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High pressure phase equilibria for binary mixtures of CO 2 + 2-pentanol, vinyl butyrate, 2-pentyl butyrate or butyric acid systems
Abstract
High pressure phase equilibrium for four binary systems, (CO2 + 2-pentanol, CO2 + vinyl butyrate, CO2 + 2-pentyl butyrate and CO2 + butyric acid), were measured at three temperatures of (313.15, 323.15 and 333.15) K and pressures up to 11 MPa. These four organic compounds are those involved in the kinetic resolution of rac-2-pentanol and their phase equilibria play a significant role in the separation processes of the reaction compounds. Phase behaviour measurements were taken using a synthetic method in a variable volume high-pressure cell. It was checked that the solubility of CO2 in the four systems decreases with increases in temperature at a constant pressure and all systems present type-I phase behaviour within scope of this work. Modifications of Henry's Law and Peng-Robinson and Soave-Redlich-Kwong equations of state combined with the Quadratic mixing rule were used to correlate experimental equilibrium data to determine the phase behaviour of these systems.
... These types of supercritical homogeneous solvents which are non-condensable at temperatures and pressures above their critical point, can diffuse through solids like a gas and dissolve materials like a liquid, among others (hexane, nitrous oxides, sulfur hexafluoride, trifluoromethane toluene, pentane etc.). The most commonly employed supercritical solvent is CO 2 due to its numerous physiochemical qualities, heat transfer characteristics, thermodynamical profile, harmless reputation, nobleness, non-corrosiveness, colourlessness, inodorousness, inexpensiveness, inflammability and eco-benign demeanor [19, 73,76,77,[82][83][84][85][86][87][88][89][90][91][92]. CO 2 with its critical temperature (32 °C) and pressure (74 bar) can also be explored with co-solvents such as methanol, and water (subcritical fluid) in order to accelerate effusion rate, shorten extraction time and enable modulation of CO 2 non-polarity profile for effective extraction of polar compounds like the non-polar compounds [19,49,[92][93][94]. ...
Due to the perceived link between sugar and diseases such as diabetes, obesity, and cardiovascular diseases, the market for low-calorific sugar alternatives or sweeteners has intensified in recent times. Stevia (Stevia rebaudiana Bertoni) is an herbaceous perennial shrub and a member of the Asteraceae family. Stevia has found use as an alternative sugar product in beverages and other foods due to its low cost, low calorific content, and health benefits. This study is a review of various technologies that have been employed by various researchers in the processing of stevia leaves into syrup, powder, or crystals. The merits and demerits of each technology for the extraction process were also discussed. It was observed that its leaves contain the highest concentration of sweeteners and that solvent extraction is the most widely adopted extraction technique by various researchers, which has been reported to give a stevioside yield of more than 90%. The use of green-assisted extraction techniques, such as supercritical fluid extraction, ultrasonic-assisted extraction, microwave-assisted extraction, pressurized fluid extraction, and enzyme-assisted extraction, offers a higher yield, better recovery, and higher purity of the steviosides. However, these technologies are yet to be utilized on an industrial scale. Post-extraction technologies such as chromatography have been reported to give an extract purity of about 97%. Other post-extraction technologies include adsorption and membrane technology for purification and/or concentration of the extract. The study also identified potential knowledge gaps that might help drive future research in the field.
... After a variation of pressure or temperature, the formation of a new phase can be observed. The new phase can be detected by visual observation [17][18][19] or by changes in certain physical properties [20][21][22]. ...
One of the crucial aspects in the design of processes of this millennium is the use of environmentally benign technologies. The introduction of supercritical fluids (SCF) and, in addition, their use with other solvents, such as ionic liquids, further diversify the applications of these fluids. SCF are powerful solvents with many unique properties. They have the mobility of gases and the dissolving power of liquid solvents, resulting in efficient high mass transfer rates and penetration into porous matrices. However, reliable and versatile mathematical models of phase equilibrium thermodynamics are needed for use in process design and viability studies. This chapter reviews experimental procedures for obtaining high-pressure phase equilibria data. In addition, phase diagrams describing binary mixtures and thermodynamic models capable of determining the conditions at phase equilibria at high pressures are considered.
... The thermodynamics and heat transfer properties of carbon dioxide (CO2) make it the preferred solvent for SFE-based extraction processes [52,57]. Several other features such as its non-toxic nature, chemical inertness, non-flammability, overall cost-effectivenes, facile availability, and environmental friendliness also represent major factors favoring the choice of CO2 as SFE solvent [52,58,59]. It also possesses other advantages such as a low critical point (31 °C, 73 bar). ...
Over the years, significant research efforts have been made to extract bioactive compounds by applying different methodologies for various applications. For instance, the use of bioactive compounds in several commercial sectors such as biomedical, pharmaceutical, cosmeceutical, nutraceutical and chemical industries, has promoted the need of the most suitable and standardized methods to extract these bioactive constituents in a sophisticated and cost-effective manner. In practice, several conventional extraction methods have numerous limitations, e.g., lower efficacy, high energy cost, low yield, etc., thus urges for new state-of-the-art extraction methodologies. Thus, the optimization along with the integration of efficient pretreatment strategies followed by traditional extraction and purification processes, have been the primary goal of current research and development studies. Among different sources, algal biome has been found as a promising and feasible source to extract a broader spectrum of bioactive compounds with point-of-care application potentialities. As evident from the literature, algal bio-products includes biofuels, lipids, polyunsaturated fatty acids, pigments, enzymes, polysaccharides, and proteins. The recovery of products from algal biomass is a matter of constant development and progress. This review covers recent advancements in the extraction methodologies such as enzyme-assisted extraction (EAE), supercritical-fluid extraction (SFE), microwave-assisted extraction (MAE) and pressurized-liquid extraction (PLF) along with their working mechanism for extracting bioactive compounds from algal-based sources to meet bio-economy challenges and opportunities. A particular focus has been given to design characteristics, performance evaluation, and point-of-care applications of different bioactive compounds of microalgae. The previous and recent studies on the anticancer, antibacterial, and antiviral potentialities of algal-based bioactive compounds have also been discussed with particular reference to the mechanism underlying the effects of these active constituents with the related pathways. Towards the end, the information is also given on the possible research gaps, future perspectives and concluding remarks.
... Thermodynamics and heat transfer properties of CO 2 make it the preferred solvent for SFE process [13]. Non-toxic, chemically inert, non-flammable, low cost, easily available, and environmentally friendly are also important features for the selection of CO 2 as SFE solvent [10,37]. In fact, CO 2 is suitable for the extraction of hydrophobic compounds due to its moderate critical temperature (31.1 °C) and pressure (72.9 bar), allowing the extraction of thermolabile compounds [14,20]. ...
Rosemary oil was extracted by supercritical carbon dioxide (CO2) as a solvent. The parameters of pressure, temperature, and ethanol as co-solvent were evaluated through a Taguchi experimental design. Extraction yield of rosemary oil increased with high pressure (350 bar) and mid-range temperature (40 °C), while the addition of ethanol as co-solvent did not improve the extraction yield. Palmitic, α-linolenic, linoleic, oleic, and stearic acid were the main fatty acids detected (3.96% w/w) in the extracted oil. The major volatile compounds found in the oil (75.74% w/w) included d-camphor, eicosane, 1,8-cineole,
tetracosane, borneol, and β-caryophyllene. The extracted oils showed antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans, while Escherichia coli was less sensitive to inhibition. Antioxidant activities on DPPH and TEAC assays were higher at 60 °C, 100 bar without ethanol, while antioxidant activity on FRAP assay was improved at 40 °C, 100 bar, and ethanol as co-solvent. Operational conditions used in the present extraction process (a variation in temperature, pressure, and co-solvent) are described.
The differences in the transport behavior and adsorption capacity of different gases in coal play crucial roles in the evolution of coal permeability. Previous studies of coreflooding experiments failed to explain the mechanism of gas flow and have attributed the variation in gas seepage flux (flow rate) at the beginning of the experiment to the change in effective stress, while the differences in the microscopic properties of different gases, such as molar mass, molecular diameter, mean molecular free path, and molecular collision frequency, were ignored. To research the effect of these gas properties on seepage flux while circumventing the effective stress, coreflooding experiments with helium (He), argon (Ar), nitrogen (N2), methane (CH4), and carbon dioxide (CO2) were designed. The results show that the gas transport velocity in coal is affected by the combination of molecular collision frequency and dynamic viscosity, and the transport velocities follow the order of ν (CH4) > ν (He) > ν (N2) > ν (CO2) > ν (Ar). A permeability equation corrected by the molecular collision frequency is proposed to eliminate differences in the permeabilities measured with different gases. The adsorption of different gases on the coal matrix causes different degrees of swelling, and the adsorption-induced swelling strains follow the order of ε (CO2) > ε (CH4) > ε (N2) > ε (Ar) > ε (He). The reduction in seepage flux and irreversible alterations in pore structure caused by adsorption-induced swelling are positively correlated with their adsorption capacities. The gas seepage fluxes after adsorption equilibrium of coal follow the order of Q (He) > Q (CH4) >Q (N2) > Q (Ar) > Q (CO2). Like supercritical CO2 (ScCO2), conventional CO2 can also dissolve the organic matter in coal. The organic molecules close to the walls of the cleats along the direction of gas flow are preferentially dissolved by CO2, and the gas seepage flux increases when the dissolution effect on the cleat width is greater than that on adsorption swelling.
This chapter illustrates the collection of phase equilibrium and high-pressure solubility data applied to four binary systems, (CO2 + 2-pentanol, CO2 + vinyl butyrate, CO2 + 2-pentyl butyrate and CO2 + butyric acid) at three temperatures of (313.15, 323.15, and 333.15) K and pressures up to 11 MPa. These four organic compounds were selected because they are implicated in the kinetic resolution of rac-2-pentanol, and their phase equilibria play an important role in the separation processes of the reaction compounds. Equilibrium data were obtained using a synthetic method in a high-pressure cell of variable volume. All systems were found to have type I phase behavior. Experimental high-pressure data showed a good correlation with density-based models and by the well-known Peng-Robinson (PR) and Soave-Redlich-Kwong (SRK) EoS coupled with the quadratic mixing rule in a semipredictive approach to describe the phase equilibrium topology of the four binary mixtures.
A closed-form multi-parameter fluid equation of state (EoS) is proposed and tested with empirical pressure isotherms of water and hydrogen. The EoS is non-algebraic but elementary, applicable in the full temperature range above the melting point, and remains accurate at high pressure. The critical-point conditions (vanishing density-derivatives of pressure) are exactly implemented in the exponential attractive term of the EoS. The singular repulsive term is structured similar to the Carnahan-Starling EoS and depends on five substance-specific parameters, which can be regressed from the critical isotherm. The temperature evolution of the EoS above the critical temperature is regressed from supercritical isotherms. In the subcritical regime above the melting point, the temperature-dependent scale factors of the EoS are inferred from the empirical coexistence curve, which is fully implemented in the EoS. The pressure singularity occurs at a limit density that is noticeably higher than predicted by universal cubic EoSs such as the Peng-Robinson EoS. The parameters of the analytic and non-perturbative EoSs of water and hydrogen are derived from high-pressure data sets.
Algae are an enormous source of polysaccharides and have gained much interest in human flourishing as organic drugs. Algal polysaccharides have aroused interest in the health sector owing to the various bioactivities namely anticancer, antiviral, immunoregulation, antidiabetic and antioxidant effects. The research community has comprehensively described the importance of algal polysaccharides regarding their extraction, purification, and potential use in various sectors. However, regardless of all the intriguing properties and potency in the health sector, these algal polysaccharides deserve detailed investigation. Hence, the present review emphasizes extensively on the previous and latest developments in the extraction, purification, structural properties and therapeutic bioactivities of algal polysaccharides to upgrade the knowledge for further advancement in this area of research. Moreover, the review also addresses the challenges, prospective research gaps and future perspective. We believe this review can provide a boost to upgrade the traditional methods of algal polysaccharide production for the development of efficacious drugs that will promote human welfare.
Graphic Abstract
Ternary VLE data produced on a static analytic apparatus with dual sampling and online chromatography are presented for CO2 + n-dodecane (nC12) + 1-decanol (C10OH) at 35, 55 and 75 °C and pressures between 68 and 200 bar. Cell interior photos illustrate the value of visual observation to gauge the extent of phase separation. Co-solvency, where the ternary mixture is more soluble than the constituent binaries, occurs in the high-nC12 region. Relative solubility, a selectivity indicator, increases with C10OH content, the average of 2.25 highlights solvent efficacy, and solutes fractionation is possible across the measured nC12:C10OH ratio range. RK-ASPEN, SR-POLAR, PR-BM and PC-SAFT correlations failed at 35 °C. At 55 and 75 °C, RK-ASPEN produced the smallest percentage average absolute deviation in equilibrium pressure of 3.1%, marginally outperforming SR-POLAR and PR-BM. SR-POLAR was best-able to correlate the acute co-solvency pinch and RK-ASPEN vapour correlations were superior. Density inversions were observed.
Vapor − liquid equilibrium (VLE) data of the binary mixtures carbon dioxide (CO2) + acetone and CO2 + pentanones (i.e. all C5-ketones, which are 3-methyl-2-butanone, 2-pentanone, and 3-pentanone) are measured at 313.15 K, 333.15 K, and 353.15 K up to a pressure of 11.8 MPa using a high pressure view cell technique based on the synthetic method. The VLE measurement results of CO2 + acetone are compared to the available experimental data from the literature in order to validate the employed experimental apparatus. In case of binary CO2 + pentanones mixtures, only for CO2 + 3-methyl-2-butanone and CO2 + 2-pentanone at 313.15 K experimental data are available in the literature. The present measurements thus complete the literature database for binary VLE of CO2 + pentanones. All present data are compared to the results from the Peng − Robinson equation of state (PR EOS) with the van der Waals one-fluid mixing rule and from the combination of the PR EOS with the UNIQUAC model through the Huron − Vidal mixing rule.
A modified Redlich-Kwong equation of state is proposed. Vapor pressures of pure compounds can be closely reproduced by assuming the parameter a in the original equation to be temperature-dependent. With the introduction of the acentric factor as a third parameter, a generalized correlation for the modified parameter can be derived. It applies to all nonpolar compounds. With the application of the original generalized mixing rules, the proposed equation can be extended successfully to multicomponent-VLE calculations, for mixtures of nonpolar substances, with the exclusion of carbon dioxide. Less accurate results are obtained for hydrogen-containing mixtures.
The development of a new two-constant equation of state in which the attractive pressure term of the semiempirical van der Waals equation has been modified is outlined. Examples of the use of the equation for predicting the vapor pressure and volumetric behavior of single-component systems, and the phase behavior and volumetric behavior of binary, ternary, and multicomponent systems are given. The proposed equation combines simplicity and accuracy. It performs as well as or better than the Soave-Redlich-Kwong equation in all cases tested and shows its greatest advantages in the prediction of liquid phase densities.
Phase equilibria of CO2 + limonene, CO2 + 1,2,3-trimethylbenzene, CO2 + p-cymene and CO2 + m-cymene systems were measured to investigate the possibility of extraction of these components from tyre derived oil using supercritical CO2. Measurements were conducted using variable-volume view cells at four temperatures between 313 and 358 K, with solute mass fractions ranging from 0.0159 to 0.635. The maximum total solubility pressure measured was 16.5 MPa. The phase behaviour of the systems indicated that an increase in system temperature leads to an increase in phase transition pressure at constant composition. The solubility differences between the components increase slightly with the temperature, however a sufficient pressure difference exists for 1,2,3-trimethylbenzene to be isolated at temperature higher than 343 K. Experimental data of four binary systems were satisfactory correlated by using the Redlich-Kwong-Soave equation of state, along with Mathias-Klotz-Prausnitz mixing rules, which include two temperature independent binary interaction parameters.
High-pressure phase behaviour data are reported for the binary systems CO2 + N-[3-(trimethoxysilyl)propyl]aniline (TMSPA) and CO2 + (3-mercaptopropyl)trimethoxysilane (MPTS). The organosilanes TMSPA and MPTS are employed to functionalise with the amino and mercapto groups, respectively, the surface of inorganic materials using supercritical CO2 as a solvent and reaction medium. The measurements were conducted in a high-pressure variable volume view cell at T = 313.2, 323.2, and 333.2 K and pressures up to p = 25.0 MPa. The CO2 mole fraction in the binary mixture was varied from 0.40 to 1.0. For both silanes, the immiscibility region enlarges as the temperature rises. For a given pressure and temperature MPTS is considerably more soluble in CO2 than TMSPA. For instance, if a temperature of 313.2 K is chosen a pressure of 8.7 MPa will suffice to assure the solubilisation of MPTS in the whole mole fraction range whereas a pressure of 21.0 MPa will be necessary for the solubilisation of TMSPA. The Peng-Robinson equation of state was used to correlate the phase equilibrium data.
Nitrile groups have strong polarity and show the non-ideal phase equilibria. Phase equilibria for the 3-phenyl propionitrile and 2-phenyl butyronitrile play an important role as organic solvents in several industrial processes. The solubility curves of binary mixture for 3-phenyl propionitrile and 2-phenyl butyronitrile in supercritical CO2 are investigated using a synthetic method at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2) K and pressure up to 34.45 MPa. Both CO2 + 3-phenyl propionitrile and CO2 + 2-phenyl butyronitrile systems have critical mixture curves that show maximums in pressure-temperature space between the critical temperatures of CO2 and 3-phenyl propionitrile or 2-phenyl butyronitrile. The solubility of CO2 for two systems at a constant pressure decreases with the increase of temperature. The CO2 + 3-phenyl propionitrile and CO2 + 2-phenyl butyronitrile systems display type-I phase behavior within scope of this work. The experimental results for the CO2 + 3-phenyl propionitrile and CO2 + 2-phenyl butyronitrile binary systems are correlated with Peng-Robinson equation of state using a mixing rule including two adjustable parameters (kij, ηij). The critical properties (pc, Tc and ω) and vapor pressure of 3-phenyl propionitrile and 2-phenyl butyronitrile were estimated with the Joback–Lyderson group contribution and Lee-Kesler method.
The effect of viscosity reduction caused by the solubilization of CO2 is studied in order to improve the biomass processing in ionic liquids. To do so, densities and viscosities of the pure ionic liquid 1-allyl-3-methylimidazolium chloride and its mixtures with CO2 up molar fractions of 0.25 and temperatures between 333 and 372 K have been experimentally determined. Viscosities were correlated as a function of temperature and CO2 molar fractions with an average relative error of 2.5%. The viscosities of other mixtures CO2 + ionic liquids were also correlated for other ionic liquids with an average relative error between 4.4 and 13%. In general these ionic liquids present a linear decrease of viscosity with CO2 molar fractions up to around 0.5 that is more pronounced at lower temperatures and depends of each ionic liquid, and can reach between 60-100% viscosity reduction with respect the viscosity of the pure ionic liquid, making the CO2 a promising co-solvent for viscosity reduction in process with ionic liquids.
The solubilities of anthracene and carbazole in liquid and supercritical isobutane have been experimentally determined in a static view cell, at temperatures from (367 to 418 K) and pressures from (3.2 to 8.6) MPa. The solubilities of anthracene varied from (7.3 to 51.8) mg of solute per gram of isobutane, whereas those of carbazole were from (1.4 to 9.9) mg of solute per gram of isobutane within the experimental range studied. These differences in solute solubilities have been explained attending to the higher vapor pressures of anthracene and its smaller dipole moment (and so stronger affinity to isobutane). The experimental solubilities have been compared to those of these solutes in propane and CO2. At similar reduced temperature and pressure conditions, it has been found that solute mole fractions are higher in isobutane than in the other two fluids (3 to 15 times and 160 to 270 times higher than in propane and CO2, respectively). Anthracene and carbazole solubilities in isobutane have been modeled by the Peng–Robinson equation of state. Good fit of the experimental results has been obtained (APD values of 6.7 % for anthracene and 9.7 % for carbazole).
Data on the phase behaviour of long chain fatty acids (octanoic, decanoic, undecanoic, dodecanoic, tetradecanoic, hexadecanoic and octadecanoic) in supercritical carbon dioxide is presented at temperatures between 308 and 358 K and pressures up to 27 MPa. No three-phase regions were observed and at constant composition, an increase in temperature leads to an increase in phase transition pressure. An increase in hydrocarbon backbone length also leads to an increase in phase transition pressure. Comparison of the measured data with literature data of n-alkanes, 1-alcohols, methyl esters and ethyl esters of the same hydrocarbon backbone length shows that carbon dioxide is able to easily distinguish between acids and n-alkanes, methyl esters or ethyl ester and, with selection of the correct conditions, carbon dioxide is also able to distinguish between acids and 1-alcohols. However, unlike for propane, the phase behaviour of an acid in carbon dioxide does not mimic that of an alkane with double the number of carbon atoms, most probably due to the effect of the quadrupole moment of carbon dioxide.
In this work, the solubility of carbon dioxide (CO2) in seven different ionic liquids (ILs) was measured using a high-pressure sapphire cell, in the pressure range of 8–22 MPa and at two temperatures, 313.2 K and 323.2 K. In order to discuss the influence of the cation, ILs based on bis(trifluoromethylsulfonyl)imide, [NTf2] were chosen. They were coupled with 1-butyl-3-methylimidazolium, [C4mim]+, 1-decyl-3-methylimidazolium, [C10mim]+, 1-butyl-1-methylpyrrolidinium, [Pyrr4,1]+, butyltrimethylammonium, [N4,1,1,1]+, methyltrioctylammonium, [N1,8,8,8]+ and trihexyltetradecylphosphonium, [P6,6,6,14]+cation. The phosphonium based cation was also combined with chloride, [Cl]−, giving an opportunity to discuss the influence of an anion as well. The solubility data obtained in this work were used to evaluate the importance of explicitly including association for describing such systems. For that purpose, we compared the solubility modelling results from two cubic equations of state (Peng–Robinson and Soave–Redlich–Kwong) with those from the Cubic Plus Association Equation of State (CPA EoS) using different association schemes for the ionic liquids. We found that for such systems there is no major advantage in considering ILs as associating components.
The ability to model and predict the behaviour of high-pressure alcohol and carbon dioxide mixtures is important for industrial purposes. The phase equilibria behaviour of four 8-carbon alcohols in supercritical carbon dioxide are measured to determine the effect of the hydroxyl group position on alcohol solubility. Experimental bubble- and dew point data are generated on a high pressure phase equilibrium cell for the systems 1-octanol, 2-octanol, 3-octanol and 4-octanol in supercritical carbon dioxide between 35 °C and 75 °C. 1-Octanol is shown to be the least soluble and, at 35 °C, exhibits a phase transition pressure 85 bar higher than that of 2-octanol. 1-Octanol also exhibits a temperature inversion near the critical temperature of carbon dioxide in the mixture critical region. 2-Octanol possesses marginally higher phase transition pressures than 3-octanol which, in turn, possesses marginally higher phase transition pressures than 4-octanol. This difference in phase equilibria is believed to result from a difference in polarity. Shifting the hydroxyl group from the first to the second carbon atom causes a large decrease in polarity and increase in solubility. Further movements toward the molecule centre result in progressively smaller polarity reductions and solubility increases, producing phase boundaries that coincide or differ minimally.
This paper is a continuation of a previous study and investigated the phase equilibria of six C8 alcohols (2,2,4-trimethyl-1-pentanol, 2,4,4-trimethyl-1-pentanol, 2-ethyl-1-hexanol, 2-propyl-1-pentanol, 4-methyl-3-heptanol and 6-methyl-2-heptanol) in supercritical carbon dioxide. Data has been measured between 308 and 348 K for alcohol mass fractions between 0.660 and 0.0162. The results show that the position, size and quantity of side chains have a significant effect on the phase behaviour by changing the shape of the molecule and the effect of the hydroxyl group on the polarity of the molecule. The pressure required for total solubility increases in the following sequence: 4-methyl-3-heptanol < 2,2,4-trimethyl-1-pentanol < 6-methyl-2-heptanol < 2,4,4-trimethyl-1-pentanol < 2-propyl-1-pentanol < 2-ethyl-1-hexanol < 1-octanol. The difference in phase behaviour is believed to be a result of a difference in shielding of the hydroxyl group. Greater shielding of the hydroxyl group results in a less asymmetric system, and this, in turn, results in higher solubility of the molecule.
High pressure vapor–liquid equilibria for the binary carbon dioxide–2-pentanol system are measured at 313.2 K. The phase equilibrium apparatus used in this work is of the circulation type in which the coexisting phases are recirculated, on-line sampled, and analyzed. The critical pressure and corresponding mole fraction of carbon dioxide at 313.2 K are found to be 8.67 MPa and 0.985, respectively, for this binary system. The phase equilibria for the ternary carbon dioxide–water–2-pentanol system are also measured at 313.2 K and at pressures of 2.0, 4.0, 6.0, 8.0, and 8.64 MPa. The ternary carbon dioxide–2-pentanol–water systems show three LLV phases over the range of pressure up to 8.64 MPa. The binary experimental equilibrium data are correlated with the Redlich–Kwong, Soave–Redlich–Kwong, Peng–Robinson, and Patel–Teja equations of state with two different mixing rules, the van der Waals and the Panagiotopoulos–Reid mixing rules. The binary experimental data are well correlated by using three equations of state and corresponding mixing rules.
Complementary isothermal (vapor+liquid) equilibria data are reported for the (CO2+3-methyl-2-butanol), (CO2+2-pentanol), and (CO2+3-pentanol) binary systems at temperatures of (313, 323, and 333)K, and at pressure range of (2 to 11)MPa. For all (CO2+alcohol) systems, it was visually monitored that there was no liquid immiscibility at the temperatures and pressures studied. The experimental data were correlated with the Peng–Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapor+liquid) equilibria compositions were found to be in good agreement with the experimental data with deviations for the mole fractions
High pressure phase equilibria for the (carbon dioxide+n-vinyl pyrrolidone) and (carbon dioxide+N,N-dimethylacrylamide) systems are measured in a static apparatus at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2) K and pressures up to 24.66MPa. These two systems exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and n-vinyl pyrrolidone or N,N-dimethylacrylamide. The solubility of n-vinyl pyrrolidone and N,N-dimethylacrylamide for the (carbon dioxide+n-vinyl pyrrolidone) and (carbon dioxide+N,N-dimethylacrylamide) systems increases as the temperature increases at a fixed pressure. The (carbon dioxide+n-vinyl pyrrolidone) and (carbon dioxide+N,N-dimethylacrylamide) systems exhibit type-I phase behavior. The experimental results for the (carbon dioxide+n-vinyl pyrrolidone) and (carbon dioxide+N,N-dimethylacrylamide) systems are correlated with the Peng-Robinson equation of state using a mixing rule including binary interaction parameters (kij and ηij).
Vapor–liquid–equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE) data for the carbon dioxide+1-nonanol system were measured at 303.15, 308.15, 313.15, 333.15, and 353.15K. Phase behavior measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between 1.15 and 103.3bar. The Soave–Redlich–Kwong (SRK) equation of state (EOS) coupled with both classical van der Waals and a Gibbs excess energy (GE) mixing rules was used in semi-predictive approaches, in order to represent the complex phase behavior (critical curve, liquid–liquid–vapor (LLV) line, isothermal VLE, LLE, and VLLE) of the system. The topology of phase behavior is correctly predicted.
High pressure phase equilibria for the (carbon dioxide+valeronitrile), (carbon dioxide+capronitrile) and (carbon dioxide+lauronitrile) systems are measured in static apparatus at five temperatures of 313.2, 333.2, 353.2, 373.2 and 393.2K and pressures up to 25.7MPa. The three carbon dioxide+nitrile systems have continuous critical mixture curves that exhibit maximums in pressure at temperatures between the critical temperatures of carbon dioxide and nitriles. The solubility of valeronitrile, capronitrile and lauronitrile for the (carbon dioxide+nitriles) systems increases as the temperature increases at a fixed pressure. The (carbon dioxide+valeronitrile), (carbon dioxide+capronitrile) and (carbon dioxide+lauronitrile) systems exhibit type-I phase behavior. The experimental results for the (carbon dioxide+valeronitrile), (carbon dioxide+capronitrile) and (carbon dioxide+lauronitrile) systems are correlated with Peng–Robinson equation of state using a mixing rule including one and two adjustable parameters.
The van der Waals equation of state, in spite of its oversimplifications, gives useful qualitative information about mixtures over a wide range of temperatures and pressures. When the Brönsted principle of congruence is used to evaluate the parameter a12 for the mixture, a wide range of properties can be predicted: excess functions (including temperature and composition dependence) and phase equilibria (including lower critical solution phenomena at high temperatures), in good qualitative agreement with experimental properties of mixtures of n-alkanes.
An apparatus based on a static-analytic method assembled in this work was utilized to perform high pressure (vapour + liquid) equilibria measurements with uncertainties estimated at <5%. Complementary isothermal (vapour + liquid) equilibria results are reported for the (CO2 + 1-propanol), (CO2 + 2-methyl-1-propanol), (CO2 + 3-methyl-1-butanol), and (CO2 + 1-pentanol) binary systems at temperatures of (313, 323, and 333) K, and at pressure range of (2 to 12) MPa. For all the (CO2 + alcohol) systems, it was visually monitored to insure that there was no liquid immiscibility at the temperatures and pressures studied. The experimental results were correlated with the Peng-Robinson equation of state using the quadratic mixing rules of van der Waals with two adjustable parameters. The calculated (vapour + liquid) equilibria compositions were found to be in good agreement with the experimental values with deviations for the mol fractions <0.12 and <0.05 for the liquid and vapour phase, respectively.
An apparatus for the measurement of vapor–liquid equilibrium (VLE, P–T–x) data and density of saturated-liquid and high-pressure liquid phase of compressed gas-organic solvent systems was designed, built and tested. A synthetic method, with recirculation of the liquid phase through a high-pressure densimeter by a magnetic driven centrifugal pump, was used. The thermodynamic equilibrium was reached in a visual cell with variable volume ranging between 30 and 60cm3. The compositions of the phases were evaluated by external gravimetric method.The estimated accuracy of the measured data was ±0.02K for temperature, ±0.05MPa for pressure, ±0.005 in mole fraction for liquid compositions and ±0.05g/L for liquid density. Vapor–liquid equilibrium data and saturated-liquid density were obtained for the following systems: carbon dioxide–ethanol and carbon dioxide–acetone at 291.15, 303.15, 313.15 and 323.15K and carbon dioxide–dichloromethane at 291.15, 303.15 and 311.15K. For the latter system, high-pressure liquid density data were measured up to 18MPa. The experimental data were correlated by both Peng–Robinson and SAFT equation of state. SAFT EOS gives better correlations of vapor–liquid data and accurate predictions of high-pressure density of the liquid phase.
Chrastil (1982) established that the solubility of a substance in a supercritical fluid can be correlated with the density of the pure supercritical gas. Recently, the solubility of supercritical fluids in different organic liquids was successfully correlated as a function solely of the supercritical fluid density, since we demonstrated that the supercritical fluid density also defines the solubility of the gas in the liquid phase. In this work, the solubility of supercritical carbon dioxide in high-molecular weight substances, such as high-molecular weight paraffins, alcohols, fatty acids, fatty acid methyl and ethyl esters, has been correlated and constants provided. More than 20 binary systems comprising around 1000 solubility data points were correlated, obtaining regression coefficients greater than 0.96 and confirming the goodness of the density-dependent equation previously reported. © 2010 American Institute of Chemical Engineers AIChE J, 2011
Precipitation of acetaminophen and tretinoin is performed using supercritical enhanced dispersion by supercritical fluids (SEDS), using carbon dioxide and ethanol as antisolvent and solvent respectively. In order to assure the no existence of immiscibilities and to determine the conditions at which the maximum attainable supersaturation is produced, it is performed a phase equilibria study of the ternary and binary systems with Peng–Robinson equation of state. The ternary equilibrium diagrams show that the maximum supersaturation matches with the mixture critical point given by the vapor–liquid diagram and also show information about the cosolvent effect of both antisolvent and solvent, proving in addition the no existence of immiscibilities at all the investigated conditions. These results are confirmed using a windowed cell. The effect of pressure, temperature and solution concentration in the precipitation process is discussed. The different particle diameters of the precipitated particles are explained with the aid of the phase equilibria diagrams, taking into account the position of experimental conditions with respect to the mixture critical point. The best results for both solids, spherical microparticles without aggregates and with a size around 0.5–0.75μm, are obtained just above the mixture critical point of the mixture antisolvent–solvent.
Some properties of carboxylic acids are reviewed, with emphasis on recent experimental data. Qualified, consistent latent heat of vaporization data were developed for the series and a two-population viewpoint is suggested. The equation of state formulated by Grenzheuser [1] is also recommended as a practical tool, and its further development is urged.
Isothermal (P, T, x, y) data have been measured for the binary system carbon dioxide + 2-propanol at temperatures from (293 to 323) K. The pressure range under investigation was between (0.68 and 8.6) MPa. The new experimental data are correlated with the Soave−Redlich−Kwong (SRK) equation of state coupled with the HVID mixing rules. A correlation of the HVID parameters with temperature is proposed by using all reliable published data and those of this study.
The phase behaviour of the pyrrole–carbon dioxide binary system was investigated in a variable volume view cell (vvvc) with a synthetic method. The experimental results were correlated by the Peng–Robinson equation of state using the Mathias–Klotz–Prausnitz mixing rule. This work was focused at the temperature- and pressure ranges of 313–343K and 7–17MPa, covering the conditions where the impregnation of different polymer substrates with pyrrole is the most likely feasible. According to the extrapolated results of the model in addition to the experimental data, the liquid–liquid immiscibility ceases above the more volatile component's critical temperature and pressure. This kind of phase behaviour was classified type-III by van Konynenburg and Scott.
The experimental solubility of dibenzofuran in near-critical and supercritical carbon dioxide and the solid–liquid–vapor (SLV) equilibrium line for the CO2+dibenzofuran system are reported. The built in-house static view cell apparatus used in these measurements is described. The solubility of naphthalene in supercritical CO2 and the CO2+naphthalene SLV line are also determined in order to assess the reliability and accuracy of the measurement technique. The solubility of dibenzofuran in carbon dioxide is determined at 301.3, 309.0, 319.2, 328.7 and 338.2K in the 6–30MPa pressure range. Solubility data are correlated using the Chrastil model and the Peng–Robinson equation of state. This equation is also used to predict the CO2+dibenzofuran SLV line. Results show the feasibility of using supercritical CO2 to extract dibenzofuran.
As a part of a series of reviews, a compilation of systems for which high-pressure phase-equilibrium data were published between 2000 and 2004 is given. Vapor-liquid equilibria, liquid-liquid equilibria, vapor-liquid-liquid equilibria,solid-liquid equilibria, solid-vapor equilibria, solid-vapor-liquid equilibria, critical points, the solubility of high-boiling substances in supercritical fluids, the solubility of gases in liquids and the solubility (sorption) of volatile components in polymers are included. For the systems investigated, the reference, the temperature and pressure range of the data, and the experimental method used for the measurements are given in 54 tables. Most of experimental data in the literature have been given for binary systems. Of the 1204 binary systems, 681 (57%) have carbon dioxide as one of the components. Information on 156 pure components, 451 ternary systems of which 267 (62%) contain carbon dioxide, 150 multicomponent and complex systems, and 129 systems with hydrates is given. Experimental methods for the investigation of high-pressure phase equilibria are classified and described. Work on the continuation of the review series is under way, covering the period between 2005 and 2008, and will be published in 2010. (C) 2009 Elsevier B.V. All rights reserved
Biocatalytic processes based on ionic liquids (ILs) and supercritical carbon dioxide are interesting alternatives to organic solvents for designing clean synthetic chemical processes to obtain pure products directly. In such enzymatic processes, the classical advantages of supercritical carbon dioxide to extract, dissolve and transport chemicals are compromised by the denaturing effect that it has on enzymes. On the other hand, ILs have shown themselves to be excellent non-aqueous environments for enzyme catalysis. Biphasic systems based on ILs and supercritical carbon dioxide have been proposed as the first approach to integral green bioprocesses in non-aqueous media, where both the biocatalytic and extraction steps are coupled in an environmentally benign and efficient reaction/separation process.
Vapor–liquid equilibria (VLE) and vapor–liquid–liquid equilibria (VLLE) data for the carbon dioxide + 1-heptanol system were measured at 293.15, 303.15, 313.15, 333.15 and 353.15 K. Phase behavior measurements were made in a high-pressure visual cell with variable volume, based on the static-analytic method. The pressure range under investigation was between 0.58 and 14.02 MPa. The Soave–Redlich–Kwong (SRK)-EOS coupled with Huron–Vidal (HV) mixing rules and a reduced UNIQUAC model, was used in a semi-predictive approach, in order to represent the complex phase behavior (critical curve, LLV line, isothermal VLE, LLE, and VLLE) of the system. The topology of phase behavior is qualitatively correct predicted.
Vapor–liquid equilibria and critical points of the systems: carbon dioxide+1-pentanol at (333.08, 343.69, 374.93, 414.23 and 426.86 K) up to 18.6 MPa and carbon dioxide+2-pentanol at (332.10, 343.61, 374.15, 397.56, 422.28 and 431.78 K) up to 15.7 MPa are reported at compositions near the critical point. An apparatus capable of measurement up to 60 MPa and 523 K based on the static-analytic method has been used to perform fast determinations of the vapor–liquid equilibria and critical pressures.The Soave, Peng–Robinson and Patel–Teja equations of state with Wong–Sandler type mixing rules and temperature independent parameters cannot predict the VLE of the carbon dioxide+1-pentanol and carbon dioxide+2-pentanol systems well (deviations >10% for pressure). Instead the EoS mixture parameters were fitted to the VLE data at each temperature, separately. In this way the calculated VLE are found to be in good agreement with the experimental data.
Vapor−Liquid equilibria for two binary mixtures at elevated pressures were determined by a novel technique of density measurement. In this investigation using two high-pressure densitometers, phase diagrams for carbon dioxide + ethanol and carbon dioxide + acetone mixtures were established at five temperatures and pressures up to 14.39 MPa. Solubilities of carbon dioxide in both ethanol and acetone were found to increase with applied pressure but decreased with increasing temperature. The solubility for carbon dioxide in acetone was found to be greater than that of carbon dioxide in ethanol.
Isothermal (P, T, x, y) data have been measured for the binary system carbon dioxide + 1-butanol at temperatures from (293.15 to 324.15) K. The pressure range under investigation was between (0.52 and 10.09) MPa. The new experimental data are correlated with the Soave−Redlich−Kwong (SRK) equation of state coupled with the Huron−Vidal infinite dilution (HVID) mixing rules. A linear correlation of the HVID parameters with the inverse temperature is proposed by using only the data of this study. The values of HVID parameters from the linear correlation were used to predict VLE at all temperatures for which published data are available. The VLE data are reasonably well predicted for engineering purposes.
This is part 4 of a series of contributions by the critical properties group of the TCTPAC Commission 1.2 on Thermodynamics, Subcommittee on Thermodynamic Data. It presents all known experimental data for the critical constants of alphatic alkanols up to C-12. Recommended critical constants are given together with their uncertainties, which increase for the more unstable higher alkanols. The critical temperatures have been converted to ITS-90.
An apparatus for the determination of the solubilities of solids and liquids in dense gases is described. The solubilities of stearic acid, oleic acid, behenic acid, tributyrin, tripalmitin, triolein, trilinolein, palmityl behenate, behenyl behenate, α-tocopherol, cholesterol, water, and cafestol in supercritical carbon dioxide at different temperatures and pressures were determined. An equation was derived from the association laws and/or from the entropies of the components and was compared with these experimental results. The equation agreed with experimental results over a wide range of pressures and temperatures. Some experimental results from the literature (naphthalene, anthraquinone, p-chloroiodobenzene) were also reproduced by means of this equation. Very good agreement with these experimental results was found, as in previous examples. The association number, heats of solution, and other thermodynamical characteristics of compounds dissolved in dense gases are discussed. The separation of α-tocopherol and tripalmitin by the supercritical carbon dioxide extraction was measured experimentally at different pressures and temperatures. The equation describing the ideal separation of two independent components by means of a dense gas extraction is described.
The kinetic resolutions of rac-1-phenylethanol and rac-2-pentanol by transesterification with vinyl esters catalysed by a commercial immobilised Candida antarctica lipase B were successfully carried out in hexane medium. This enzyme showed very high enantioselectivity for both substrates. The influence of the water content of the medium on the synthetic activity, selectivity and enantioselectivity of the enzyme was analysed, with the optimal amount of water about 100 ppm. Our results also showed that the activity per gram enzymatic derivate of CaLB was slightly higher with butyl butyrate as acyl donor.
Les résolutions cinétiques du rac-1-phényléthanol et du rac-2-pentanol par transestérification avec des esters vinyliques catalysée par une lipase B Candida antarctica commerciale immobilisée ont été effectuées avec succès dans un milieu à l'hexane. Cet enzyme a montré une énantiosélectivité très élevée pour les deux substrats. L'influence du contenu en eau du milieu sur l'activité synthétique, la sélectivité et l'énantiosélectivité de l'enzyme a été analysée, la quantité d'eau optimale étant d'environ 100 ppm. Nos résultats ont montré également que l'activité par gramme de dérivé enzymatique du CaLB était légèrement du butyrate de butyle comme donneur d'acyle.
The volumetric and thermodynamic functions correlated by Pitzer and co-workers analytically represented with improved accuracy by a modified BWR equation of state. The representation provides a smooth transition between the original tables of Pitzer et al. and more recent extensions to lower temperatures. It is in a form particularly convenient for computer use.
Critical temperatures and pressures of some organic compounds were measured. There is good agreement between the observed critical pressures and values obtained by extrapolation of equations representing the variation of vapour pressure with temperature in the region of the normal boiling point. An incremental scheme relating critical temperatures to normal boiling points is described and is used for the correlation of the critical temperatures, obtained in this and other investigations, of more than 150 compounds.
Pressure-composition isotherms are obtained for binary mixtures of carbon dioxide with formic acid, acetic acid, butyric acid, valeric acid, caproic acid, and caprylic acid at temperatures of 35.0-120.0 °C and pressures up to 250 bar. The accuracy of the experimental apparatus was tested by comparing the measured phase equilibrium data of the carbon dioxide-acetic acid system at 40.0 and 60.0 °C with those of Laugier et al. These six carbon dioxide-polar solute systems exhibit type I phase behavior, which is characterized by an uninterrupted critical mixture curve that has a maximum in pressure. In each system, the mixture critical point increases as the temperatures increases, and also the mixture critical pressure increases as the molecular weight increases. On the contrary, the carbon dioxide-formic acid system shows a higher mixture critical pressure compared with those of the other systems. The experimental data are modeled using both the statistical associating fluid theory (SAFT) and the Peng-Robinson (P-R) equation of state. The SAFT equation of state reasonably models the pressure-composition isotherms for these six systems only if two temperature-independent mixture parameters are used for each system. The P-R equation of state calculated the phase behavior with one or two temperature-independent mixture parameters.
Simple group-contribution methods are proposed to estimate eleven important physical properties of pure materials. A common set of structural groups was employed. High accuracy is not claimed, but the proposed methods are often as accurate as or more accurate than techniques in common use today.
Immobilized Candida antarctica lipase B (CALB) was successfully used as catalyst to synthesize butyl butyrate from butyl vinyl ester and 1-butanol in supercritical carbon dioxide (scCO2) with excellent results. The catalytic behaviour of the enzyme immobilized on an acrylic support has been studied in a stirred tank reactor, showing that a decrease in both the water content and the scCO2 density enhanced the synthetic activity and selectivity (>99.0%). Then, ceramic membranes were coated with hydrophilic polymers, and then used to covalently attach CALB. These active membranes were applied for continuous butyl butyrate synthesis in a cross-flow reactor with different organic solvents and supercritical conditions, as reaction media. A clear enhancement in the synthetic activity and selectivity was observed with the decrease in fluid density for both liquids and scCO2 media. However, all supercritical conditions assayed enhanced up 84-folds respect to the organic solvents the synthetic activity of the lipase-membrane derivative. For the best supercritical conditions (60 °C, 8 MPa), the enzymatic membrane was assayed by repetitive operational cycles of 6 h/day, showing a 360 cycles half-life time in their synthetic activity.
High pressure phase equilibria of supercritical carbon dioxide with n-alkanes, n-C12, n-C16, n-C20, n-C24, n-C28 and n-C36, have been measured over the temperature range of 313–367 K, and are reported in this work. Of the various equations of state investigated, it was found that the Patel Teja equation of state provided the best fit of the CO2–n-alkane systems.
A review of systems is given, for which experimental high-pressure phase-equilibrium data were published in the period between 2005 and 2008, continuing a series of reviews. To find candidates for articles that are of interest for this survey a three-stage search strategy was used including a systematic search of the contents of the 17 most important journals of the field. Experimental methods for the investigation of high-pressure phase equilibria were classified, described and illustrated using examples from articles of the period between 2005 and 2008. For the systems investigated, the reference, the temperature and pressure range of the data, and the experimental method used for the measurements is given in 54 tables. Vapor–liquid equilibria, liquid–liquid equilibria, vapor–liquid–liquid equilibria, solid–liquid equilibria, solid–vapor equilibria, solid–vapor–liquid equilibria, critical points, the solubility of high-boiling substances in supercritical fluids, the solubility of gases in liquids and the solubility (sorption) of volatile components in polymers are included. Most of experimental data in the literature has been given for binary systems. Of the 1469 binary systems, 796 (54%) have carbon dioxide as one of the components. Information on 206 pure components, 535 ternary systems of which 355 (66%) contain carbon dioxide, 163 multicomponent and complex systems, and 207 systems with hydrates is given. A continuation of the review series is planned, covering the years from 2009 to 2011.
Dynamic membranes with immobilized Candida antarctica lipase B (CALB) were successfully applied for butyl propionate synthesis in a recirculating bioreactor in supercritical carbon dioxide medium and in room temperature ionic liquid/supercritical carbon dioxide biphasic systems at 50 °C and 80 bar.In room temperature ionic liquid/supercritical carbon dioxide biphasic systems, the immobilized enzyme coated with three different ionic liquids based on dialkylimidazolium cations, showed an increase in the selectivity of the process (up to 99.5%) compared with supercritical carbon dioxide assayed in the absence of room temperature ionic liquid. For the RTILs assayed, it was observed that the increase in activity was in agreement with an increase in the partition coefficients of the substrates between RTIL and hexane.Additionally, a model based on the Ping Pong Bi–Bi mechanism with competitive alcohol inhibition is proposed to describe the kinetics of the transesterification reaction in supercritical carbon dioxide.
Liquid–vapor (LV) and liquid–liquid (LL) phase equilibria in the carbon dioxide + pyrrole system were measured at temperatures between 313 K and 333 K, and pressures between 8.4 MPa and 15.1 MPa. The data were used to predict the overall phase behavior of the system using the Patel–Teja equation of state and the Mathias–Klotz–Prausnitz mixing rules with two temperature-independent parameters. The calculations suggest that the carbon dioxide + pyrrole system may exhibit type IV phase behavior according to the classification of Scott and van Konynenburg.
A method is described for the minimization of a function of n variables, which depends on the comparison of function values at the (n + 1) vertices of a general simplex, followed by the replacement of the vertex with the highest value by another point. The
simplex adapts itself to the local landscape, and contracts on to the final minimum. The method is shown to be effective and
computationally compact. A procedure is given for the estimation of the Hessian matrix in the neighbourhood of the minimum,
needed in statistical estimation problems.
High-pressure fluid phase equilibria: experimental methods and systems investigated
- M Christov
- R Dohrn
M. Christov, R. Dohrn, High-pressure fluid phase equilibria: experimental methods
and systems investigated (1994-1999), Fluid Phase Equilib. 202 (2002) 153-218,
http://dx.doi.org/10.1016/S0378-3812(02)00096-1.
Enzymatic synthesis of chiral intermediates for drug development
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R.N. Patel, Enzymatic synthesis of chiral intermediates for drug development, Adv.
Synth. Catal. 343 (2001) 527-546, http://dx.doi.org/10.1002/1615-4169(200108)
343:6/7<527:AID-ADSC527>3.0.CO;2-I.
PE 2000: A Powerful Tool to Correlate Phase Equilibria
- O Pfohl
- S Petkov
- G Brunner
O. Pfohl, S. Petkov, G. Brunner, PE 2000: A Powerful Tool to Correlate Phase
Equilibria, Herbert Utz Verlag, München, Germany, 2000.