Direct Extraction of Propionic Acid from Propionibacterium acidipropionici Broths with Tri‐n‐octylamine

The direct reactive extraction of propionic acid from Propionibacterium acidipropionici broths with solutions of tri‐n‐octylamine in dichloromethane, n‐butyl acetate or n‐heptane underlined the strong negative influence of the cells, due to the blockage of the interface by their adsorption. The magnitude of this effect <#>depends on the affinity of the cells for the organic phase, which is more important for n‐heptane, but only at biomass concentrations below 18 g L^–1 d.w. (dry weight). Moreover, the interfacial mass transfer of the acid is also controlled by the solvent polarity, and is accelerated from n‐heptane to dichloromethane and by the addition to the organic phase of 1‐octanol as a phase modifier. The influences of the biomass concentration, the rotation speed and the solvent dielectric constant were included in a mathematical model describing the solute mass flow from the aqueous to the organic phase.     

Application of lipase immobilized on nylon‐6 for the synthesis of butyl acetate by transesterification reaction in n‐heptane

A purified alkaline thermotolerant bacterial lipase from Bacillus coagulans BTS‐3 was immobilized on nylon‐6 matrix activated by glutaraldehyde. The matrix showed ～ 70% binding efficiency for lipase. The bound lipase was used to perform transesterification in n‐heptane. The reaction studied was conversion of vinyl acetate and butanol to butyl acetate and vinyl alcohol. Synthesis of butyl acetate was used as a parameter to study the transesterification reaction. The immobilized enzyme achieved ～ 75% conversion of vinyl acetate and butanol (100 mmol/L each) into butyl acetate in n‐heptane at 55°C in 12 h. When alkane of C‐chain lower or higher than n‐heptane was used as an organic solvent, the conversion of vinyl acetate and butanol to butyl acetate decreased. During the repetitive transesterification under optimal conditions, the nylon bound lipase produced 77.6 mmol/L of butyl acetate after third cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Solvent extraction of some metal ions with di‐2‐methylnonylphosphoric acid into heptane

Di‐2‐methylnonylphosphoric acid (HA) as an extractant was investigated for the extraction of divalent metal ions into heptane at an aqueous ionic strength of 0.10 mol dm^?3 (NaClO₄) and at 25 °C. The extraction ability of metal complexes decreased in the order Cd(II) ≈ Mn(II) > Cu(II) > Co(II) > Ni(II). The metal complexes extracted were found to be all monomeric species for these metal ions using a slope analysis method. The curve fitting method was also applied to analyze the types of metal complexes extracted: MnA₂3HA and MnA₂4HA for manganese(II), CdA₂3HA and CdA₂4HA for cadmium(II), CuA₂2HA and CuA₂3HA for copper(II), CoA₂3HA and CoA₂4HA for cobalt(II) and NiA₂4HA and NiA₂5HA for nickel(II). Further, the extraction constants for the extracted metal complexes were evaluated. © 2002 Society of Chemical Industry     

Factors affecting catalytic performance in yadh-catalyzed reductions in non-conventional media

The effects of parameters including water content, the amount of celite and the co-factor regeneration system on reduction of benzaldehyde to benzyl alcohol by yeast alcohol dehydrogenase (YADH) immobilized on celite in non-conventional media were investigated. Kinetic parameters (apparent) such as V_max, K_m, and k_car for different organic solvents used (butyl acetate, hexane, heptane and i-octane) were determined. K_m values for benzaldehyde increased as the solvent was varied in the following manner: butyl acetate < hexane < i-octane < heptane. The highest K_m value (20.26 mmol/L) was noted in heptane and the lowest (3.24 mmol/L) in butyl acetate. The V_max value in heptane was more than an order of magnitude higher than that in butyl acetate. Catalytic efficiencies (as expressed by k_car/K_m) ranged from 0.703 × 10^?4 L/mol · s for hexane to 0.171 × 10^?4 L/mol · s for butyl acetate. In general, linear relationships were observed between k_car/K_m and the following solvent physico-chemical constants: dielectric constant logarithm of the saturated molar solubility of water in the organic solvents, log S_w/o, logarithm of partition coefficient of organic solvent in water/octanol two-phase system, log P, Hildebrand solubility parameter, δ, and solvatochromism of pyridinium-N-phenoxide betaine dye, ET(30).     

Effective separation of aromatic hydrocarbons by pyridine‐based deep eutectic solvents

Many promising qualities of deep‐eutectic solvents made them suitable solvents in separation process. In this work, the pyridine‐based deep eutectic solvents were designed and synthesized with N‐ethylpyridinium bromide and two HBDs (N‐formyl morpholine and levulinic acid). Two ternary systems, benzene + cyclohexane + DES and toluene + n‐heptane + DES, were studied by the liquid‐liquid extraction. The effect of different HBDs, extraction time, volume ratio of DES to system solution, and the initial concentration of aromatic were studied. The DES with N‐formyl morpholine showed better separation performance than that with levulinic acid. The liquid‐liquid extraction equilibrium could be obtained in 10 minutes. The volume ratio of DES to system solution was set as 1:1. Both DESs showed their best separation performance at low temperatures (20°C) and low aromatic concentration system. For the benzene + cyclohexane system, the distribution coefficient of benzene was 1.733 and the selectivity was 23.8 at 20°C. For the toluene + n‐heptane system, the distribution coefficient of toluene was 0.853 and the selectivity was 40.7. Tie‐lines for two ternary systems were obtained, and the Othmer‐Tobias correlation was used to check the reliability of the obtained liquid‐liquid extraction experimental data. The experimental LLE data were correlated using the NRTL model and the calculated data correlated significantly with the experimental data.     

Synthesis of n‐butyl acetamide over immobilized lipase

BACKGROUND: The conversion of carboxylic esters to amides can be accomplished efficiently by enzymatic catalysis. Amidation of benzyl acetate with n‐butyl amine was studied in non‐aqueous media using immobilized lipases. RESULTS: The activities of immobilized lipases, Novozym 435, Lipozyme RM IM and Lipozyme TL IM were evaluated in the synthesis of n‐butyl acetamide, among which Novozym 435 was the best. The process was optimized by studying various process parameters. Benzyl acetate conversion of 46% was achieved in 8 h for a mole ratio of 3:1 of n‐butyl amine to benzyl acetate with 3.67 g L^?1 Novozym 435 in toluene at 55 °C. A model based on an ordered bi–bi mechanism fitted the initial rate data very well and the rate constant and inhibition constants were calculated by non‐linear regression analysis. The initial rate studies showed that the Michaelis constant for benzyl acetate was low indicating high affinity between the enzyme and the reactant. CONCLUSION: A novel, efficient and environmentally benign enzymatic process is reported for the synthesis of n‐butyl acetamide. This method is general and can be used to synthesize analogous compounds in optically enriched form, since it is difficult to make such amides directly from carboxylic acids and amines by purely chemical means. The theoretical predictions and experimental data matched very well. Copyright © 2008 Society of Chemical Industry     

Coproduction of Ethyl Acetate and n‐Butyl Acetate by Using a Reactive Dividing‐Wall Column

The performance of the reactive distillation dividing‐wall column for coproduction of ethyl acetate and butyl acetate was experimentally studied. n‐Butanol and ethanol are raw reaction materials that react with acetic acid in the reaction zone to produce n‐butyl acetate and ethyl acetate, respectively. n‐Butyl acetate is not only a product, but also acts to remove water generated by the esterification reactions. The effects of various parameters, such as catalyst loading per stage, reflux ratio, liquid split and molar feed ratios, ethyl acetate/n‐butyl acetate purity, pressure drop, and total energy consumption, are investigated. Results show that ethanol could be completely converted and the products could be easily separated, which shows great industrial application potential in the coproduction of ethyl acetate and n‐butyl acetate.     

Effect of Solvent on Nanoparticle Production of β‐Carotene by a Supercritical Antisolvent Process

Production of micro‐ to nano‐sized particles of β‐carotene was investigated by means of solution‐enhanced dispersion by supercritical fluids (SEDS). β‐Carotene was dissolved in dichloromethane (DCM), N,N‐dimethylformamide (DMF), n‐hexane, or ethyl acetate, and supercritical CO₂ served as an antisolvent. The effects of the organic solvents, operating pressure, and temperature were examined. The morphologies of the particles produced by the SEDS were observed by field emission‐scanning electron microscopy and particle sizes were determined by image analysis. Irregularly shaped microparticles were produced in the system with DCM and DMF solution. Plate‐like microparticles were generated by using n‐hexane solution and irregular nanoparticles by ethyl acetate solution. The optimum operating conditions were found to be ethyl acetate as solvent in a defined pressure and temperature range.     

The Influence of the Alkyl Chain Length on Extraction Equilibrium of Cu(II) Complexes with 1‐Alkylimidazoles in Aqueous Solution/Organic Solvent Systems

Abstract

The partition of Cu(II) complexes with 1‐alkylimidazoles (with alkyl ranging from 1‐n‐butyl through 1‐n‐hexadecyl) between the aqueous ((0.5HL, K)NO₃) and organic phase has been studied at 25°C. The organic solvents used were toluene, p‐xylene, tetrahydronaphthalene, dichloromethane, 2‐ethyl‐1‐hexanol, and others. Extraction curves have been shown to be displaced towards lower pH values with increasing alkyl chain length of the alkyl substituent. Stability constants of the Cu(II) complexes with the 1‐alkylimidazoles have been determined in the aqueous phase as well as the number of compounds extractable into the organic solvent, and their partition ratios. Stability constants of the complexes did not depend on the alkyl chain length. One or two complexes were transferred to the organic phase. Partition ratios of these complexes, P ₁ and P ₂, increased rapidly with increasing alkyl chain length. They were higher in magnitude than those of their Co(II), Ni(II), and Zn(II) counterparts.     

Synergistic extraction and separation study of rare earth elements from nitrate medium by mixtures of sec‐nonylphenoxy acetic acid and 2,2′‐bipyridyl

BACKGROUND: Synergistic extraction has been proven to enhance extractability and selectivity. Numerous types of synergistic extraction systems have been applied to rare earth elements, among which sec‐nonylphenoxyacetic acid (CA100) has proved to be an excellent synergistic extractant. In this study, the synergistic enhancement of the extraction of holmium(III) from nitrate medium by mixtures of CA100 (H₂A₂) with 2,2′‐bipyridyl (bipy, B) in n‐heptane has been investigated. The extraction of all other lanthanides (except polonium) and yttrium by the mixtures in n‐heptane has also been studied. RESULTS: Mixtures of CA100 and bipy have significant synergistic effects on all rare earth elements, for example holmium(III) is extracted as Ho(NO₃)₂HA₂B with the mixture instead of HoH₂A₅, which is extracted by CA100 alone. The thermodynamic functions, ΔH^o, ΔG^o, and ΔS^o have been calculated as 2.96 kJ mol^?1, ? 6.23 kJ mol^?1, and 31.34 J mol^?1 K^?1, respectively. CONCLUSION: Methods of slope analysis and constant molar ratio have been successfully applied to study the synergistic extraction stoichiometries of holmium(III) by mixtures of CA100 and bipy. Mixtures of these extractants have also shown various synergistic effects with other rare earth elements, making it possible to separate them. Thus CA100 + bipy may be used to separate yttrium from other lanthanides at appropriate ratios of the extractants. Copyright © 2011 Society of Chemical Industry     

Synergistic extraction of rare earths(III) from chloride medium with mixtures of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate

The synergistic effect of 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazalone‐5 (HPMBP, HA) and di‐(2‐ethylhexyl)‐2‐ethylhexylphosphonate (DEHEHP, B) in the extraction of rare earths (RE) from chloride solutions has been investigated. Under the experimental conditions used, there was no detectable extraction when DEHEHP was used as a single extractant while the amount of RE(III) extracted by HPMBP alone was also low. But mixtures of the two extractants at a certain ratio had very high extractability for all the RE(III). For example, the synergistic enhancement coefficient was calculated to be 9.35 for Y³⁺, and taking Yb³⁺ and Y³⁺ as examples, RE³⁺ is extracted as RE(OH)A₂.B. The stoichiometry, extraction constants and thermodynamic functions such as Gibbs free energy change ΔG (?17.06 kJ mol^?1), enthalpy change ΔH (?35.08 kJ mol^?1) and entropy change ΔS (?60.47 J K^?1 mol^?1) for Y³⁺ at 298 K were determined. The separation factors (SF) for adjacent pairs of rare earths were calculated. Studies show that the binary extraction system not only enhances the extraction efficiency of RE(III) but also improves the selectivity, especially between La(III) and the other rare earth elements. Copyright © 2006 Society of Chemical Industry     

Study on the Synthesis of n‐Butyl Acetate by Catalytic Rectification

With Hβ zeolite as the catalyst and θ rings as the fillings, the technological process of synthesizing n‐butyl acetate with acetic acid and n‐butanol in a Φ 30 mm and 2 m tall catalytic rectifying column was studied. The influence of factors such as catalyst loading height, material feed site, reflux ratio and feed rate on the esterification reaction and the rectification effect was investigated. The study results suggested that the appropriate conditions of n‐butyl acetate synthesis by catalytic rectification include: The height ratio of the rectifying section, the reaction section and the stripping section is 1:1:1; acetic acid and n‐butanol are fed in upside and downside of the reaction section, respectively; the reflux ratio is 2.5; the liquid hourly space velocity of n‐butanol is 0.64 h^–1. Under these conditions, the mass fraction of n‐butyl acetate in the column bottom is 98.64 %, and the total yield of n‐butyl acetate is 91.5 %.     

A Highly Efficient Tandem Reaction of 2‐(gem‐Dibromovinyl)phenols(thiophenols) with Organosilanes to 2‐Arylbenzofurans (thiophenes)

2‐Arylbenzofurans(thiophenes) were prepared through an efficient tandem elimination–intramolecular addition–Hiyama cross‐coupling reaction. In the presence of tetra‐(n‐butyl)ammonium fluoride (TBAF), palladium(II) acetate [Pd(OAc)₂] and triphenylphosphine (PPh₃), the reaction of 2‐(gem‐dibromovinyl)phenols(thiophenols) with phenyl(trialkoxy)silanes proceeded smoothly and generated the corresponding products with good yields in one‐pot. It should be noted that TBAF plays an important role in the tandem reaction.     

Carbon Dioxide Absorption into Stirred Emulsions of n‐Alkanes

Volumetric mass transfer coefficients k_La for CO₂ absorption into n‐alkane/water emulsions were determined at oil volume fractions of 0–100 % in a stirred tank at a stirring speed of 1000 min^?1. The oil was n‐heptane, n‐hexadecane, or n‐dodecane. The decrease of k_La with increasing volume fraction of dispersed oil can be uniformly correlated to the emulsion viscosity with the power of ?0.72. Only the addition of n‐heptane caused a strong increase of the mass transfer coefficient. Upon addition of the surfactant sodium dodecyl sulfate to n‐heptane emulsions, k_La decreased as for the other oils. The increase can therefore be attributed to the spreading of n‐heptane on the bubble surface enabling gas‐oil contact, whereas spreading is inhibited by the ionic surfactant.     

Solvent extraction of gold(I) from alkaline cyanide solution by dibutylcarbitol (DBC) with n‐octanol

BACKGROUND: Currently, cyanidisation is preferred for the extraction of gold because it has a number of advantages over other methods. Gold(I) can be extracted with various extractants, but there are no reports on the extraction of gold(I) from cyanide solution by dibutylcarbitol (DBC). In this work the extraction of gold(I) from alkaline cyanide solution using DBC with n‐octanol was studied. Several factors affecting the percentage extraction of gold(I), including DBC concentration, diluent concentration, equilibrium time, phase ratio, pH and gold concentration in aqueous phase, were investigated. RESULTS: The results showed that 96.2% of gold(I) could be extracted using an organic phase composed of 40% (v/v) DBC, 50% (v/v) n‐octanol and 10% (v/v) odourless kerosene. The extraction was quite fast and equilibrium could be established within 2 min. Stripping of the gold‐laden organic phase was carried out using sodium sulfite (Na₂SO₃) and sodium thiosulfate (Na₂S₂O₃) solutions, with Na₂S₂O₃ proving better than Na₂SO₃. The percentage stripping of gold(I) was 96.5% when the Na₂S₂O₃ concentration was 4% (w/w), and the stripping capacity of gold(I) exceeded 311.3 mg L^?1 when the phase ratio (A/O) was equal to 0.2. CONCLUSION: Gold(I) can be extracted from aqueous cyanide solution by DBC in the presence of n‐octanol and efficiently stripped by aqueous Na₂S₂O₃ solution. This method has the potential for practical application in the extraction and separation of gold. Copyright © 2008 Society of Chemical Industry     

Influence of the Steric Hindrance,Ligand Hydrophobicity,and DN of solvents on Structure and Extraction of Cu(II) Complexes of 1‐Alkyl‐2‐Ethylimidazoles

Abstract

Formation of Cu(II) complexes of 1‐alkyl‐2‐ethylimidazoles (where alkyl=propyl, butyl, pentyl, hexyl, and octyl) has been studied by using the liquid‐liquid partition method, at 25°C and a fixed ionic strength of the aqueous phase (I=0.5; (HL)NO₃, KNO₃). The complexes were extracted with 2‐pentanone, 2‐butanol, isoamyl alcohol, 2‐ethyl‐1‐hexanol, dichloromethane, trichloromethane, and toluene. The length of the 1‐alkyl group and the nature of solvent have been shown to influence the extraction process. Extraction curves (log D_M vs. pH) are displaced towards lower pH's with increasing chain length of the 1‐alkyl substituent and donor number of the solvents. Stability constants of the complexes in aqueous solution were determined as well as their partition ratios between the aqueous and organic phase. The stability of the Cu(II) complexes increased with increasing 1‐alkyl chain length. The stability constants are comparable with β_n ones for the Cu(II) complexes of 1‐alkyl‐2‐methylimidazoles, but smaller than those of the Cu(II)–1‐alkylimidazole counterparts. The P_c‐partition ratios of the 1‐alkyl‐2‐ethylimidazole complexes with Cu(II) are high, and increased with increasing 1‐alkyl chain length and the donor number of the solvents. Both the strong steric effect of the ethyl substituent at position 2 and the bulkiness of the 1‐alkyl‐2‐ethylimidazole molecules as well as the strong electron‐donating properties of the solvent molecules have an effect on the change of the coordination number of Cu(II) from 6 to 4. The 4‐coordinate Cu(II) complexes (distorted tetrahedron) are more readily extractable by organic solvent than are the 6‐coordinate ones and for this reason their partition constants, P_c, are high. This finding offers the possibility of extraction of the Cu(II) ions from a mixture cations.     

Cloud point and solvent extraction study of uranium(VI) by 8‐hydroxyquinoline

BACKGROUND: Cloud point extraction (CPE) is an attractive alternative to solvent extraction. However, comparisons between both techniques are lacking. In this paper, the extraction of uranium(VI) using 8‐hydroxyquinoline (HQ) as chelating agent was studied by CPE using Triton X‐114 as non‐ionic surfactant and by solvent extraction using CHCl₃ as diluent. RESULTS: Using CPE, a quantitative extraction was observed for pH higher than 4.5 with a HQ/U ratio of 10. Using solvent extraction an increase in the HQ/U ratio up to 50 is necessary to obtain a near quantitative extraction. Both extraction systems were then compared with respect to the nature of extracted species, and the extraction constants determined using log‐log analysis of the extraction data. In the solvent extraction system, the extracted species were identified as UO₂Q₂ and the corresponding extraction constant was found to be log k_ex = ? 3.6 ± 0.2 on the molar scale. Considering that UO₂Q₂ is also the extracted species in CPE, a slightly higher extraction constant, i.e. log k_ex = ? 2.5 ± 0.3, was found. CONCLUSION: Such a small difference in favour of the CPE system may arise from the combination of various phenomena, including effects of temperature and effects of ‘extractant environment’. However, a change in the nature of the extracted species, namely from UO₂Q₂ in the solvent extraction system to the formation of adducts, i.e. UO₂Q₂(HQ) and UO₂Q₂(HQ)₂ in the CPE system, due to higher HQ concentration in the surfactant‐rich phase compared with chloroform, cannot be precluded, but requires confirmation. Copyright © 2012 Society of Chemical Industry     

INFLUENCE OF SOLVENT POLARITY ON INTERFACIAL MECHANISM AND EFFICIENCY OF SUCCINIC ACID REACTIVE EXTRACTION WITH TRI-n-OCTYLAMINE

This article presents the results of a comparative study of reactive extraction of succinic acid with tri-n-octylamine (TOA) dissolved in solvents with different dielectric constants (dichloromethane, n-butyl acetate, and n-heptane), with and without octan-1-ol addition as phase modifier. The positive effect of octan-1-ol on extraction efficiency was quantified by means of amplification factors. For all studied systems, the addition of octan-1-ol into the solvent phase led to an increase of extraction efficiency, the most important effect being recorded for the solvent with the lowest polarity, namely n-heptane. The maximum value of amplification factor was reached for pH = 6 and indicated an increase of reactive extraction yield of about 1.26 times for dichloromethane, 1.55 times for n-butyl acetate, and 2.88 times for n-heptane.     

Effect of temperature,solvent, Lewis acid and additives on the polymerization of tert‐butyl vinyl ether using Lewis acid‐induced N‐methyleneamines as cationic initiators

N‐Methyleneamines, formed by treating 1,3,5‐trimethylhexahydro‐1,3,5‐triazines with Lewis acids, have been shown to be capable initiators in the cationic polymerization of tert‐butyl vinyl ether, yielding polymers with amine functionality at the chain ends. Previous work was limited to titanium(IV) chloride (TiCl₄) as the Lewis acid in dichloromethane solvent at 0 °C (with resulting polymers possessing relatively broad polydispersity index (PDI) values near 2), while this contribution details the effect of reaction parameters on the polymeric products; specifically, the role of temperature, solvent, Lewis acid and additives. Ultimately, performing the polymerization at ?78 °C in dichloromethane with TiCl₄ as the Lewis acid and tetra‐n‐butylammonium chloride (nBu₄NCl) as the additive afforded the best control over the system, with polymers formed possessing low PDI values (<1.2). Dramatic changes in number‐average molecular weight and PDI were observed in polymers formed by initiating systems of Lewis acid‐induced N‐methyleneamines, with temperature, solvent, Lewis acid and additives all playing a role. By varying single parameters, optimization of the system was achieved. Copyright © 2009 Society of Chemical Industry     

Fischer‐Tropsch Synthesis Over Co‐Ru/γ‐Al2O3 Catalyst in Supercritical Media

The Fischer‐Tropsch synthesis (FTS) in gaseous and supercritical phases was examined in a continuous, high‐pressure fixed‐bed reactor by employing a cobalt catalyst (Co‐Ru/γ‐Al₂O₃). The kinetic modeling of the FTS was investigated in the reactor over a 60–80 mesh cobalt catalyst. The Langmuir‐Hinshelwood kinetic equation was used for both the Fisher‐Tropsch (FT) and water gas shift (WGS) reactions. The kinetic model was applied for simulation of the reactor with 16–20 mesh cobalt catalyst. The simulation results showed a good agreement with the experimental data. The experimental data showed that higher CO conversion and lower CH₄ and CO₂ selectivities were achieved in supercritical media compared to the gaseous phase. The BET surface area and pore volume enhancement results provided evidence of the higher in situ extraction and greater solubility of heavy hydrocarbons in supercritical media than in gaseous phases. Furthermore, the effects of supercritical solvent such as n‐pentane, n‐hexane, n‐heptane and their mixtures were studied. Moreover, the influence of reaction temperature, H₂/CO ratio, W/F_(CO+H2) and pressure tuning in the supercritical media FT synthesis were investigated, as well as the effect of the supercritical fluid on the heat transfer within the reactor. The product carbon distribution had a similar shape for all types of solvents and shifted to lighter molar mass compounds with increasing temperature, H₂/CO ratio, and W/F_(CO+H2). Finally, the product distribution shifted to higher molar mass hydrocarbons with increasing pressure. As a result, one may conclude that a mixture of hydrocarbon products of the FTS can be used as a solvent for supercritical media in Fischer‐Tropsch synthesis.