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Showing papers on "Hexane published in 2004"


Journal ArticleDOI
TL;DR: In this article, the application of 20 kHz high-intensity ultrasound during extraction of oil from two varieties of soybeans (TN 96-58 and N 98-4573) using hexane, isopropanol and a 3:2 hexane-isopropol mixture was evaluated.

430 citations


Journal ArticleDOI
TL;DR: In this article, the effect of transmembrane pressure on the flux and retention of PAN/PDMS composite membranes is investigated and the van?t Hoff equation is interpreted using Osmotic phenomena similar to those of aqueous systems.

135 citations


Journal ArticleDOI
TL;DR: The initial quality characteristics (free fatty acid content, oil color, phospholipid content) of crude oil extracted under these optimum conditions were analyzed using various analytical methods based on the standard methods of AOCS and were found to be comparable to the oil extracted with hexane as discussed by the authors.
Abstract: Edible oil extraction with petroleum derivatives as solvents has caused safety, health, and environmental concerns everywhere. Thus, finding a safe alternative solvent will have a strong and positive impact on environments and general health of the world population, considering the scale of oil extraction operations worldwide. The extraction of oil from rice bran by d-limonene and hexane (for comparison) has been carried out at their respective boiling points at various solvent-to-meal ratios and for various extraction times. The preliminary data suggested that the optimum solvent-to-meal ratio and extraction time required for d-limonene extraction of rice bran oil to be 5:1 and 1 h respectively. The initial quality characteristics (free fatty acid content, oil color, phospholipid content) of crude oil extracted under these optimum conditions were analyzed using various analytical methods based on the standard methods of AOCS and were found to be comparable to the oil extracted with hexane. The initial positive result has paved the way for further studies on issues related to meal qualities as well as to a scale-up of the method in the near future.

109 citations


Journal ArticleDOI
TL;DR: MFI-type zeolite membranes prepared by liquid phase hydrothermal synthesis on tubular commercial supports were used to remove model pollutants n -hexane, formaldehyde and benzene present at very low concentration levels (2-230ppmv) in indoor air.

100 citations


Journal ArticleDOI
TL;DR: Unexpectedly, the unsaturated FAME and TAG samples were found to elute more slowly at higher temperatures, a result just the opposite to the usual temperature effect noted in gas and most liquid chromatography systems.

82 citations


Journal ArticleDOI
TL;DR: In this article, the effects of the flow rate, inlet concentration of hexane, water vapor concentration and ozone dosage on the conversion of trace hexane in three processes were investigated, respectively.
Abstract: The degradations of trace hexane in the gas phase by O 3 /UV, TiO 2 /UV and O 3 /TiO 2 /UV were studied. The effects of the flow rate, inlet concentration of hexane, water vapor concentration and ozone dosage on the conversion of hexane in the three processes were investigated, respectively. The experimental results showed that the addition of ozone significantly increase photocatalytic degradation of hexane. The reaction rates of hexane by O 3 /UV and O 3 /TiO 2 /UV increased linearly with an increase of ozone addition, which increased faster in O 3 /UV than in O 3 /TiO 2 /UV. L–H bimolecular model was successfully used to correlate photocatalytic reaction rate data under various hexane and water vapor concentrations. A new model combining L–H model and ozone photolysis was developed to correlate reaction rate data of hexane in O 3 /TiO 2 /UV.

79 citations


Journal ArticleDOI
TL;DR: In this article, the textural characterization of MCM-41 by hexane was employed and confirmed analyses using nitrogen as a probe whereas energetic parameters such as CBET were found to be dramatically low.

47 citations


Journal ArticleDOI
TL;DR: Several solvents were evaluated for extracting free long-chain FA (LCFA) from a fermentation medium as mentioned in this paper, including chloroform, chloromethane/methanol, hexane, and hexane/methyl tert-butyl ether (MTBE) (1∶1).
Abstract: Several solvents were evaluated for extracting free long-chain FA (LCFA) from a fermentation medium. Chloroform, chloroform/methanol (1∶1), hexane, and hexane/methyl tert-butyl ether (MTBE) (1∶1) were evaluated as alternative extraction solvents. Parameters considered for optimizing LCFA recoveries included pH and ionic strength. Maximal LCFA recoveries were obtained by adding 2 mL of the hexane/MTBE (1∶1) solvent mixture, 80 μL of 50% H2SO4, and 0.05 g NaCl to 1 mL of the aqueous sample and mixing for 15 min at 200 rpm. This method quantified saturated LCFA [capric acid (C10∶0) to stearic acid (C18∶0)] and unsaturated LCFA with 18 carbons [linoleic acid (C18∶2) and oleic acid (C18∶1)] with a 98 to 100% recovery. Caproic (C6∶0) and caprylic (C8∶0) acids were characterized by 27 and 76% recoveries, respectively.

42 citations


Journal ArticleDOI
TL;DR: In this article, a class of molecules described by the general formula H-(CC) m H (where m is an integer) can be synthesized using an electric arc between graphite electrodes submerged in an organic solvent such as methanol, n-hexane, n -dodecane, decahydronaphthalene or acetonitrile.

41 citations


Journal ArticleDOI
TL;DR: In this paper, the effects of supercritical fluid (SCF) solvents (pentane or hexane) on product distributions from Fischer−Tropsch synthesis (FTS) over an alumina-supported cobalt catalyst in a fixed-bed-reactor was studied.
Abstract: This study is designed to examine the effects of supercritical fluid (SCF) solvents (pentane or hexane) on product distributions from Fischer−Tropsch synthesis (FTS) over an alumina-supported cobalt catalyst in a fixed-bed-reactor. The influence of reaction conditions (such as temperature, pressure, syngas feed ratio, contact time, and space velocity) on the FTS hydrocarbon product distributions in the supercritical solvents was studied. Changing the density-dependent bulk thermophysical properties of the supercritical pentane medium, by tuning either temperature (210−250 °C) or pressure (45−65 bar), resulted in notable effects on the (C6+) hydrocarbon product distributions and selectivity. One particular set of experiments was designed to directly compare hexane and pentane solvent effects at constant density (ca., ρ = 0.3 g/cm3) and temperature (240 °C) where significantly higher pressure was required in pentane to achieve this density. Interestingly, both pentane and hexane supercritical FTS performed ...

39 citations


Journal ArticleDOI
TL;DR: In this paper, the results in terms of free fatty acids contents were compared with those obtained when n-hexane was used as the solvent, and no significant differences between the oils extracted by both methods were found.
Abstract: Pumpkin, Cucurbita ficifolia, seed oil was extracted with supercritical carbon dioxide (SC-CO2) in the temperature range of 308–318 K and in the pressure range of 18–20 MPa. In addition, the influence of the superficial velocity within a tubular extractor was studied. The oil content determined by a Soxhlet apparatus was 43.5%. Physical and chemical characteristics of the oil were obtained. The results in terms of free fatty acids contents were compared with those obtained when n-hexane was used as the solvent, and no significant differences between the oils extracted by both methods were found. The main fatty acid was ω6-linoleic acid (about 60%), followed by palmitic acid (about 15%) and oleic acid (about 14%). Oxidative stability was studied by using the induction time determined by the Rancimat method. The oil obtained by supercritical fluid extraction (SFE) was less protected against oxidation (4.2 h for SFE-extracted oil and 8.3 h for the pumpkin seed oil extracted with n-hexane). The oil extracted by SC-CO2 was clearer than that extracted by n-hexane, showing some refining. The acidity index was 5.5 for the n-hexane extracted oil. For the oils extracted by SC-CO2, two analyses were made: for the oils obtained at 15 min of extraction time, for which the acidity indices varied from about 15 to 20, and for the remaining oils (extracted until 150 min), for which the acidity indices varied from about 2 to 2.6. The central composite nonfactorial design was used to optimise the extraction conditions, using the Statistica, version 5, software (Statsoft). The best results, in terms of oil recovered by SC-CO2, were found at 19 MPa, 308 K and a superficial velocity of 6.0×10−4 ms−1.

Journal ArticleDOI
TL;DR: The experimental liquid-liquid equilibrium data on propionic acid-water-solvent ternary mixtures at a temperature of 298.15 K were presented in this article, where the tie line data were correlated using the methods of Othmer-Tobias and Hand.
Abstract: The experimental liquid-liquid equilibrium data on propionic acid-water-solvent ternary mixtures at a temperature of 298.15 K are presented. The solvents are n-hexane, cyclohexane, cyclohexanol and cyclohexyl acetate. The distribution coefficients and separation factors are reported. The tie line data are correlated using the methods of Othmer-Tobias and Hand. The experimental results are compared with the values predicted by the UNIFAC group-contribution method.


Journal ArticleDOI
Fu-An Wang1, Liu-cheng Wang1, Jian-chi Song1, and Lei Wang1, Hai-song Chen1 
TL;DR: Using the Glew−Hildebrand saturation technique, the solubilities of bis(2,2,6,6-tetramethyl-4-piperidinyl) maleate in hexane, heptane, octane, m-xylene, and tetrahydrofuran at temperatures from 253.15 k to 310.15 K were measured with the help of the classical equilibrium method as discussed by the authors.
Abstract: Using the Glew−Hildebrand saturation technique, the solubilities of bis(2,2,6,6-tetramethyl-4-piperidinyl) maleate in hexane, heptane, octane, m-xylene, and tetrahydrofuran at temperatures from 253.15 K to 310.15 K were measured with the help of the classical equilibrium method. The experimental data were correlated with the modified Apelblat equation.

Journal ArticleDOI
TL;DR: In this paper, the effect of ultrasound and microwave assistance in enhancing extraction oil yields from soybeans when different solvent types are used for extraction was investigated in two separate experiments and the results indicated that the efficiency of the extraction process depends greatly on the molecular affinity between solvent and solute and that process assistance tested in this study cannot overcome inherent deficiencies in solvent-solute interactions.
Abstract: The effect of ultrasound and microwave assistance in enhancing extraction oil yields from soybeans when different solvents are used for extraction was investigated in two separate experiments. Each study involved a three-factor factorial following a completely randomized design that was replicated three times. Treatment factors investigated in the microwave processing study were microwave pretreatment time (0, 0.5, 1, and 2 min), solvent (isopropanol, hexane, and 3:2 hexane-isopropanol mixture), and extraction time (0.5, 1, 1.5, 2, and 3 h). Ultrasonic intensity (0, 16.4, 20.9, and 47.6 W/cm2) was substituted as a treatment factor in the sonication study. Solvent extraction was accomplished by immersion of ground soybeans in a given volume of solvent at ambient temperature. While oil yields did not approach the 19.2% analyzed oil content of the TN 96-58 used as the test material, they were found to increase with both intensity of the process assistance and extraction time under the conditions of the studies, particularly with hexane and the mixed solvent. The highest yield result of 12.21 g from 100 g soybeans was obtained with the mixed solvent under 47.6 W/cm2 sonication. The results obtained with the mixed solvent with both microwave pretreatment and ultrasound assistance are difficult to explain in terms of physical chemistry. The results with isopropanol indicate that the efficiency of the extraction process depends greatly on the molecular affinity between solvent and solute and that process assistance tested in this study cannot overcome inherent deficiencies in solvent-solute interactions.

Journal ArticleDOI
TL;DR: In this paper, the potential of a novel extraction method, consisting of a combination of pressurized liquid extraction (PLE) using 1:9 (v/v) dimethyl sulfoxide (DMSO)/acetonitrile (1:9, v/v), was examined.

Journal ArticleDOI
TL;DR: The solvent extraction process of Jojoba oil from the meal cake obtained after the mechanical pressing of jojoba seeds was studied in this paper, where commercial hexane and petroleum ether were used as solvents and extraction was carried out at temperatures ranging from 30 to 55 °C using solvent-to-solid ratios, R between 2 and 15 L/kg.
Abstract: The solvent extraction process of jojoba oil from the meal cake obtained after the mechanical pressing of jojoba seeds was studied. Commercial hexane and petroleum ether were used as solvents and the extraction was carried out at temperatures ranging from 30 to 55 °C using solvent-to-solid ratios, R between 2 and 15 L/kg. The equilibrium compositions of the solvent and solid phases were determined. Based on the equilibrium data, the partition coefficient or distribution ratio, D of the oil between both phases was estimated. Also, the number of extraction stages necessary to achieve a certain degree of oil recovery has been determined using different hexane-to-meal ratios. Jojoba oil was also tested for its physical and chemical properties including chemical composition, percentage fatty acid, peroxide value, flash point, fire point, pour point, refractive index, saponification and iodine values. The stability of jojoba oil during storage at room temperature and during heat treatment was also studied.

Journal ArticleDOI
TL;DR: In this paper, the authors investigated the selective separation of benzene from hydrocarbon mixtures by way of liquid-liquid extraction using aqueous solutions of unsubstituted α-cyclodextrin (αCD), βCD and seven kinds of substituted CDs.

Journal ArticleDOI
TL;DR: In this article, a supercritical phase Fischer-Tropsch reaction over a SiO 2 supported cobalt catalyst in a fixed-bed reactor was studied, and the results showed that the 1-olefin content of the products in the super-critical phase fixed bed reactor was obviously higher than that in the gas phase fixed-board but slightly lower than the super critical phase fluidized bed.

Journal ArticleDOI
26 Jul 2004-Vacuum
TL;DR: In this paper, the results of amorphous hydrogenated carbon (a-C:H) films deposited by direct ion beam deposition method were analyzed by Raman spectroscopy, ellipsometry, and electrical resistance measurements.

Journal ArticleDOI
TL;DR: In this article, the activity and selectivity of Ni/MgO catalysts in pre-reforming of n -hexane with steam (S/C, 1.5-3.5) in absence and presence of H 2 (H 2, 2) was investigated.
Abstract: The activity–stability pattern of a 19 wt.% Ni/MgO catalyst in the pre-reforming ( T , 450 °C; P , 10 bar) of n -hexane with steam (S/C, 1.5–3.5) in absence and presence of H 2 (H/C, 2) has been investigated. Deactivation profiles of the kinetics of CH 4 and CO/CO 2 formation indicate that the activity, selectivity and stability are closely related. Hydrogenation of carbon species to methane is a critical step involving the occurrence of coking in the pre-reforming of hexane. Thermodynamic analysis of the outlet reaction stream signals that the net coking rate depends upon the relative kinetics of carbon methanation (MET, C+2H 2 ⇄CH 4 ) and gasification/water–gas-shift (GAS, C+H 2 O⇄H 2 +CO; WGS, CO+H 2 O⇄CO 2 +H 2 ) reactions, while negligible appears the contribution of the Bouduard reaction path (DISP, 2CO⇄C+CO 2 ).

Journal ArticleDOI
TL;DR: In this article, a gas phase oxidative cracking (GOC) or catalytic oxidative cracking (COC) was investigated for the preparation of light alkenes by the GOC process and hexane in the COC process.
Abstract: The preparation of light alkenes by the gas phase oxidative cracking (GOC) or catalytic oxidative cracking (COC) of model high hydrocarbons (hexane, cyclohexane, isooctane and decane in the GOC process and hexane in the COC process) was investigated in this paper. The selection for the feed in the GOC process was flexible. Excellent conversion of hydrocarbons (over 85%) and high yield of light alkenes (about 50%) were obtained in the GOC of various hydrocarbons including cyclohexane at 750°C. In the GOC process, the utilization ratio of the carbon resources was high; CO dominated the produced COX (the selectivity to CO2 was always below 1%); and the total selectivity to light alkenes and CO was near or over 70%. In the COC of hexane over three typical catalysts (HZSM-5, 10% La2O3/HZSM-5 and 0.25% Li/MgO), the selectivity to COX was hard to decrease and the conversion of hexane and yield of light alkenes could not compete with those in the GOC process. With the addition of H2 in the feed, the selectivity to COX was reduced below 5% over 0.1% Pt/HZSM-5 or 0.1% Pt/MgAl2O4 catalyst. The latter catalyst was superior to the former catalyst due to its perfect performance at high temperature, and with the latter, excellent selectivity to light alkenes (70%) and the conversion of hexane (92%) were achieved at 850°C (a yield of light alkenes of 64%, correspondingly).

Journal ArticleDOI
TL;DR: Silver-ion HPLC (Ag-HPLC) has been utilized to separate a variety of unsaturated fatty acid methyl esters by configuration, location or number of olefinic or acetylenic bonds.

Patent
15 Nov 2004
TL;DR: In this paper, mixtures of turmeric extract oils are discussed and methods for treating inflammation, arthritis and rheumatoid arthritis and a pharmaceutical dosage form of the refined turmeric oil combination.
Abstract: Disclosed herein are mixtures of turmeric extract oils. One mixture of turmeric oils is the hexane soluble fraction obtained by dissolving turmeric powder in hexane to form a hexane mixture, filtering the hexane mixture and evaporating the hexane from the turmeric oil mixture. A more refined turmeric oil combination is the oil left after the turmeric oil mixture is dissolved in hexane, placed on a silica gel/hexane chromatography column, and eluted with hexane into fractions that were then evaporated, thereby leaving the refined turmeric oil combination. Also disclosed are methods for treating inflammation, arthritis and rheumatoid arthritis and a pharmaceutical dosage form of the refined turmeric oil combination.

Journal ArticleDOI
TL;DR: Gas anti-solvent crystallization (GASC) has been utilized for refining of crude lecithin (L) from its solution in hexane (H) with dense carbon dioxide as the antisolvent, leaving behind its oil in the solution as mentioned in this paper.
Abstract: Gas anti-solvent crystallization (GASC) has been utilized for refining of crude lecithin (L) from its solution in hexane (H) with dense carbon dioxide as the anti-solvent, leaving behind its oil in the solution. The performance of the process has been evaluated in terms of the lecithin content and its recovery in the final solid product. The effects of various process parameters have been analyzed at temperatures in the range of 283–313 K, pressures in the range of 15–80 bar, initial oil in crude lecithin in the range of 20–60 wt.% and hexane in the feed solution in the range of 80–95 wt.%. The crystallization of lecithin is facilitated by a drastic reduction of its solubility in hexane solution due to CO 2 dissolution which varied in the range of 40–75 wt.% CO 2 at temperatures in the range of 283–313 K. However, any phase separation of oil was avoided which occurred with more than 63 wt.% CO 2 in the solution. The highest value of selectivity of lecithin (defined as the ratio of the wt.% ratios of lecithin and oil in the product to that in the feed solution) was observed at 298 K and 65 bar for a complete (100%) recovery lecithin, and the selectivity decreased on lowering the temperature to 283 K. At any temperature, crystallization of lecithin occurred over a range of pressure or a range of CO 2 dissolution, allowing different combinations of enrichment and recovery of lecithin from the feed solution. The highest enrichment in the product was 98.6 wt.% lecithin with 78% recovery and this could be obtained at 298 K and 58 bar, starting from the crude lecithin feed having 60 wt.% oil. For a lower initial oil content, even a lower pressure was required to obtain a final solid product having the same lecithin content. Also, the lecithin content in the final product increased with an increase in the hexane-to-feed ratio, as oil remained miscible in the excess hexane.

Journal ArticleDOI
TL;DR: In this article, a scanning electron microscope was used to observe the impact of different processes on the structure of leaves and essential oil bearing trichomes, and extracts obtained were analyzed by gas chromatography (GC and GC coupled to mass spectroscopy (GC/MS) to determine their chemical composition.
Abstract: Rosemary oil may be isolated by three different processes, including steam distillation, water distillation and controlled instantaneous decompression. The concrete resulting from extraction by volatile organic solvents was also made using hexane, dichloromethane and ethanol. The oils and extracts obtained were analyzed by gas chromatography (GC) and gas chromatography coupled to mass spectroscopy (GC/MS) in order to determine their chemical composition. A scanning electron microscope was used to observe the impact of different processes on the structure of leaves and essential oil bearing trichomes.

Journal ArticleDOI
TL;DR: In this paper, a supercritical n-butane isomerization was investigated at the supercritical state in a flow type reactor, and the performance of the studied catalysts was observed in the latter conditions.
Abstract: n -Butane isomerization was investigated at the supercritical state in a flow type reactor. Sulfated zirconia (SZ), heteropolyacids (HPA) of the Keggin type H 3 PW 12 O 40 (HPWO), H 4 SiW 12 O 40 (HSiWO) supported on titania, H-mordenite (HM) were studied as catalysts at 488, 533 and 573 K and 6.1, 11.0 and 13.8 MPa, respectively. Gas-phase isomerization was carried out on the same catalysts for comparison. Rapid deactivation of the studied catalysts was observed in the latter conditions. Conducting the reaction of n -butane isomerization in the supercritical phase resulted in the stable activity. No poisoning of catalysts was observed. It was shown that even the catalyst aged in the gas-phase isomerization can be reactivated by the supercritical media and the catalyst performance can attain the initial value of 20–25% conversion, when the n -butane density is in the vicinity of its critical value or higher. The selectivity for i -butane reached 80% on SZ and supported HSiWO/TiO 2 catalysts in supercritical n -butane. At the same time, the i -butane selectivity on HM zeolite did not exceed 40% at 25% conversion. Cracking side reactions predominated at an elevated temperature (573 K) on the zeolite catalyst yielding the following by-products: propane, n -pentane, i -pentane and traces of ethane and hexane.

Journal ArticleDOI
TL;DR: Novel R- and S-spiro nucleosides have been synthesized using the Pseudomonas cepacia lipase catalyzed resolution of racemic compound 2, synthesized in seven steps starting from diethoxyketene and diethyl fumarate.

Journal ArticleDOI
TL;DR: In this article, temperature-programmed desorption of n-hexane from commercial ZSM-5 and Y zeolites, performed in a flow system using carrier gas saturated with n -hexane vapor, was studied by means of TG.

Journal ArticleDOI
TL;DR: In this article, the adsorption enthalpies and entropies of hexane and propene on the micropores of the mordenite MSM-20 have been estimated.
Abstract: Hexane and propene fully penetrate within the micropores of the Fe-MFI zeolite and strongly adsorb. Decane, tetradecane, isooctane and toluene have a very limited access to the micropores and probably adsorb at the micropore mouths where then can act as reducing agents for NO. Linear alkanes (C6–C8), isoheptane and toluene have an easy access to the micropores of the mordenite MSM-20. Henry constants, adsorption enthalpies and entropies have been estimated. Pre-adsorbed carbon dioxide inhibits adsorption of propene and hexane on the Fe-MFI.