESs, washing treatment using alkaline solution is necessary process in recycling process of LLESs.