Showing papers on "Hexane published in 2008"
TL;DR: In this article, a co-solvent (hexane, carbon dioxide, KOH) was added to the reactants in order to decrease the operational temperature and pressures and increase the conversion efficiency of methanol.
164 citations
TL;DR: Isopropanol was the best solvent for the extraction of Gamma-tocopherol and gamma-tocotrienol as compared with hexane for both microwave-assisted and conventional solvent extraction and was better for oil yield extraction at high temperatures.
143 citations
TL;DR: The 2D-GC-TOF-MS method showed to be a useful and fast technique to determine the composition of (upgraded) pyrolysis oil and is potentially a very useful tool for exploratory catalyst research and kinetic studies.
111 citations
TL;DR: In this article, the chemical composition of both commercial and pilot scale supercritical carbon dioxide (SC-CO2) processed WGO was examined, and it was shown that the SCCO2 extraction method could eliminate the degumming step from edible oil refining processes.
Abstract: Wheat germ oil (WGO) is a specialty product with a very high nutritional value. The chemical composition of both commercial and pilot scale supercritical carbon dioxide (SC-CO2) processed WGO was examined. This study showed that methods used for oil extraction and refining did not have a significant effect on the fatty acid composition of the oil. SC-CO2 extracted oil had a higher tocopherol content than that of commercially hexane extracted oil. The phospholipid content of the SC-CO2 extracted oil was very low indicating that the SC-CO2 extraction method could eliminate the degumming step from edible oil refining processes. Although the conventional chemical oil refining technique reduced the tocopherol content of the WGO, it was possible to concentrate tocopherols in WGO by using physical refining methods such as molecular distillation.
108 citations
01 Jan 2008
TL;DR: In this article, the effects of particle size, temperature and type of solvent on the extraction kinetic and thermodynamic parameters were studied and the maximum oil yields were 41.11% for ethanol and 44.29% for n-hexane at 50 o C.
Abstract: In this experiment, Neem oil extraction from Neem seeds (Azadirachta indica A. Juss) with n-hexane and ethanol are presented. Effects of particle size, temperature and type of solvent on the extraction kinetic and thermodynamic parameters were studied. Results showed that the maximum oil yields were 41.11% for ethanol and 44.29% for n-hexane at 50 o C, and 0.425-0.71 mm particle size. Based on psycho-chemical characteristics analysis showed that increasing temperature decreased iodine value but caused saponification, acid, and peroxide value became higher, which means higher extraction temperature result on higher oil yield but lower oil quality. The kinetic of neem oil extraction was derived from mass transfer rate equation. It also found that H ∆ is positive, S ∆ is positive, and G ∆ is negative indicating that this process are endotermic, irreversible, and spontaneous.
106 citations
TL;DR: Investigation of the adsorption mechanism in aqueous solution revealed that hydrogen bonding and hydrophobic interaction were the main driving forces.
73 citations
TL;DR: In this article, the supercritical fluid extraction (SFE) of wheat germ oil was studied and the response surface methodology (RSM) was used to optimize the parameters of supercritical carbon dioxide extraction.
63 citations
TL;DR: The findings collectively suggest that EC1 may be a useful biological resource for removal of cyclohexane, hexane, and other recalcitrant hydrocarbons.
55 citations
TL;DR: In this paper, the authors used near-infrared spectroscopy (NIR) for quantification of the phases in equilibrium of a system composed of vegetable oils + anhydrous ethanol + hexane.
Abstract: The objective of this work was to determine liquid–liquid equilibrium data at (298.3 ± 0.2) K for systems of interest in biodiesel production, such systems being composed of vegetable oils + anhydrous ethanol + hexane. The measurements were performed using near-infrared spectroscopy (NIR) for quantification of the phases in equilibrium. The following vegetables oils were investigated: pretreated cottonseed oil, corn oil, canola oil, refined soybean oil, and degummed soybean oil. Initially, with the purpose of validating the NIR methodology, equilibrium data for the system composed of pretreated cottonseed oil (neutral) + commercial linoleic acid + anhydrous ethanol were determined at (298.2 ± 0.1) K by a conventional method based on acid–base titration and solvent evaporation and by the NIR method. The relative errors between the phase compositions determined by both analytical methods were 2.1 % for the alcoholic phase and 2.0 % for the oil phase. The mass balance errors for all investigated systems vari...
54 citations
TL;DR: In this article, a co-solvent was added to the reaction mixture to improve the reaction process, and then a novel idea was presented in which catalysis and supercritical effect were coupled together.
52 citations
TL;DR: In this paper, nanoporous titania membranes, with pore sizes ranging from 1 to several nm, were prepared by sol-gel processing and applied to permeation of hexane as a model nonaqueous solution system.
TL;DR: In this paper, the results of a study on the use of two ionic liquids as an extraction solvent in the separation of the azeotropic mixture of hexane with ethyl acetate were determined from (293.15 to 303.15) K.
Abstract: This work reports the results of a study on the use of the two ionic liquids as an extraction solvent in the separation of the azeotropic mixture of hexane with ethyl acetate. Experimental densities, speeds of sound, and refractive indices of the binary mixtures of ethyl acetate + hexane or + 1-hexyl-3-methylimidazolium hexafluorophosphate (HMIM PF6) were determined from (293.15 to 303.15) K, since they are necessary to determine liquid-liquid equilibria. Excess molar volumes, changes of refractive index on mixing, and deviations in isentropic compressibility for the above systems were calculated. Liquid-liquid equilibria (LLE) were determined for the ternary systems hexane + ethyl acetate + HMIM PF6 or 1-octyl-3methylimidazolium hexafluorophosphate (OMIM PF6) at 298.15 K and atmospheric pressure. The values of selectivity and distribution ratio were derived from the tie-line data. Experimental liquid-liquid equilibria data were correlated with the NRTL and UNIQUAC equations. These equations were verified to accurately correlate the experimental data.
TL;DR: In this article, a Chinese brown coal was extracted with carbon disulfide and the extract was gradiently eluted with nhexane and ethyl acetate (EA)/n-hexane mixed solvents with different concentrations of EA in a silica gel-filled column.
Abstract: Shengli coal, a Chinese brown coal, was extracted with carbon disulfide and the extract was gradiently eluted with n-hexane and ethyl acetate (EA)/n-hexane mixed solvents with different concentrations of EA in a silica gel-filled column. A series of fatty acid amides, including fourteen alkanamides (C{sub 15}-C{sub 28}) and three alkenamides (C{sub 18} and C{sub 22}), were isolated from the coal by this method and analyzed with a gas chromatography/mass spectrometry. 26 refs., 2 figs., 2 tabs.
TL;DR: The physical and chemical indices of African breadfruit (Treculia Africana) seed oil extracted with polar (isopropanol, Hexane and butanol) and non polar (Acetone) solvents were investigated.
Abstract: The physical and chemical indices of African breadfruit (Treculia Africana) seed oil extracted with polar (isopropanol, Hexane and butanol) and non polar (Acetone) solvents were investigated. The oil (19.85%) and energy contents 452.35 (Kcal) suggest that African breadfruit seeds are a high-energy food. The yields were significantly (P ≤ 0.05) different with hexane extracted (non-polar solvent) oil having 19.85% whilst oil extracted with polar solvents ranged from 15.58 -19.30%. Melting points were 34, 27, 26, 21 I¦C for oil extracted with hexane, isopropanol, butanol and acetone respectively. Smoke points were within the limits of 170 – 255 I¦C for the four oil samples. Iodine values ranged from 14.50 (hexane extracted) t0 25.17 (acetone extracted). Saponification values ranged from 125.89-267.85 while peroxide values were 3.20 mg/kg (hexane) and 3.60-3.83 mg/kg for polar solvents. Free fatty (oleic) acid of oil extracted with hexane was 1.71% and polar solvent extraction ranged from 1.65-1.78%. Hexane had the least peroxide value (8.74 mg/kg) compared to higher values for oil extracted with the polar solvents (9.10 - 9.83 mg/kg).
Keywords: African breadfruit, Treculia Africana, oil extraction, saponification, fatty acids, peroxide value, thiobarbituric acid.
TL;DR: A revised liquid alkane force field based on the charge equilibration formalism for incorporating electrostatic nonadditive effects arising from local polarization is presented.
Abstract: We present a revised liquid alkane force field based on the charge equilibration formalism for incorporating electrostatic nonadditive effects arising from local polarization. The model is a revision of earlier work by Patel and Brooks, specifically addressing deficiencies in the dihedral potential, electrostatic, and Lennard-Jones (van der Waals) parameters of the force field. We discuss refinement of the alkane backbone torsion potential to match high-level ab initio relative conformational energetics for pentane, hexane, and heptane. We further discuss refinement of the electrostatic and Lennard-Jones (van der Waals) parameters to reproduce the experimental polarizability, liquid density, and vaporization enthalpy of hexane. Finally, we calculate bulk liquid properties including densities, vaporization enthalpies, self-diffusion constants, isothermal compressibilities, constant pressure heat capacities, and NMR T 1 relaxation times for a series of linear alkanes ranging from hexane to pentadecane based on the current revised model. We also compute free energies of hydration for pentane, hexane, and heptane. The revised force field offers a significantly improved overall description of these properties relative to the original parametrization. The current alkane force field represents a platform for ongoing development of a CHARMM (Chemistry at Harvard Molecular Mechanics) polarizable force field for lipids and integral membrane proteins.
TL;DR: In this article, the authors studied the reaction of propionic acid using tri-n-octylphosphine oxide (TOPO) in hexane and found that the reaction was first order in propionic acids and first order first order TOPO with the overall rate constant as 46.91 (m 3 /kmol) 2 /s.
Abstract: Organophosphorous compounds have been widely used in inorganic analysis for the extraction and separation of inorganic acids or metal species. Since these compounds can form hydrogen bonds to proton donors, they can also be used for the extraction of acidic organic compounds. Therefore, the reactive extraction of propionic acid using tri-n-octylphosphine oxide (TOPO) in hexane was studied. Equilibrium and kinetics experiments were performed. The extraction of propionic acid using n-heptane, light liquid paraffin, heavy liquid paraffin and hexane was studied and hexane was found to be most suitable diluent. The equilibrium complexation constant for the propionic acid-TOPO complex was determined to be 0.702 m 3 /kmol. The extraction was found to be first order in propionic acid and first order in TOPO with the overall rate constant as 46.91 (m 3 /kmol) 2 /s.
TL;DR: During the operation of the biofilter under non‐aseptic conditions, the addition of bacterial antibiotics did not have a relevant effect on hexane removal, confirming the role of fungi in the uptake of hexane and that bacterial growth was intrinsically limited by an adequate performance of the composites.
Abstract: The removal of volatile organic compounds (VOC) in biofilters packed with organic filter beds, such as peat moss (PM) and pine sawdust (PS), frequently presents drawbacks associated to the collapse of internal structures affecting the long-term operation. Poly(ethylene ether carbonate) (PEEC) groups grafted to these organic carriers cross linked with 4,4′-methylenebis(phenylisocyanate) (MDI) permitted fiber aggregation into specific shapes and with excellent hexane sorption performance. Modified peat moss (IPM) showed very favorable characteristics for rapid microbial development. Water-holding capacity in addition to hexane adsorption almost equal to the dry samples was obtained. Pilot scale hexane biofiltration experiments were performed with the composites after inoculation with the filamentous fungus Fusarium solani. During the operation of the biofilter under non-aseptic conditions, the addition of bacterial antibiotics did not have a relevant effect on hexane removal, confirming the role of fungi in the uptake of hexane and that bacterial growth was intrinsically limited by an adequate performance of the composites. IPM biofilter had a start-up period of 8–13 days with concurrent CO2 production of ∼90 g m−3 h−1 at day 11. The final pressure drop after 70 days of operation was 5.3 mmH2O m−1 reactor. For modified pine sawdust (IPS) packed biofilter, 5 days were required to develop an EC of about 100 g m−3 h−1 with an inlet hexane load of ∼190 g m−3 h−1. Under similar conditions, 12–17 days were required to observe a significant start-up in the reference perlite biofilter to reach gradually an EC of ∼100 g m−3 h−1 at day 32. Under typical biofiltration conditions, the physical–chemical properties of the modified supports maintained a minimum water activity (aw) of 0.925 and a pH between 4 and 5.5, which allowed the preferential fungal development and limited bacterial growth. Biotechnol. Bioeng. 2008;100: 864–871. © 2008 Wiley Periodicals, Inc.
TL;DR: Interfacial tension measurements performed at the water/air and water/oil interfaces provided all the necessary information for the determination of the adsorption parameters by taking partition into account, and allowed the comparison of the advertisersorption properties at both interfaces which showed an increase of the Adsorption equilibrium constant and a decrease of the maximum surface concentration at theWater/oil interface compared to water/ air.
Abstract: Adsorption isotherms have been determined at the water/oil interface for five biphasic systems involving surfactants (non-ionic and ionic) present in both phases at partition equilibrium The systems studied were polyoxyethylene(23)lauryl ether (Brij35) in water/hexane and four ionic surfactants, hexadecyltrimethylammonium bromide (CTAB), and a series of three tetraalkylammonium dodecylsulfate (TEADS, TPADS, and TBADS) in water/CH 2Cl 2 Interfacial tension measurements performed at the water/air and water/oil interfaces provided all the necessary information for the determination of the adsorption parameters by taking partition into account These measurements also allowed the comparison of the adsorption properties at both interfaces which showed an increase of the adsorption equilibrium constant and a decrease of the maximum surface concentration at the water/oil interface compared to water/air The values of the critical aggregation concentration showed, in all cases, that only the surfactant dissolved in the aqueous phase contribute to the decrease of the water/oil interfacial tension In the case of the four ionic surfactants, the critical aggregation concentration obtained in biphasic conditions were lowered because of the formation of mixed surfactant-CH 2Cl 2 aggregates
TL;DR: The results from using hexane as solvent compared to water suggest that surface-adsorbed hydroxyl and molecular water, present on mineral oxides under ambient conditions, may be a key determinant of the adsorbate architecture.
TL;DR: In this paper, a volumetric/gravimetric method was used to measure adaption rates of 2,2-dimethylbutane (DMB) from the liquid phase into MFI zeolite crystals.
TL;DR: In this article, diarylamine-substituted 1,8-naphthalimide derivatives were synthesized and characterized by FT-IR, 1 H, 13 C NMR, mass spectra and elemental analyses.
TL;DR: The results of the GC-MS analyses showed that the seed oil extracted contained N-methylanthranyl acid methyl, fatty acids (such as palmitic, stearic, oleic, linoleic, and linolenic acid), and physiologically active substances of β-sitosterol and squalene.
Abstract: Extraction of Citrus junos seed was carried out at temperatures of 40–70 °C, pressures of 20–50 MPa, and CO2 flow rate of 3 ml/min with supercritical carbon dioxide to obtain the valuable compounds. Seed oil was also extracted by using Soxhlet extraction with hexane as the solvent during 360 min for comparison with the efficiency of supercritical carbon dioxide extraction. Gas chromatography–mass spectrometry (GC–MS) was used to analyze the components present in the seed oil and Gas chromatography-flame ionization detector (GC-FID) was used to quantify their amounts. Among the conditions studied, the highest extraction yield was obtained at higher pressure and temperature (50 MPa and 70 °C). The extraction yield was about 29.5% of the seed, which was almost comparable to that of hexane Soxhlet extraction (33.8%). The results of the GC–MS analyses showed that the seed oil extracted contained N-methylanthranyl acid methyl, fatty acids (such as palmitic, stearic, oleic, linoleic, and linolenic acid), and physiologically active substances of β-sitosterol and squalene.
TL;DR: In this article, pure and strontium-II-added CuAl 2 O 4 composites were investigated for their sensing properties towards volatile organic compounds (VOCs) like benzene, toluene, hexane, heptane and acetic acid.
Abstract: Pure and strontium(II)-added CuAl 2 O 4 composites prepared by sol–gel technology were investigated for their sensing properties towards volatile organic compounds (VOCs) like benzene, toluene, hexane, heptane and acetic acid. X-ray diffraction, scanning electron microscopy (SEM) and nitrogen adsorption/desorption isotherms at 77 K were employed to identify the structural phases, surface morphology and BET surface area of the composites, respectively. The results revealed that the sensitivity factor increased with an increase in temperature up to the optimum temperature at which the maximum sensitivity was obtained and thereafter progressively decreased. Among all the composites tested, CuSA5 (the Cu:Sr molar ratio was kept as 0.2:0.8) showed the highest sensitivity to all VOCs under investigation. The sensitivity factor ( S f ) data in the studied temperature range for all the vapors were employed to fit the Gaussian function. The fit parameters revealed that the data satisfactorily fitted for hexane and acetic acid vapors than the other vapors taken for the study.
TL;DR: In this article, an Abraham solvation equation with five descriptors was used to correlate the experimental solvation enthalpies of 118 solutes in hexane at 298'K to within a standard deviation of 1.82'kJ/mol.
Abstract: Data have been assembled from the published literature on the enthalpies of solvation for gaseous solutes dissolved in the linear alkane solvents, pentane through hexadecane. A total of more than 500 experimental data points were compiled. It is shown that an Abraham solvation equation with five descriptors can be used to correlate the experimental solvation enthalpies of 118 solutes in hexane at 298 K to within a standard deviation of 1.82 kJ/mol for a dataset that spans a range of 89 kJ/mol. Division of the experimental values into a training set and test set shows that there is no bias in predictions, and that the predictive ability of the hexane solvent correlation is better than 2 kJ/mol. The 500+experimental values were combined into a single dataset and used to derive a generic alkane Abraham model correlation equation that predicted the enthalpies of solvation of gaseous solutes in linear alkane solvents to within a standard deviation of 1.82 kJ/mol, which was comparable in predictive accuracy to the solvent-specific Abraham correlation equations derived for hexane (1.82 kJ/mol), heptane (1.85 kJ/mol), and hexadecane (1.84 kJ/mol).
TL;DR: In this article, three methods to recover occluded oil and obtain lecithin from wet gums were assayed: direct extraction of oil with cold acetone (Method I), extraction after water elimination under vacuum (Method II) and by solvent partition with hexane/ethanol (Method III).
Abstract: BACKGROUND: Wet gums produced during aqueous degumming of crude soybean oils are currently processed to produce lecithin or added to meals to increase their nutritive value for animal feed. Oils occluded in these gums are generally not recovered or processed. In this work, three methods to recover occluded oil and obtain lecithin from wet gums were assayed: direct extraction of oil with cold acetone (Method I), extraction after water elimination under vacuum (Method II) and by solvent partition with hexane/ethanol (Method III). RESULTS: Higher oil yields (up to 588 g kg−1 of occluded oil) were obtained when water was eliminated before extraction (Methods II and III). No significant differences were observed in lecithin yields between three methods (720–807 g kg−1 of dried gums). Recovered oils had acidity = 16.7–21.7 g kg−1 as oleic acid, TOTOX (total oxidation) values ≤ 8.82, unsaponifiable matter = 9.0–12.1 g kg−1, and Phosphorus = 87–330 mg kg−1. Lecithins obtained by Methods I, II and III hexane phase had the same purity level (610–691 g of total measured phospholipids kg−1). CONCLUSIONS: The occluded oil in soybean wet gums can be recovered, with quality and stability indexes compatible with their reinsertion in the productive process, by water elimination and extraction with acetone. Lecithins can be obtained with different phospholipid composition and diverse application fields. Copyright © 2008 Society of Chemical Industry
TL;DR: It was found that more than 70% of adsorbed chlorinated aromatics was easily recovered from the channel-type gamma-CD by simply washing with n-hexane, and chlorinate aromatics were completely removed from the insulating oil even by the regenerated adsorbent, indicating that the Gamma-CD assembly can be easily regenerated and recycled.
Abstract: This paper describes the complete removal of chlorinated aromatic compounds from insulating oil by a channel-type γ-cyclodextrin (γ-CD) assembly as a new adsorbent. Using this type of adsorbent (50−60 wt % of oil), 1,2,4- and 1,3,5-trichlorobenzenes, 2- and 4-chlorobiphenyls (2- and 4-MCBs), 4,4‘-dichlorobiphenyl (4,4‘-DiCB), and 3,4,4‘-trichlorobiphenyl (3,4,4‘-TrCB), whose initial concentrations were 100 ppm, were completely removed from the insulating oil. Competitive adsorption experiments using a mixture of 2-MCB and 4-MCB or a mixture of 4-MCB, 4,4‘-DiCB, and 3,4,4‘-TrCB revealed that selective adsorption based on the shape and size of the chlorinated aromatics was achieved by the channel-type γ-CD assembly, implying that inclusion into the cavity of the channel-type γ-CD was responsible for the removal of chlorinated aromatics from insulating oil. It was also found that more than 70% of adsorbed chlorinated aromatics was easily recovered from the channel-type γ-CD by simply washing with n-hexane, a...
TL;DR: In this article, a new lipase immobilization method, textile cloth immobilization, was developed for biodiesel fuel production from transesterification of soybean oil, and the effect of flow rate of reaction liquid, solvents, reaction time, and water content on the biodiesel yield was investigated.
Abstract: The characteristic of biodiesel fuel production from transesterification of soybean oil is studied. The reactant solution is the mixture of soybean oil, methanol, and solvent. A new lipase immobilization method, textile cloth immobilization, was developed in this study. Immobilized Candida lipase sp. 99-125 was applied as the enzyme catalyst. The effect of flow rate of reaction liquid, solvents, reaction time, and water content on the biodiesel yield is investigated. Products analysis shows that the main components in biodiesel are methyl sterate, methyl hexadecanoate, methyl oleate, methyl linoleate, and methyl linolenate. The test results indicate that the maximum yield of biodiesel of 92% was obtained at the conditions of hexane being the solvent, water content being 20 wt%, and reaction time being 24 h.
TL;DR: In this article, the solvent extraction of Ni(II) from aqueous solution using triethylamine (TEA) in hexane as the diluent was investigated.
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28 Oct 2008TL;DR: An azeotrope-like mixture consisting essentially of chlorotrifluoropropene and at least one component selected from the group consisting of pentane, hexane, methanol, and trans-1,2-dichloroethene was proposed in this article.
Abstract: An azeotrope-like mixture consisting essentially of chlorotrifluoropropene and at least one component selected from the group consisting of pentane, hexane, methanol, and trans-1,2-dichloroethene.
TL;DR: In this article, the influence of the silica/alumina ratio (SAR) on the adsorption equilibrium of hexane isomers on MFI zeolites was investigated.