High Extraction Ability Research Articles

Efficient divalent metal cation extractions with di-ionizable calix[4]arene-1,2-crown-4 compounds

Di-ionizable calix[4]arene-1,2-crown-4 ethers in the cone conformation were synthesized and their conformation and regioselectivity verified by NMR spectroscopy. These new ligands exhibited high Ba 2+ selectivity in competitive solvent extraction of alkaline earth metal cations from aqueous solutions into chloroform. The selectivity order was Ba 2+>>Sr 2+>Ca 2+>Mg 2+ with Ba 2+/Sr 2+ selectivity exceeding 100. The ligands also exhibited high extraction ability for Pb 2+ and for Hg 2+ in single species extraction. With variation of proton-ionizable groups, which are oxyacetic acid moieties and N-(X)sulfonyl oxyacetamide units with X=methyl, phenyl, 4-nitrophenyl, and trifluoromethyl, ‘tunable’ ligand acidity was obtained.

Novel calix[4]arene-thiacrown ether for selective and efficient extraction of Ba(II), Pb(II), and Hg(II)

A di-ionizable p-tert-butylcalix[4]arene-1,3-thiacrown-5 ether extractant was synthesized. Its cone conformation and polyether ring attachment regioselectivity were verified by NMR spectroscopy. The metal ion-complexing properties of this ligand were evaluated by solvent extractions of metal cations from aqueous solutions into chloroform. The ligand was found to be an efficient extractant with Ba2+ selectivity in competitive solvent extraction of alkaline earth metal cations. It also exhibits high extraction ability for Pb2+ and for Hg2+ in single species solvent extractions.

Anomalous effects in extraction of lanthanides and actinides with bidentate neutral organophosphorus extractants. Role of proton hydrate solvates

Extraction of europium, lithium, and acids from nitric acid and perchloric acid media with solutions of bidentate neutral organophosphorus compounds (BNOPCs) in polar diluents (dichloroethane, meta-nitrobenzotrifluoride, and trifluoromethyl phenyl sulfone) was studied. It was found that cationic complexes of BNOPCs with proton hydrates or lithium cation are formed in the organic phase. BNOPC hydrate solvates H+ · nH2O · mBNOPC extract europium substantially better than do free BNOPCs. The main differences of BNOPCs from monodentate extractants are anomalous aryl effect (AAE) and perchlorate and synergic (the latter is observed in the presence of chlorinated cobalt dicarbollide) effects, which are connected with specific properties of proton hydrate solvates with BNOPC. The existence of BNOPC cationic complexes found by IR spectroscopy in polar diluents was confirmed by ESI-MS. The effect of preorganization of the extractant molecule and the change from the solvate mechanism of the metal ion extraction to the cation-exchange mechanism are apparently responsible for the high extraction ability of proton hydrate solvates with BNOPCs.

Pyrolysates of raw vitrinites and their residues after CS2-NMP solvent extraction and its significance for petroleum geology

Binary solvent (CS2-NMP) has extreme high extraction ability to coals, and it can extract most bitumens out of coals and vitrinites. And large amount of messages on side chains and their distribution character in vitrinites should be acquired through flash pyrolysis before and after binary solvent (CS2-NMP) extraction. A few low maturated coals have been selected and vitrinites are handpicked from coals. Then vitrinites have been extracted using different solvents in the order of polarity. Flash pyrolysis-Gas Chromatography/Mass spectrum has been applied to samples. The result shows that CS2-NMP is efficient for the extraction of vitirnites, giving much higher extraction yield than common solvents. Production ratio of liquid hydrocarbons in pyrolysates of vitrinites extracted with CS2-NMP is lower than that of raw vitrinites. And relative ratio of each component in pyrolysates has changed apparently. Production ratio of aliphatic hydrocarbons, especially those long chain aliphatics have decreased much after mixed solvent extraction. It shows that bitumens extracted with CS2-NMP have largely contributed to pyrolysates, especially those aliphatics in pyrolysates.

Competition, Innovation Incentives and No-Compete Clauses

This paper sheds light on the changing nature of the firm and firm boundaries, and offers an explanation for why innovative, human capital intensive firms tend to operate in competitive environments. We develop a model in which employees' incentives to acquire human capital, a necessary input for innovation, depend on the number of firms competing for employee human capital. A key insight of our paper is that firms operating in the same industry have a higher degree of relatedness, since they invest in more compatible technologies. This implies that employees in more competitive industries develop human capital that can be transferred more easily from one firm to another and, thus, can extract more rents (i.e., greater wages) from their firms. Anticipating their higher rent extraction ability, employees invest more in human capital and innovate more. Thus, competition in the market for innovation promotes innovation. We show that, under certain conditions, firms prefer to operate in a competitive product market in order to become more innovative. In this way, competition emerges endogenously and leads to more innovation. We also show that horizontal mergers may be detrimental to innovation generation, and that firms may prefer to preserve a competitive environment in order to provide better incentives for their employees. Finally, our paper has implications for the choice of industry standards, such as open source technologies, and the adoption of contractual measures that hinder employee mobility, such as no-compete clauses.

Synthesis, structure, and complexation properties of tetraamide derivatives of thiacalix[4]arene in different conformations

The interaction of p-tert-butylthiacalix[4]arene with N,N-diethylchloroacetamide was studied in the presence of alkali metal carbonates in acetone. Three stereoisomers, viz., cone, partial cone, and 1,3-alternate, of the tetraamide derivative of thiacalixarene substituted at the lower rim were synthesized selectively using the template effect of alkali metal cations, as well as a complex of the 1,3-alternate stereoisomer with potassium chloride. The structures of the compounds synthesized were studied by 2D NMR spectroscopy. A high extraction ability of the compounds toward alkali metal cations was demonstrated.

A useful approach toward the synthesis and metal extractions with polymer appended thioalkyl calix[4]arenes

This article describes a convenient method for the synthesis of two new polymeric resins via nucleophilic substitution reactions involving 5,11,17,23-tetrakis[(propylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 4, and 5,11,17,23-tetrakis[(methylthio)methyl]-25,26,27,28-tetrahydroxycalix[4]arene 6, as precursors with Merrifield's resin. The extraction studies were made using both liquid–liquid extraction and solid–liquid batchwise sorption procedures. The calix[4]arene based polymeric resins have high extraction ability toward metal cations and Na2Cr2O7 as compared to their monomeric precursors.

Solvent extraction and stripping of silver ions in room-temperature ionic liquids containing calixarenes.

We found that a calix[4]arene-bearing pyridine is soluble in a typical room-temperature ionic liquid (RTIL), 1-alkyl-3-methylimidazolium hexafluorophosphate. Pyridinocalix[4]arene showed a high extraction ability and selectivity for silver ions. The extraction performance of the calix[4]arene was greatly enhanced by dissolution in RTILs compared to in chloroform. In a competitive extraction test using five different metal ions (Ag+, Cu2+, Zn2+, Co2+, Ni2+), only silver ions were transferred by the calix[4]arene from the aqueous feed phase into the RTILs, through a cation-exchange mechanism. The pyridinocalix[4]arene was found to form a stable 1:1 complex with silver ions, both by slope analysis and by Job's method. Since it is easy to strip silver ions from RTILs by controlling the aqueous-phase pH, the extraction performance of calix[4]arene in RTILs was maintained after five repeated uses.

Interrelationships between water use and growth traits in biomass-producing willows

Water use, drought response and growth were examined under controlled conditions in four interbreeding willow species from different geographical origins (two clones of Salix viminalis L., one clone of S. viminalis × S. schwerenii E. Wolf and one clone of S. purpurea L.). The levels of soil water depletion that plants could sustain without wilting varied markedly between the clones. The level of drought resistance expressed this way was positively related to resistance to xylem cavitation, negatively related to the maximum stomatal conductance, and positively related to early stomatal closure. The rate of stomatal closure, however, was negatively related to the resistance to xylem cavitation. Prior to drought, there were no significant differences between leaf-specific hydraulic conductances of the clones when whole plants were considered. However, there were differences if the roots and shoots were considered separately. Drought resistance was negatively related to maximum growth yields. This is probably because resources were diverted away from leaf production to the production of denser wood (wood density was positively related to cavitation resistance), and, for one clone, to the growth of a larger root system. In addition, because the level of drought resistance was negatively related to the maximum stomatal conductance, growth may have been adversely affected as a result of reduced photosynthesis. Given its high water extraction ability, one of the clones started to wilt sooner than expected, although only lateral shoots were affected. This appeared to indicate a strategy of sacrificing expendable shoots.

Extraction of heptavalent technetium from nuclear waste streams with 2-nitrophenyl octyl ether

Technetium-99, in the form of Tc(VII), is one of major problems in the management and disposal of nuclear waste in view of its long half-life in combination with high geochemical mobility. Solvent extraction is an important separation technique to remove99Tc from liquid nuclear waste streams. 2-nitrophenyl octyl ether (NPOE) shows high extraction ability for Tc(VII) from water and NaOH solutions (>99.5%) in spite of the lack of donating atoms. Upon extraction from alkaline solutions, TcO4-associates with NPOE molecules in 1:1 stoichiometry where the co-extracted cation is expected to play an important role in the extraction mechanism. At pH > 4 the Tc(VII) distribution is relatively insensitive towards changes in pH, while at decreasing pH (<4) the distribution ratio decreases sharply. The strong dependency of the Tc(VII) distribution on the acidity is very useful for developing efficient extraction-stripping systems. This study showed that NPOE is an excellent compound for the removal of technetium from alkaline nuclear wastes.

CO-ADSORPTION AND RATE OF EXTRACTION IN A COPPER CHLORIDE SYSTEM CONTAINING DECANOL AND HYDROPHOBIC PYRIDINE ACID DERIVATIVES

ABSTRACT The model compounds di-2-ethylhexyl pyridine-3,5-dicarboxylate and N,N,N',N'-tetrahexyl pyridine-3,5-dicarboxamide were synthesised and their copper(II) extraction properties from chloride solutions were described. The effect of decanol used as a modifier on copper extraction was studied. The interfacial tension at the toluene/water interface was measured for systems containing the individual extractants and their mixtures with decanol. It was found that decanol affects the composition of the mixed adsorbed layer at the toluene/water interface. However, decanol significantly decreases only the rate of copper extraction with di-2-ethylhexyl pyridine-3,5-dicarboxylate. The effect disappears at high concentrations of the ester and is almost negligible for N,N,N',N'-tetrahexylpyridine-3,5-dicarbox-amide, which shows significantly higher extraction ability in comparison to the ester.

GOLD EXTRACTION FROM THIOSULFATE SOLUTIONS USING MIXED AMINES

ABSTRACT The extraction of gold from thiosulfate solutions with amine oxide and its mixture with amines has been studied, the results show that the amine oxide (TRAO) has a higher extraction ability for gold compared with tertiary amine. It can extract gold from neutral and weakly alkaline thiosulfate solutions, similar to the primary amine as extractant. The addition of TRAO enhances the extent of gold extraction with primary, secondary, and tertiary alkyl amines, respectively. The stoichiometry for the extraction of gold from thiosulfate solutions using the mixed solvent containing the primary amine N1923 and the amine oxide TRAO was investigated using slope analysis. The compositions of the gold extraction species with mixed organic solvents are proposed.

Separation of platinum and palladium by liquid surfactant membranes utilizing a novel bi-functional surfactant

Using a bi-functional surfactant which has abilities both as an emulsifier and a carrier, the separation of platinum and palladium by liquid surfactant membranes (LSMs) has been conducted in a stirred tank. The effects of several operational conditions on the behavior of metal extraction and the emulsion stability in LSMs were systematically studied. The bi-functional surfactant not only stabilized a W / O emulsion in a relatively low concentration but also showed a high extraction ability for platinum. Using the bi-functional surfactant, platinum was extracted quickly and concentrated effectively from an external feed solution into an internal recovery phase of W / O emulsions through a thin liquid membrane. Further, the extraction kinetics of the metals by LSMs containing the bi-functional surfactant was examined. The hydrophobic structure of the surfactants was found to be one of the important factors in ensuring a high extraction rate of metal ions by LSMs. An interfacial reaction model which takes into account the adsorption of the surfactant at the interface has been proposed to evaluate the permeation rate of metals by LSMs. The newly developed surfactant appears to be one of the best surfactants currently available for platinum-group metal extraction by liquid surfactant membranes.

高引火点有機溶剤を用いた金属粉末射出成形体の抽出脱脂

In this paper, solvent debinding of injection molded metal powder by organic solvents of high flashing point was studied. The binder was composed of polyplopylene, paraffin wax and urethane wax. The urethane wax was suitable for rapid solvent debinding by high flashing point organic soIvent. DecaIin(f.p.54.9°C) and Tetralin (f.p.80.2°C) were used as high flashing point organic solvent. The solvent debinding with Decalin and Tetralin was compared with Xylene(f.p.25.6-29.4°C) and Dichloromethane (b.p.40.0°C). flecalin and Tetralin at 50°C exhibited as high extraction ability as Xylene at 20°C. Furthermore, the solvent mixtures(Dichloromethane:Decalin=5:5, 4:6, 3:7) at 50°C exhibited higer extraction ability, and it was comparable with the extraction ratio of Xylene at 50°C to be higher temperature than the flushing point. However, as the organic solvents of high flashing point have the slow volatilization property, it was necessary to dry in vacuum or in blower after solvent extraction. In spite of the fact, it was proved that the organic solvents of high flashing point can be effectively used as substitute for the conventional solvents.

Liquid-Liquid Extraction of Transition and Alkali Metal Cations by New Calixes.

The liquid-liquid extraction of various metal ions by a couple new calix [4] arenes, which have aminobenzene carboxylic acid, benzothiazole, and benzoxazole, thiomethyl, and pyrazple group the upper rim of calix. These ligands ofextraction ability for metal cations including alkali and transition metal onesusing picrate counter ion have been examined. Benzothiazole and benzoxazolemodified calix [4] arene derivatives (4 and 5 respectively) were converted tothe phenol derivatives using BBr3. The benzothiazole phenol derivative (6) shows high selective extraction ability for Cu2+ and Hg+, but the benzoxazolederivative (7) does show extractability for only Hg+. On the other hand, themethoxy calix [4] arene derivatives except thiomethyl appended derivative (8) show higher metal binding ability in this system.

Extraction of Organic Dianionic Species with Dicationic Extractants and Their Application to Anion Selective Electrode

Abstract Dicationic type anion-exchange extractants, CnBP, extracted organic dianionic species to a much greater degree as compared with classical monocationic extractants (Capriquat, etc.). This high extraction ability was applied to poly(vinyl chloride) (PVC) membrane electrode (coated-wire type). The electrode was found to be highly selective to 1,5-naphthalenedisulfonate anion (NDS2−).

New applications of crown ethers. Part 6. Structural effects of bis(benzocrown ether)s and substituted benzocrown ethers on solvent extraction and complexation of alkali-metal cations

Bis(benzocrown ether)s consisting of benzo-15-crown-5 (B15C5), benzo-18-crown-6(B18C6) and/or benzo-21-crown-7 (B21C7) with the following linking chains, -(CH2)n-(n= 2 and 8), -(CH2)3-O-, -O-(CH2)6-O-, and -(O-CH2CH2)n-O-(n= 2–5), were prepared and their complexation behaviour was characterized using solvent extraction of alkali-metal picrates and complexation with alkali-metal chlorides. Bis(benzocrown ether)s were distinguished from the corresponding mono(benzocrown ether)s by their remarkable high extraction ability of a cation larger than the hole size of a crown unit, the so-called ‘biscrown effect’. Bis(B15C5)s (4a–h) and bis(B18C6)s (5a–h) preferentially extracted K+ and Cs+, respectively. Bis(benzocrown ether)s containing the B21C7 unit (6a)–(8a) did not show this ‘biscrown effect’ because of the large hole size of B21C7. An unsymmetrical bis(crown ether)(7b) consisting of B15C5 and B18C6 selectively extracted Rb+. The ‘biscrown effect’ was favourably exerted with the oligoethyleneglycol linkage rather than the hydrocarbon one. Little or no effect of lipophilic groups or donor oxygens in the side chain of mono(benzocrown ether)s was observed in the extraction of alkali-metal picrates. Stability constants were determined by the ion-selective electrode method in 90% methanol aqueous solution at 25 °C. In bis(B15C5)s with Na+, and bis(B18C6)s with Na+ or K+, two crown rings in one molecule acted as two individual moieties. Bis(B15C5)s bound with K+ to form preferentially an intramolecular 2 : 1 crown ether unit-K+ complex. Both bis(B15C5)s with Cs+ and bis(B18C6)s with Cs+ systems also showed the ‘biscrown effect’.