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Organic Phase (organic + phase)
Selected AbstractsFacilitated Transfer of Alkali Metal Ions by a Tetraester Derivative of Thiacalix[4]arene at the Liquid,Liquid InterfaceELECTROANALYSIS, Issue 12 2008Akgemci, Emine Guler Abstract The facilitated transfer of alkali metal ions (Na+, K+, Rb+, and Cs+) by 25,26,27,28-tetraethoxycarbonylmethoxy-thiacalix[4]arene across the water/1,2-dichloroethane interface was investigated by cyclic voltammetry. The dependence of the half-wave transfer potential on the metal and ligand concentrations was used to formulate the stoichiometric ratio and to evaluate the association constants of the complexes formed between ionophore and metal ions. While the facilitated transfer of Li+ ion was not observed across the water/1,2-dichloroethane interface, the facilitated transfers were observed by formation of 1,:,1 (metal:ionophore) complex for Na+, K+, and Rb+ ions except for Cs+ ion. In the case of Cs+ a 1,:,2 (metal:ionophore) complex was obtained from its special electrochemical response to the variation of ligand concentrations in the organic phase. The logarithms of the complex association constants, for facilitated transfer of Na+, K+, Rb+, and Cs+, were estimated as 6.52, 7.75, 7.91 (log ,1°), and 8.36 (log ,2°), respectively. [source] Sonoelectrochemistry in Acoustically Emulsified Media: The Detection of LeadELECTROANALYSIS, Issue 21 2003Peter Tom Abstract The double extraction of target lead ions which are then voltammetrically quantified via acoustically assisted anodic stripping voltammetry is demonstrated. The technique involves first the extraction of lead from the aqueous volume into an organic phase containing the ligand dithizone (diphenylthiocarbazone). Second, the chelated lead is then stripped into a clean electrochemically clean aqueous solution where the lead from the original solution can be quantified. This method is shown to be applicable in electrochemically fouling media, providing a high sensitivity with a limit of detection for lead in the order of 10,7,mol,dm,3. A theoretical extraction model is presented for the optimal conditions of extraction. The technique is applied to the analysis of lead in wine samples offering quantitative data, which is in good agreement with those obtained from an independent technique (AAS). [source] Assessment of sediment quality of Yangtze River estuary using zebrafish (Danio rerio) embryosENVIRONMENTAL TOXICOLOGY, Issue 3 2010Lingling Wu Abstract Yangtze River estuary is one of the largest estuaries worldwide. In this study, the sediment quality of Yangtze River estuary was evaluated using zebrafish (Danio rerio) embryos. Freshly fertilized zebrafish eggs (2 h after fertilization) were exposed to the whole sediment and its organic phase of extract, respectively. The parameters, including survival rate, abnormality, hatching rate, and heart rate of the zebrafish embryos, were recorded during the 96-h exposure. The results demonstrated that the concentrations of heavy metals (Zn, Cu, Cd, Ni, Cr, and As) and low-molecular weight PAHs (Fluorene) in the sediment of Yangtze River estuary exceeded their corresponding effects range low values. The maximum concentrations of Zn and Fluorene in the sediment samples were 239.6 ,g/g and 45.9 ng/g, respectively. In both whole sediment test and organic extract test, the survival rate and heart rate of zebrafish embryos were reduced, as well as abnormalities and delayed hatching were induced. For example, the highest mortality of the embryos was 39% in the whole sediment exposure. Overall, the occurrence of toxic compounds in the sediment of Yangtze River estuary may have potentially teratogenic effect on biota. The sediment from the upstream of Yangtze River estuary have more observed toxic effects on zebrafish embryos than that form the downstream. Therefore, more attention should be paid to control these pollutants, especially heavy metals in the Yangtze River estuary. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010. [source] Resolution of Racemic N -Benzyl ,-Amino Acids by Liquid-Liquid Extraction: A Practical Method Using a Lipophilic Chiral Cobalt(III) Salen Complex and Mechanistic StudiesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 7 2008Pawel Dzygiel Abstract The efficient resolution of racemic N -benzyl ,-amino acids (N -Bn-AA) has been achieved by a liquid-liquid extraction process using the lipophilic chiral salen,cobalt(III) complex [CoIII(3)(OAc)]. As a result of the resolution by extraction, one enantiomer (S) of the N -benzyl ,-amino acid predominated in the aqueous phase, while the other enantiomer (R) was driven into the organic phase by complexation to cobalt. The complexed amino acid (R) was then quantitatively released by a reductive (CoIII,,,CoII) counter-extraction with aqueous sodium dithionite or L -ascorbic acid in methanol. Thereductive cleavage allowed to recover the [CoII(3)] complex in good yield, which could be easily re-oxidized to[CoIII(3)(OAc)] with air/AcOH and reused with essentially no loss of reactivity and selectivity. Investigation on the nitrogen substitution indicates that the presence of a single benzyl group on the amino acid nitrogen is important to obtain high enantioselectivity in the extraction process. The kinetic vs. thermodynamic nature of the resolution process was also investigated with an enantiomeric exchange experiment, which shows that the liquid-liquid extraction with [CoIII(3)(OAc)] is an equilibrium process operating under thermodynamic control. In the absence of a suitable crystal structure of the [CoIII(3)(N -Bn-AA)] complexes, computational and spectroscopic studies were used to investigate how the N -benzyl ,-amino acids are accommodated in the "binding pocket" of the chiral cobalt complex. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] Carrier-Mediated Transport of Toxic Heavy Metal Ions in Bulk Liquid MembranesEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 6 2004Lucia Brinchi Abstract Transport through a dichloromethane liquid membrane has been studied to investigate the ability of 1,1,7,7-tetraethyl-4-tetradecyldiethylenetriamine (TE14DT), previously tested for the transport of copper, to act as a carrier for toxic heavy metal ions such as Cd2+, Pb2+ and Hg2+. The carrier displayed a remarkable capability to extract all the metal ions from the source to the organic phases but only cadmium was efficiently transported across the membrane. The experimental conditions optimised for the transport of copper are inadequate for lead and mercury. In fact, the inefficacy of their transport could be due, as regards lead, to the slow diffusion of the complex through the membrane, while mercury remained in the organic phase because of the high stability of the mercury-carrier complex. Selectivity tests using binary mixtures of the metal ions showed TE14DT's capability to transport copper or cadmium also in the presence of lead in the source phase. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004) [source] Preventing biofilm formation: promoting cell separation with terpenesFEMS MICROBIOLOGY ECOLOGY, Issue 3 2007Carla C.C.R. De Carvalho Abstract Both carveol and carvone were effective in dispersing Rhodococcus erythropolis cells that were being stimulated to aggregate by the presence of organic solvents. The two terpenes influenced the fatty acid composition of the cell membrane, decreasing the percentage of fatty acids with more than 16 carbon atoms, and thus cell hydrophobicity, and also the degree of saturation of the fatty acids. In the presence of 250 ,mol of terpene, the volume of biofilm was reduced by one third in comparison with biofilms in the absence of terpenes. The percentage of aggregated cells was also found to depend on carvone concentration during the bioconversion of carveol to carvone, in a membrane reactor. The extent of cell aggregation decreased from 90% to 10% when carvone concentration reached ca. 48 mM in the organic phase. [source] Generation of Monodisperse Inorganic,Organic Janus Microspheres in a Microfluidic DeviceADVANCED FUNCTIONAL MATERIALS, Issue 10 2009Naveen Prasad Abstract This study presents a simple synthetic approach for the in situ preparation of monodisperse hybrid Janus microspheres (HJM) having organic and inorganic parts in a PDMS-based microfluidic device. Based on the mechanism of shear-force-driven break-off, merged droplets of two photocurable oligomer solutions having distinctive properties are generated into an immiscible continuous phase. Functionalized perfluoropolyether (PFPE) as the organic phase and hydrolytic allylhydridopolycarbosilane (AHPCS) as the inorganic phase are used for the generation in aqueous medium of HJM with well-defined morphology and high monodispersity (average diameter of 162,µm and a 3.5% coefficient of variation). The size and shape of the HJM is controlled by varying the flow rate of the disperse and continuous phases. The HJM have two distinctive regions: a hydrophobic hemisphere (PFPE) having a smooth surface and a relatively hydrophilic region (AHPCS) with a rough, porous surface. In addition, pyrolysis and subsequent oxidation of these HJM convert them into SiC-based ceramic hemispheres through the removal of the organic portion and etching off the silica shell. The selective incorporation of magnetic nanoparticles into the inorganic part shows the feasibility of the forced assembly of HJM in an applied magnetic field. [source] Lipid and protein changes in chilled sea salmon (Pseudopercis semifasciata): effect of previous rosemary extract (Rossmarinus officinalis L.) applicationINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 6 2009Valeria Tironi Summary The aim of this work was to analyse the effect of rosemary extract application (200 and 500 ppm) on lipid oxidation, colour and protein modifications during the chilled storage (1.0 ± 0.7 °C) of sea salmon (Pseudopercis semifasciata). Lipid oxidation and ,3-22:6 fatty acid content modification were prevented by the addition of rosemary extract. Analysis of interaction between lipid oxidation products and proteins by fluorescence showed no relationship between their temporal changes in the aqueous phase and the lipid oxidation evolution since a similar behaviour was observed in both absence and presence of antioxidant. Protein extractability, sodium dodecyl sulphate-polyacrylamide gel electrophoresis, differential scanning calorimetry and lysine content determinations revealed no differences between muscle untreated or treated with rosemary. Fluorescent compounds evolution in organic phase would be in relation with the appearance of lipid oxidation products. In addition, rosemary extract partially prevented the loss of red colour in chilled muscle. Although protein alterations could not be prevented, rosemary extract shows to be a promissory antioxidant in sea salmon muscle. [source] Fluorous Surface-Active Distannoxane CatalystsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 9 2010Akihiro Orita Abstract Fluorous distannoxanes (XRf2SnOSnRf2X)2,n,H2O (Rf=C6F13C2H4) (1: X=C8F17SO3, n=10; 4: X=Cl, n=0) (1) catalyze the Mukaiyama aldol reaction and the allylation of aldehydes with tetraallyltin at room temperature in fluorous/organic biphasic solvent systems, in which the reactions proceed more rapidly than in a single organic or fluorous solvent. Due to the unique surface activity of 1, the catalyst, organic substrate(s), and reagent(s) are distributed in both organic and fluorous phases to facilitate smooth reactions. Upon dilution with toluene after the reaction, the catalyst concentrates to the fluorous phase, while the organic substances migrate to the organic phase to effect facile catalyst recovery and recycling. By virtue of such a unique solvophilicity, a new version of fluorous biphase technology has been developed. [source] Donor-Stabilized Phosphenium Adducts as New Efficient and Immobilizing Ligands in Palladium-Catalyzed Alkynylation and Platinum-Catalyzed Hydrogenation in Ionic LiquidsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 10 2009Samer Saleh Abstract The straightforward synthesis of a new donor-stabilized phosphenium ligand 3d by addition of bromodifurylphosphine to 1,3-dimethylimidazolium-2-carboxylate 1 is described. The obtained ligand exhibits a very strong ,-acceptor character, comparable to that of triphenyl phosphite [P(OPh)3] or of tris-halogenophosphines, with a ,CO(A1) at 2087,cm,1 for its nickel tricarbonyl complex. This ligand, as well as the related 3a which was obtained from chlorodiphenylphosphine, were tested in palladium-catalyzed aryl alkynylation and in the platinum-catalyzed selective hydrogenation of chloronitrobenzenes, both in an ionic liquid phase. In CC bond cross-coupling we observed that the increase of the ,-acceptor character in ligand 3d, due to the introduction of an additional electron-withdrawing group, provides a very efficient catalyst in the alkynylation reaction of aryl bromides with phenylacetylene, including the deactivated 4-bromoanisole or the sterically hindered 2-bromonaphthalene. The catalytic activity decreases with recycling due to the sensitiveness of ligands to protonation in the ionic phase. Conversely, a multiple recycling of the metal/ligand system in non-acidic media was achieved from platinum-catalyzed hydrogenation of m- chloronitrobenzene. The catalytic results obtained by employing the complex of platinum(II) chloride with 3a [trans -PtCl2(3a)2] in comparison with the non-ionic related trans -tris(triphenylphosphine)platinum dichloride [trans -PtCl2(PPh3)2] complex clearly indicate that the simultaneous existence of a strong ,-acceptor character and a positive charge within the ligand 3a significantly increases the life-time of the platinum catalyst. The selectivity of the reaction is also improved by decreasing the undesirable formation of dehalogenation products. This cationic platinum complex trans -PtCl2(3a)2 is the first example of a highly selective catalyst for hydrogenation of chloronitroarenes immobilized in an ionic liquid phase. The system was recycled six times without noticeable metal leaching in the organic phase, and no loss of activity. [source] Network density control in epoxy,silica hybrids by selective silane functionalization of precursorsADVANCES IN POLYMER TECHNOLOGY, Issue 2 2005Luca Prezzi Abstract Following previous work on the compatibilization of organic,inorganic hybrids through coupling reactions with the precursor components, the present study evaluates the relative efficiency of different types of coupling agents on the morphology and properties of epoxy,silica hybrids. In particular, this investigation compares the effects of introducing trialkoxysilane functional groups at the chain end (using amine- and mercapto-silanes) with similar types grafted in the middle of the chain of the constituent resin (using an isocyanate silane). The use of coupling agents with a basic character (amine silane type) brings about the formation of denser networks in both constituent phases of the resulting epoxy,silica hybrid, which is manifest through a large increase in the Tg and a more extensive suppression of the molecular relaxations within the glass transition regions. Increasing the number of alkoxysilane functional groups at the chain end, with the use of a bis-aminosilane, has a relatively minor effect on the morphology and dynamic mechanical spectra of the resulting epoxy,silica hybrids. It was also found that while the incorporation of small amounts of a high molecular weight epoxy resin causes considerable plasticization of the organic phase, much larger amounts of organic (aliphatic) co-agent within the siloxane phase are required to deteriorate those properties that are related to the inorganic character of the hybrid material. © 2005 Wiley Periodicals, Inc. Adv Polym Techn 24:91,102, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20033 [source] Effects of bivalve shell particles of hyriopsis cumingii on the performances of epoxy resin studied by positron annihilationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Xudong Sun Abstract Mussel shell particles sized in micrometer level have been prepared with a ball mill. The X-ray powder diffractrometer (XRD) and Fourier transform infrared (FTIR) results proved that the shell particles contained mainly CaCO3 in the form of aragonite, together with small amount of organic phase. EP modified with shell particles showed a much rougher fracture surface than unfilled EP. The mechanical properties have been improved obviously by adding the shell particles in EP from 1% to 5%. The particle would occupy a number of free volume holes of the EP matrix. This would lead to a decrease in the total free volume concentration of the composites. The particles acted as a bridge to make more molecules interconnected for the good interfacial adhesion, resulting in a reduction of the free volume hole size in the interfacial layers. I2 reached its highest value when 3% shell particles were added and then decreased as the shellparticles content increased. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Hydrocarbon degradation by thermophilic Nocardia otitidiscaviarum strain TSH1: physiological aspectsJOURNAL OF BASIC MICROBIOLOGY, Issue 6 2007Majid Zeinali Abstract Indigenous thermophilic hydrocarbon degraders are of special significance for the bioremediation of oil-contaminated desert soils with ambient temperature of 45,50 °C. The first objective of this study was to demonstrate the hydrocarbon-degrading capability of Nocardia otitidiscaviarum TSH1 (DSM 45036) which grows optimally at 50 °C. Analysis of the metabolic profile of the strain TSH1 showed that it could metabolize phenol, intermediate-chain-length n -alkanes and some polycyclic aromatic hydrocarbons (PAHs) ranging in size from two to four fused rings efficiently, but not toluene and xylene. N. otitidiscaviarum TSH1 was able to survive and grow at phenol concentrations up to 875 mg l,1. For the first time, the physiological response of a thermophilic Nocardia strain to poorly available hydrophobic compounds was also investigated. When grown on a mineral salt medium with hexadecane, N. otitidiscaviarum TSH1 showed very high affinity for the organic phase. Additionally, PAH-grown cells were considerably hydrophobic. The capacity of PAH-utilizing N. otitidiscaviarum TSH1 isolate to produce biosurfactants was also investigated. Fatty acids (C14,C18) were detected by GC-MS analysis during bacterial growth in PAH supplemented mineral media. High cell surface hydrophobicity and capability of N. otitidiscaviarum TSH1 to degrade different hydrocarbons at 50 °C may make it an ideal candidate to treat oil-contaminated desert soils. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Extraction of alcohol using emulsion liquid membrane consisting of paraffin oil as an organic phase and lecithin as a surfactantJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 2 2010B.S. Chanukya Abstract BACKGROUND: This paper reports on the use of a liquid emulsion membrane involving paraffin light oil as membrane phase and lecithin as surfactant for the extraction of alcohol from anthocyanin extract and simulated pineapple wine. RESULTS: The extraction of alcohol was found to depend on the many factors such as surfactant concentration, contact time, stirring speed, stirring time, and ratio of membrane emulsion to feed volume. Results showed that optimum conditions for maximum alcohol extraction (25%) were lecithin concentration 3%, contact time 20 min, stirring speed 250 rpm and ratio of membrane emulsion to feed volume 1:2. Multistage extraction using this liquid emulsion membrane was found to completely remove alcohol from anthocyanin extract and from simulated pineapple wine in seven stages and five stages, respectively. CONCLUSION: This liquid emulsion membrane was found to be a useful method for the extraction of alcohol from aqueous feed. Copyright © 2009 Society of Chemical Industry [source] Computer simulation of flow-sheets for the solvent extraction of uranium: a new route to delay the effect of chemical degradation of the organic phase during uranium recovery from acidic sulfate mediaJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2009Alexandre Chagnes Abstract BACKGROUND: The extractants used in solvent extraction processes undergo degradation under thermal, chemical and radiolytical stresses. In the case of uranium plants, tri- n -octylamine, used as an extractant, slowly degrades into di- n -octylamine. Such degradation causes a gradual depletion of the uranium extraction isotherms and as a result, of the efficiency of uranium recovery from feed solutions. The present work highlights a new route to delay this depletion of the extraction efficiency, merely by optimizing the flow-sheets involved in the process. Five flow-sheets have been compared for uranium recovery from acidic sulfate media by a solution of 0.146 mol L,1 tri- n -octylamine in kerosene modified with 5% w/w 1-tridecanol and stripping with a 199 g L,1 Na2CO3 solution. These five flow-sheets include the classical counter-current flow-sheet with four mixers,settlers in extraction and three mixers,settlers in stripping and four unusual combined solvent extraction flow-sheets with two independent extraction stripping loops and with one or two feed inlets. RESULTS: Computer simulation supplied evidence of the strong influence of the studied flow-sheets on the sturdiness of the process. More precisely, the unusual combined solvent extraction flow-sheets appeared to be significantly more efficient than the classical counter-current one and it is shown that an advantage of this can be to delay the negative impact of gradual degradation of tri- n -octylamine on uranium recovery efficiency from acidic sulfate media. CONCLUSION: The replacement of classical counter-current flow-sheets with a unique extraction-stripping loop in unusual combined flow-sheets with two or more independent extraction-stripping loops and with one or more feed inlets is a fruitful approach to delay the periodic addition of fresh tri- n -octylamine necessary for counter-balancing the progressive degradation of the extraction solvent and, as a result, to delay the gradual depletion of the efficiency of uranium recovery. Copyright © 2009 Society of Chemical Industry [source] Cobalt removal from waste-water by means of supported liquid membranesJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2009Kim Verbeken Abstract BACKGROUND: Supported liquid membranes (SLM) are an alternative technique to remove and recover metals from diluted process solutions and waste-water. In the present work, the removal of Co(II) from a synthetic CoSO4 solution containing initial amounts of cobalt(II) in the range 100,200 ppm (0.1,0.2 g dm,3) has been studied on a pilot scale. By performing batch equilibrium experiments, the optimal settings, i.e. the composition of the organic phase, the pH of the feed, the type and concentration of the stripping agent were determined. RESULTS: It is shown that the equilibrium characteristics of a synergistic extractant mixture containing di-2-ethyl-hexylphosphoric acid (D2EHPA) and 5-dodecylsalicylaldoxime (LIX 860-I) are superior to D2EHPA. Both hydrochloric acid and sulfuric acid have been evaluated as stripping solutions in liquid,liquid extraction tests and as the receiving phase in a SLM configuration. Although equilibrium tests showed no difference in stripping characteristics between both chemicals, it was observed that in a SLM configuration the stability of the system when hydrochloric acid is used is poor. With a commercially available SLM module (Liqui-Cel Extra-Flow 4 × 28) having a surface area of 19 m2, a steady Co(II) flux of 0.140 gm,2h,1 has been obtained at influent concentrations of cobalt between 100 and 200 ppm with 3 mol dm,3 sulfuric acid as stripping phase. CONCLUSIONS: The results obtained show that a supported liquid membrane containing a synergistic mixture of LIX 860-I and D2EHPA gives the possibility of recovering cobalt from dilute solutions. Copyright © 2008 Society of Chemical Industry [source] Improvement of enantioselectivity and stability of Klebsiella oxytoca hydrolase immobilized on Eupergit C 250LJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2008Pei-Yun Wang Abstract BACKGROUND: A simple procedure was employed to covalently immobilize a Klebsiella oxytoca hydrolase (SNSM-87) onto epoxy-activated supports of Eupergit C 250L via multipoint covalent attachment. The resultant biocatalyst was explored for the hydrolytic resolution of a variety of (R,S)-2-hydroxycarboxylic acid ethyl esters. RESULTS: With the hydrolytic resolution of (R,S)-ethyl mandelate in biphasic media as the model system, optimal conditions of 55 °C, pH 6 buffer and isooctane as the organic phase were selected for improving the enzyme stability (activity retained from 10% to 50% at 96 h) and enantioselectivity (VSVR,1 value enhanced from 44 to 319) in comparison to the performance of free enzyme. Moreover, the immobilized enzyme retained its activity and enantioselectivity after eight cycles of hydrolysis at 55 °C. When applying the resolution process to other (R,S)-2-hydroxycarboxylic acid ethyl esters, 2.4- to 4.0-fold enhancements of the enantioselectivity in general were obtainable. CONCLUSIONS: The enantioselectivity enhancement, good reusability and easy recovery after reaction indicate that the immobilized SNSM-87 may have the potential as an industrial biocatalyst for the preparation of optically pure 2-hydroxycarboxylic acids. Copyright © 2008 Society of Chemical Industry [source] Liquid,liquid extraction of cadmium(II) by Cyanex 923 and its application to a solid-supported liquid membrane systemJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 9 2005Ana María Rodríguez Abstract The extraction of cadmium(II) by Cyanex 923 (a mixture of alkylphosphine oxides) in Solvesso 100 from hydrochloric acid solution has been investigated. The extraction reaction is exothermic. The numerical analysis of metal distribution data suggests the formation of CdCl2.2L, HCdCl3.2L and H2CdCl4.2L (L = ligand) in the organic phase. The results obtained for cadmium(II) distribution have been implemented in a solid-supported liquid membrane system. The influences of feed phase stirring speed (400,1400 min,1), membrane composition (carrier concentration: 0.06,1 mol dm,3) and metal concentration (0.01,0.08 g dm,3) on cadmium transport have been investigated. Copyright © 2005 Society of Chemical Industry [source] Separation of cobalt and nickel from acidic sulfate solutions using mixtures of di(2-ethylhexyl)phosphoric acid (DP-8R) and hydroxyoxime (ACORGA M5640)JOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 5 2004Arisbel Cerpa Abstract DP-8R and ACORGA M5640 extractants diluted in Exxsol D100 were used to co-extract cobalt and nickel from aqueous acidic sulfate media. The influences of equilibration time, temperature, equilibrium pH and reagent concentrations on the extraction of both metals have been studied. It was observed that both cobalt and nickel extraction are slightly sensitive to temperature but are pH dependent. Metal extraction equilibria are reached within about 5 min contact time. In addition, cobalt extraction depends on the extractant concentration in the organic phase. For a solution containing 0.5 g dm,3 each of cobalt and nickel and an initial pH of 4.1, conditions were established for the co-extraction of both metals and selective stripping (with H2SO4) of cobalt and nickel. Using the appropriate reagent concentrations the yield (extraction stage) for both metals exceeded 90%, and stripping of cobalt and nickel was almost quantitative. Copyright © 2004 Society of Chemical Industry [source] Extraction and recovery of gold from KAu(CN)2 using cetyltrimethylammonium bromide microemulsionsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2001Tian-Xi Zhang Abstract Extraction and stripping of KAu(CN)2 from alkaline solution by a w/o microemulsion formed with cetyltrimethylammonium bromide (CTAB) using 198Au(I) tracer has been investigated. Various parameters, such as the Au(I) concentration in aqueous phase, concentrations of halide ions, NH4SCN and thiodiethylene glycol in stripping solution as well as the relationship between water and Au(I) concentration in the organic phase in the extraction and stripping of Au(I) were studied. The results show that almost all of the Au(I) in the aqueous phase was extracted into the organic phase. The water content decreased significantly with an increase in Au(I) concentration in the organic phase, contrary to the results of a system with tributyl phosphate (TBP) as cosolvent. Almost all of the extracted Au(I) (,98%) can be recovered with pure thiodiethylene glycol as the stripping agent, and ,93% of the Au(I) is stripped with high concentrations of NH4SCN(>3.0,mol,dm,3) or KI (>2.0,mol,dm,3). © 2001 Society of Chemical Industry [source] Liquid,liquid extraction of Hg(II) from acidic chloride solutions using bis-2-ethylhexyl sulfoxideJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2001Tania Francis Abstract The liquid,liquid extraction of Hg(II) from acidic chloride solutions has been studied using bis-2-ethylhexyl sulfoxide (B2EHSO) as an extractant. For comparison, extraction studies have also been carried out using di- n -octyl sulfoxide (DOSO) and diphenyl sulfoxide (DPhSO). The extraction data have been analysed by both graphical and theoretical methods taking into account aqueous phase speciation and all plausible complexes extracted into the organic phase. These results demonstrate that Hg(II) is extracted into xylene as HgCl2.3R2SO (where R2SO represents the sulfoxide). The equilibrium constant of the extracted complex has been deduced by non-linear regression analysis. The developed liquid,liquid extraction procedure has been applied for the recovery of mercury from the brine-sludge of a Chlor-Alkali plant. © 2001 Society of Chemical Industry [source] Toward greener separations of rare earths: Bifunctional ionic liquid extractants in biodieselAICHE JOURNAL, Issue 9 2010Yinghui Liu Abstract Ionic liquids (ILs) containing quaternary phosphonium cations and phosphonic acid anions were explored as novel extractants for rare earths (RE) separation. They were considered to be bifunctional ionic liquid extractants (bif-ILEs), since both cations and anions of ILs were involved in the extraction. Trihexyl(tetradecyl)phosphonium bis 2,4,4-trimethylpentylphosphinate (Cyphos IL 104), as a bif-ILE, together with propylene carbonate (PC), dimethyl carbonate (DMC), and soybean oil methyl ester (SBME, biodiesel) as diluents was employed in the extraction of RE(III) from aqueous solutions. Acidified Cyphos IL 104 (HNO3 -Cyphos IL 104) exhibited high solubility in three diluents, and higher extraction efficiency than bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex 272) because of the coextraction of RE(III) by quaternary phosphonium cation and phosphonic acid anion in organic phase. Additionally, this coextraction mechanism could eliminate the loss of IL. The physical properties and miscibility test results indicated that SBME was an excellent solvent for RE(III) extraction. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] Influence of elevated pressure and particle lyophobicity on hydrodynamics and gas,liquid mass transfer in slurry bubble columnsAICHE JOURNAL, Issue 3 2010Vinit P. Chilekar Abstract This article reports on the influence of elevated pressure and catalyst particle lyophobicity at particle concentrations up to 3 vol % on the hydrodynamics and the gas-to-liquid mass transfer in a slurry bubble column. The study was done with demineralized water (aqueous phase) and Isopar-M oil (organic phase) slurries in a 0.15 m internal diameter bubble column operated at pressures ranging from 0.1 to 1.3 MPa. The overall gas hold-up, the flow regime transition point, the average large bubble diameter, and the centerline liquid velocity were measured along with the gas,liquid mass transfer coefficient. The gas hold-up and the flow regime transition point are not influenced by the presence of lyophilic particles. Lyophobic particles shift the regime transition to a higher gas velocity and cause foam formation. Increasing operating pressure significantly increases the gas hold-up and the regime transition velocity, irrespective of the particle lyophobicity. The gas,liquid mass transfer coefficient is proportional to the gas hold-up for all investigated slurries and is not affected by the particle lyophobicity, the particle concentration, and the operating pressure. A correlation is presented to estimate the gas,liquid mass transfer coefficient as a function of the measured gas hold-up: . © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Preparation of polymer-supported polyethylene glycol and phase-transfer catalytic activity in benzoate synthesisAICHE JOURNAL, Issue 3 2010Baojiao Gao Abstract The crosslinked polymeric microspheres (GMA/MMA) of glycyl methacrylate (GMA) and methyl methacrylate (MMA) were prepared by suspension polymerization. Polyethylene glycol (PEG) was grafted on GMA/MMA microsphers via the ring-opening reaction of the epoxy groups on the surfaces of GMA/MMA microspheres, forming a polymer-supported triphase catalyst, PEG-GMA/MMA. The Phase-transfer catalytic activity of PEG-GMA/MMA microspheres was evaluated using the esterification reaction of n -chlorobutane in organic phase and benzoic acid in water phase as a model system. The effects of various factors on the phase transfer catalysis reaction of liquid,solid,liquid were investigated. The experimental results show that the PEG-GMA/MMA microspheres are an effective and stable triphase catalyst for the esterification reaction carried out between oil phase and water phase. The polarity of the organic solvent, the ratio of oil phase volume to water phase volume and the density of the grafted PEG on PEG-GMA/MMA microspheres affect the reaction rate greatly. For this investigated system, the solvent with high polarity is appropriate, an adequate volume ratio of oil phase to water phase is 2:1, and the optimal PEG density on the polymeric microspheres is 15 g/100 g. Triphase catalysts offer many advantages associated with heterogeneous catalysts such as easy separation from the reaction mixture and reusability. The activity of PEG-GMA/MMA microspheres is not nearly decreased after reusing of 10 recycles. © 2009 American Institute of Chemical Engineers AIChE J, 2010 [source] Process intensification using a two-phase system and micromixing for consecutive and reversible reactionsAICHE JOURNAL, Issue 6 2009Yoshihito Okubo Abstract This study aimed to find reaction conditions that improve the yield of target intermediate products, using a two-phase system and a microspace for first-order consecutive and reversible reactions. As a result, the yield of target products with a two-phase system can be surpassed by that of a single-phase system through selecting the organic phase such that the partition coefficient of the raw material to the aqueous phase is large, and that of the target product to the organic phase is also large. In addition, the volume ratio of two phases and the liquid,liquid interfacial area are also important factors for improving the target product yield. In a microspace, the microfluid segments can be designed both arbitrarily and precisely, and thus it is possible to control the interfacial area and mass transfer rates accurately. Utilization of a microspace can play a significant role in intensifying a two-phase system. © 2009 American Institute of Chemical Engineers AIChE J, 2009 [source] Kinetics of separating multicomponent mixtures by nondispersive solvent extraction: Ni and CdAICHE JOURNAL, Issue 4 2001Inmaculada Ortiz A model for nonsteady metals separation using nondispersive solvent extraction presented explicitly accounts for selective separation of multicomponent solutions and concentration of separated components in a back-extraction phase. The separation process comprises extraction and back-extraction steps carried out in two different hollow-fiber modules, connected through the organic phase, together with three homogenization tanks. The model is based on a set of coupled differential equations describing mass balances of metallic solutes in the fluid phases. To be applied in its simplest form, it requires the knowledge of three characteristic parameters, two parameters related to the chemical reactions, and one mass-transport parameter. The latter describes the mass-transport rate through pores of the hollow-fiber membrane filled with the organic phase. The mathematical model was checked against the kinetic results of the separation of Cd/Ni mixtures working with high-concentration solutions and obtaining the characteristic parameters of this system. [source] Influences of alkyl group chain length and polar head group on chemical skin permeation enhancementJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2001Kevin S. Warner Abstract Previous investigations in our laboratory on the influence of the n -alkanols and the 1-alkyl-2-pyrrolidones as skin permeation enhancers for steroid molecules as permeants demonstrated that the enhancer potencies (based on aqueous concentration values) of these two homologous series were the same when compared at the same alkyl chain length; that is, the contribution of the hydroxyl group and that of the pyrrolidone group to enhancer potency were the same. The purpose of the present study was to further investigate what was believed to be a somewhat surprising finding, and two additional homologous series, the 1,2-alkanediols and N,N -dimethylalkanamides, were selected for study as enhancers. Corticosterone (CS) flux enhancement along the lipoidal pathway of hairless mouse skin stratum corneum was determined with 1,2-hexane-, 1,2-octane-, and 1,2-decanediol and with N,N -dimethylhexanamide, N,N - dimethylheptanamide, N,N -dimethyloctanamide, and N,N -dimethylnonanamide as enhancers. The enhancement factor (E) for the lipoidal pathway was calculated from the CS permeability coefficient and the CS solubility data over a 4 to 100 range of E values. Comparisons of the enhancer potencies of all four homologous series revealed that the enhancer potencies of all were very nearly the same when compared at equal alkyl group chain length. Moreover, the contribution of each of the polar head groups toward the enhancer potency was essentially constant, independent of the alkyl group chain length. It was reasoned that this outcome was either the result of the random selection of four polar head groups making the same contribution to enhancer potency or the result of these particular polar head groups not contributing to enhancer potency. To test the hypothesis that the former was more likely than the latter and that a suitable semipolar organic phase may mimic the microenvironment of the polar head group at the site of enhancer action, n -octanol,phosphate buffered saline (PBS) and n -hexane,PBS partition coefficients were determined for all the enhancers. The n -octanol,PBS partition coefficients for the enhancers, but not the n -hexane,PBS partition coefficients, were very nearly the same when compared at equal alkyl group chain lengths; this result supports the hypothesis that each of the four polar head groups likely contributes the same toward the enhancer potency and locates in the semipolar region of the hairless mouse skin stratum corneum lipid bilayers, which is well-approximated by water-saturated n -octanol. © 2001 Wiley-Liss, Inc. and the American Pharmaceutical Association J Pharm Sci 90:1143,1153, 2001 [source] Two-phase flow electrosynthesis: Comparing N -octyl-2-pyrrolidone,aqueous and acetonitrile,aqueous three-phase boundary reactionsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 1 2009Stuart M. MacDonald Abstract A microfluidic double channel device is employed to study reactions at flowing liquid,liquid junctions in contact with a boron-doped diamond (BDD) working electrode. The rectangular flow cell is calibrated for both single-phase liquid flow and biphasic liquid,liquid flow for the case of (i) the immiscible N -octyl-2-pyrrolidone (NOP),aqueous electrolyte system and (ii) the immiscible acetonitrile,aqueous electrolyte system. The influence of flow speed and liquid viscosity on the position of the phase boundary and mass transport-controlled limiting currents are examined. In contrast to the NOP,aqueous electrolyte case, the acetonitrile,aqueous electrolyte system is shown to behave close to ideal without ,undercutting' of the organic phase under the aqueous phase. The limiting current for three-phase boundary reactions is only weakly dependent on flow rate but directly proportional to the concentration and the diffusion coefficient in the organic phase. Acetonitrile as a commonly employed synthetic solvent is shown here to allow effective three-phase boundary processes to occur due to a lower viscosity enabling faster diffusion. N -butylferrocene is shown to be oxidised at the acetonitrile,aqueous electrolyte interface about 12 times faster when compared with the same process at the NOP,aqueous electrolyte interface. Conditions suitable for clean two-phase electrosynthetic processes without intentionally added supporting electrolyte in the organic phase are proposed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Substituent effects on ion complexation of para - tert -butylcalix[4]arene esters,JOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 11 2006Márcio Lazzarotto Abstract Phenoxy-carboxy-methoxy- p-tert -butylcalix[4]arene esters were synthesized in order to evaluate the role of electronic parameters on the complexation of alkaline metal cations. Extraction constants of metal picrates to organic phase were determined. Plots of log (KR/KH) against Hammett , and , gave good linear correlations. The best correlations with , were obtained for K+ and Rb+, while the best correlations with , were obtained for Li+ and Na+. All Hammett plots gave a straight descending line, which is consistent with a dependence of the electronic density on the CO. Treatment of data using the Yukawa,Tsuno equation revealed a variation in the contribution of resonance in the complexation of alkaline metal ions, which is maximum for Na+ and minimum for Rb+. Electronic parameters were calculated for a related acyclic model structure and only the HOMO energy showed a good correlation with log (KR/KH). Copyright © 2007 John Wiley & Sons, Ltd. [source] Synthesis and characterization of secondary-amine-functional microparticlesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 15 2004E. Banu Altinta Abstract Secondary-amine-functional microparticles were prepared in the range of 50,250 ,m through the suspension polymerization of styrene, divinylbenzene (DVB), and 2-(tert -butylamino)ethyl methacrylate (tBAEMA). This study focused on the effects of the DVB, tBAEMA, initiator, and stabilizer concentrations and shaking rate on the experimental amine content, swelling ratio, average particle size, and particle size distribution. The suspension polymerization experiments were carried out in two different systems. In the first system, an organic phase, including the monomers and initiator, was dispersed in an aqueous medium in the presence of Al2(SO4)3. Al2(SO4)3, in the presence of an amine monomer (pH , 10), formed colloidal Al(OH)3, which built a nonsticky layer on the surface of the polymerizing droplets that prevented them from coalescing and aggregating. Individual and spherical particles within the range of 50,200 ,m were obtained by this polymerization method. The second method was similar to the first polymerization protocol, except that a certain amount of sodium dodecyl sulfate was added as a costabilizer in the presence of Al2(SO4)3. In these experiments, individual and spherical particles were obtained within the range of 130,250 ,m. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem: 3708,3719, 2004 [source] | ||||||||||||||||||||||||||||||||||