Copper(I) ions are generally unstable in aqueous solution and readily disproportionate to copper(II) and copper(0). In this work, copper(I) is formed and stabilized under aerobic conditions by the addition of glutathione (GSH) which acts as a reducing and complexing agent. The extraction of Cu(I) with heterocyclic bidentate amines such as 2,9-dimethyl-1,10-phenanthroline (dmp), 2,9-dimethyl-4,7-diphenyl- 1,10-phenanthroline, and 2,2’-biquinoline has been studied in the presence of GSH.The formation of the Cu(I)-GSH complex in the aqueous solution was confirmed by spectrophotometry under aerobic conditions.Time-course measurements of the absorbance indicated that the Cu(I)-GSH complex retained stability toward re-oxidation by air for at least 6 h in the presence of a 10-fold excess of GSH at pH 5-7.The quantitative extraction of copper(I) was accomplished with 5.0 × 10⁻⁴ M dmp in chloroform or 1,2-dichloroethane in the presence of 5.0 × 10⁻⁴ M GSH and 0.10 M ClO₄⁻ at pH 3-6. The extracted species was found to be Cu(dmp)₂ClO₄ by the substoichiometric extraction method.

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A phenylurea derivative of a trident molecule has been prepared as a novel solvent extraction reagent for precious metal ions to compare the extraction ability of precious and base metals with the corresponding monopodal analogue in nitrate media. The phenylurea type of trident extraction reagent exhibited extractive selectivity for palladium over other precious and base metals in nitrate media. The extraction ability of the trident extraction reagent for palladium was superior to that of the monopodal analogue. The extraction mechanism of palladium with the trident extraction reagent was determined by slope analysis and from the peak shift for the FT-IR and ¹H-NMR spectra of the extraction reagent before and after metal loading. Stripping from the organic phase after forward extraction was carried out to separate palladium and silver.

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Zn(II) sorption from aqueous solutions was studied on polymeric hydrophobic microcapsules (MCs) containing 2-ethylhexylphosphonic acid mono-2-ethylhexyl ester as the extractant (PC-88A). The microcapsules were synthesised by adding this extractant during in situ radical polymerisation using styrene and ethylene glycol dimethacrylate (EGDMA) as starting monomers and benzoyl peroxide as the polymerisation initiator. SEM analysis of the microcapsules indicated that they had a spherical shape and a rough surface. A set of experiments was designed to study Zn(II) sorption behaviour onto MCs using aqueous solutions containing 100 mg/L of Zn(II) with an initial pH of 4.0. A Langmuir isotherm model fitted the experimentally observed equilibrium sorption data well. Results of kinetics experiments conducted between 293 and 323 K were well explained by a pseudo-second order kinetic model with an activation energy of 43.27 kJ mol^-1.Calculated thermodynamic parameters revealed that the chemisorption process was spontaneous and exothermic. The observed negative entropy change indicated that the metal bound to the extractant on the surface of MCs would generate a moderately ordered structure.

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A thermal-swing adsorption system for Eu(III) was developed using the thermosensitive polymer, poly(N-isopropylacrylamide) (PNIPAM), combined with the acidic extractants, acid phosphoxy ethyl methacrylate (Phosmer-M) or acrylic acid. The phase transition of the PNIPAM/acidic extractant copolymers was successfully achieved by changing the temperature around the lower critical solution temperature (LCST). The thermal-swing adsorption of Eu(III) was correspondingly achieved by changing the temperature of the aqueous solution. The adsorption ability of Eu(III) was increased when the temperature became higher than the LCST, due to the change in the hydrophobicity as well as in the volume of the copolymer. The difference in the adsorption at lower and higher temperatures against the LCST was increased with decreasing crosslinking agent during the preparation of the copolymer. The copolymer possessed sufficient loading and release capacity for Eu(III) even in repeated processes of the thermal-swing adsorption.

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The amphiphilic biodegradable polymer surfactant, poly(ethyleneoxide monooleate)-block- poly(D,L-lactide) (MOPEO-PLA), was shown to form microemulsions in chloroform solution and to extract water and protein into their microemulsions from the aqueous phase. The water content in the chloroform phase significantly increased with the MOPEO-PLA concentration, indicating that a MOPEO-PLA microemulsion was formed with a large amount of water molecules. The largest amount of cytochrome c in the MOPEO-PLA microemulsion phase was extracted when the pH of the aqueous phase was close to the pI value for cytochrome c, and the degree of extraction increased at higher temperatures. From these results, the main factor for the extraction of cytochrome c was found to be the hydrophobic interaction between MOPEO-PLA and cytochrome c. The MOPEO-PLA microemulsion provides a benign extraction process for proteins. A MOPEO-PLA microemulsion system would provide a new encapsulation system in a biodegradable polymer matrix for delivery of proteins and peptides.

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The extraction of luteolin and apigenin from the leaves of Perilla frutescens (L.) Britt. by liquid carbon dioxide (CO₂) was carried out at 5, 20 and 25 ºC. The extraction pressure was from 8.5 to 14 MPa. The extraction yields were compared with yields obtained by other solvent extraction methods, such as supercritical CO₂ extraction and conventional aqueous alcohol extraction. We conducted qualitative and quantitative analyses for luteolin and apigenin in the extract by HPLC and analyzed the extraction behavior. The effect of two operating parameters, temperature and pressure of liquid CO₂, on the extraction yield was investigated using the single-factor method. The yields of luteolin and apigenin in the extraction were significantly improved by the operating temperature, whereas a change in the selectivity of the extract was not observed.

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Air-exposed di(2-ethylhexyl) dithiophosphate (Phoslex DT-8^®) has been previously shown to be able to selectively extract scandium ions from waste water produced during zirconium refining. In the absence of exposure to air, Phoslex DT-8^® is not effective for scandium ion extraction, therefore, a compound produced by air-oxidation was suspected to be responsible for the selective extraction of the metal. In the present study, we employed ³¹P NMR spectroscopy and mass spectrometry in order to identify this active species. We revealed that a sulfur atom of Phoslex DT-8^® was substituted for an oxygen atom on oxidation yielding O,O-bis(2-ethylhexyl) hydrogen thiophosphate (BOHTP). This compound was subsequently synthesized in high purity, and was confirmed to possess similar extraction capabilities for scandium as the oxidized Phoslex DT-8^®.

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The salting-out phase separation behavior of the water–tetrahydrofuran (THF) homogeneous system with co-adding a hydrophilic ionic liquid, 1-butyl-3-methylimidazolium chloride ([C₄mim]Cl), and NaCl was investigated. In the water–THF/[C₄mim]Cl biphasic system, the lower phase showed a relatively large volume and low polarity compared with that in the water–THF/NaCl system, because of the coexistence of THF and [C₄mim]Cl. In the water–THF/[C₄mim]Cl–NaCl mixed salting-out agent system, the lower phase polarity depended on the composition of the salting-out agents. Furthermore, the distribution behavior of Fe(III)– and Zn(II)–chloro complexes in the mixed salting-out agent system was investigated to show the potential for application of the system for the extraction separation of metals as their chloro-complexes.

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In this study, the extraction behavior of calixarene derivatives by using the multiphase parallel flow technique was investigated. Using a partially-modified microfluidic device, the extraction rate of silver and palladium ions from the aqueous phase with calix[4]arene derivatives was evaluated. As a result, the time necessary for silver ion to reach equilibrium was 15 s. In the case of palladium extraction, the extraction percentage was 80 % at 8 s reaction time. In the conventional batch method, the times necessary for silver and palladium extraction to reach equilibria were about 72 h and 5 min, respectively. These results showed that increasing the liquid-liquid interface area is effective in the solvent extraction of metal ions with calix[4]arene derivatives. The correlation between the difference in the functional groups of calix[4]arenes and their effect on the rate of extraction at the parallel flow liquid-liquid interface was considered.

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An exchange between lanthanide ions (Ln³⁺) in a solution and coordinated yttrium ions (Y³⁺) takes place in a coordination polymer (CP) formed by Y³⁺ and di-(2-ethylhexyl) phosphoric acid (Hdehp). Through this cation exchange, Ln³⁺ is adsorbed on the CP depending on the coordination power with Hdehp. Accordingly, the Ln³⁺ with the larger atomic number is more preferably adsorbed into the CP. This adsorption is affected by the concentration of H⁺, C_H+, in the solution. For example, at C_H+=10^-5 M, Y³⁺ is replaced directly by the incoming Ln³⁺ with a 1:1 stoichiometry. In a limited higher C_H+ region, the CP becomes a gel and the Ln³⁺/Y³⁺ exchange is enhanced therein.

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The ionic liquid (IL), 1-butyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([Bmim][Tf₂N]), was evaluated as an extractant without dilution for the separation and recovery of precious metals. Au(III) was efficiently extracted from the aqueous phase to the IL phase, and a concentrated Au(III) solution almost 8 times higher than the initial feed solutions could be produced. In contrast, Pd(II) was rarely extracted and Pt(IV) was partly extracted under the present experimental conditions. Furthermore, the effect of the IL anions on the extraction ability for the metal ions was examined, and it was found that an IL having an anion component slightly more hydrophilic compared to [Tf₂N], such as 1-butyl-3-methylimidazolium hexafluorophosphate [Bmim][PF₆], showed a higher extraction ability than [Bmim][Tf₂N]. It was suggested that the extraction proceeded via an anion exchange mechanism and it was shown that ILs could be effective extractants for the separation of precious metals.

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We report here the effect of lauryl alcohol (LA), an effective organic solvent for in situ extraction for production of paclitaxel, on the production of taxanes (10-deacetyl baccatin III, baccatin III and cephalomannine) in a suspension callus culture of Taxus cuspidata. The culture conditions for enhancing production of the taxanes by avoiding feed-back inhibition of paclitaxel were examined. Increased callus growth and production amounts of the taxanes except cephalomannine were obtained in the LA-medium culture systems compared to the control culture where LA was not added. This result suggested that LA influenced the cellular and/or enzymatic activities involved in the biosynthetic pathway of paclitaxel.

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A finely monodispersed oil-in-water (O/W) emulsion was obtained under high temperature and pressure conditions (240 ^oC and 10 MPa). A coarse emulsion stabilized by Tween 20 was prepared in advance from the decane / water system to be treated under the subcritical conditions. The treated coarse emulsion was thereafter mixed with the aqueous solution including surfactants to improve the monodispersity of the oil droplets. The subcritical condition could supply sufficient energy to produce finely dispersed oil droplets (~233 nm in diameter).

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Simulated electroless nickel plating liquid wastes have been processed by using an emulsion flow extractor of a counter current type with a special focus on the influence of dilution of the liquid wastes on the extraction performance. The emulsion flow extractor provides efficient liquid–liquid extraction without the need for additional stirring or shaking. The solvent used in the present study was a Shellsol D70 solution containing LIX84-I as the extractant for nickel and PC88A as an accelerating agent. As a result, it was found that increasing the degree of dilution with water resulted in an improvement in nickel extractability obtained from the emulsion flow experiments with a maximum value of 96% as well as those obtained from batch experiments. Droplet sizes at the lower and the upper parts of the emulsion phases, estimated by using high-speed microscope, were 214 ± 36 µm and 415 ± 110 µm, respectively.

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