Chrastil Equation Research Articles

Predicting the solubility of solids in supercritical carbon dioxide using the Chrastil equation with parameters estimated from a group contribution method

Predicting the solubility of a solid in supercritical carbon dioxide (scCO2) can be useful for many applications. However, an accurate prediction is extremely difficult since current methods require knowledge about the properties of the solid in question or lengthy computational calculations and often yield significant deviations. Here, a new approach is proposed that allows the solubility of any solid in supercritical carbon dioxide to be rapidly predicted based solely on the structural formula of the solute. This approach is based on the prediction of Chrastil’s parameters using group contribution methods (GCMs) followed by their use in Chrastil’s equation. For this purpose, group contribution methods to estimate Chrastil’s parameters were developed using more than 6000 experimental data points from 210 solids. These parameters were used to predict the solubility data of 30 solids (around 1300 experimental points) in pure scCO2 with Chrastil’s equation, obtaining a relatively accurate fit for 70 % of the experimental points. The average absolute relative deviation was 51.22 % (less than 8.31 · 10−4 in absolute deviation), while the logarithmic deviation was 10.83 %. The deviations obtained were substantially lower than other estimations proposed in the literature. This methodology is easily extended, faster, and more accurate than other methods and does not require the use of computational methods or the estimation of solid properties. Moreover, new ways to predict the solubility of solids in supercritical carbon dioxide can be developed in the future based on this methodology.

Influence of ionic liquid on polar organic compounds solubility in dense CO2 phase

Accurate measurement and prediction of the phase behaviour of mixtures involved in a chemical process are crucial for its optimisation. Given the importance of CO2 conversion technologies and considering possible benefits of CO2-ionic liquid biphasic systems, i.e., facilitating a product separation, we investigated the high-pressure behaviour of components of interest in a recently developed process of cyclic carbonate synthesis directly from CO2 and potentially bio-based alcohols. The solubility of 1,2-butanediol and 1,2-butylene carbonate in a dense carbon dioxide phase was determined experimentally at the temperature of 313.2 K and pressures between 6 and 18 MPa. The influence of 1-hexyl-3-methylimidazolium tris(pentafluoroethyl)trifluorophosphate ionic liquid, [hmim][FAP], as a solvent, on the solubility of these compounds in CO2-rich phase, in ternary (CO2 + 1,2-butanediol + [hmim][FAP]), CO2 + butylene carbonate + [hmim][FAP]) and quaternary (CO2 + 1,2-butanediol + butylene carbonate + [hmim][FAP]) mixtures was investigated. The experimental results of the two binary systems were correlated using the density-based Chrastil equation. The knowledge of phase equilibria behaviours reported in this work will be useful for designing chemical conversions of carbon dioxide using [hmim][FAP] ionic liquid as reaction solvents.

Solubility in supercritical carbon dioxide of two novel amine derivatives of 2,3-dichloronaphthalene-1,4-dione (dichlone)

Dichlone (2,3-dichloronaphthalene-1,4-dione) is an important antimicrobial agent for agriculture, which effectiveness could be improved by modifying its structure, while the recovery of high-purity synthesized derivatives from a reaction mixture could be accomplished by extracting them with supercritical carbon dioxide. Two new amine derivatives, 2-chloro-3-((4-chlorobenzyl)amino)naphthalene-1,4-dione (dCl-2B-Cl) and 2-chloro-3-((4-chlorophenethyl)amino)naphthalene-1,4-dione (dCl‐3P‐Cl), were synthesized from dichlone, and their solubility in supercritical carbon dioxide was measured afterwards at (313, 323 and 333) K and a pressure range from (8−33) MPa. Experimental solubilities spanned from (10.3·10-6 to 22.1·10-6) mol·mol-1 for dCl-2B-Cl, and from (32.7·10-6 to 131·10-6) mol·mol-1 for dCl‐3P‐Cl. The solubility data of the dichlone family (dichlone, dCl-2B-Cl, dCl‐3P‐Cl, 2‐(benzylamino)‐3‐chloronaphthalene‐1,4‐dione (dCl-2B) and 2-chloro-3-(phenethylamino)naphthalene-1,4-dione (dCl‐3P)) was compared using three models, i.e., the Chrastil equation, the Molecular Connectivity Indices model, and the Statistical Associating Fluid Theory of Variable Range and Mie Potential equation of state, to identify the quantitative structure-property relationship between them. Solubility had an inverse relation with solute size and polarity, but there were some exceptions that could be explained by performing a stereochemical analysis, which showed that steric effects involved in the folding of dCl‐3P and dCl‐3P‐Cl provided them a better geometry for solvation than dCl-2B and dCl-2B-Cl, respectively, making them more soluble. This demonstrates that the solute geometry is an important factor in the solvation process, and it must be represented accurately to develop better predictive models.

Solubility of probenecid in supercritical carbon dioxide and composite particles prepared using supercritical antisolvent process

The solubilities of probenecid in supercritical carbon dioxide (CO2) were measured in terms of mole fraction ranging from 0.13 × 10−5 to 1.45 × 10−5 at temperatures from 313.2 K to 353.2 K and pressures from 15 MPa to 31 MPa. The solubility data were correlated with the dimensionally consistent Chrastil equation, Garlapati and Madras equation, Mendez-Santiago and Teja equation, Kumar and Johnston equation, and the Peng-Robinson equation of state to deviations of 12.3 %, 6.7 %, 9.7 %, 8.1 %, and 16.2 %, respectively. Due to the low solubility nature, supercritical antisolvent (SAS) process was used for designing composite particles of probenecid and poly(lactide-co-glycolide) (PLGA). The effects of operating parameters on particle morphology, recovery and drug loading were studied. Through SAS, PLGA coated probenecid particles were successfully obtained. The recovery could be higher than 80 %, and the probenecid concentration could be up to 75 mg/mL. Moreover, results of dissolution studies reveal the PLGA coated composite particles can accelerate the dissolution rate by about 10 and 2.4 times, comparing with the unprocessed probenecid and SAS-processed probenecid without PLGA.

Solubility studies on 2-hydroxyisobutyric acid in supercritical carbon dioxide: Solubility evaluation and application to actinide extraction

• First report on solubility of 2-hydroxyisobutyric acid in SCCO 2. • Solubility correlated with semi-empirical/empirical and equation of state models. • Development of supercritical method for recovery of actinide ions. • Demonstration of recovery of U and Th from aqueous/solid/cellulose matrix. The solubility of 2-hydroxyisobutyric acid in supercritical carbon dioxide is experimentally determined using a flow saturation technique. The experimental solubility data was generated at 308, 313, 318 and 323 K with pressures ranging from 10 to 20 MPa. The solubility data was found to range from 0.4 × 10 −3 mol·mol −1 to 5.7 × 10 −3 mol·mol −1 . The solubility data was correlated with two semi-empirical equations, Mendez-Santiago and Chrastil equation. The self-consistency of the data is verified with Mendez-Santiago model. Peng-Robinson equation of state combined with van der Walls mixing rules was also employed to correlate the solubility data. All three models have successfully correlated the solubility data with an average deviation of < 7%. Based on the solubility data, supercritical fluid extraction based method was developed for the recovery of uranium and thorium from solid/liquid matrices (cellulose matrix, uranyl and thorium nitrates, aqueous medium) using 2-hydroxyisobutyric acid as a ligand.

Photosensitizing Furocoumarins: Content in Plant Matrices and Kinetics of Supercritical Carbon Dioxide Extraction.

Furocoumarins are a group of plant phytoalexins exhibiting various bioactive properties; the most important of which are photosensitization and alteration of P450 cytochrome activity. Supercritical fluid extraction with carbon dioxide has been proposed as a green alternative for an organic solvent extraction of the furocoumarins. Four plant matrices rich in furocoumarins were extracted with CO2 at a temperature of 80 °C and pressure of 40 MPa, as these conditions were characterized by the highest solubility of furocoumarins. The extracts collected were analyzed using the HPLC method and the results obtained were used for the mathematical modeling of the observed phenomena. The total content of the furocoumarins in the matrices was 4.03–26.45 mg g−1 of dry weight. The impact of the process parameters on the solubility was consistent with the Chrastil equation. The broken plus intact cell model proved to be suitable to describe extraction curves obtained. The research proved the possibility of supercritical carbon dioxide utilization for the extraction of the furocoumarins from plant material and provided valuable data for prospective industrial-scale experiments.

Solid solubility measurement of ipriflavone in supercritical carbon dioxide and microparticle production through the rapid expansion of supercritical solutions process

In this study, the solid solubilities of ipriflavone in supercritical CO2 were measured by using a semi-flow apparatus. The Chrastil equation, Mendez-Santiago and Teja equation, and a solution model developed from the regular solution model and Flory–Huggins equation were adopted to correlate the measured solubility data. Because the solubility in mole fraction of ipriflavone can be as high as 10−4, the rapid expansion of supercritical solutions (RESS) process was adopted to produce ipriflavone microparticles. The effects of the operating parameters of the RESS process on the mean particle size of ipriflavone were evaluated and discussed. In addition, based on the results of powder X-ray diffraction, differential scanning calorimetry, and Fourier-transform infrared spectrometry analysis, particulate ipriflavone exhibited consistency with the unprocessed sample in terms of crystal structure, melting temperature, and spectrometric properties.

Development of CO2 utilized flame retardant finishing: Solubility measurements of flame retardants and application of the process to cotton

2,2′-oxybis-(5,5-dimethyl-1,3,2,-dioxaphosphorinane-2,2′-disulfide) (5060) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) are widely used in the flame-retardant finishing of polymers due to their excellent fire protection properties and environmentally friendly characteristics. In this work, solubility of 5060 and DOPO were measured at pressures ranging from 16 to 24 MPa with different temperatures in supercritical CO2. With the rising of system pressure and temperature, the solubility of 5060 and DOPO increase, and DOPO exhibits a higher solubility than 5060 in the same supercritical CO2 fluid conditions. Moreover, five semi-empirical models, namely Chrastil equation, Mendez-Santiago-Teja equation, Kumar-Johnston equation, Garlapati-Madras equation as well as Sung-Shim equation, were used to correlate the experimental solubility of the flame retardants. The results showed that Sung-Shim model presents better fitting effect with the AARD values of 21.5% for 5060 and 12.2% for DOPO. In addition, experiments were also conducted with 5060 and DOPO to determine the feasibility of flame-retardant finishing in supercritical CO2.

Modeling the solubility of Alkyl Ketene Dimer in supercritical carbon dioxide: Peng-Robinson, group contribution methods, and effect of critical density on solubility predictions

Alkyl Ketene Dimer (AKD) is a sizing agent commonly introduced into cellulose substrates during papermaking to improve its hydrophobicity. High-pressure impregnation of this solute with supercritical carbon dioxide (scCO2) into cellulose and other substrates can achieve excellent hydrophobicity of the substrate, and may be used as an alternative technique to traditional coating (sizing) methods. In this study, the solubility of AKD in scCO2 was modelled using Peng-Robinson equation of state (PR-EOS) with van der Waals mixing rules, and volume-translated PR-EOS (VTPR). Given the unavailability of AKD's experimental critical properties and vapor pressure data, group contribution estimation methods (GCEM) were used to determine these physical constants. Available experimental data from another research group, collected using cloud-point and extraction methods, was used to regress binary interaction parameters and compare the resulting model's capability in predicting solubility. The models for each experimental method predicted crossover pressures within a small range, but fitted the cloud-point experimental data much better than the extraction data, showing good agreement at pressures beyond 15 MPa and all temperatures investigated. The VTPR model showed the least agreement with experimental data. A relative standard deviation of 0.26 was obtained between modelled and experimental data for the cloud-point method, and 0.42 for the extraction method data. The models were confirmed with the Chrastil equation, and strongly demonstrated the linear relationships predicted by this expression. The models additionally predicted a change in temperature dependence around the critical density, with a common linear relationship independent of temperature being observed at densities below the critical value. This newly observed behavior, not predicted by the Chrastil equation, sets the groundwork for further fundamental investigations, while the developed models will assist the design of alternative sizing processes involving AKD and scCO2.

Dyeing kinetics of acid dyes onto soybean/casein/polyvinyl alcohol and soybean/polyvinyl alcohol blend fibers

Two acid dyes C.I. Acid Blue 113 and C.I. Acid Blue 168 were applied to soybean/casein/polyvinyl (SCP) alcohol blend fibers and soybean/polyvinyl (SP) alcohol blend fibers, and the dyeing kinetics of two fibers were compared. Three kinetic equations, namely Chrastil, Cegarra-Puente and Vickerstaff, were used to fit the experimental dyeing rate points, showing that the best result was obtained by the Chrastil equation. Due to the ratio of acidic amino acids and basic amino acids for SCP was lower than SP fibers, the amino group amount of SCP fibers was higher than that of SP fibers. So SCP fibers displayed slightly higher dyeing rates and dye adsorption values at equilibrium stages than SP fibers. Furthermore, the dyeing of SCP fibers exhibited lower activation energies and higher dyeing rate constants than that of SP fibers and therefore showed slightly lower dependence on temperature.

Solubility of three natural compounds with insecticidal activity in supercritical carbon dioxide: Experimental measurements and predictive modeling with the GC-EoS

In this work, the solubility of thymoquinone, R-(+)-pulegone and 1-octen-3-ol in supercritical CO2 is determined in a range of conditions typical of supercritical fluid processes such as extraction, fractionation and impregnation. These compounds were selected based in their insecticidal activity which may enable to apply them as biopesticides. Solubility was measured using a semicontinuos method in the temperature range of 45–65 °C and pressure of 8–12 MPa, at a CO2 flowrate of 0.05–0.10 g/min, which was verified to be low enough to ensure saturation. Solubilities were predicted using the Group Contribution Equation of State (GC-EoS) and compared to the experimental results, with a good agreement. Consistency of the data was tested using the density-based Chrastil equation.

Mass transfer and hydrodynamic study of supercritical carbon dioxide extraction of 1,8-cineole from small cardamom seeds

ABSTRACTThis study investigates mass transfer and hydrodynamic parameters of supercritical carbon dioxide (sc-CO2) extraction of 1,8-cineole from small cardamom seeds (SCs). Solubility of 1,8-cineole in sc-CO2, its diffusivity, and release kinetics from SCs have been explored. A correlated Chrastil equation has been developed for predicting solubility under varying extraction conditions. Empirical correlations among Reynolds, Schmidt, and Sherwood numbers considering Wilke–Chang equation for diffusivity showed a better fit as compared with those obtained using Stokes–Einstein equation. The extraction kinetics was in agreement with the Sovová model showing plug flow behavior. Release kinetics of 1,8-cineole from SCs was best explained by the Higuchi model. A high R2 value (0.93) of the empirical equation involving dimensionless numbers suggested that the extraction process has been satisfactorily modeled. This model would help in scaling up the production of this significant biotherapeutic molecule from cardamom and similar seed matrices.

Process Optimization of Supercritical Carbon Dioxide Extraction of 1,8-Cineole from Small Cardamom Seeds by Response Surface Methodology: In Vitro Antioxidant, Antidiabetic and Hypocholesterolemic Activities of Extracts

Optimization of supercritical carbon dioxide (SC-CO2) extraction parameters was carried out employing a full factorial design of experiments and response surface methodology, to obtain an extract possessing the best combination of 1,8-cineole content (32.18 mg/g dry seeds) and therapeutic properties (antioxidant, antidiabetic and hypocholesterolemic). A batch size of 25 g of small cardamom seeds when extracted at 200 bar, 50°C for 90 min at a flow rate of 2 L/min of gaseous CO2, provided an extract having the best combination of 1,8 cineole content along with antioxidant (IC50 values of 65±0.3 μg/ml), antidiabetic (IC50 values of 0.78±0.05 mg/ml indicating inhibitory activity on α-amylase) and hypocholesterolemic (84.52 % inhibition of micellar solubility of cholesterol) properties. A Chrastil equation was developed to validate yields 1,8-cineole in the extracts with its solubility in SC-CO2 under varying experimental conditions. This extract is a promising nutraceutical supplement and could be further used in designer foods.

Measurement of solid solubility of warfarin in supercritical carbon dioxide and recrystallization study using supercritical antisolvent process

The solid solubility of an anticoagulant, warfarin, in supercritical CO2 was measured using a semiflow type apparatus at 308.2, 318.2, and 328.2 K from 10 to 18 MPa. The data were correlated using the Chrastil equation and the Méndez-Santiago and Teja equation. The average deviations for calculated and measured solubilities were approximately 10%. Warfarin was recrystallized using a supercritical crystallization process. Because of the extremely low solubility of warfarin in supercritical CO2 (mole fraction on the order of 10−6), the supercritical antisolvent (SAS) process was adopted. The effects of SAS operating parameters were compared and discussed including the operating temperature, operating pressure, solution concentration, spraying nozzle diameter, CO2 flow rate, and solution flow rate. The experimental results proved that low operating temperatures, high solution concentrations, high CO2 flow rates, and low solution concentrations produce small warfarin crystals, whereas the effects of operating pressure and spraying nozzle diameter are negligible. Warfarin crystals with regular habit and mean particle size of 6.6 μm were successfully obtained. Further comparison on solid-state property of warfarin before and after SAS operations was investigated by PXRD, DSC, TGA and FTIR analysis.

Supercritical carbon dioxide extraction of lutein from yellow maize (Zea mays) kernels: process optimization based on lutein content, antioxidant activity, and ω-6/ω-3 fatty acid ratio.

Yellow maize kernels were subjected to supercritical carbon dioxide (SC-CO2) extraction to obtain a lutein-rich extract with potential nutraceutical properties. SC-CO2 extraction parameters (pressure and temperature) were optimized by employing a full-factorial (32) design of experiments and response surface methodology, based on yield of lutein, antioxidant activity, and ω-6/ω-3 fatty acid ratio of the extracts. A Chrastil equation was also developed for predicting the solubility of lutein in SC-CO2 under different extraction conditions. The optimized extraction condition was obtained at 500bar, 70°C for 90min, at which the extract was found to possess a unique combination of the highest lutein yield (275.00±3.50μg/g of dry weight), along with a well-balanced ω-6/ω-3 fatty acid ratio (3:1). Moreover, the total phenol content and antioxidant activity were also found to be the highest at this condition. This lutein-rich extract is a promising nutraceutical or dietary supplement in the food industry.

Supercritical CO2 extraction of oil from Jatropha curcas: An experimental and modelling study

Experimental and modelling investigations of supercritical CO2 extraction of oil from Jatropha curcas were conducted at a pressure range of 20–40MPa and a temperature range of 313–333K at a CO2 flow rate of 0.4kg/h. The extraction yield was estimated to be about 0.6kgoil/kgbiomass for all experiments. The model of broken and intact cells published by Sovová was applied. It was found that the extraction of type B was the most suited extraction type to apply as the experimental extraction curves exhibit three parts. Whatever the pressure and the temperature applied, the asymptotic yield at infinite time was found to be the same. At 20MPa, increasing the temperature from 313 to 323K enhances the extraction kinetics. A retrograde solubility zone was found at 30 and 40MPa. The Jatropha curcas oil solubility in SC-CO2 was determined and the data were modelled with the Chrastil equation.

Supercritical Extraction Process of Allspice Essential Oil

Allspice essential oil was extracted with supercritical carbon dioxide (SC-CO2) in a static process at three different temperatures (308.15, 313.15, and 318.15 K) and four levels of pressure (100, 200, 300, and 360 bar). The amount of oil extracted was measured at intervals of 1, 2, 3, 4, 5, and 6 h; the most extraction yield reached was of 68.47% at 318.15 K, 360 bar, and 6 h of contact time. In this supercritical extraction process, the distribution coefficient (KD), the mean effective diffusion coefficient (Def), the energy of activation (Ea), the thermodynamic properties (ΔG0, ΔH0, and ΔS0), and the apparent solubility (S) expressed as mass fraction (w/w) were evaluated for the first time. At the equilibrium the experimental apparent solubility data were successfully correlated with the modified Chrastil equation.

Reduction of lauric acid in coconut copra by supercritical carbon dioxide extraction: Process optimization and design of functional cookies using the lauric acid‐lean copra meal

AbstractLauric acid, the principal saturated fat in coconut copra, was extracted using supercritical carbon dioxide (SC‐CO2) to obtain “lauric acid‐lean copra meal.” Fatty acid methyl ester gas chromatograph (FAME‐GC) analysis of oil recovered from copra meal by Soxhlet extraction, showed highest reduction in lauric acid (78.16%), post SC‐CO2 extraction of 20 g ground copra (particle size (dp) of 0.42 mm) at 50°C, 40 MPa and 55 min of extraction at a flow rate of 1 L/min of gaseous CO2. At these extraction conditions, the solubility of lauric acid in SC‐CO2 was found to be the highest. A correlated Chrastil equation was also developed for the determination of solubility of lauric acid in SC‐CO2 at different temperature–pressure regimes. Functional cookies designed with lauric acid‐lean copra meal as a replacement of butter, showed high sensory appeal, low oxidation and appreciable antioxidant potency.Practical applicationsCoconut copra although rich in antioxidants, has saturated fatty acids, which are of concern for cardiovascular diseases (CVDs). This study reports on process engineering of coconut copra to reduce its lauric acid content, the principal saturated fatty acid, by supercritical carbon dioxide (SC‐CO2) extraction. Furthermore, a Chrastil equation has been developed for predicting the solubility of lauric acid at different temperature–pressure regimes of SC‐CO2 extraction, to obtain a lauric acid‐rich oil fraction. The data generated from this work could be employed for pilot plant and commercial scale extractions of lauric acid‐rich oil from coconut copra and other oilseed crops. This work has also exhibited a unique application of the lauric acid‐lean copra meal, post SC‐CO2 extraction. The copra meal has been successfully employed in designing functional antioxidant‐rich cookies, without compromising sensory attributes of popular butter cookies. This lauric acid‐lean copra meal is a potential new designer fat for confectionery industries.

Extraction of edible avocado oil using supercritical CO2 and a CO2/ethanol mixture as solvents

Avocado oil is similar to olive oil, it can be used as an ingredient in functional foods since it contain high contents of vitamins and phytosterols and its triacylglycerols contain high contents of unsaturated fatty acid. The present study sought to evaluate the technical viability of extraction of avocado oil by supercritical technology using GRAS solvents (Generally Recognized as Safe). Freeze-dried avocado (Persea Americana) pulp with 65% lipids was subjected to supercritical extraction in a fixed bed at temperatures of 40, 60, and 80 °C and pressures of 200, 300 and 400 bar, using supercritical carbon dioxide (scCO2) as a solvent in a first step, and a scCO2/ethanol mixture (93/7 w/w) in a second step. Extraction curves (mass of oil extracted versus extraction time) were obtained from the overall extraction yields, and from this curve the solubility of oil in scCO2 was calculated. The extraction appeared to be technically viable to obtain up to 98% oil recovery. The solubility values correlated well with the Chrastil equation, and presented similar order of magnitude to the solubility of oils reported in literature.

Effect of liquid ammonia treatment on the pore structure of mercerized cotton and its uptake of reactive dyes

Structural changes in mercerized cotton by liquid ammonia (LA) treatment were investigated and correlated with changes in dyeability of cotton fabrics with reactive dyes. The pore structures of mercerized cotton and mercerized-liquid ammonia (M-LA) treated cotton were characterized by inverse size exclusion chromatography (ISEC). Results showed that when the mercerized cotton was subjected to LA treatment, cumulative accessible volume of smaller pores (e.g., 25.2 Å) increased, whereas that of the larger pores (e.g., 56.7 Å) decreased. These results might be related to the changes in the amorphous region of cotton fiber. The decrease in crystallinity of cotton fiber would increase accessible volume of smaller pores. The larger pores might be compressed by extrusion during swelling of microfibrils or elementary fibrils in water. The change in dyeability of fabrics with reactive dyes of various molecular weights could be rationalized using the observed changes in pore structure. Results also showed that ISEC was more suitable than the method employing Chrastil's diffusion equation for analyzing the pore structure of cotton fiber.