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This paper presents density experimental data for pure cis-decalin and trans-decalin, along with carbon dioxide + n-decane + cis-decalin (or + trans-decalin) ternary systems for a temperature from ...

The phase behavior of petroleum fluids under reservoir conditions provides fundamental information for an adequate crude oil production scheme. Recently, complex phase transitions have been studied...

Densities of the carbon dioxide + n-decane binary system and carbon dioxide + n-decane + naphthalene ternary system have been measured up to 130 and 100 MPa, respectively, by using a vibrating tube...

Surfactants are widely used in industrial applications associated with several solvents. Therefore, it is worthy to know the nature of the molecular interactions present in surfactants and cosurfac...

International audience

Liquid–liquid equilibrium data are widely used in many industrial sectors. For this reason, it is important to know thermodynamics binary mixture data to better understand molecular interactions be...

Asphaltenes precipitation is still a challenge for the petroleum industry during crude oil production and processing. Pressure, composition, and temperature variation can induce asphaltenes destabi...

Emulsion formation is one of the most important problems faced by petroleum companies to guarantee the flow of fluids during petroleum production, once its formation is often associated to the colloidal state of asphaltenes in petroleum. For this reason, chemical additives should be frequently used to stabilize the asphaltenes and reduce or prevent emulsion formation. Unfortunately, it does not exist any widespread chemical compound that could be used for petroleum reservoirs indistinctly. Consequently, scanning and screening analysis for new compounds should be performed with the purpose to find more efficient and eco-friendlier demulsifiers. In this paper, four different chemical routes (hydrogenation, ethoxylation, formaldehyde polycondensation, and ethoxylation of formaldehyde polycondensation) have been used to synthetize four new products from cardanol to evaluate their activity as demulsifier agents. These additives were characterized by FTIR and 1H NMR analysis. The demulsification activity were studied in emulsions using three Brazilian crude oil produced with a 30% (v/v) brine cut, 60 and 240 g/L NaCl of salinity, at different pH (range from 3 to 10), under agitation (3200 rpm). Bottle test was carried out at 60 °C in graduated tubes for water separability tests, by adding a constant composition (200 ppm) of each chemical tested. The results show that demulsification is more significant for ethoxylated compounds, at neutral pH.

Surfactants are widely used for academic and industrial purposes. For this reason, thermodynamic and physical properties of surfactant and cosurfactant mixtures can provide important information about the nature of the molecular interactions present. In this work, volumetric and transport data of surfactant binary mixtures of the ethanol + Igepal series (Igepal CO-520, Igepal CO-630, Igepal CO-720, and Igepal CA-720) were determined experimentally within a range of temperature of T = 293.15–323.15 K, at atmospheric pressure. From these data, the following derivative properties have been calculated: the excess molar volume, viscosity deviation, and coefficient of thermal expansion. All of these mixtures showed that attractive intermolecular forces are dominant.

The formation of emulsions is recognized to be a challenging problem during crude oil production and processing. Emulsion stability and interfacial properties were investigated in this work for paraffinic modified Brazilian crude oils. Crude oil modifications were made by the addition of two different non-endogenous paraffins, n-hexadecane and a commercial paraffinic pool (melting point range of 53–57 °C), to a heavy crude oil, here, named P1, based on asphaltene destabilization results previously published (Romero Yanes, J. F.; Feitosa, F. X.; do Carmo, F. R.; de Sant’Ana, H. B. Paraffin Effects on the Stability and Precipitation of Crude Oil Asphaltenes: Experimental Onset Determination and Phase Behavior Approach. Fluid Phase Equilib. 2018, 474, 116−125, 10.1016/j.fluid.2018.07.017). Paraffinic modified oils were emulsified with synthetic brine (pH 7 and 60 g L–1 NaCl) to identify the phases of the emulsion formed when varying the water content from 10 to 90% (v/v) and temperature from 30 to 80 °C. Fro...

International audience; In this work, phase behavior was analyzed for recombined mixtures of a Brazilian pre-salt crude oil with carbon dioxide and methane. This oil was sampled at stock tank conditions during a well-test, and mixtures with gas were prepared with a gas molar composition ranging from 20.0 to 86.0 mol %. Their phase behavior was investigated from 293.15 to 378.15 K and up to 100.0 MPa. Direct phase transition detections were achieved by using a full visibility PVT cell, coupled with a short-wave infrared camera. At this wavelength, crude oil has a lower absorbance, and it has been noted that macroscopic phase transitions can be easily detected by visual inspection. For the pseudo-binary system crude oil + carbon dioxide systems, liquid–liquid phase transitions were observed when the gas content is higher than 70.0 mol %. In addition, at the higher carbon dioxide composition, an asphaltic phase was formed at high pressures together with liquid–liquid phases. Similarly, crude oil and methane systems presented a liquid–liquid immiscibility region at methane composition above 60.0 mol % in all temperature domain studied. The Peng–Robinson equation of state was used for modeling purposes, and liquid–liquid and liquid–liquid–vapor transitions were qualitatively described. Additionally, it was observed that liquid–liquid equilibria behavior was highly dependent on the crude oil heavy fraction immiscibility because of the increasing system asymmetry by increasing mixture gas content.

A wide variation in composition and thermodynamic properties is expected for different reservoir fluids, from simplest one containing only methane and light compounds, to those with high compositional complexity. In this work, phase behavior of six different reservoir fluids recombined with methane was compared and contrasted. From our past work [Romero Yanes et. al. (2019), DOI:10.1016/j.fuel.2019.115850], a low asphaltene crude oil (28.0 °API, 0.68 wt % n-C7 asphaltenes), here referred as BRO, has presented a complex phase behavior when mixed with methane, especially when methane content is around 75.0 mol%. Based on these results, it was studied in this work the phase behavior of six different crude oil mixed with 75.0 mol% of methane. Samples main characteristics can be summarized as follows: a light condensate fluid (P1, 44.0 °API, and not detected n-C7 asphaltenes), three medium crude oils [(P2, 30.8 °API, and 0.09 wt % n-C7 asphaltenes); (P3, 26.0 °API, and 0.54 wt % n-C7 asphaltenes); and (P4, 25....

Low viscosity lactam-based ionic liquids (ILs) were evaluated as extractor solvents in organic components separation. Experimental data for liquid-liquid equilibrium (LLE) were obtained from the toluene + heptane + IL, cyclohexene + cyclohexane + IL and phenol + water + IL systems at 298.15 K and atmospheric pressure. The reliability of experimental data has been verified by the Othmer-Tobias, Bachman and Hand equations. ILs γ-butyrolactam acetate (BTA), γ-butyrolactam butyrate (BTB), and γ-butyrolactam hexanoate (BTH); and e-caprolactam acetate (CPA) and e-caprolactam hexanoate (CPH) were used. It has been observed that anion structures influence on all miscibility of ternary mixtures, while cation structures influence on cyclohexene + cyclohexane + IL. Ionic liquids containing lower chain anions (BTA, BTB and CPA) formed two phases with heptane and toluene mixture. However, ILs containing higher chain anions (BTH and CPH) formed heterogeneous systems only with the water + phenol mixture. Only BTA showed partial miscibility in the cyclohexene + cyclohexane system. ILs containing acetate anion presented selectivity higher than 1 in aromatic and aliphatic separation. This also happened on lower concentrations of cyclohexene in olefin and paraffin separation. CPA presented selectivity higher than BTA in liquid-liquid extraction of toluene from heptane. In this system, BTA and CPA can be reused for three times without changes in the chemical structure of ILs and with a small reduction in selectivity (5.4 to 3.8 for BTA and 17.2 to 11.8 for CPA). The thermodynamic model NRTL was used to obtain binary interaction parameters and to correlate LLE experimental data for toluene + heptane + IL system. A comparison between experimental and calculated data indicates a good representation of data. ILs containing hexanoate anion presented degradation in water, the hexanoic acid remained in organic-phase, while γ-butyrolactam was transferred to water-phase. Therefore, it was not possible to determine LLE data.

Asphaltenes and resins make a major contribution for the formation of stable water-in-oil emulsions during crude production, which could affect process operations and increase costs. The purpose of this investigation is to study the influence of these molecular substances from two different crude oil samples (regarding asphaltene stability) on the water-model oil interfacial tension, along with their effect on the emulsion stability. Asphaltene stability of these crude oils presented a marked difference when studied in our past work, with asphaltene precipitation onset that vary from 56 to 75 n-heptane wt %, despite their similar SARA composition. This difference on asphaltene stability was contrasted in this work with the chemical characterization, interfacial activity, and emulsion behavior of crude oil asphaltenes, resins, and their mixtures using toluene solutions. For each crude oil, resins and asphaltenes were extracted and characterized by XRD, SEM/EDS, FTIR, and elemental analysis, to better understand their molecular structure and surface-active species content. Then, it was prepared different model oil solutions in toluene, varying the content of asphaltenes and resins (500, 1,000, and 2000 mg/L). Additionally, it was prepared 2000 mg/L asphaltene/resin mixtures with different ratios (75:25 wt%, 50:50 wt%, and 25:75 wt%). Dynamic interfacial tension between the model oil and water was measured by intermediate of a Du Nouy ring method. Afterward, each model system was emulsified by adding water (at the same volumetric ratio) in a bottle test and stability was analyzed. For the sample with lower stable asphaltenes, a rapid stabilization of the dynamic interfacial tension (IFT) was observed, together with a decrease of IFT from 26.8 to 24.2 mN/m at the limit of asphaltene content studied. On the contrary, for the high stable asphaltenes sample, a transient dynamic IFT behavior was observed, until reach 12.0 mN/m (the lower operational equipment limit). Similar results were obtained for resins model solutions for both crude oils tested. For asphaltene obtained from the sample with lower asphaltene stability, the emulsions presented high stability (for a 24 h test). Besides for the high asphaltene stability sample and resins model oils, all emulsions prepared were unstable. Useful insights are given by the oil fractions chemical characterization, suggesting that smaller sized molecules from high stable crude oils have a predominant effect on IFT reduction, while larger molecules from less stable oils are responsible for the emulsion stability.

Asphaltene precipitation has been related with flow assurance problems in all the stages of crude oil production and processing. The destabilization of asphaltenes in crudes depends on temperature, pressure and composition variations. The latter variable was specifically studied in this work throughout compositional modifications of Brazilian dead oils, by adding three different paraffins on the crudes (n-hexadecane, docosane and a commercial paraffinic pool). These paraffins were firstly added in a crude oil, here named P1 (16.5 °API, 6.34 wt % asphaltenes), and the resulting modified crudes were analyzed in terms of asphaltene yield and stability using n-heptane as precipitant. Asphaltenes precipitation onset was affected by the inclusion of all the paraffins tested in the same extension; at the maximum paraffin addition of 10 wt%, onset decreases by 5 ± 1 n-heptane wt %. Similar results were verified for other two different oils P2 (17.7 °API, 6.29 wt% asphaltenes) and P3 (16.7 °API, 1.55 wt% asphaltenes). The solids obtained from the different systems were analyzed by FT-IR spectroscopy, observing that the alkyl content of the asphaltenes was not affected by the inclusion of heavy paraffins. Precipitation behavior was evaluated by using literature reported thermodynamic models based on modifications of the Regular Solution Theory. This model reproduced qualitatively the experimental precipitation behavior and the asphaltene solvency affectation by paraffin addition in the crudes.

A comprehensive study regarding the estimation of normal boiling points, critical temperatures, critical pressures, and acentric factors of biodiesel-related esters is presented. Such properties are crucial for simulations of chemical processes involving biodiesel. Although reliable experimental data are available for some esters, their determination for all the existing biodiesel components is an expensive and cumbersome task. In view of that, this work aimed to investigate the performance of group contribution and corresponding state models in the calculation of these properties. The estimation models were tested in terms of accuracy and of the plausibility of combining experimental and calculated values without violating the expected physical behavior for corresponding pairs of esters and for esters belonging to the same homologous series. The main outcome of this work is a recommendation of the most feasible models for engineering applications.

A pore-expanded mesoporous silica (SBA-15) was investigated for the immobilization of a recombinant Candida antarctica lipase B (LIPB). The influence of contact time and medium pH during adsorption, as well as thermal and solvent stability of the immobilized enzyme were evaluated. The best prepared biocatalyst was then evaluated in a model esterification reaction, the production of two flavour esters (e.g. methyl and ethyl butyrate) and in a model hydrolysis reaction, the ethyl hexanoate hydrolysis. The biocatalyst maintained high activity and operational stability even after five successive cycles of synthesis. A commercial C. antarctica lipase B was also immobilized on SBA-15 and evaluated under the same conditions, achieving similar volumetric productivities. In addition, the biocatalyst SBA-15-LIPB was tested in ethyl hexanoate hydrolysis. The influence of reactional medium pH was conducted (pH 5, 7 and 9.2) and the highest biocatalyst activity was at pH 5 (about 636.3 U/genzyme). SBA-15-LIPB and SBA-15-LIPB-GA (crosslinked biocatalyst) were reused for 5 cycles, retaining, after the third cycle, 56.6 and 76.80%, respectively, of its initial activity. The prepared biocatalysts were able to catalyze the model reactions (esterification and hydrolysis) with high activity and reasonable stability.

Zn and ZnSn coatings were electrodeposited on carbon steel surfaces from choline chloride and ethylene glycol solvent (1ChCl:2EG). The corrosion resistance of the coatings was investigated in a 3.5% NaCl solution, and the results revealed that Zn deposition was favored by increasing bath temperature and electrodeposition potential. Besides, Zn-enriched coatings were also obtained from Sn-rich Zn/Sn baths, and the coating morphologies were affected by these parameters. Finally, the ZnSn layer (14% Sn) electrodeposited at −1.3 V and 363 K increased the corrosion resistance up to 6 times towards the pure Zn layer under the same conditions.

Several models based on the Group Contribution concept and on the Corresponding States Principle were reviewed for the estimation of vapor pressures and enthalpies of vaporization of fatty acid methyl and ethyl esters commonly occurring in biodiesel. The accuracy of each model was tested by comparing its output values to experimental data obtained from the literature. For vapor pressures, the number of occurrences where the methods failed completely have also been analyzed. Efforts were made to identify the best method for the estimation of each property and it was observed that the models’ reliability depend on the type of ester and on the operational conditions (pressure and temperature) considered.

Asphaltenes insolubility is recognized as an important flow assurance problem during crude oil production. In this work, phase behavior for crude oil + methane and crude oil + methane + carbon dioxide mixtures were studied for two Brazilian pre-salt crude oil samples, with low asphaltenic content. From PVT compressibility experimental data, phase equilibria were studied based on solubility parameter, cohesive energy, and internal pressure approach. For the crude oil + methane systems, methane content was evaluated from 25.0 to 75.0 mol%, at a temperature range from 313.15 to 373.15 K. No asphaltene precipitation was observed and a minimal solubility parameter was reached at the richest methane content. Additionally, a marked reduction of cohesive energy was observed increasing methane content, probably associated to the system asymmetry. For the crude oil + methane + CO2 systems, a constant gas composition of 75.0 mol% was studied. Carbon dioxide (CO2) content varied from 0.0 to 100.0 mol%, balanced with methane, for a temperature domain of 343.15 to 383.15 K. For these systems, asphaltene insolubility regions were detected. Moreover, the addition of CO2 contributed to asphaltene stabilization. Solubility parameter and internal energy increases were properly identified for these mixtures and it could be associated to the asphaltene region reduction.

Nanoclays have been successfully introduced into the asphalt, either separated or in the form of polymer/bitumen blends, improving mechanical and rheological properties. In this paper, the organoclay montmorillonite (OMMT) was prepared to be used as an additive for bitumen and for a polymer modified bitumen. A nanoclay Cloisite® 20 A (CLO), was also investigated for comparison purposes. A bitumen was modified with 4% nanoclays (OMMT and CLO), with 4% SBS, and with 4% SBS/nanoclay. All modified bitumens (MB) exhibited higher G ∗ and lower δ, indicating an improvement in the stiffness and in the elasticity. SBS/Nanoclay MB presented similar rheological behavior compared to SBS MB which may result in cost savings. The addition of SBS and SBS/OMMT resulted in increase in PG grade and decrease in non-recoverable creep compliance (J nr ) indicating a better rut resistant compared to pure bitumen.

Oil industry has encountered a series of difficulties associated with flow assurance of petroleum fluids, especially those related with stable emulsion formation. Such emulsified systems could present problems during transportation, handling, and refining, because of their relation to operational factors, as follows: fluid viscosity, processing energy expenditure, and water coproduction. For this reason, the addition of interfacial active compounds, often polymers, is used in an attempt to phase separation in industrial processes. In this paper, five different chemical surfactants, referred to here as MACO 1, MACO 2, R1, R2, and R3, were synthesized based on castor oil. These additives were characterized by Fourier Transform Infrared (FTIR), Size-Exclusion Chromatography (SEC), and Thermogravimetrical Analyses (TGA). The demulsification activity was studied in synthetic emulsions by using two Brazilian crude oils and 30% (v/v) brine cut with 60 and 240 g/L NaCl, at neutral pH, and average droplet diameter of 10 μm. Bottle tests were carried out at 60 °C in graduated ASTM test tubes for 2 h, varying additive concentration from 100 to 5000 ppm. Interfacial tension measurements were performed to elucidate the demulsification activity in water-oil interface, at the same bottle test experimental conditions. These results were discussed on the basis of the oil characterization, mechanisms of demulsifying action, as well as interfacial tension data. Ward and Tordai equation was applied according to asymptotic approximations to evaluate additives diffusivity. The results show that demulsification is more significant for MACO 1, with maximum water resolution of around 90% for both emulsion systems.

Over the last decade, ionic liquids (IL) have attracted considerable attention for their potential to replace traditional volatile organic solvents due to their well-known physico-chemistry properties. This is an important topic for industrial applications today, and have been the subject of extensive literature studies. Nevertheless, there is still a lack of experimental thermodynamics data on aqueous mixtures, i.e., ionic liquids + water, especially volumetric and transport properties. These data could provide essential information about interactions and molecular phenomena in such mixtures. To investigate volumetric and transport properties for ionic liquids + water, density and viscosity data of the protic ionic liquids 2-hydroxydiethanolamine formate (2-HDEAF), 2-hydroxydiethanolamine acetate (2-HDEAA), water and their binary mixtures were measured at T = (293.15 to 343.15) K and atmospheric pressure. Excess molar volumes and deviation of viscosity were computed from experimental density and viscosity values and were fit to the Redlich-Kister equation. We observed a negative behavior for both ionic liquids + water mixtures that can be attributed to a shrinkage of the mixtures.

In this work, different methods capable of estimating some properties of fatty acid methyl esters (FAMES) and fatty acid ethyl esters (FAEES) have been evaluated. The results for Tb indicated that the methods of Constantinou and Gani and Marrero and Gani should be applied for FAMES and FAEES, respectively. The evaluation of the methods for critical properties and acentric factor was performed by comparisons between the experimental values and output values by the Racket–Soave equation. The results indicated that different packages should be applied for FAMES, FAEES, and hydroxy-esters. For critical volume estimations, the method of Marrero and Pardillo should be used for any alkyl ester present in biodiesel. Three versions of the group contribution (GCVOL) method as well as the Rackett–Soave equation were employed to estimate pure alkyl esters and biodiesel density. All these methods showed good results in moderate temperatures, but only Rackett–Soave is indicated for high temperatures. A final validation...

This work aimed to study the production of a biosurfactant by a new strain of Bacillus subtilis ICA56 isolated from a Brazilian mangrove and to evaluate its functional properties and applicability for bioremediation. The use of agro-industrial wastes (glycerol, sunflower oil, cheese whey and cashew apple juice) as alternative substrates for biosurfactant production was tested as this may lead to a reduction in the cost of the bioprocess. Glycerol was the best carbon source yielding 1290 mg L −1 of crude biosurfactant. The critical micellar concentration of the crude biosurfactant produced by ICA56 was 25 mg L −1 and, at this concentration, it was able to reduce the surface tension of the water from 72 to 30 mN m −1 and to reduce the interfacial tension on a water/gasoline system from 15 to 3 mN m −1 . Furthermore, the crude biosurfactant retained its tensoative properties in a broad range of pH, temperature and salinity and it was not toxic to Artemia salina . In this work, model experiments were conducted to simulate the removal of hydrocarbons and heavy metals from contaminated environmental systems in the laboratory by the crude biosurfactant produced by ICA56. Results showed that it was very efficient, highlighting its potential for bioremediation.

In the petrochemical industry, the separation of aromatics from alkanes is a complex process due to the overlapping boiling points and azeotrope formation in specific operational conditions. In this work, 2-hydroxy ethylammonium formate (2-HEAF) and glycerol were evaluated as an extractor solvent of toluene from decane + toluene mixtures, by comparing with widespread solvent used in industrial applications, sulfolane. New liquid–liquid equilibrium (LLE) data for three ternary systems: {decane (1) + toluene (2) + glycerol (3); decane (1) + toluene (2) + [2-HEAF] (4); and decane (1) + toluene (2) + sulfolane (5)} at T = (303.15 and 333.15) K and atmospheric pressure has been studied. Heterogeneous region in LLE diagram presents a wide area and are not influenced by temperature, in the studied domain. From experimental data, distribution coefficients and selectivity parameters have been used determined and used to evaluate the efficiency of the studied solvents (sulfolane, glycerol and 2-HEAF) to extract toluene from decane. Two thermodynamics models (NRTL and UNIQUAC) were used to obtain binary interaction parameters. These models have been also used to correlate LLE experimental data for the studied ternary systems. A comparison between experimental and calculated data indicate that better agreement has been performed by using NRTL model.

This work presents density (ρ) and dynamic viscosity (η) data and correlations for binary systems containing (linseed or corn) oil, (linseed or corn) biodiesel and petroleum diesel at T = 293.15 K to 333.15 K in steps of 10 K for the linseed system and T = 293.15 K to 373.15 K in steps of 20 K for the corn system and atmospheric pressure. Density data were adjusted by a proposed function showing a second-order behavior with mole fraction (x) and a linear behavior with temperature. Viscosity data were adjusted to an equation with temperature (T) and mass fraction (w) as independent variables with an exponential dependence of the inverse of temperature and proportional dependence with mass fraction. All correlations presented good agreement to experimental data based on the R2 and chi-square (χ2) statistical analyses. The absolute average error (AAE) was calculated to evaluate the accuracy of predictive models used to estimate density and viscosity for all five pseudopure compounds. Isobaric expansion (αp) ...

Aromatic hydrocarbons are usually extracted from reformed naphtha, which are multicomponent mixtures with aliphatic hydrocarbons. These components have very close boiling point, which makes distillation process not so efficient and economically infeasible. For this reason, aromatics compounds are usually separated from aliphatic compounds by intermediate of solvent extraction unit operation. In this work, liquid–liquid equilibrium (LLE) data for systems containing decane + toluene + diethylene glycol (DEG) and decane + toluene + triethylene glycol (TEG) at T = (303.15 and 333.15) K and atmospheric pressure were studied. It was observed that temperature hardly influence the size of the two-phase region. Distribution coefficient and selectivity have been calculated from those experimental data. For all systems studied, selectivity parameter showed values greater than 1 indicating that the extraction is possible by using DEG and TEG as extractor solvents. Additionally, selectivity values ​​increase with increasing glycol carbon chain. LLE have been correlated by intermediate of NRTL and UNIQUAC activity coefficients.

During the biodiesel production process, generally, two purification steps are performed. The first is a settling process in order to remove the main byproduct (glycerol). Nevertheless, this simple stage is insufficient to achieve purity levels required for commercial specifications. Second, a water washing is used to remove an excess of alcohol and other contaminants. Given the importance of equilibrium data for operation and optimization for liquid–liquid extraction unit operation, the study of liquid–liquid equilibrium (LLE) for methylic cottonseed biodiesel + methanol + water and ethylic cottonseed biodiesel + ethanol + water systems are studied at (293.15 and 313.15) K at atmospheric pressure. LLE data have been quantified by intermediate of two different techniques (titration and densimetric). From these experimental data, distribution coefficients and selectivity have been calculated. As expected, a good extraction capacity of water to remove alcohol has been observed. The reliability of the experi...

Sulfolane, alcohols, and glycols are commonly used as solvents in different industrial recovery processes. The focus of the present work is to measure volumetric (densities, ρ) and transport (dynamic viscosity, η) properties of the binary mixtures sulfolane + 2-butanol (or 2-propanol, diethylene glycol, or triethylene glycol) within a temperature range from T = 303.15 K to T = 343.15 K, at atmospheric pressure. Densities and viscosities were measured using a viscodensimeter (Anton Paar SVM 3000 Digital Oscillation U-tube). The experimental results of density and viscosity for both pure and binary systems show a decrease with increasing temperature, as expected for liquids. Excess volumes and viscosity deviations were obtained from the experimental data and fit using a Redlich–Kister type equation. VE values show a dual behavior, presenting positive and negative data, depending on the nature of the liquid mixtures, whereas Δη values are negative in the whole composition range in all systems studied. Therma...

Biodiesel is considered a good alternative for diesel engines, given its characteristics, for being non-toxic and for being a more environmental-friendly fuel. A liquid–liquid equilibrium (LLE), comprising biodiesel + glycerol + alcohol, occurs during the production of biodiesel. The use of reliable thermodynamics models is essential to describe biodiesel + glycerol + alcohol systems as to design and analyze the process and its equipment. In this work, experimental data of 34 different systems (27 for biodiesel + glycerol + alcohol; and 7 for methyl oleate + glycerol + methanol) were used for parameter estimation and to evaluate four of the main activity coefficient models (ASOG, UNIFAC, UNIFAC-LLE and UNIFAC-Dortmund) that could be used with biodiesel systems. Additionally, binary parameters for glycerol/methanol, methanol/methyl oleate and glycerol/methyl oleate have been estimated by NRTL and UNIQUAC models. Root mean square deviations (RMSD) have been used to compare experimental and simulated data. RMSD analysis showed that the UNIFAC-Dortmund model was the model that best represented the biodiesel liquid–liquid equilibrium. Best representation of the system followed the order: UNIFAC-Dortmund > ASOG > UNIFAC-LLE > UNIFAC > UNIQUAC > NRTL.

A new group contribution method based on GCVOL model developed by Elbro et al. in 1991 [Elbro, H. S.; Fredenslund, A.; Rasmussen, P. Ind. Chem. Eng. Res. 1991, 30, 2576–2582] is proposed for the estimation of ionic liquids density over a wide range of temperature and pressure. A total of 102 new groups for ionic liquids were introduced to the already 60 existing groups revised and proposed in 2003 by Ihmels and Gmehling [Ihmels, E. C.; Gmehling, J. Ind. Chem. Eng. Res. 2003, 42, 408–412]. These groups were proposed based on a collection of density data from literature. The databank contains data of 864 different ionic liquids, including dicationic and tricationic species, and a total of 21 845 data points, covering a temperature range of 251.62–473.15 K and a pressure range of 0.1–300.0 MPa. An average absolute relative deviation (%AARD) of 0.83% was obtained, indicating that our model is able to predict densities of a great variety of ionic liquids accurately.

Glycerol, a co-product of the biodiesel industry, may be a suitable raw material for the production of high added-value compounds by the microorganisms. This study aimed to use the glycerol obtained from the biodiesel production process as the main carbon source for biosurfactant production by Bacillus subtilis ATCC 6633. Results indicated that the strain lowered the surface tension of the cell-free fermented broth to 31.5 ± 1.6 mN/m, indicating the production of biosurfactant. The critical micelle concentration (CMC = 33.6 mN/m) obtained was similar to the previously reported for biossurfactants isolated from other Bacillus. The produced biosurfactant was able to emulsify n-hexadecane and soybean oil.

Biodiesel is usually produced by transesterification reactions, by intermediate of a catalytic reaction in which a source of triglycerides (from vegetable, animal or residual oils) reacts with excess of alcohol producing as main product biodiesel and as side-product glycerol. After those reactions, it is usually necessary to purify the biodiesel produced by settling process. This step is followed by liquid–liquid extraction (wash up) unit operation. Systematic studies on biodiesel washing process, especially as function of composition data, are still scarce in the literature. Liquid–liquid equilibrium data provide important means to the development and design of equipment and also in the optimization of the extraction processes. This paper, as part of continuing study in our research group, reports equilibrium data for different ternary systems of methanol + water + (soybean, corn or brown shell of coconut, here named coconut) biodiesel at 293.15 and 313.15 K at atmospheric pressure. Experimental data were carried out in equilibrium cells, by using a bath, in order to control the temperature of the system. From experimental data, distribution coefficients of methanol have been determined. The quality and reliability of the tie-line were tested by Othmer-Tobias and Hand correlations. Liquid–liquid equilibrium (LLE) data were correlated with the following activity coefficient models: NRTL, UNIQUAC and UNIFAC, with a global deviation error of 1.34%, 1.34% and 4.13%, respectively.

Phase behavior of reservoir fluids is crucial for an efficient production development project. In this paper, a new dataset of phase transitions of Brazilian pre-salt crude oil mixed with methane systems is presented and phase behavior discussed under different analytical technics. A series of mixtures of a dead crude (API 28.0, 0.68 wt% of asphaltenes) with 65.0, 67.5, 70.0, 72.5, and 75.0 mol% of methane were studied by constant mass expansion in a PVT cell, coupled with a high-pressure microscopy (HPM). Pressure-volume data shows slight phase transition, with a not evident break due to difference on compressibility, specially by increasing methane molar content. For this reason, beside of visual observation, a near-infrared (NIR) transmittance was used for a proper identification of bubble point pressure. NIR transmittance also allow the detection of phase transitions above bubble point, that was confirmed by intermediate of by HPM analysis. A dispersion of fine particles was detected, and it was associated with asphaltenes onset, for the systems with high content of gas (72.5 and 75.0 mol% of methane). NIR transmittance along with micrographs taken during system pressurization confirm a low asphaltene hysteresis redissolution, with no flocs and mayor aggregates formation and rapid redissolution after system pressurization. This phenomenon could be related to the low content of asphaltenes on the crude oil sample.

The current study presents some fundamental observations on the effects of the welding heat input in the chemical composition, microstructure, hardness and petroleum corrosion resistance of the fusion zone, formed by the AWS E309MoL austenitic stainless steel covered electrode and the AISI 410S ferritic stainless steel, being a dissimilar welding procedure. Such welding configurations are widely used as an overlay of equipment in the petroleum and gas industries. The welds were performed with the application of three different levels in heat inputs (6, 9 and 12 kJ/cm). Samples of the weld metals were conventionally prepared for the microstructural characterization by light microscopy and scanning electron microscopy. A corrosion test with samples immersed in heavy oil heated at 300 °C, was carried out for a period of 60 h. The corrosion rate was determined by the weight loss given after the aforesaid test. The fusion zone microstructure has a typical δ-ferrite acicular morphology, from which the level of δ-ferrite was duly altered with the increases of the welding heat input, due to the variations in the composition of the weld metal caused by dilution. It was also concluded that the chemical composition and the weld metal microstructure had a slight influence in the material’s corrosion rate. As a matter of fact, the corrosion rate of the weld metals evaluated herein, was considered satisfactory with few variations between the welding heat inputs duly applied.

Liquid–liquid equilibria (LLE) data play an important role in the project and design of separation processes. The aim of this work was to study the LLE data of the solubility (binodal) curves and tie-lines for the glycerol (1) + ethanol (2) + coconut biodiesel (3) system at two different temperatures [(293.15 and 323.15) K], at atmospheric pressure. From the experimental data, it could be observed that the relative mutual solubility of ethanol is higher in the glycerol phase than the biodiesel phase. A consistency analysis has been performed by using the Othmer–Tobias correlation. The experimental liquid–liquid data were correlated by using two local composition models (NRTL and UNIQUAC) for the activity coefficient calculation. From these models, binary parameters have been determined. Distribution coefficients and separation factors were measured to evaluate the extracting capability of the ethanol used as a solvent.

This work presents density (ρ) and viscosity (μ) data and correlations of binary and ternary blends containing soybean oil, soybean biodiesel, and petroleum diesel. The data were obtained for different composition ranges, for binary blends data were obtained in a mass fraction (w) in an interval of 0.100 to 0.900. Additionally, ternary data were taken by a random range, at T = (293.15, 313.15, 333.15, 353.15, and 373.15) K, at atmospheric pressure. The experimental data were compared to predictive models based on group contribution method. Density and viscosity data were correlated by a temperature and composition equation (T and w, as independent variables). A statistical analysis has been designed by using chi-square distribution, which revealed an agreement between experimental and estimated data better than 99.5 %.

Liquid–liquid equilibrium (LLE) data for the ternary system (cottonseed biodiesel + glycerol + ethanol) have been determined at T = 293.15, 313.15 and 333.15 K and atmospheric pressure. The solubility (binodal) curves and tie-line compositions were obtained by means of density measurements. The reliability of the data has been tested by using Othmer–Tobias equation, with a squared correlation coefficient better than 0.99 for all systems studied. Selectivity and distribution coefficients have been determined from equilibrium data. Experimental LLE data have been correlated using NRTL model with an average global deviation of 0.89%. Additionally, binary interaction parameters of ternary systems components have been calculated.

Glycerol, a co-product of biodiesel production, was evaluated as carbon source for biosurfactant production. For this reason, seven non-pathogenic biosurfactant-producing Bacillus strains, isolated from the tank of chlorination at the Wastewater Treatment Plant at Federal University of Ceara, were screened. The production of biosurfactant was verified by determining the surface tension value, as well as the emulsifying capacity of the free-cell broth against soy oil, kerosene and N-hexadecane. Best results were achieved when using LAMI005 and LAMI009 strains, whose biosurfactant reduced the surface tension of the broth to 28.8 ± 0.0 and 27.1 ± 0.1 mN m(-1), respectively. Additionally, at 72 h of cultivation, 441.06 and 267.56 mg L(-1) of surfactin were produced by LAMI005 and LAMI009, respectively. The biosurfactants were capable of forming stable emulsions with various hydrocarbons, such as soy oil and kerosene. Analyses carried out with high performance liquid chromatography (HPLC) showed that the biosurfactant produced by Bacillus subtilis LAMI009 and LAMI005 was compatible with the commercially available surfactin standard. The values of minimum surface tension and the CMC of the produced biosurfactant indicated that it is feasible to produce biosurfactants from a residual and renewable and low-cost carbon source, such as glycerol.

Biodiesel has many advantages because it is a biodegradable, nontoxic fuel and its production results in less particulate matter. For this reason it has been studied in many fields of science as a substitute for mineral fuels. Short chain alcohols such as ethanol have been used for extraction of soybean and sunflower biodiesel in the literature. The present paper reports liquid–liquid equilibrium data for systems containing soybean biodiesel + glycerol + ethanol at (293.15 and 323.15) K and sunflower biodiesel + glycerol + ethanol at (298.15 and 313.15) K. Binodal curves were obtained by the cloud-point method, while tie-line compositions were obtained by density measurements. The values of distribution coefficients and selectivities indicate that the ethanol is a good solvent for the extraction of soybean biodiesel and sunflower biodiesel from glycerol. The reliability of experimentally measured tie-line data can be ascertained by applying the Othmer–Tobias equation. The experimental data were correlated...

This paper presents the values of viscosity (η) and density (ρ) of binary blends of sunflower biodiesel + diesel and of fish oil biodiesel + diesel over the entire range of proportion at several temperatures. Temperatures of (293.15, 313.15, 333.15, 353.15, and 373.15) K at atmospheric pressure were studied. Excess volumes (VE) and deviations of viscosities (Δη) have been calculated from the experimental data. These thermodynamic properties are essential in the understanding of intermolecular interactions between different molecules of biodiesel, and it is important in the design of several equipments used in the biodiesel industry. The excess viscosity has been fitted using the Redlich–Kister polynomial equation. A modified Rackett's equation was used to estimate the density. The viscosity for the biodiesels was estimated using three models: Thomas, Orrick–Erbar, and modified Sastri–Rao. The critical properties were estimated by the Rackett's equation, together with the Marrero–Gani method of group contr...

Densities, ρ, of binary mixtures of diesel + soybean biodiesel and n-hexadecane + soybean biodiesel have been measured as a function of the composition at different temperatures (293.15, 313.15, 333.15, 353.15, and 373.15) K and atmospheric pressure, over the entire composition range, using an Anton Paar SVM 3000 oscillating U-tube densimeter. The excess molar volume, VE, and excess partial molar volume, VE, of the binary mixtures were calculated from the density data. These data have been correlated using the Redlich−Kister type function in terms of mass fraction (w), with a maximum standard deviation of 0.152 cm3·mol−1. The excess volumes are positive for the soybean biodiesel + diesel system. The values of the excess volume for the system soybean biodiesel + n-hexadecane are also positive and an inversion of sign in VE is observed at higher molar fractions of soybean biodiesel (around x1 = 0.60 to 0.80). The excess partial volume at infinite dilution has been also calculated.

Density ρ and viscosity η were measured for binary mixtures of cotton seed + babassu and soybean + babassu biodiesel over the composition range at several temperatures of (293.15, 313.15, 333.15, 353.15, and 373.15) K and atmospheric pressure. The viscosity deviation (Δη) was determined and fitted by a Redlich−Kister type function in terms of mass fraction (w). The Joback’s method combined with Lee−Kesler and Rackett equations were used to calculate the densities of the binary mixtures of cotton seed + babassu and soybean + babassu biodiesel. The experimental and estimated density values gave almost identical values with a relative differences of less than 0.21 %. The Ceriani’s group contribution method was used to predict the viscosity, with a maximum relative deviation of 31 %.