The Box-Behnken design was used to investigate the effect of three independent variables-extraction time, temperature, and solvent-to-solid ratio on the total sugar content (TS) in the aqueous extract of date fruits. Response surface methodology (RSM) analysis revealed that the optimal extraction conditions were 35 min, 42.3 degrees C, and 65.6 mL/g. Under these conditions, the experimental value for TS was 503.49 +/- 12.21 mg fructose equivalent/g dry matter, closely matching the predicted value of 507.57 +/- 52.71 mg fructose equivalent/g dry matter. This agreement validates the model's accuracy and confirms the effectiveness of RSM for optimizing the extraction parameters. Compared with conventional extraction methods, the optimized ultrasound-assisted approach employed in this study reduced solvent use, shortened extraction time, and significantly improved sugar yield. Furthermore, this study highlights the relevance of scientific optimization techniques in the agro-industrial extraction of sugars and in characterizing dates by their quality index (r = TS/water content) with high precision.
Current industrial gold extraction processes primarily rely on toxic solvents and additives, which, despite their high efficiency, pose significant environmental and health hazards. Developing greener and more sustainable alternatives is therefore essential. Deep eutectic solvents (DESs) have recently gained attention as promising green solvents due to their tunable physicochemical properties and potential for selective metal extraction. In this study, we introduce a novel type V DES composed of N,N-diethylbenzamide (DEBA) and thymol (Thy), designed using COSMO-RS-predicted solid-liquid equilibrium phase diagrams to ensure eutectic behavior. DEBA-Thy demonstrated outstanding selectivity for Au3+ across a broad concentration range, achieving extraction efficiencies above 97%, while those of Pt4+ and Pd2+ remained below 10%. Slope analysis indicated a 1:1 stoichiometry for the Au(DES) complex. Additionally, cytotoxicity testing showed an EC50 value of 72.09 & micro;mol/L, suggesting lower toxicity compared to conventional solvents. These findings support DEBA-Thy as a promising, sustainable solvent for selective gold recovery.
Sulfate leach solutions of spent ternary lithium-ion batteries (LIBs) contain abundant Mn, Co, Ni, and Li. The selective separation of these elements is an essential treatment for their recovery. Current extraction technology achieves this through a sequential extraction process using multiple extractant systems, resulting in the use of numerous reagents, a long process, and low separation efficiency. The development of a more selective separation method is thus desired. In this paper, we introduce a novel method for the stepwise separation of Ni, Co, Mn, and Li from sulfate leach solutions of spent LIBs through solvent extraction using a single extractant system comprising a 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (P507)/5,8-diethyl-7-hydroxy-6-dodecanonoxime (LIX63) mixture. First, Ni, Co, and Mn are completely co-extracted, leaving Li in the raffinate. Then, Ni, Co, and Mn in the loaded organic solutions are stepwise stripped and separated using 0.05 mol/L, 2.0 mol/L, and 8.0 mol/L H2SO4 solutions, respectively. This novel process is expected to contribute to the hydrometallurgical recovery of spent ternary LIBs.
The development of greener solvent systems for platinum group metal extraction is important for sustainable hydrometallurgy. This study systematically investigated how hydrogen-bonding interactions in hydrophobic deep eutectic solvents (DESs) affect the extraction of platinum (Pt), palladium (Pd), iron (Fe), and copper (Cu). Trioctylphosphine oxide (TOPO) was combined with lauric acid (LauA) or lauryl alcohol (LauOH) to prepare DESs with different hydrogen-bonding strengths. LauA/TOPO exhibited strong hydrogen bonding, altering the extraction behavior compared to TOPO alone and enabling the selective extraction of Pt and Fe at higher acidity. In contrast, LauOH/TOPO showed similar extraction behavior to TOPO, facilitating Pt and Pd separation under milder conditions. Dilution with dodecane reduced the extraction efficiency due to increased activity of hydrogen bond donors. These findings demonstrate the critical role of intermolecular interactions in designing DES-based extraction systems for efficient and selective metal recovery.
A total of 150 deep eutectic solvents (DESs) with varying salt, hydrogen bond donor, and molar ratios were studied to develop a screening tool for separating toluene-heptane mixtures. The activity coefficient at infinite dilution (gamma degrees) of each DES was predicted using COSMO-RS, and selectivity (S degrees), capacity (C degrees), and performance index (PI) were calculated. Key DES properties, including density, viscosity, melting/freezing point, surface tension, and conductivity, were compiled from the literature to create a DES property library. A comprehensive screening tool with four evaluation criteria was developed, which identified ethyl triphenylphosphonium bromide:ZnCl2 (1:4) as the optimal solvent for toluene-heptane separation. Tetrabutylbased DESs exhibited higher S degrees, while phenyl phosphonium-based DESs showed higher C degrees. DESs with Cl-anions provided higher selectivity, whereas those with Br-anions had higher capacity. Generally, DESs with high S degrees also showed high PI, indicating superior separation performance.
Ion-pair reactions play a key role in the extraction of anionic metal ions -such as chlorinated, fluorinated, or sulfated ions, and oxonium anions- through the use of cationic extractants whose amino N atoms are protonated under acidic conditions. Focusing on these reactions, we investigated the extraction of Zr, Hf, Nb, and Ta anionic metal species present in sulfuric and hydrofluoric acids, and oxonium anions of group 6 and 7 elements, including Tc, Re, Cr, Mo, and W, under various conditions. The distribution ratio, D(M), for some anions exceeded 100. NTAamide (hexaalkyl-nitrilotriacetamide), having a tetradentate mode, exhibited the highest D values among all extractants tested. Monovalent oxonium anions, such as Tc and Re, showed higher D values than divalent anions, and these anions were efficiently extracted from acids containing affinitive anions, such as HF, HCl, and H2SO4, rather than from HNO3 and HClO4.
To recover In(III) and Ga(III) from waste electronics and solar panels, we examined 3,5-di-tert-butylsalicylic acid (DBSA) as a selective extractant for these metals. DBSA selectively extracted In(III) and Ga(III) from Zn(II) and Cd(II), although their mutual separation was not achieved. Therefore, a deep eutectic solvent (DES) that is liquid at room temperature was prepared by mixing solid DBSA with solid tri-n-octylphosphine oxide (TOPO). TOPO alone did not extract any metals. The DES exhibited higher selectivity for In(III) and Ga(III) over Zn(II) and Cd(II) at lower pH values due to its synergistic effect with TOPO. To clarify the extracted species of In(III), the extraction equilibria of In(III) with DBSA alone and the DES were quantitatively investigated. Quantitative back extraction of In(III) was achieved using dilute acidic solutions. In addition, the DES without organic solvents succeeded in the mutual separation of In(III) and Ga(III) from Zn(II) and Cd(II).
Vanadium is widely used in industry as a steel alloying element and catalyst. Due to the uneven distribution of vanadium resources, its recovery from spent vanadium materials has become increasingly important. In this study, we extracted vanadium (V) from acidic media, using the bifunctional ionic liquid [P-66614][D2EHPA], consisting of Cyphos IL 101 ([P-66614][Cl]) and bis(2-ethylhexyl)phosphoric acid (D2EHPA), as the extractant. The extractability of vanadium using this bifunctional ionic liquid was slightly higher than that using Cyphos IL 101 alone or a simple mixture of Cyphos IL 101 and D2EHPA. The species of vanadium extracted at high hydrochloric acid concentrations was ([P-66614][D2EHPA])(2)(HVOCl3). The vanadium extracted in the organic phase was quantitatively recovered using 1 mol/L aqueous ammonia.
Novel phosphoric and phosphonic acid type ion exchange resins were synthesized as impregnation type resins and surface functional group type resins in the present work, and their adsorption and separation abilities for rare earth metals were investigated. The impregnation type resins were synthesized using 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) as a porogen during the synthesis of polymer beads, while the surface functional group type resins were synthesized by immobilizing the phosphoric acid ester ligand onto polymer beads. All ion exchange resins exhibited adsorption ability for dysprosium. The separation abilities for dysprosium and europium with the impregnation type resins were consistent with those with the conventional solvent-impregnated resin containing PC-88A, while almost no selectivity was obtained with the surface functional group type resins. The impregnation type resin can be applied to column operation, and the selective adsorption of dysprosium over neodymium can be achieved by combining a scrubbing method.
The separation and recovery of dysprosium (Dy) and neodymium (Nd) from waste Nd magnet was investigated using a solvent-impregnated resin loaded with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester. The leaching solution obtained from the magnet contained Dy and Nd, together with a large amount of iron (Fe). Since Fe suppressed the adsorption of Dy and Nd, ascorbic acid was added to the leaching solution to reduce Fe(III) to Fe(II), enabling their selective adsorption. Although the separation of Dy and Nd was difficult using the conventional frontal separation mode in column operation, the separation was achieved in the gradient elution mode. The proposed separation and recovery process, based on a connected column system, yielded Dy with a purity of 98.9 wt% and a recovery yield of 96.9%, and Nd with a purity of 96.2 wt% and a recovery yield of 95.6%.
In this study, the ionic liquid methyl trioctylammonium di-(2-ethylhexyl) phosphate (A336P204) was prepared to extract magnesium (Mg) from brine with a high Mg/lithium (Li) ratio. The effects of the extraction time, the pH of the initial aqueous phase, the volume fraction of ionic liquid in the organic phase, and the phase ratio on the extraction efficiencies of Mg2+ and Li+ were investigated. Under the optimal conditions, the single extraction efficiencies of Mg2+ and Li+ were 90.5% and 11.5%, respectively. The stripping efficiency of Mg2+ reached 93.3% using 1 mol/L HCl as a stripping agent with a volume ratio of the aqueous phase to the organic phase of 2. A336P204 has good cyclic stability, indicating its high potential for Mg2+ extraction from Mg2+-rich solutions.
Pillararenes are a series of novel macrocyclic compounds discovered in the 2000s. However, solvent extraction based on ion exchange using pillararene derivatives is currently limited. Recently, a pillar[6]arene hexaacetic acid derivative (OctP[6]CH2COOH) has been developed as a new acidic extractant. In this study, the extraction of amino acid esters using OctP[6]CH2COOH was investigated. The extraction of tryptophan methyl ester using OctP[6]CH2COOH was much greater than that using the 6-fold equivalent monomer analog. The extraction of more hydrophobic cationic guests was relatively high. This process is based on a proton exchange reaction. The results of slope analysis and Job plot analysis confirmed the formation of a 1:1 complex between OctP[6]CH2COOH and the guest cation.
We found the regularity between phase transfers and the conformations of single giant linear double-stranded deoxyribonucleic acid (DNA; lambda DNA and T4GT7DNA) molecules in the aqueous two-phase system (ATPS) containing 4.0% polyethylene glycol (PEG), 7.4% dextran, and 0 - 20 mM (1 M = 1 mol dm-3) Mg2+by in situ fluorescence microscopy. The DNAs tended to show a conformational change from an elongated random-coil state to a compacted globule state with an increase in the PEG and Mg2+ concentrations. The random-coiled DNAs underwent phase transfer across the ATPS interface from the PEG-rich top phase to the dextran-rich (PEG-poor) bottom phase, and vice versa. The globular DNAs were trapped at the ATPS interface and were not detached. In addition, the conformational change of the DNAs from the globule state to the random-coil state occurred at the ATPS interface at 6 - 9 mM Mg2+. The conformational change of the shorter DNA (lambda DNA) at the ATPS interface took less time than that of the longer DNA (T4GT7DNA).
"Emulsion-flow" is an innovative technique of liquid-liquid extraction, utilizing the counter-current flow of both aqueous and organic phases in the form of droplets. It maintains a broad operational range across various phase velocities, primarily attributed to the steady droplet layer due to rapid drop coalescence in the layer. This study sheds a light on the importance of the droplet size and liquid flow in the droplet layer in the column. To simplify the analysis of droplet coalescence, no mass transfer was considered in the experiment, but the interaction was focused on between n-heptane and deionized water droplets. With the assumption of uniformed droplet size D-32, queueing theory has been applied to predict the average droplet coalescence time, tau and the droplet layer height, H with D-32 as well as a fitting parameter, n. The physical meaning of n was elucidated as the product between droplet distance and space time. Due to the similarity with the structure of a foam layer, the foam drainage model was analogically used to describe the speed of liquid flow among droplets, and to predict the organic phase hold-up, phi(org) within the droplet layer. The result revealed observed values of phi(org) aligned well with the shape coefficient, f, in a narrow deviation range.
In this study, a new extractant has been developed for mutual separation of Cu(II) / Fe(III) and Cd(II) / Zn(II) from acidic media. These metals are mainly discharged from smelting and refining processes of copper, zinc, and lead. However, the mutual separation of these metals is difficult due to their similar chemical properties. In order to separate these metals, isooctyl thioglycolate (IOTG) which has carbonyl and thiol groups was proposed as a new extractant. Furthermore, 1-dodecanethiol (DOTH) with only a thiol group was used for comparison. We found that IOTG in toluene can selectively separate Cu(II) over Fe(III) and Cd(II) over Zn(II). We paid attention to the selective extraction of Cd(II) with high toxicity and examined the extraction equilibria of Zn(II) and Cd(II) in detail. These extraction equilibria are determined by the conventional slope analysis method from 1 M aqueous ammonium nitrate solution. It was found that the selective extraction of Cd(II) over Zn(II) is due to the formation of the binuclear Cd(II) complexes while Zn(II) is extracted as the mononuclear complex. Furthermore, the stripping of Cd(II) and Zn(II) extracted into the organic phase was achieved using appropriate concentrations of various acids.
Rhodium (Rh) and palladium (Pd) in high-level radioactive waste are primarily fission products. This study focused on understanding the extraction behavior of these platinum group elements (PGEs) using the novel extractants N,N,N',N',N",N"-hexaoctylnitriloacetamide (HONTA) and alkyl diamideamine (ADAAM). Both extractants showed affinity for Pd, with distribution coefficients significantly exceeding 1, demonstrating their effectiveness in Pd separation. In contrast, the distribution coefficients for Rh were consistently below 10(-1), indicating low extraction efficiency from nitric acid. However, by leveraging the salting-out effect with calcium nitrate hydrate, a distribution coefficient of similar to 570 for Rh was achieved using HONTA. To overcome the difficult back-extraction of PGEs with HONTA, experiments were conducted using HEDTA and thiourea. Back-extraction with HEDTA in high-concentration nitric acid (> 2 M) resulted in similar to 90% extraction of Pd, while thiourea-based back-extraction with nitric acid yielded over 40% extraction for Rh, with the maximum of 62.7% achieved using hydrochloric acid.
This study compared the quantity and quality of essential oil extracted from agarwood bark using subcritical water (Sub-CW), Soxhlet, and hydro-distillation (HD). From this study, Sub-CW is considered the most practical method for extraction of essential oil from agarwood bark as it produced the highest percentage of oil yield (4.89%) at the shortest extraction period (5 min) as compared to the Soxhlet (2.19%, 6 h) and HD methods (0.15%, 12 h). The highest oil yield was collected at a Sub-CW extraction temperature of 135 degrees C. From GC analysis, oil extracted using Sub-CW contains three oxygenated sesquiterpenes, which are epoxybulnesene, caryophyllene oxide, and kusunol.
Magnitude of the masking effect of carboxylic, amic-acidic, and amidic compounds through Ln and Am extractions by tetraoctyl diglycolamide (TODGA) is compared, and their properties are studied in this paper. The compounds used are diglycol, ethylenediamine, diethylenetriamine-type, and two other amides (dioxaoctane diamide and nitrylotriacetamide). The results show that below pH 1.2, where carboxylic acids are less dissociated, amide O atoms have higher reactivity with lanthanides than O atoms in carboxyl groups. Seeing the Ln patterns (D(Ln) vs. their atomic number), the compounds primarily show high reactivity, with middle and heavy Ln having a higher charge density than light Ln. Four amide compounds are employed in this work. Those with tertiary amine N atoms have pH dependence on D(Ln) due to protonation and dissociation from amine N atoms. However, amides with no amine N atoms have no pH dependence.
The zwitterionic surfactant 3-(nonyldimethylammonio)-propyl sulfate (C-9-APSO(4)) exhibits unique reversible temperature-dependent phase separation properties, which can be used for the extraction of watermiscible negatively charged gold nanoparticles (AuNPs) without any aggregation at high concentrations using only temperature change. This study investigated the extraction behaviors and properties of AuNPs transferred from the water phase to a small volume of the surfactant-rich phase. The AuNPs retained both their original shapes and sizes after temperature-dependent phase separation step. In addition, the concentration of AuNPs was enriched by a factor of 150 in the surfactant-rich phase without any changes in the sizes and shapes of AuNPs. The capacity was 63.7 mu g (Au) present in 10 mu L of the surfactant-rich phase (i.e., the saturated concentration was 1.6 x 10(12) particles/mL for 60 nm AuNPs). Furthermore, the extraction percentage was greater than 99% regardless of the pH (in the pH range of 2 - 12).
