Characterization of the Solvent Properties of Glycerol Using Inverse Gas Chromatography and Solubility Parameters

The production of glycerol from the synthesis of biodiesel has led to a market surplus of this polyhydric alcohol and additional research to find new applications for this versatile chemical. This study involves the use of inverse gas chromatography (IGC) to characterize the solute–solvent interactions between glycerol and a homologous series of aliphatic alcohols, in which the latter components are at infinite dilution in the glycerol, which is the stationary phase contained in a packed GC column. The IGC experiments were conducted between 51.5 and 111 °C for the n-alcohols ranging from methanol to n-butanol. All of the n-alcohol homologs exhibited positive deviations from Raoult’s law as based on mole fraction activity coefficients values ranging from 1.86 to 14.4. The measured mole fraction activity coefficients of the alcoholic solutes in glycerol showed good agreement with literature values, and in some cases with those predicted using existing theoretical models. The mole fraction activity coefficients increased going from methanol to n-butanol, reflecting the change in the alcohol’s cohesive energy densities relative to that for glycerol. The total solubility parameter of glycerol calculated from IGC data was found to be 34.8 MPa^1/2 which is in good agreement with that obtained using Hansen solubility parameter approach (31.6 MPa^1/2). This data can be used to characterize the solvent properties of glycerol as well as to provide thermodynamic data for the removal of the alcoholic solutes from glycerol.     

Partitioning of Carboxylic Acid between Oil and Water Phases. Experimental,Correlation, and Prediction

Partition coefficients for the carboxylic acids (A) acetic and formic acids between oil and water were measured, correlated, and predicted. The experiments were conducted by equilibrating the systems, soybean oil (SO)–H₂O–A and fatty acid methyl ester (FAME)–H₂O–A, at 40 °C employing different compositions. The partition coefficients were correlated using the UNIQUAC model and, also, predicted by calculating the activity coefficients of the carboxylic acid in the two phases using a group contribution method, the UNIFAC equation. Agreement of experimental partition coefficients values with those estimated by UNIFAC are fair. Other experimental data from literature were also correlated and are discussed.     

Biodiesel production from soybean oil using calcined Li–Al layered double hydroxide catalysts

The transesterification of soybean oil to fatty acid methyl esters was studied using a calcined Li–Al layered double hydroxide catalyst. The catalyst exhibited high activity, with near quantitative oil conversion being obtained under mild conditions (reflux temperature of methanol) and short reaction times (≤ 4 h). The influence of relevant parameters (catalyst calcination temperature, methanol to oil mole ratio, catalyst charge and reaction duration) was examined.     

江汉凝析油的合理利用

根据江汉凝析油的组成特点 ,以江汉凝析油为原料提取了 30 #发泡剂油、6#抽提溶剂油和 1 2 0 #建材溶剂油 ,并利用江汉凝析油试制了水包油乳液型清蜡剂 ,获得了较为满意的结果 ,为凝析油的合理利用开辟了新的途径     

Performance studies of various cracking catalysts in the conversion of canola oil to fuels and chemicals in a fluidized-bed reactor

Studies were conducted at atmospheric pressure at temperatures in the range of 400–500°C and fluidizing gas velocities in the range of 0.37–0.58 m/min (at standard temperature and pressure) to evaluate the performance of various cracking catalysts for canola oil conversion in a fluidized-bed reactor. Results show that canola oil conversions were high (in the range of 78–98 wt%) and increased with an increase in both temperature and catalyst acid site density and with a decrease in fluidizing gas velocity. The product distribution mostly consisted of hydrocarbon gases in the C₁–C₅ range, a mixture of aromatic and aliphatic hydrocarbons in the organic liquid product (OLP) and coke. The yields of C₄ hydrocarbons, aromatic hydrocarbons and C₂–C₄ olefins increased with both temperature and catalyst acid site density but decreased with an increase in fluidizing gas velocity. In contrast, the yields of aliphatic and C₅ hydrocarbons followed trends completely opposite to those of C₂–C₄ olefins and aromatic hydrocarbons. A comparison of performance of the catalysts in a fluidized-bed reactor with earlier work in a fixed-bed reactor showed that selectivities for formation of both C₅ and iso-C₄ hydrocarbons in a fluidized-bed reactor were extremely high (maximum of 68.7 and 18 wt% of the gas product) as compared to maximum selectivities of 18 and 16 wt% of the gas product, respectively, in the fixed-bed reactor. Also, selectivity for formation of gas products was higher for runs with the fluidized-bed reactor than for those with the fixed-bed reactor, whereas the selectivity for OLP was higher with the fixed-bed reactor. Furthermore, both temperature and catalyst determined whether the fractions of aromatic hydrocarbons in the OLP were higher in the fluidized-bed or fixed-bed reactor.     

色谱法测烷烃和芳烃在正三十六烷中的热力学参数

通过气相色谱法,测定芳烃和部分正烷烃在正三十六烷中的亨利系数和无限稀释活度系数,同时测定正三十六烷的冰点.测定时考虑了固定液流失量和气相非理想性的校正,并用溶液热力学理论分析和讨论了无限稀释活度系数和温度的关系以及亨利系数和溶质碳数的关系.结果表明:无限稀释活度系数随着温度的升高而减少,亨利系数随着溶质碳数的增加而减少.     

Effect of extraction solvents on oxidative stability of crude soybean oil

Oxidative stabilities of crude soybean oils obtained by different extraction solvents such as hexane, water and Folch's solvent (mixture of two volumes of chloroform and one volume of methanol) were determined by gas chromatographic analyses of headspace and peroxide value of oil samples. For the determination of oxidative stability of oil samples, total volatile compounds formation, molecular oxygen disappearance in the headspace and peroxide value of oil samples were measured. Iodine value (133–136), saponification value (195–198), unsaponifiable matters (0.3–0.4%), iron (0.6 ppm), sterols content (2,400–2,590 ppm), tocopherols content (1,250–1,520 ppm) and fatty acid composition of crude oils obtained by different solvent extraction were not significantly different. Acid value of Folch-extracted oil was the highest as 1.3, whereas those of hexane-and aqueous-extracted oils were 0.5 and 0.4, respectively. Crude soybean oil extracted by Folch's method was found to contain the most phosphorus, while hexane- and aqueous-extracted oils contained similar amounts of phosphorous. Crude soybean oil obtained by Folch extraction was most stable in oil oxidation, and oxidative stabilities of oils obtained by hexane and aqueous extraction, which were significantly much less stable than Folch-extracted oil, were not significantly different during ten weeks storage.     

Measurement of activity coefficients at infinite dilution for hydrocarbons in imidazolium-based ionic liquids and QSPR model

The separations of olefin/paraffin, aromatic/aliphatic hydrocarbons or olefin isomers using ionic liquids instead of volatile solvents have interested many researchers. Activity coefficients γ ^∞ at infinite dilution of a solute in ionic liquid are generally used in the selection of solvents for extraction or extractive distillation. In fact, the measurement of γ ⁻⁸ by gas-liquid chromatography is a speedy and cost-saving method. Activity coefficients at infinite dilution of hydrocarbon solutes, such as alkanes, hexenes, alkylbenzenes, styrene, in 1-allyl-3-methylimidazolium tetrafluoroborate ([AMIM][BF₄]) and 1-butyl-3-methyl imidazolium hexafluorophosphate ([BMIM][PF₆]), 1-isobutenyl-3-methylimidazolium tetrafluoroborate ([MPMIM][BF₄]) and [MPMIM][BF₄]-AgBF₄ have been determined by gas-liquid chromatography using ionic liquids as stationary phase. The measurements were carried out at different temperatures from 298 to 318 K. The separating effects of these ionic liquids for alkanes/hexane, aliphatic hydrocarbons/benzene and hexene isomers have been discussed. The hydrophobic parameter, dipole element, frontier molecular orbital energy gap and hydration energy of these hydrocarbons were calculated with the PM3 semi-empirical quantum chemistry method. The quantitative relations among the computed structure parameters and activity coefficients at infinite dilution were also developed. The experimental activity coefficient data are consistent with the correlated and predicted results using QSPR models.     

Measuring and Modeling Liquid–Liquid Equilibria for a Soybean Oil, Oleic Acid, Ethanol, and Water System

Vegetable oils can be deacidified by liquid–liquid extraction based on differences in polarity between triglycerides and fatty acids and differences in solubility. Information on the equilibrium between the phases of such systems is important for designing separation processes. The present paper reports experimental data for the extraction of fatty acid from soybean oil by (ethanol + water) as a mixed-solvent for system of soybean oil + oleic acid + ethanol + water at 30 °C at different water contents. The liquid–liquid equilibrium data of the systems were used to obtain interaction parameters in the universal quasi-chemical theory (UNIQUAC) activity coefficient model. These parameters can be used to predict equilibrium data of ternary and quaternary systems. The deviations between experimental and calculated compositions in both phases for each system using this model were calculated. The distribution coefficients and the selectivity factors of solvents for extraction of fatty acid from oil at 30 °C were calculated. Increasing of the water content as the co-solvent decreased the distribution coefficients and increased the selectivity factors of mixed-solvents, therefore considering the economical and practical aspects the optimum water content may be used for extracting oleic acid from soybean oil. We concluded that (ethanol + water) as a mixed-solvent can be used for extracting fatty acids from edible oils in a normal temperature.     

Drying properties of metathesized soybean oil

Soybean oil was metathesized with the standard homogenous metathesis catalyst, which consisted of tungsten hexachloride (WCl₆) and tetramethyl tin (Me₄Sn) in chlorobenzene as solvent. The reactions were terminated at different time intervals. Soybean oil was mixed with metathesized soybean oil in the presence of cobalt-drier to evaluate drying properties. Five weight percentage (% w) of metathesized oil was found to be all that was needed to decrease the drying time of soybean oil from 312 to 182 min. Drying times for heat-polymerized soybean oil with Gardner-Holdt viscosity of Z₁–Z₂ and Z₃–Z₄ were 71 and 75 min, respectively. In both cases, 5% weight metathesized soybean oil in the blend gave the best results for reducing drying time to 67 and 69 min, respectively. Statistician.     

Physicochemical Characteristics and Composition of Indian Soybean Oil Deodorizer Distillate and the Recovery of Phytosterols

The deodoriser distillate (DOD) of Indian soybean oil obtained from two industries processing soybean oil was investigated for its physicochemical characteristics, its composition of tocopherols, phytosterols, fatty acids and recovery of phytosterols for use in nutraceutical products. It was found that the two DOD samples studied were dark in color and had higher amounts of free fatty acids (22.7 and 49.9%), unsaponifiable matter (11.8 and 21.9%) (5–10 times found in soybean oil), total tocopherols (1957–2256 mg/100 g) (20 times the amount in soybean oil), and 6–10% of phytosterols (12–20 times the soybean oil). The fatty acids found were palmitic (23.2–25.5%), stearic (1.4–2.4%), oleic (23.8–26.1%), linoleic (40.4–41.1%) and linolenic (2.7–3.2%) acids. The unsaponifiable matter (21.9%) and phytosterols (8.7%) content of DOD-2 were higher than in DOD-1 and hence was more suited for isolation of phytosterols. Using hexane and water for crystallisation, the DOD-2 yielded a phytosterol fraction with lower recovery of 13.2–17.8% while treatment with alkali to remove FFA and the glycerides followed by organic solvent extraction yielded unsaponifiable matter containing phytosterols with a recovery of 74.6%. Later the unsaponifiable matter was purified by double crystallisation into a mixture of phytosterols of 87% purity containing β-sitosterol (34.3%), stigmasterol (3.1%) and campesterol (50.1%). The product may find use in foods, pharmaceuticals, cosmetics and allied industries probably as a nutraceutical.     

Ba–ZnO catalysts for soybean oil transesterification

The transesterification of soybean oil to biodiesel using Ba–ZnO as a solid catalyst was investigated. The Ba–ZnO sample with loading of 2.5 mmol/g Ba on ZnO and being calcined at 873 K for 5 h, was found to be the optimum catalyst, which could exhibit the highest basicity and the best catalytic activity for the reaction. When the transesterification reaction was carried out at reflux of methanol (338 K), with a 12:1 molar ratio of methanol to oil and a catalyst amount of 6 wt.%, the conversion of soybean oil was 95.8%. Furthermore, XRD, XPS, DTA–TG and the Hammett indicator method were employed for the catalyst characterizations, and the relation between the catalytic efficiency and the basicity of the catalysts was also discussed.     

Effect of low intake of n−3 fatty acids during development on brain phospholipid fatty acid composition and exploratory behavior in rats

The effect of dietary restriction of n−3 fatty acids during development on brain phospholipid fatty acid composition and exploratory behavior has been studied in male Sprague Dawley rats. Female rats were fed semipurified diets containing either 5.5% safflower oil or 6% soybean oil for 6 wk prior to mating and throughout gestation and lactation. Control rats were maintained on laboratory chow. The male pups were weaned to the diets of the dams except for one group which was switched from safflower to soybean oil at weaning. Behavioral studies and brain phospholipid analyses were conducted at 16–18 wk of age. Rats fed safflower oil showed significantly lower levels of 22∶6n−3 in phospholipids of synaptic membranes and myelin than rats fed soybean oil or chow. The decrease in 22∶6n−3 was compensated for by an increase in 22∶5n−6, the total content of polyunsaturated fatty acids remaining approximately constant. The brain phospholipid fatty acid composition of rats switched from safflower to soybean oil at weaning was similar to that of rats fed soybean oil throughout the experiment. There was no difference in spontaneous locomotor activity among the different dietary groups. However, rats raised on safflower oil displayed a significantly lower exploratory activity (horizontal movements and rearings) in a novel environment than rats fed soybean oil or chow. In contrast to the brain phospholipid fatty acid composition, there was no recovery of exploratory behavior in rats raised on safflower oil and switched to soybean oil at weaning suggesting a specific requirement of n−3 fatty acids during development.     

Equilibrium distributions of key components of spearmint oil in sub/supercritical carbon dioxide

Effects of temperature (at 35, 45 or 55°C) and pressure (10–110 atm) on the relative distribution coefficients of the twelve key components of spearmint oil (essential oil ofMentha cardiaca; Scotch spearmint) at equilibrium in dense CO₂ were investigated under conditions ranging from subcritical to supercritical regions. Effects of vapor pressure, molecular weight and polarity of the key components on their equilibrium distributions in sub/supercritical CO₂ are discussed. At 35°C, all key components of spearmint oil are equally soluble in dense CO₂ within the 12–102 atm pressure region. At 45 and 55°C, the key components are equally soluble for pressures greater than about 60 atm. However, around either 45°C/27 atm or 55°C/35 atm conditions, the relative distribution coefficients of all monoterpene hydrocarbons and of isomenthone (an oxygenated monoterpene) exhibit maxima, which are due to significantly higher vapor pressures of these components and significantly lower solvating power of the dense-gas solvent at these particular temperatures and pressures. Vapor-pressure effects, coupled with the decrease in solvating power, dominate the effects of polarity and molecular mass of the key components. Deterpenation of spearmint oil with dense CO₂ is possible around either 45°C/27 atm or 55°C/35 atm, where the monoterpene hydrocarbons tend to concentrate in the CO₂-rich phase.     

Hydrogen peroxide variables in increasing epoxidation efficiency

Summary Variations in quantity and concentration of hydrogen peroxide were studied in epoxidation of soybean oil by using the partially preformed peracetic acid epoxidation method. Use of a hydrogen peroxide/olefin mole ratio as low as 1.05/1 yields epoxidized soybean oil that meets the low iodine number and high epoxide content characteristics required for stabilizer-plasticizer use. Use of a hydrogen peroxide/olefin mole ratio as low as 0.50/1 results in more than 95% hydrogen peroxide utilization and yields epoxidized soybean oil containing more than two epoxide groups per molecule. Products of this type may be of interest for recently proposed applications in alkyd, polyester, and epoxy resins. Increasing the hydrogen peroxide concentration to 70% in epoxidation permits reduction of acetic acid usage to half that required when 50% hydrogen peroxide is used. Agitation control is also necessary for optimum results. A two-step epoxidation method can be used to avoid formation of potentially detonable mixtures in epoxidation with 70% hydrogen peroxide by the partially preformed peracetic acid method. Presented at the 32nd annual meeting, American Oil Chemists' Society, Chicago, Ill., October 20–22, 1958.     

Effects of soybean pretreatments on crude oil quality

The effects of soybean pretreatments, including infrared (IR) radiation, oven toasting, microwave heating and live steam treatment on crude oil quality were investigated. Free fatty acid, oxidation value, carbonyl value and tocopherol content were used to monitor crude soybean oil quality. All soybean pretreatments were effective in improving the quality of oils from 15 and 18% moisture beans. Based on the analyses, recommended treatments are 3–4 min for IR at 220V–250W; 1 min for microwave heating at 650 W–2450 mHz; 1–1.5 min for steam heating; and 100–120°C, 30 min for oven toasting. Heat treatment of high-moisture soybeans before extraction yielded crude oil with a lower content of phosphatidic acid as compared to that of the untreated beans.     

Quenching mechanism and kinetics of ascorbyl palmitate for the reduction of the gamma irradiation-induced oxidation of oils

The effects of 0, 250, 500, and 1000 ppm (wt/vol) ascorbyl palmitate (AP) on the gamma irradiation-induced oxidation of soybean oil, cottonseed oil, corn oil, tallow, lard, or linoleic acid either in a solvent mixture (benzene/methanol, 4:1 vol/vol) or in methanol, was studied immediately after gamma irradiation with a dose of 1–5 kGy. Steady-state kinetic approximation was used to determine a quenching mechanism and quenching rate constant of AP on the gamma irradiation-induced oxidation of purified soybean oil in a solvent mixture (benzene/methanol, 4:1 vol/vol). Irradiation greatly increased oxidation of all oils, as was expected. AP was extremely effective at minimizing oxidation in all oils, and its effectiveness was concentration dependent. AP showed significantly greater antioxidative activity than α-tocopherol for the reduction of oxidation in all oils (P<0.05). The steady-state kinetic studies indicated that AP quenched oxygen only to minimize the oxidation of oils. The calculated total quenching rate of AP was 7.51×10⁷ M⁻¹s⁻¹. The present results clearly show the effective oxygen quenching ability of AP for the reduction of gamma irradiation-induced oxidation of oils.     

Hyperchlorinated fatty acids: I. Tentative methods of synthesis

The hyperchlorination of fatty acids was studied by four methods using mainly stearic acid. This acid was first submitted to the action of nascent chlorine from NaCl electrolysis, for which the best results never exceeded 43% of fixed chlorine (about 6 Cl atoms per mole of acid), with a yield of 30% based on the acid. Stearic acid was also submitted to electric discharges in CCl₄, and so transformed into various chlorinated and unsaturated compounds, which indicate a near simultaneity of chlorination and dehydrochlorination. However, when the time of contact of the acid with the reactive solution was reduced, formation of only saturated chlorinated compounds occurred, of which the chlorine content, in the best case, was 54% (9 Cl/mole). Direct photochlorination of acid without solvent gave a product containing a maximum of 8 Cl atoms per mole (about 50%). Finally, direct photochlorination of the fatty acid in CCl₄ led to a hyperchlorinated acid containing 68.3% Cl (16–17 Cl/mole), and minor, more or less polymerized products. Although the second and third methods readily afford stearic acid chlorinated to the extent of about 50%, this value, corresponding to an average of 0.5 Cl/C atom, appears to be a barrier that can only be overcome by employing photochlorination in an inert solvent, such as CCl₄.     

Analysis of furanoid esters in soybean oil and the effect of variety and environment on furanoid ester content

An improved method was developed to analyze the major furanoid esters in soybean oil. The method is based on urea fractionation of the methyl esters, silver ion chromatography, and gas chromatography of the furanoid concentrate. Activation of the soybean lipoxygenase decreased the amount of furanoid ester recovered from the oil, but the degumming of crude soybean oil and the choice of solvent used to extract soybean lipids caused no change in furanoid ester content. Fifty-six soybean varieties, representing a wide range in maturity group and geographical origin, were grown in Puerto Rico and used to determine the range of furanoid ester contents. Furanoid ester II ranged from 0.033–0.29 mg/g, and ester III ranged from 0.058–0.27 mg/g. The two major furanoid esters were positively correlated with each other and with maturity group. Growth environment as well as variety caused significant differences in furanoid content. Journal Paper No.J-17180 of the Iowa Agriculture and Home Economics Experiment Station, Ames, IA, 50011, Project No. 3414.     

Isolation and quantitative determination of sterol oxides in plant-based foods: Soybean oil and wheat flour

Soybean oil and wheat flour were analyzed for the content of sitosterol oxides. The method involved chromatography on a Lipidex-5000 column and enrichment on a disposable NH₂-column, yielding a sterol fraction and a sterol oxide fraction. Each fraction was separated as trimethylsilyl-ethers on a methyl silicone capillary column. Analysis of crude and freshly refined soybean oil showed no detectable levels of the isomeric 5,6-epoxysitosterols, the epimeric 7-hydroxysitosterols and 5,6-dihydroxysitosterol at the detection limit of 0.2 ppm. Storage of a refined soybean oil for one year at 4°C caused no significant increase in the level of free sitosterol oxides when compared to the freshly refined soybean oil. Analysis of three wheat flours (at 2, 8 and 36 months) revealed that the samples contained variable levels of 5α,6α-epoxysitosterol (5.4–55 ppm in the lipids), 5β,6β-epoxysitosterol (0.2–29 ppm), 7α-hydroxysitosterol (9.3–118 ppm) and 7β-hydroxysitosterol (9.7–126 ppm).