Recovery of lithium from salt-lake brine by liquid–liquid extraction using TBP-FeCl3 based mixture solvent

In this study, a complete cyclic process was developed for the lithium extraction from high-concentration salt-lake brine by using a high flash point, low water solubility, and low toxicity diluent mixed with the TBP-FeCl₃-based organic solvent. The process was composed of four sections, including extraction, scrubbing, stripping, and regeneration. The optimal conditions for each section were determined first. Then, a 13-stage cyclic extraction process was designed and validated experimentally for the high lithium concentration brine, which reached 8.612 g/L. By using the diluent at the optimized conditions, the overall recovery of lithium was higher than 96%. The stripping liquid contained 38.87 g/L Li⁺, while all the ratios of impurities of sodium, potassium, and magnesium to lithium were less than 0.1. The aims of enrichment and purification of Li⁺ from the complicated brine system were achieved by the developed extraction process with little Fe loss, which provided the technical support for the development of the salt-lake lithium resource.     

Comparison of supercritical fluid and solvent extraction methods in extracting γ-oryzanol from rice bran

Organic solvents were compared with supercritical CO₂ relative to efficiency for extracting lipid and γ-oryzanol from rice bran. A solvent mixture with 50% hexane and 50% isopropanol (vol/vol) at a temperature of 60°C for 45–60 min produced the highest yield (1.68 mg/g of rice bran) of γ-oryzanol among organic solvents tested. The yield of γ-oryzanol without saponification was approximately two times higher (P<0.05) than that with saponification during solvent extraction. However, the yield (5.39 mg/g of rice bran) of γ-oryzanol in supercritical fluid extraction under a temperature of 50°C, pressure of 68,901 kPa (680 atm), and time of 25 min was approximately four times higher than the highest yield of solvent extraction. Also, a high concentration of γ-oryzanol in extract (50–80%) was obtained by collecting the extract after 15–20 min of extraction under optimized conditions.     

Recovery of γ-oryzanol from rice bran oil byproduct using supercritical fluid extraction

The residue of fatty acids distillation from rice bran oil soapstock (RFAD-RBOS) is a byproduct from rice bran oil industry. It contains a large amount of γ-oryzanol, which is a valuable antioxidant. The main objective of this work was to investigate the recovery of γ-oryzanol from the RFAD-RBOS using supercritical fluid extraction (SFE). The Soxhlet technique was conducted in order to compare results with SFE. The influence of process parameters over SFE was evaluated in terms of global yield, γ-oryzanol content, γ-oryzanol recovery rate, and fatty acids composition. The mathematical modeling of SFE overall extraction curve (OEC) was also investigated. The condition of 30 MPa/303 K presented the maximum global yield (39 ± 1%, w/w), maximum γ-oryzanol recovery rate (31.3%, w/w), relatively high γ-oryzanol content (3.2%, w/w), and significant presence of monounsaturated and polyunsaturated fatty acids. The logistic model presented the best fit to experimental OEC.     

Modeling of extraction of β-carotene from apricot bagasse using supercritical CO2 in packed bed extractor

This work investigates the modeling of β-carotene extraction from industrial waste product of apricot bagasse at the production of fruit juice. Shrinking core model was selected as the best mathematical model, which characterize the extraction process, after take into consideration of mass transfer mechanisms such as adsorption, diffusion, solubility, and desorption. Effect of main separation parameters such as pressure, temperature, CO₂ flow rate, and particle size on the extraction yields were researched at the supercritical fluid extraction system of laboratory scale and the results were compared with the results obtained from the solution of mathematical model.     

Liquefaction of rice straw in sub- and supercritical 1,4-dioxane–water mixture

The critical liquefaction of rice straw in sub- and supercritical 1,4-dioxane–water mixture was investigated in a 500 mL autoclave at temperature of 260–340 °C, resistance time of 0–20 min, and volume ratios 0–100 vol.% (1,4-dioxane:mixture). The yields of oil and PA + A (preasphaltene and asphaltene) were in the range of 29.64–57.30 wt.% and 6.42–22.68 wt.%, depending on the temperature, resistance time and volume ratio. The synergistic capability of 1,4-dioxane–water mixture could allow the great decomposition of the tubular structure of lignocelluloses. It was shown by the results that the “oxygen-transfer” reaction, deoxygenation and decarboxylation may occur in the liquefaction of rice straw with 1,4-dioxane–water mixture, while deoxygenation and decarboxylation may be the main reaction. The oil and PA + A fractions obtained at different volume ratios were analyzed by FTIR and GC–MS to investigate the effect of the ratios on the type of the compounds in the liquid products. It is shown that the nucleophilic and hydrolytic functions of water might be weaken at the higher ratio of 1,4-dioxane runs, resulting the lower amount of phenolic, acidic, hydrocarbon and ester derivatives in the oil and PA + A fractions.     

Purification of bioxylitol by liquid–liquid extraction from enzymatic reaction mixture

Xylitol purification is the most difficult step of the whole manufacturing process, and its purification being of commercial importance. This study aimed to purify bioxylitol by liquid–liquid extraction (LLE) from enzymatic reaction mixture. Bioxylitol extraction was conducted under various conditions of extraction time (45–105 min), sample to solvent ratio (SSR) (1:1–1:9 v/v), and number of extraction stages (NES) (1–9 n), and the response surface method was followed to optimize the variables. Xylitol separation was markedly affected by SSR and NES. Optimum time, SSR, and NES determined were 60 min, 1:4.5 (v/v), and 5 (n), respectively. Xylitol extraction yield attained was 78.14% (w/w) at these conditions. This research reveals the feasibility of clarifying bioxylitol produced via enzymatic reduction of xylose by LLE using ethyl acetate.     

Liquid–liquid extraction of toluene from its mixtures with aliphatic hydrocarbons using an ionic liquid as the solvent

The knowledge of liquid–liquid equilibria (LLE) of the ternary systems (alkane/toluene/ionic liquid) is essential to develop thermodynamic models for liquid–liquid extraction of aromatics such as toluene from its mixtures with aliphatic hydrocarbons. In this study, new experimental LLE data for the ternary systems (hexane and heptane/toluene/1-methyl-3-octylimidazolium tetraflouroborate) are measured at T = 298.15 K and atmospheric pressure. The capability of ionic liquid for extracting toluene from its azeotropic mixture with aliphatic hydrocarbons (hexane and heptane) has been evaluated by the selectivity and solute distribution coefficients. The Othmer–Tobias equation has been applied to check the consistency of the experimental tie-lines. Finally, the obtained experimental LLE data are satisfactorily correlated by the nonrandom two-liquid model.     

Enrichment of diterpenes in green coffee oil using supercritical fluid extraction – Characterization and comparison with green coffee oil from pressing

Supercritical fluid extraction (SFE) was used to obtain green coffee oil (Coffea arabica, cv. Yellow Catuaí) enriched in the diterpenes, cafestol and kahweol. To obtain diterpenes-enriched green coffee oil relevant for pharmaceuticals, a central composite rotational design (CCRD) was used to optimize the extraction process. In this study, pressure and temperature did not have influences on cafestol and kahweol concentrations, but did affect the total phenolic content (TPC), which ranged from 0.62 to 2.62 mg GAE/g of the oil. The analysis and quantification of diterpenes according to gas chromatography indicated that green coffee oil from SFE presented a cafestol content of 50.2 and a kahweol content of 63.8 g/kg green coffee oil under optimal conditions. The green coffee oil produced from conventional pressing methods presented lower diterpenes content of 7.5 and 12.8 g/kg green coffee oil for cafestol and kahweol, respectively. When SFE was used, the content of the diterpenes in the same green coffee beans was relatively higher, approximately 85% for cafestol and 80% for kahweol. Green coffee oil from SFE also presented fatty acids, such as palmitic acid (9.3 mg MAE/g green coffee oil), the polyunsaturated linoleic acid (ω-6; 11 mg MAE/g green coffee oil) and oleic acid (ω-9; 3.8 mg MAE/g green coffee oil). The physical properties for green coffee oil produced from SFE and conventional pressings showed that densities and viscosities decreased with temperature. For oils produced from both extractions, the density behaviors were similar with values ranging from 0.9419 g/cm³ (25 °C) to 0.9214 g/cm³ (55 °C) from pressings and 0.9365 g/cm³ (25 °C) to 0.9157 g/cm³ (55 °C) for the oil obtained by the SFE. The dynamic viscosity for the pressed oil ranged from 127.8798 mPa × s (25 °C) to 35.0510 mPa × s (55 °C); for the oil from SFE, these lower values ranged from 84.0411 mPa × s (25 °C) and 24.2555 mPa × s (55 °C).     

Response surface optimization of supercritical CO2 extraction of α-tocopherol from gel and skin of Aloe vera and almond leaves

Supercritical fluid extraction (SFE) was studied as an alternative technology in the pharmaceutical industry for the separation of α-tocopherol from gel and skin of Aloe vera and almond leaves. The influence of operating conditions was investigated on the recovery of supercritical carbon dioxide (SC-CO₂) extraction of α-tocopherol from three-year old Aloe vera (Aloe barbadensis Miller) leaf gel. The obtained results were compared with the conventional Soxhlet extraction. Response surface methodology (RSM) was applied to optimize effective variables on the extracted recovery of α-tocopherol. The maximum α-tocopherol recovery of 53.41% from Aloe vera gel was obtained with employing RSM predicted optimal operating conditions of 32 MPa, 45.91 °C, 0.84 ml SC-CO₂/min and 140 min for extraction. The α-tocopherol extraction yield for gel and skin of Aloe vera and almond leaves at these optimal operating conditions were obtained 1.53, 16.29 and 2.61 mg/100 g dry sample, respectively.     

Many-body effects in some thermodynamic properties of supercritical CO2, CO2–Ar,and CO2–CH4 using HFD-like potentials from molecular dynamics simulation

Molecular dynamics simulation has been performed to obtain the pressure and self-diffusion coefficient of supercritical carbon dioxide using a two-body HFD (Hartree–Fock dispersion)-like potential determined via the inversion of reduced viscosity collision integrals at zero pressure. We have also obtained pressures of CO₂–Ar and CO₂–CH₄ fluid mixtures at constant temperatures at different densities using new accurate two-body HFD-like potential functions. To take many-body forces into account, the three-body potentials of Hauschild and Prausnitz [27], Wang and Sadus [30], [38], Oakley et al. [3], and Guzman et al. [33] have been used with the two-body potentials. The significance of this work is that the modified many-body potential of Hauschild and Prausnitz (extended as a function of density, temperature, and molar fraction) has been used with the two-body HFD-like potentials of CO₂, CO₂–Ar, and CO₂–CH₄ systems to improve the prediction of the pressure values without requiring an expensive three-body calculation. The results are in good agreement with experimental values.     

Preparation of itraconazole/HP-β-CD inclusion complexes using supercritical aerosol solvent extraction system and their dissolution characteristics

The purpose of this study was to investigate the feasibility of a supercritical fluid process, called aerosol solvent extraction system (ASES), for producing solid-state inclusion complexes of itraconazole (ITR) with 2-hydroxypropyl-β-cyclodextrin (HP-β-CD). ITR was complexed with HP-β-CD at temperatures of 35–55 °C, pressures of 83–140 bar, CO₂ densities of 0.498–0.801 g/cm³, and solution concentrations of 1–5% (w/v). The ASES-processed inclusion complex powders were observed to consist of agglomerates of very fine (100–500 nm) particles. From the experimental results of X-ray diffraction and differential scanning calorimetry, it was found that ITR intermolecularly interacted with the HP-β-CD cavity, resulting in the formation of inclusion complex. Furthermore, the ASES-processed ITR/HP-β-CD powders showed a significant enhancement in the ITR solubility (up to 753.6 μg/mL) in an aqueous medium of pH 1.2. The aqueous solubility of ITR increased with pressure at a constant temperature, and we could obtain a relatively high solubility of 341 μg/mL at 140 bar and 35 °C. In a solution concentration range of 1–5% (w/v), the solubility increased with decreasing concentration, yielding 289–407 μg/mL. When the molar ratio of ITR to HP-β-CD was varied from 1:1 to 1:3, the ITR solubility increased with HP-β-CD content, giving a value of 753.6 μg/mL for the 1:3 ratio. For the ASES-processed ITR/HP-β-CD powders, the percent dissolution of ITR also increased considerably and about 90% of ITR was dissolved within 5–10 min.     

Selective removal of magnesium from lithium-rich brine for lithium purification by synergic solvent extraction using β-diketones and Cyanex 923

In the production of battery-grade and high-purity Li₂CO₃, it is essential to remove magnesium impurities. The state-of-the-art solvent extraction (SX) process using Versatic Acid 10 and D2EHPA co-extracts 3.3–5.5% lithium, while removing 86–98% magnesium. Here, we demonstrate that synergic SX systems containing a β-diketone (HPMBP, HTTA or HDBM) and Cyanex 923 are highly selective for magnesium extraction over lithium (separation factor α > 1,000). The extracted magnesium and lithium complexes have the stoichiometry of [Mg∙A₂∙(C923)₂] and [Li∙A _x∙(C923)₂] (x = 1, 2), respectively (A represents deprotonated β-diketone). The three β-diketone synergic SX systems all considerably outperformed the Versatic Acid 10 system for magnesium removal from a synthetic solution containing 24 g L⁻¹ Li and 0.24 g L⁻¹ Mg. In a three-stage batch counter-current extraction, the HPMBP and Cyanex 923 synergic SX system removed 100% magnesium with only 0.6% co-extraction of lithium. This excellent Mg/Li separation is the best result reported so far.     

Correlation between quantity of defect and supersaturation in RDX crystallization using γ-butyrolactone and water as solvent

The crystallization of RDX (cyclotrimethylenetrinitramine) was carried out using cooling crystallization. Effect of cooling rate and antisolvent to solvent ratio on the inclusion was studied. Qualitative observation of internal crystal defects was performed by optical microscopy with matching refractive index. The quantitative amount of inclusions was determined by measuring concentration of solid. Effect of the cooling rate and the antisolvent to solvent ratio on supersaturation was investigated. The supersaturation affected significantly the inclusion of mother liquor inside the crystals. The higher supersaturation induced the more agglomeration, that caused the formation of the more inclusions inside RDX crystals. From morphological study, defect is formed in course of transformation from plate-like to polygon shape. An empirical correlation of the inclusion fraction of RDX with the relative supersaturation was obtained.     

Extraction of oil and β-sitosterol from peach (Prunus persica) seeds using supercritical carbon dioxide

Oil was extracted from the peach (Prunus persica) seeds by supercritical carbon dioxide. Principal phytosterols (stigmasterol, campesterol and β-sitosterol) that have been known to have cholesterol lowering properties were investigated in the extracted oil. Based on gas chromatography–mass spectrometry (GC–MS) analysis, β-sitosterol was identified in the peach seed oil. The effects of temperature, pressure, flow rate of supercritical CO₂, mean particle size of the seeds and extraction time on the amounts of extracted oil and β-sitosterol were investigated. Supercritical fluid extractions were performed in a range of 35–55 °C, 160–240 bar, 4–8 ml CO₂/min, 0.3–1.7 mm and 1–4 h for mentioned parameters. The results indicated that the amounts of oil and β-sitosterol extracted from the peach seeds were optimal with values of 35.3 g/100 g seed and 1220 mg/kg seed respectively at 40 °C, 200 bar, 7 ml/min, 0.3 mm and 3 h.     

Hydrolysis of mechanically pre-treated cellulose catalyzed by solid acid SO_4~(2-)-TiO_2 in water–ethanol solvent

An efficient catalyst SO_4~(2-)-TiO_2(ST) from industrial metatitanic acid has been successfully prepared to catalyze hydrolysis of ball-milling cellulose. The results show that the highest catalytic efficiency is obtained for ST calcined at 450 °C(ST-450) with the yield of 21.8% glucose, 13.0% 5-HMF and 4.2% furfural at 200 °C for30 min. The ball milling of cellulose and solid acid catalyst significantly enhances the cellulose hydrolysis. The high Lewis to Br?nsted acid sites ratio for ST-450 induced by bidentate ligands between SO_4~(2-)and TiO_2 benefits high organics yield, and high total acid sites contribute to the high cellulose conversion. The large pore volume of0.29 cm~3·g~(-1) and appropriate pore size of 7.35 nm of ST-450 also contribute to the high performance. High reaction temperature over 200 °C exhibits negative effect on glucose and 5-HMF yield due to undesired side reactions, while furfural product is stable in the reaction system. The bidentate ligands between SO_4~(2-)and TiO_2 are considered as active acid sites for cellulose hydrolysis in water–ethanol solvents.     

The measurement of the solubility of electrolytes in water—miscible organic solvent mixture by using the “solventing out” process

Twenty water—MOS-electrolyte systems were studied. An analytical expression which describes the relative solubility S/S^w as a function of the MOS amount, v, was found. Expressions for predicting the solubility constants λ and v₀/1 + v₀ from precipitation constants were found. These constants are applicable to the entire range, in most cases, and applicable for most of the range in other cases.     

Separation of Cu from dilute Cu–Ni–Co bearing bioleach solutions using solvent extraction with Chemorex CP-150

Solvent extraction of Cu from simulated and real bioleaching solutions obtained from a complex Cu–Ni–Co bearing tailing was investigated using Chemorex CP-150 extractant. The effects of several critical parameters, namely pH, contact time, extractant concentration, metal ion concentration, and organic/aqueous phase ratio on Cu extraction were evaluated. Isotherm studies showed that more than 99.9% Cu was transferred with a single stage for each of the extraction and stripping steps. A mixed Ni–Co sulfide was produced from the extraction effluent. A developed flow sheet was proposed to treat Cu–Ni–Co bearing sulfidic tailings by bioleaching, jarosite precipitation, solvent extraction, and sulfide precipitation processes.     

Supercritical fluid extraction of α- and β-acids from hops compared to cyclically pressurized solid–liquid extraction

In this paper, two solid–liquid extraction techniques, supercritical fluid extraction (SFE) with and without modifiers and cyclically pressurized solid–liquid extraction with a Naviglio Extractor, were compared on the basis of extraction of acidic compounds contained in hops flowers. The hops extracts were analyzed by electro-kinetic capillary chromatography (MECK). The results showed that the technique using supercritical carbon dioxide was more effective for the isolation of β acids; the use of ethanol as a co-solvent, as reported in the literature, produced a heterogeneous extract, while cyclically pressurized solid–liquid extraction showed a greater extraction capacity for α acids. Consequently, both techniques are valid for the extraction of α and β acids from hops. By suitably varying the parameters of the two extractive procedures, it will be possible to obtain extracts for use in the production of beer and dietary supplements and drugs. Furthermore, based on the SFE CO₂ extraction process, a mathematical model was applied to the examined process, and a numerical simulation was performed, leading to a model that provides direction for the optimization of further experiments.     

Experimental investigation of operating conditions for preparation of PVA–PEG blend membranes using supercritical CO2

Poly(vinyl alcohol)–polyethylene glycol, PVA–PEG, blended membrane were prepared using supercritical fluid assisted phase-inversion method, in which scCO₂ was used as the anti-solvent. Poly(vinyl alcohol) was utilized as the main polymer, polyethylene glycol as the additive, and dimethyl sulfoxide (DMSO) as the solvent of these polymers. Taguchi method was used to investigate the effect of some operating parameters on the morphology of the membranes. The L16 orthogonal array was selected under the following conditions: pressure (100, 135, 165 and 200 bar), temperature (40, 45, 50 and 55 °C) and PEG weight percent (0, 0.33, 0.66, and 1%). Total polymer concentration of solutions in all experiment was constant at 10% (w/w). The morphology of the obtained porous membranes was characterized by scanning electron microscopy. Through changing the conditions in each experiment, the average pore diameter changed between 3.75 and 12.2 μm. Results from analysis of variance (ANOVA) indicate that PEG concentration was the most significant factor on the average pore size of prepared membranes by 78.7%. This is the first work announcing preparation of PVA–PEG membrane using supercritical CO₂.