Mixture Of Ethyl Esters Research Articles

Effect of Addition of a Mixture of Ethyl Esters of Polyunsaturated Fatty Acid of Linseed Oil to Liquid Feed on Performance and Health of Dairy Calves.

This study aimed to determine the effect of supplementing liquid feeds with a mixture of ethyl esters of polyunsaturated fatty acid of linseed oil (EEPUFA; α-linolenic acid-64.5%, linoleic acid-16.1%, and oleic acid-19.4%) on feed intake, body weight gain, feed efficiency, and health of dairy calves. Thirty-six healthy female Holstein-Friesian calves (7 d of age, 41.2 ± 4.0 kg) were assigned to one of two treatment groups (18 calves per group), i.e., control or EEPUFA, and fed liquid feed (whole milk (WM) or milk replacer (MR)) either without or with 10 mL/d of EEPUFA supplementation, respectively, for 56 days (till 63 d of age). Average daily intake of WM and MR was similar between treatments (p = 0.94). Average daily total DM intake and average daily starter feed DM intake were higher for the EEPUFA group (p = 0.05 and p = 0.01, respectively). The average daily body weight gain was also higher for the EEPUFA group (55 g/d; p = 0.03), although final body weight turned out not to be significantly different between groups (75.6 kg vs. 79.0 kg, control vs. EEPUFA, respectively; p = 0.20). Supplementation of liquid feeds with EEPUFA did not affect feed efficiency (p = 0.37) and most of investigated health parameters. However, the percentage of days with diarrhea relative to the number of days receiving treatment was higher in the control group than the EEPUFA group (76 vs. 42, respectively; p = 0.04). Although the results of this preliminary study are promising, further research is needed to establish the dose effect of EEPUFA on the performance and health of calves.

Synthesis and characterization of polyvalent high-performance synthetic base oil for drilling operations in recalcitrant and unconventional oil and gas reservoirs

Synthetic ester fluid is one of the most widely recommended drilling fluids for unconventional and recalcitrant reservoirs owing to its numerous technical advantages, high sustainability, non-toxic and inherently biodegradable. However, there are serious concerns about its thermal and hydrolytic stability at high temperatures and pressures (HTHP) as well as its viscosity and flow characteristics in low temperature climates such as deep-water wells. Hence, its inability to maintain stable borehole and flat rheology characteristics may invariably threaten its application under these aforementioned scenarios.In this study, a high-performance ternary mixture of synthetic ethyl esters of plants oil (SEEP mixture) fluid was synthesized by a non-catalyzed supercritical ethanol transesterification process using coconut, castor seed and linseed oil as starting materials. The nature, chemistry and fluid particle interactions of the individual components that make up the synthetic ester fluid were critically studied. The process equipment consists of a continuous flow reactor equipped with a PID controlled furnace as heat source to the reactor and a high- pressure transducer. The conversion efficiency was monitored by an Agilent 5500a FTIR machine with attenuated total reflectance (ATR) system while a GC-EIMSD system was used for fatty acid ester compositional analysis. The oil was extracted by a Soxhlet apparatus mechanism. The extracted Plant oil and the synthetic esters were characterized under standard recommended laboratory procedures by API, ASTM and the European Union (EN) standard protocols. Also, fluid's toxicity and biodegradability tests were conducted according to OECD recommended practices. The results were compared with existing synthetic hydrocarbon fluids (SHFs) for HTHP and deep-water wells.The conversion efficiency of the non-catalyzed transesterification process was 96.50%. The amount of oil yield from the plant oil after Soxhlet extraction is commendable. Hence, synthetic ester fluid raw materials are readily available in large quantities and in a sustainable manner. The GC-MS analysis shows that the coconut oil contains 92% saturated fatty acid. Whereas, the castor seed oil contains 98.31% unsaturated fatty acid with 89.75% of mono-unsaturated ricin-oleic acid (D-12-hydroxyoctadec-cis-9-enoic acid). The linseed oil has high content of linolenic acid with 89.60% unsaturated fatty acid. The designed fluid has excellent lubricity characteristics, extremely low cloud and pour point temperatures, higher oxidative stability, low peroxide value, lower copper strip corrosion value and lower kinematic viscosity and density variations with temperatures which signals flat rheology when used to form a synthetic based mud. Also, its flash point and auto-ignition temperatures are high and thus forestall possible fire hazard in high temperature zones. Finally, the fluid is non-toxic and inherently biodegradable.

Microbial activity evaluation and aerobic transformation of deep water offshore synthetic drilling fluids in soil: A case study of ternary mixture of synthetic ethyl esters of plants oil (Seep mixture) synthetic drilling fluid in agbami (Niger delta) deep water field

Approval for offshore discharge of cuttings drilled with synthetic-based drilling Fluids (SBFs) by environmental regulatory and protection agencies usually require detailed laboratory biodegradation analysis of the base fluid chemicals among others. This concept of using biodegradation test as an environmental fluid-compliance criterion is that a fluid that degrades readily in the laboratory will not persist for an extensive period of time in the offshore environment.Hence, this research focuses on microbial activity measurement and aerobic biodegradation of a newly developed synthetic ester fluid named “ternary mixture of synthetic ethyl esters of plants oil (SEEPmixture)” and its’ comparison with already existing synthetic deep water fluids (SHBF and SEBF) in Agbami deep water field. The chemical composition and components of each drilling fluid sample was analyzed by a GC system combined with a high resolution accurate mass (HRAM) spectrometer while a Fourier transform infra-red (FTIR) spectroscopy was used for functional group identification.The microbial activity of each soil sample that was contaminated with different base oils (drilling fluids) and that of the uncontaminated soil sample (control) was determined by trapping the carbon IV Oxide (CO2) evolved from each soil sample with a strong alkali solution of barium hydroxide (Ba(OH)2) as the microbial biomass actively decompose soil organic matter. The degradation of the drilling fluid chemicals was monitored under aerobic conditions.The soil contaminated with SEBF fluid chemical experienced a low microbial activity due to its low respiration (low amount of evolved carbon IV oxide per mg of soil) but a more pronounced adverse effect on microbial activity was experienced by soil contaminated with SHBF chemical. While microbial activities were not impaired with the SEEP mixture fluid chemical presence in the soil. Meanwhile, in regards to soil aerobic transformation, the SEEP mixture fluid took the shortest time of 13.6 days for it to decompose to half of its original concentration (5mg/kgsoil) from an initial concentration of 10 mg/kg soil. This implies that the fluid sample is readily and inherently biodegradable in soil. Whereas, the SHBF fluid sample required about 34.50 days for it to decompose to half of its original concentration. This indicates its non-readily biodegradable nature in soil. The half-life of the SEBF was 25 days and thus not readily biodegradable.

WLTC and real-driving emissions for an autochthonous biofuel from wine-industry waste

Residues from the wine industry constitute an abundant feedstock for biodiesel production in wine-producing countries. The use of grapeseed oil, together with bioethanol obtained from distillation of wine surplus or grape skins and stalks and wine lees, as reagents in the transesterification reaction, results in a mixture of fatty acid ethyl esters (FAEE), which is a fully renewable, autochthonous, and waste-derived biofuel. In this work, a blend of FAEE produced from grape seed oil with diesel fuel was selected based on a study of fuel properties, and the optimal blend, with 30% v/v of FAEE, was tested in a Euro 6 engine following the Worldwide harmonized Light-duty Test Cycle (WLTC) and a Real Driving Emissions Cycle (RDE), as required in the new certification procedures. Engine performance and emissions from this blend and a commercial diesel fuel were compared. The FAEE blend showed a significant potential to reduce particle emissions, both in mass and number (from 23% in number to 46.5% in mass for WLTC, and from 56% in number to 61% in mass for RDE), and CO (25.5% for WLTC and 39% for RDE) but penalized NOx (32% higher in WLTC and 26.4% higher in RDE).

Flash point prediction with UNIFAC type models of ethylic biodiesel and binary/ternary mixtures of FAEEs

In order to guarantee safe handling of a combustible liquid, such as biodiesel, it is important to be aware of its Flash Point (FP). Thus, the present study focused on FP experimental measurement and thermodynamic correlation of binary and ternary mixtures of saturated or unsaturated fatty acid ethyl esters (FAEEs) as surrogates for biodiesel. FP of different types of ethylic biodiesel in terms of feedstock (canola, corn, cotton and soy oils) were also measured and compared with the predicted values. Experiments were carried out in agreement with the standard closed cup procedure ASTM D6450. Liaw’s model was applied to FP prediction, with liquid phase non-ideality description accounted for by UNIFAC group contribution models (Original UNIFAC, UNIFAC-Dortmund and UNIFAC-Bessa with revised parameters for fats). FP prediction accounting for non-ideality proved to be accurate, with some difference between the UNIFAC type models and Root Mean Square Deviations (RMSD) varying from 0.27 K to 3.95 K for binary and ternary mixtures.

In Situ Transesterification of Marine Microalgae Biomass via Heterogeneous Acid Catalysis

Microalgae have been widely considered as a promising alternative to renewable feedstock to biofuel production. Considering the many oleaginous strains of microalgae, this work assessed the potential of two species, Chlorella minutissima and Nannochloropsis gaditana, to be tested as raw material for ethyl esters production of biodiesel value. This work demonstrates an efficient pilot-size photoautotrophic growth of the two strains using 40-L bubble-column photobioreactors, providing lipid productivities of around 15.2 and 8.7 mg L−1 day−1 for C. minutissima and N. gaditana, respectively. The lipid-bearing biomass, which presented fatty acids composition similar to vegetable oils, such as soybean, rich in palmitic, oleic, and linoleic acids, was then assayed in direct trans/esterification reactions using ethanol as acyl donor, lipid extracting and solvent for the liquid phase in a pressurized reactor. The reactions, which were catalyzed by a heterogeneous acid catalyst (12-molybdophosphoric acid supported onto aluminum oxide), demonstrated an efficient route for producing a product mixture containing ester contents greater than 96.5 wt%, total conversion of triacylglycerols, and low levels of mono- and diacylglycerols, promoting an ethyl ester mixture with possible integration within the biodiesel market specifications.

Comparison of Chemical and Enzymatic Methods for the Transesterification of Waste Fish Oil Fatty Ethyl Esters with Different Alcohols.

Fatty acid esters of 2-ethyl-1-hexanol (EH), 2-hexyl-1-decanol (HD), and isopropanol have been obtained from a mixture of ethyl esters obtained as a fish oil byproduct. Homogeneous base catalysis with alkaline hydroxides and alkoxides has been compared with the use of two commercially available immobilized lipases. The enzymatic methodology is more efficient in the case of the largest alcohol (HD) mainly because of the high stability of the immobilized enzymes upon recovery and reuse. In contrast, the use of a base as a catalyst is highly favorable in the case of isopropanol because of the rather poor activity of the lipases and the low price of the bases. With EH, the activity of lipases is good but the recoverability is not as efficient; hence, basic catalysts are again the most attractive alternative. The mixtures of esters obtained may be useful as hydraulic liquids given their viscosity values.

Effects of n-3 fatty acids on growth, antioxidant status, and immunity of preweaned dairy calves

This study aimed to estimate the influences of flax oil and a mixture of ethyl esters of fatty acids from flax oil added to a milk replacer (MR) formulation on the biochemical, immunological, and antioxidant status of blood, production parameters, and health of calves. Twenty-seven Holstein-Frisian calves were assigned to 3 groups: the control group without fat added to the diet (CON, n = 9), a group receiving ethyl esters of flax oil (10 g/d) with lyophilized apples (25 g; MRE), or a group receiving flax oil (10 g/d) with lyophilized apples (25 g; MRL). The study was conducted from d 14 to d 42 of life. Intake of MR and feed were recorded daily, and fecal scores, rectal temperature, and body weight were recorded weekly. Laboratory blood tests were conducted every 7 d from d 14 to 42. Supplementation with the formulation containing ethyl esters of flax oil (MRE) positively affected health, average daily weight gain, growth rate, and feed efficiency. Intake of the starter feed was lower in the calves receiving the formulation with flax oil (MRL). The MRE formulations lowered the concentrations of triglycerides, total cholesterol, and LDL fraction in blood serum and decreased the total antioxidant capacity (TAS) and levels of glutathione peroxidase (GPx). The MRL formulation increased TAS and GPx levels in blood serum. The MRE treatment limited the circulating levels of tumor necrosis factor. The MRE and MRL preparations lowered the concentration of SFA (C16:0, C18:0, C18:1) in blood serum, and MRE significantly increased levels of α-linolenic acid. The MRE and MRL preparations beneficially affected production and physiological parameters. Our data support the idea that supplementation with n-3 fatty acids improves calf growth and metabolic and oxidative functions in young calves.

Synthesis and characterization of monoacylglycerols through glycerolysis of ethyl esters derived from linseed oil by green processes.

The synthesis of monoacylglycerol (MAG) through the glycerolysis of ethyl ester mixture (biodiesel) was investigated in this study from linseed oil, low-cost alternative feedstock, using an alkaline catalyst with green reagent. The transesterification double step process (TDSP), reaction with ethanol to ethyl esters yielded 97%. In the glycerolysis reaction, the optimum operating condition was in a temperature of 130 °C with 5% sodium hydroxide (NaOH) in 1 : 5 biodiesel–glycerol and 12 h reaction time, in open reactor. The reaction conditions showed an interesting conversion and monoacylglycerol yield of 98% and 76%, respectively. The determination and characterization of reaction products was carried out by Gas Chromatography (GC) method, Infrared Spectroscopy (IR), Thermogravimetric Analysis (TGA) and Hydrogen Nuclear Magnetic Resonance Spectroscopy (1H NMR).

Predicting the surface tension of mixtures of fatty acid ethyl esters and biodiesel fuels using UNIFAC activity coefficients

This work presents the use of a formal thermodynamic model together with UNIFAC activity coefficients model, without any further adjustable parameter, to predict the surface tension of biodiesel fuels based on the equality of chemical potentials between the vapor-liquid interface and liquid bulk. The biodiesel samples included in this work were reported previously in the open literature. They were produced from vegetable oils such as: canola, coconut, corn, cottonseed, hazelnut, lard, palm, peanut, rapeseed, safflower, soybean, sunflower, and Walnut. Surface tension values for 18 samples of binary, ternary and quaternary mixtures of fatty acid ethyl esters (FAEEs) at T = 298.15 were predicted with an average absolute relative deviation (AARD) = 1.39%. Surface tension values for 31 biodiesel samples composed by fatty acid methyl esters (FAMEs) were also predicted at temperatures from 303.15 K to 353.15 K. The AARD value obtained for the 78 experimental points of biodiesel samples was 1.86% which shows a very good agreement with experimental measurements. In the UNIFAC method, predictions of surface tension values for the mixtures are based on the knowledge of the values of the surface tension for the pure components; these values were obtained from different sources. Also, two simple mixing rules on mass and mole fraction basis were used to predict the surface tension of biodiesel fuels. The AARD value obtained from the comparison between experimental and calculated values were: 2.77% and 2.91% for mixing rules on mass and mole fractions, respectively.

Methanolysis of Low FFA Waste Vegetable Oil using Homogeneous Base Catalyst for Biodiesel Production: New Process Design

Biodiesel is an alternative liquid biofuel consists of a mixture of methyl or ethyl esters. It can be produced through transesterification where low molecular weight alcohol (e.g. methanol or ethanol) reacts with lipid or fat (triglyceride) to produce biodiesel (fatty acid methyl ester FAME) and glycerol as a valuable byproduct. The most common method of biodiesel production is base catalyzed transesterification where alkaline material such as potassium hydroxide is used as a catalyst. This paper presents a suggested new process design of a biodiesel plant that treats about 24 tons/ day of low free fatty acids, FFA, waste vegetable oil and WVO.

Critical aggregates concentration of fatty esters present in biodiesel determined by turbidity and fluorescence.

Biodiesel for combustible engine is available as mixture of fossil diesel and fatty esters obtained by transesterification of vegetable oils. The use of biodiesel reduces the amount of SOx, mainly. However, it was already observed that biodiesel has a different behavior in environment in cases of accidental spill and groundwater contamination. It was noticed that the biodegradation of hydrocarbons (cyclic and aliphatic) in the presence of biodiesel are speeded, although the mechanism is still unclear. Considering the chemical structure of fatty esters, it was investigated the formation of aggregates in water solution by fatty esters present in commercial biodiesel. In Brazil, biodiesel is composed by 95% of fossil diesel and 5% of fatty esters mixture. In this work, fatty esters were treated as neutral surfactant, i.e., it was treated as a molecule with polar and non-polar part. Turbidity and fluorescence were used to determine the critical aggregates concentration (CAC). Water solutions containing fatty esters were examined exploiting changes in turbidity and fluorescence intensity of pyrene. Abrupt changes were attributed to aggregates formation, following the same behavior of traditional amphiphilic compounds. It was determined the CAC for ethyl palmitate, ethyl stearate, ethyl oleate, and ethyl linoleate. The values of CAC for fatty esters varied from 1.91 to 4.27μmol/L, while CAC for the mixture of esters (biodiesel) was 2.01 for methyl esters and 1.19 for ethyl esters, both prepared using soybean oil. The aggregates formation was also determined by fluorescence measurements considering the changes in intensity of peaks I and III of pyrene. Pyrene senses the changes in environment polarity. The values found of CAC by fluorescence for individual ethyl esters varied from 1.85 to 3.21μmol/L, while mixtures of ethyl esters was 2.23 and 2.07μmol/L for mixture of methyl esters. The results clearly showed that fatty esters form aggregates and might be responsible for speed degradation of compounds by accommodation of them in inner part of aggregates.

Isolation of Non‐methylene Interrupted or Acetylenic Fatty Acids from Seed Oils Using Semi‐preparative Supercritical Chromatography

AbstractPreparative scale supercritical fluid chromatography was used for isolating and purifying uncommon non‐methylene interrupted or acetylenic polyunsaturated fatty acids ethyl esters from seed oils. Fractionation of Biota orientalis seed oil ethyl esters was performed by supercritical fluid chromatography to obtain juniperonic acid [(5Z,11Z,14Z,17Z)‐eicosa‐5,11,14,17‐tetraenoic acid], a non‐methylene interrupted polyunsaturated fatty acid. Fractionation of sandalwood seed oil ethyl esters yielded ximenynic acid [(E)‐octadec‐11‐en‐9‐ynoic acid], an acetylenic polyunsaturated fatty acid. The effects of CO2 flow rate, column stationary phase and particle size were explored to optimize ximenynic and juniperonic ethyl ester recovery and purity from ethyl ester mixtures using online UV/Vis detection. Particle size, followed by the stationary phase, were found to be the most important parameters to achieving good separation. Under optimized conditions, ximenynic and juniperonic ethyl ester purities greater than 99 and 95%, respectively, were achieved in a one step process without co‐solvent. The isolation and recovery of juniperonic acid from biota seed oil free fatty acids was also attempted. Using free fatty acids as the feed material, the non‐methylene interrupted polyunsaturated sciadonic acid was also able to be separated from other compounds including juniperonic acid under some conditions, and gave an increase in concentration of more than 17 times.

Phase equilibrium data and modeling of ethylic biodiesel, with application to a non-edible vegetable oil

Contributing to extending the knowledge for the design and operation of biodiesel production processes, isobaric PTxy vapor-liquid equilibria data of ethanol+ethyl hexanoate, 1-pentanol+ethyl hexanoate and 1-pentanol+ethyl octanoate at two different pressures are reported for the first time. Consistency tests were applied to attest the quality of the collected data, for these especially complex measurements. Besides that, vapor pressures of the pure ethyl esters have also been measured. For modeling purposes, the Lyngby and Dortmund UNIFAC variants were used to predict the VLE phase diagrams. Generally, the predictions are of very good quality, being the UNIFAC-Do (Dortmund) better, as the deviations in temperature and vapor compositions are always lower to 1.0K and 0.020, respectively. Checking for the viability for extrapolations in pressure, CPA EoS was also applied to the modeling of the experimental data with very good results. Finally, aiming at examining the model capabilities to describe multicomponent systems, VLE measurements involving two alcohols and the fatty acid ethyl ester mixture obtained from non-edible vegetable oil have been carried out showing the good performance of the predictive models.

The clinical relevance of omega-3 fatty acids in the management of hypertriglyceridemia.

Hypertriglyceridemia (triglycerides > 150 mg/dL) affects ~25 % of the United States (US) population and is associated with increased cardiovascular risk. Severe hypertriglyceridemia (≥ 500 mg/dL) is also a risk factor for pancreatitis. Three omega-3 fatty acid (OM3FA) prescription formulations are approved in the US for the treatment of adults with severe hypertriglyceridemia: (1) OM3FA ethyl esters (OM3EE), a mixture of OM3FA ethyl esters, primarily eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Lovaza®, Omtryg™, and generics); (2) icosapent ethyl (IPE), EPA ethyl esters (Vascepa®); and (3) omega-3 carboxylic acids (OM3CA), a mixture of OM3FAs in free fatty acid form, primarily EPA, DHA, and docosapentaenoic acid (Epanova®). At approved doses, all formulations substantially reduce triglyceride and very-low-density lipoprotein levels. DHA-containing formulations may also increase low-density lipoprotein cholesterol. However, this is not accompanied by increased non-high-density lipoprotein cholesterol, which is thought to provide a better indication of cardiovascular risk in this patient population. Proposed mechanisms of action of OM3FAs include inhibition of diacylglycerol acyltransferase, increased plasma lipoprotein lipase activity, decreased hepatic lipogenesis, and increased hepatic β-oxidation. OM3CA bioavailability (area under the plasma concentration-time curve from zero to the last measurable concentration) is up to 4-fold greater than that of OM3FA ethyl esters, and unlike ethyl esters, the absorption of OM3CA is not dependent on pancreatic lipase hydrolysis. All three formulations are well tolerated (the most common adverse events are gastrointestinal) and demonstrate a lack of drug-drug interactions with other lipid-lowering drugs, such as statins and fibrates. OM3FAs appear to be an effective treatment option for patients with severe hypertriglyceridemia.

Binary mixtures of fatty acid ethyl esters: Solid-liquid equilibrium

Biodiesel is a renewable fuel that is commonly used in diesel engines around the world mostly in blends with the conventional diesel. There are many studies concerning its production and its properties and a series of them confirms the biodiesel advantages when compared with conventional diesel in relation of the environmental impacts. In spite of many advances concerning the biodiesel production and properties its behavior at low temperatures is worst than the conventional diesel, and, unfortunately, low temperature property information concerning fatty acid ethyl esters (FAEE) and the biodiesel is still scarce for researchers. This paper presents nine solid-liquid phase diagrams of FAEE binary mixtures to complement the studies of FAEE phase diagram previously reported. All of the phase diagrams have been determined using differential scanning calorimetry (DSC) and also modelled using both the Predictive UNIQUAC and the ideal solution models. The results have been shown good correlation between experimental and modelled data.

Liquid–liquid equilibrium data for systems important in biodiesel production, involving vegetable oils + ethyl esters + monoacylglycerols and diacylglycerols + anhydrous ethanol, at 303.15 and 318.15 K

In biodiesel production from vegetable oils, mono- and diacylglycerols are intermediate compounds of transesterification reaction of triacylglycerols with short chain alcohols, and may contaminate the final product, when the fatty ester conversion is not complete. Thus, this study aims to determine the liquid–liquid equilibrium data of systems important to biodiesel production, containing triacylglycerols (TAG) of refined oils (soybean, cottonseed and rice bran)+commercial mixture of fatty acid ethyl esters (linoleate and oleate)+diacylglycerols (DAG)+monoacylglycerols (MAG) of commercial mixture of partial acylglycerols+anhydrous ethanol at (303.15 and 318.15K). The High Performance Size Exclusion Chromatography (HPSEC) method was used for quantification of all components: TAG, DAG, MAG, fatty acid ethyl esters and ethanol in both phases in equilibrium. The preference of fatty acid ethyl esters and DAG for the oil phase is consistent with the reported data in literature. The mass fraction of MAG was greater in the solvent phase. The average deviation between experimental and calculated compositions, using NRTL model, was less than 0.60%. Using the original version of UNIFAC model with two different set of parameters, the deviations varied within the range of (4.25–11.45)%.

Rapid Preparation of Acid-Stable and High Dehydration Performance Mordenite Membranes

Highly intergrown mordenite membranes were rapidly prepared on seeded aluminum supports by microwave-assisted synthesis. Both the thicknesses of the zeolite layer and the sizes of the zeolite crystals of the mordenite membranes were highly dependent on the synthesis time. With a SiO2:0.08Al2O3:0.2Na2O:0.1NaF:35H2O precursor synthesis gel, a compact and 0.75 μm thick mordenite crystal layer was successfully prepared on the aluminum support at 170 °C for 3 h. The as-synthesized mordenite membrane exhibited excellent water perm-selectivity and long-term stability for dehydration of alcohol/water, acetic acid/water, and acetic acid/ethanol/water/ethyl ester mixtures by pervaporation. For dehydration of 90 wt % acetic acid/water solution, the corresponding flux and separation factor (water over acetic acid) of the membrane remained at 0.44 kg·m–2·h–1 and 2300, respectively, at 75 °C even after 59 days of immersion.

High pressure solid–liquid equilibrium of fatty acid ethyl esters binary systems

The solid–liquid phase diagrams of three binary mixtures of fatty acids ethyl esters (FAEEs), formed by ethyl laurate, ethyl myristate and ethyl palmitate, were measured using high pressure microscopy in the range of 0.1–80MPa. In a first step, the melting temperatures of pure FAEEs have been determined showing a linear dependence from the pressure. The binary phase diagrams are only slightly affected by the pressure, even in very large pressure ranges such as those studied in this work. The modeling of the phase diagrams was attempted using a predictive approach previously developed by one of the authors in the case for n-alkane mixtures. The model was able to provide an accurate description of the high pressure solid–liquid equilibrium of FAEE mixtures. Average absolute deviations between experimental and predicted liquidus curve varied from 0.7 to 2.8K in the entire interval of pressures.

Development of a Predictive Equation of State for CO2 + Ethyl Ester Mixtures Based on Critical Points Measurements

To design and optimize the noncatalytic supercritical process for biodiesel production based on ethanolysis and using carbon dioxide as a cosolvent, thermodynamic models are required to predict the fluid phase equilibria of the various mixtures involved within. This work is an attempt to extend the PPR78 predictive cubic equation of state to CO2 + ethyl ester systems. To do so, 105 mixture critical points of 11 CO2 + (saturated and unsaturated) ethyl ester mixtures were preliminary measured using a synthetic-dynamic apparatus. With the use of these data as well as vapor–liquid equilibrium data collected in the open literature, 2 new groups were added to the PPR78 model (the ester group −COO– and the ethyl acetate group) and 10 PPR78 group-interaction parameter values were determined. Although the PPR78 model offers a good predictive capacity, it is observed that the prediction may deteriorate with the ethyl ester chain length or the presence of double C═C bonds.