Experimental investigation and modeling of the solubility of carvedilol in supercritical carbon dioxide

This study was aimed to measure the solubility of carvedilol in the temperature and pressure ranges of 308⿿338 K and 160 bar to 400 bar, respectively. In this direction, a homemade high pressure visual equilibrium cell was used to measure the solubility of carvedilol using a static method coupled with gravimetric technique. The results revealed that the carvedilol solubility was ranged between 1.12 ÿ 10^⿿5 and 5.01 ÿ 10^⿿3 based on the mole fraction (mole of carvedilol/mole of carvedilol + mole of CO₂) in this study as the temperature and pressure was changed. Finally, the results were correlated using four density-based semi-empirical correlations including Chrastil, Mendez⿿Santiago⿿Teja (MST), Bartle et al., and Kumar and Johnston (K-J) models. Results revealed that although the K-J model leads to the lowest average absolute relative deviation percent (AARD %) of 6.27%, but it could not be considered as the most accurate correlation since all the used four correlations introduces AARD % of about 6⿿10% which may be in the same range as the experimental error.     

Experimental studies of solubility of elemental sulphur in supercritical carbon dioxide

In recent years, more and more problems of elemental sulphur deposits in natural gas transmission line systems have been reported. Available experimental data on the solubility of sulphur in gases are in too high ranges of temperature, pressure and hydrogen sulphide amount compared to the transport conditions of natural gas. An original experimental apparatus, designed from the study of available works on this subject, is presented and allows the measurement of sulphur solubility. An equilibrium cell establishes the solid–gas equilibrium in conditions of natural gas transportation. To measure the amount of sulphur contained in a known volume of gas, a sample of saturated gas is withdrawn from the equilibrium cell by the way of a flash and pass through a trapping solution. Gaseous elemental sulphur is reactively absorbed into a trapping mixture. Gas chromatography (GC) allows an indirect quantification of sulphur. Experimental isotherm data of sulphur solubility in supercritical carbon dioxide are presented and compared to available studies.     

Measurement and modeling solubility of bioactive coumarin and its derivatives in supercritical carbon dioxide

To design a supercritical fluid extraction process for the separation of bioactive substances from natural products, a quantitative knowledge of phase equilibria between target biosolutes and solvent is necessary. How-ever, mostly no such information is available in literature to date. Thus in the present study, illustratively the solubility of bioactive coumarin and its various derivatives (i.e., hydroxy-, methyl-, and methoxy-derivatives) in supercritical CO₂ were measured at 308.15–328.15 K and 10–30 MPa. Also, the pure physical properties such as normal boiling point, critical constants, acentric factor, molar volume and standard vapor pressure for coumarin and its derivatives were estimated. By these estimated information, the measured solubilities were quantitatively correlated by an approximate lattice equation of state proposed recently by the present authors.     

Solubilities of sub‐ and supercritical carbon dioxide in polyester resins

In supercritical carbon dioxide (CO₂) assisted polymer processes the solubility of CO₂ in a polymer plays a vital role. The higher the amount of CO₂ dissolved in a polymer the higher is the viscosity reduction of the polymer. Solubilities of CO₂ in polyester resins based on propoxylated bisphenol (PPB) and ethoxylated bisphenol (PEB) have been measured using a magnetic suspension balance at temperatures ranging from 333 to 420 K and pressures up to 30 MPa. An optical cell has been used to independently determine the swelling of the polymers, which has been incorporated in the buoyancy correction. In both polyester resins, the solubility of CO₂ increases with increasing pressure and decreasing temperature as a result of variations in CO₂ density. The experimental solubility has been correlated to the Sanchez–Lacombe equation of state. POLYM. ENG. SCI. 46:643–649, 2006. © 2006 Society of Plastics Engineers     

Representing experimental solubility of phenylephrine hydrochloride in supercritical carbon dioxide and modeling solute solubility using semi-empirical correlations

Phenylephrine is used as a decongestant sold as an oral medicine, as a nasal spray, or as eye drops. Phenylephrine is now the most common over-the-counter decongestant in the United States. In this regard, measuring the solubility of phenylephrine hydrochloride seems applicable in supercritical carbon dioxide-based processes dealing with this drug. The obtained solubility data obtained by a static method coupled with gravimetric method were in the range of 1.01 × 10⁻⁴ to 2.89 × 10⁻³ based on the mole fraction at the different temperature and pressure ranges of 308.15–338.15 K and 160–400 bar, respectively. In addition, the solubility data were used to obtain the adjusting parameters of semi-empirical correlations namely Kumar and Johnston, Bartle et al., Chrastil and Mendez-Santiago-Teja using a simple data regression.     

Measurement and correlation solubility of cefixime trihydrate and oxymetholone in supercritical carbon dioxide (CO2)

The equilibrium solubilities of cefixime trihydrate and oxymetholone in supercritical carbon dioxide (CO₂) were measured using a “static method”. Cefixime trihydrate is a cephalosporin antibiotic drug and Oxymetholone is a 17alpha-alkylated anabolic-androgenic steroid drug. The experimental measurements for cefixime trihydrate were performed at temperatures of 308, 318 and 328 K as well as pressure range from 183 to 335 bar. The solubility of oxymetholone was determined at 308, 318 and 328 K and pressure range from 121 to 305 bar. The experimental solubility data (mole fraction) for cefixime trihydrate and oxymetholone was greater than 1.6 × 10⁻⁷ and 1.6 × 10⁻⁵ and less than 3.02 × 10⁻⁷ and 1.49 × 10⁻⁴, respectively. The solubilities for two drugs in CO₂ were correlated by using four semi-empirical models such as Bartle, Kumar and Johnstone (K–J), Mendez-Santiago and Teja (M–T) and Chrastil models. The results obtained from the semi-empirical models show that there is good agreement between the experimental data and the results of semi-empirical models. By using the correlation results, the heat of drug–CO₂ solvation and heat of drug vaporization for cefixime–CO₂ and oxymetholone–CO₂ systems may be approximately estimated. Also, the Peng–Robinson (PR) cubic equation of state (CEOS) along with the van der Waals combining rule was applied to correlate the drugs solubilities in supercritical CO₂. The average absolute deviation between the experimental data and the results of PR equation for cefixime trihydrate and oxymetholone was 11.92% and 11.74%, respectively.     

Hyperbranched poly(ether-siloxane) amphiphiles of surprisingly high solubility in supercritical carbon dioxide

In this work, we present a simple method for preparation of an inexpensive CO₂-philic amphiphiles for solubilization and related applications. The poly(ether-siloxane)s we have synthesized showed very good solubility in supercritical carbon dioxide, despite the fact they contained hydrophilic polyether structures. So far, incorporation of any type of substituents to the poly(dimethylsiloxane) (PDMS) chains resulted in decrease of the solubility in scCO₂. We showed that, it is possible to obtain copolymers containing both hydrophilic (polyether) and hydrophobic (polysiloxane) parts which have better solubility in scCO₂ than respective homopolymers. The proposed synthetic route should allow the design of a wide range of related CO₂-philic hyperbranched materials.     

Estimation of solubility of solids in supercritical carbon dioxide

Peng-Robinson equation of state(PR EOS)was chosen for modeling the thermodynamic be-havior of supercritical(SC)-CO_2/Solid systems.The necessary critical constants and acentric factorof the solute were obtained by the Sigmund and Trebble(1992)method based on the molecular weightand boiling temperature,and the vapor pressure of the solute was calculated by its meltingtemperature and heat of fusion.This approach compared very favorably with the conventional corres-ponding state theory,but without using critical constants and vapor pressure of solutes.Four mixingrules were tested for the calculation of solid solubility in SC-CO_2.van der Waals(vdW)mixing rulewith one parameter was considered to be most suitable for the estimation of solubility.A simplecorrelation was developed for the SC-CO_2/solid binary interaction coefficient k_(ij) with the meltingtemperature of pure solutes.The solubilities of solids in SC-CO_2 were estimated for eleven binarysystems at various temperatures,the total absolute average     

Analyzing the solubility of fluoxetine hydrochloride in supercritical carbon dioxide

In the pharmaceutical industry where the supercritical fluid-based technologies are utilized it is very important and vital to know the accurate value of the equilibrium solubility of solids required for the engineers to determine the size of the equipments. According to this requirement, the purpose of this study was measuring the solubility of fluoxetine hydrochloride with IUPAC name of 3-phenyl-3-[4-(trifluoromethyl)phenoxy]propan-1-amine hydrochloride using a static method coupled with gravimetric method. The measured solubility data at the temperature and pressure range of 308.15–338.15 K and 16–40 MPa was ranged between 2.65 × 10⁻⁵ and 8.12 × 10⁻⁴ based on the mole fraction. The results revealed that the solubility was increased when the pressure was increased while the effect of the temperature was more complex. Finally, the measured solubility data were correlated using three different correlations namely Bartle et al., Mendez-Santiago–Teja and Kumar and Johnston. The results of modeling revealed that the Bartle et al. model leads to the lowest average absolute relative deviation (AARD %) of 9.48.     

胆甾醇在超临界CO2中的溶解度测定与关联

利用动态法测定了胆甾醇在超临界CO2中的溶解度。在10—30 MPa,313—343 K下,胆甾醇的溶解度摩尔分率为10-6—10-4。引入与密度有关的混合规则,将二元交互参数表示为密度的函数,采用PR状态方程,关联胆甾醇在超临界CO2中的溶解度。改进后的溶解度模型克服了采用经典混合规则的PR方程不能很好地关联胆甾醇大分子物质的缺陷,大大提高了关联精度。     

Measurement and calculation of solubility of quinine in supercritical carbon dioxide

Solubility of quinine in supercritical carbon dioxide(SCCO_2) was experimentally measured in the pressure range of 8 to 24 MPa, at three constant temperatures: 308.15 K, 318.15 K and 328.15 K. Measurement was carried out in a semi-dynamic system. Experimental data were correlated by iso-fugacity model(based on cubic equations of state, CEOS), Modified Mendez–Santiago–Teja(MST) and Modified Bartle semi-empirical models. Two cubic equations of state: Peng–Robinson(PR) and Dashtizadeh–Pazuki–Ghotbi–Taghikhani(DPTG) were adopted for calculation of equilibrium parameters in CEOS modeling. Interaction coefficients(k_(ij) l_(ij)) of van der Waals(vdW) mixing rules were considered as the correlation parameters in CEOS-based modeling and their contribution to the accuracy of model was investigated. Average Absolute Relative Deviation(AARD) between correlated and experimental data was calculated and compared as the index of validity and accuracy for different modeling systems. In this basis it was realized that the semi-empirical equations especially Modified MST can accurately support the theoretical studies on phase equilibrium behavior of quinine–SCCO_2 media. Among the cubic equations of state DPGT within two-parametric vd W mixing rules provided the best data fitting and PR within one-parametric vd W mixing rules demonstrated the highest deviation respecting to the experimental data. Overall, in each individual modeling system the best fitting was observed on the data points attained at 318 K, which could be perhaps due to the moderate thermodynamic state of supercritical phase.     

超临界CO2流体中染料溶解度研究进展

综述了超临界CO2流体中染料溶解度的测试装置与方法。分析了超临界CO2流体工艺参数与染料化学结构对分散染料溶解度的影响规律；总结了国内外近二十年的分散染料在超临界CO2流体中溶解度数据，并介绍了分散染料在超临界CO2中的溶解度增溶技术。指出加强染料结构对其溶解性能作用原理及影响规律剖析，超临界CO2中染料溶解行为数据库构建，染料拼色与配色研究三方面为未来的研究重点。     

Coumarin solubility and extraction from emburana (Torresea cearensis) seeds with supercritical carbon dioxide

Coumarin is an active principle found in several vegetable species with a characteristic smell of vanilla. It is widely used as a perfume fixer, paint and spray additive, and in cleaning products. It also possesses clinical value due to antibiotic and analgesic properties, besides its potential use in the treatment of cancer and AIDS. The objective of this work was to obtain solubility data for coumarin under several conditions, as well as to evaluate process parameters for its extraction from emburana seeds with supercritical CO₂. The process parameters studied were temperature, pressure, CO₂ flow rate and particle size of the seeds. The solubility in supercritical CO₂ was correlated using the Peng–Robinson equation. Solid-supercritical fluid and liquid-supercritical fluid equilibria were considered and correlated separately, with L-SC presenting better results due to the effect of the melting point depression of coumarin under high pressure. The results showed significant effects of pressure and temperature on the extraction yield and also, the smaller the particle size of the seeds, the better the yield.     

Artificial Neural Network modeling of solubility of supercritical carbon dioxide in 24 commonly used ionic liquids

Application of supercritical CO₂ for separation of ionic liquids from their organic solvents or extraction of various solutes from ionic liquid solvents have found great interest during recent years. Knowledge of phase behaviors of the mixtures of supercritical CO₂+ionic liquids is therefore drastic in order to efficiently design such separation processes. In this communication, Artificial Neural Network procedure has been applied to represent the solubility of supercritical CO₂ in 24 mostly used ionic liquids. An optimized Three-Layer Feed Forward Neural Network using critical properties of ionic liquids and operational temperature and pressure has been developed. Application of this model for 1128 data points of 24 ionic liquids show squared correlation coefficients of 0.993 and average absolute deviation of 3.6% from experimental values for calculated/estimated solubilities. The aforementioned deviations show the prediction capability of the presented model.     

Solubility of cyproheptadine in supercritical carbon dioxide; experimental and modeling approaches

Solubility of solute in supercritical fluids at different pressures and temperatures is one of the most important parameters necessary for design of any supercritical fluid-based processes. Among different supercritical fluids, carbon dioxide is one of the most widely used solvents due to its useful and green characteristics. In this work, with the assist of supercritical carbon dioxide as the solvent, solubility of cyproheptadine in different temperatures (308–338 K) and pressures (160–400 bar) are measured using static method. The obtained results demonstrated that solubility of cyproheptadine ranged between 3.35 × 10⁻⁵ and 3.09 × 10⁻³ based on mole fraction. A closer examination of measured solubility data show that not only solubility of cyproheptadine increases by increasing pressure but also experiences a cross over pressure about 200 bar. At last, the measured solubility data are correlated using four widely used density based correlations namely Mendez Santiago–Teja (MST), Kumar and Johnston (KJ), Bartle et al., and Chrastil models. The obtained results demonstrated that the best correlative capability was observed for KJ model leads to the average absolute relative deviation percent (AARD %) of 6.3%.     

Investigation of machinability in milling of Inconel 718 with solid Sialon ceramic tool using supercritical carbon dioxide (scCO2)-based cooling conditions

Milling of hard-to-machining materials is still a challenge since the high cutting temperature caused by the cooling lubrication problems and the property of materials. This paper proposes the use of supercritical carbon dioxide (scCO₂), supercritical carbon dioxide based minimum quantity lubrication cutting fluid (scCO₂-MQL), and supercritical carbon dioxide based minimum quantity lubrication with oil droplets cutting fluid (scCO₂-OoW) as the eco-friendly cooling-lubrication methods for milling of Inconel 718 superalloy. The cutting forces, cutting temperatures, surface roughness, surface topographies, subsurface characteristics and tool wear were performed to quantify the effect of various cooling methods. The results indicated that the application of scCO₂-based cooling conditions was an effective cooling and lubrication technology for the ceramic tool since it could reduce the cutting force and temperature and improve the surface finish with lower peaks and valleys dispersion compared with other cooling conditions. Compared with the scCO₂-MQL, only scCO₂ and dry milling conditions, the topographies of machined surface under the scCO₂-OoW condition have been significantly improved. Furthermore, the scCO₂-OoW cooling technique has facilitated the removal of debris adhering to the ceramic tool and improved lubrication of the cutting zone.     

Experimental measurement and correlation for solubility of piroxicam (a non-steroidal anti-inflammatory drugs (NSAIDs)) in supercritical carbon dioxide

Since the knowledge of pharmaceutical solubilities in the supercritical carbon dioxide is one of the first essential necessities for designing the supercritical carbon dioxide-based processes, solubility of piroxicam a non-steroidal anti-inflammatory drug was experimentally measured. In this regard, a static method coupled with gravimetric method was used to measure the solubility of piroxicam in the supercritical carbon dioxide in temperature and pressure range of 308.15–338.15 K and 16–40 MPa, respectively. The obtained solubility data were in the range of 1.17 × 10⁻⁵ and 5.12 × 10⁻⁴ based on the mole fraction (mole piroxicam/(mole piroxicam + mole CO₂)) then modeled using four different density based correlations namely Bartle et al., Mendez-Santiago-Teja, Chrastil and Kumar and Johnston models. The results of error analysis revealed that the used correlations were potential to correlate the solubility of piroxicam with minimum and maximum average absolute relative deviation percents (AARD%) of 14.4% and 15.2%, respectively.     

Measurement and correlation for the solid solubility of non-steroidal anti-inflammatory drugs (NSAIDs) in supercritical carbon dioxide

The solubilities for three non-steroidal anti-inflammatory drugs (NSAIDs) of nabumetone, phenylbutazone and salicylamide in supercritical carbon dioxide were measured in this study using a semi-flow type apparatus. The experimental data were taken at 308.2, 318.2 and 328.2 K, over the pressure range from 10 to 22 MPa. The measured results were then correlated using semi-empirical equation presented by Chrastil, and that presented by Mendez-Santiago and Teja. With optimally fitted parameters, these two equations yielded satisfactory results where the average absolute relative deviation (AARD) was below 7%. Furthermore, the solid solubilities of these three compounds and seven other NSAIDs in supercritical carbon dioxide were correlated by applying the regular solution model coupled with a Flory–Huggins term. The solution model, which has fewer parameters than the semi-empirical equations, yielded comparable correlation results. The parameters in the solution model could be generalized for the specific group of NSAIDs. Finally, the predicted solubilities of 10 NSAIDs in supercritical carbon dioxide were demonstrated to be reliable.     

苯甲酸在含夹带剂的超临界CO2中溶解度的研究

采用流动法研究和测定了苯甲酸在35、50℃下,10.0—30.0MPa范围内,在纯超临界CO2和含醇系列夹带剂的超临界CO2中的溶解度。实验研究表明,醇系列夹带剂的加入均可明显增大苯甲酸的溶解度,但4种醇的增强作用随着碳链的增加而略有减弱。论述了温度、压力对溶解度的影响,并用Sovova方程对实验数据进行了回归。     

A novel equation of state (EOS) for prediction of solute solubility in supercritical carbon dioxide: Experimental determination and correlation

Solubility data of organophosphorous metal extractants in supercritical fluids (SCF) are crucial for designing metal extraction processes. We have developed a new equation of state (EOS) based on virial equation including an untypical parameter as BP/RT, reduced temperature and pressure for prediction of solute solubility in supercritical carbon dioxide (SC CO₂). Solubility experimental data (solubility of tributylphosphate in SC CO₂) were correlated with the two cubic equations of state (EOS) models, namely the Peng–Robinson EOS (PR‐EOS) and the Soave–Redlich–Kwong EOS (SRK‐EOS), together with two adjustable parameter van der Waals mixing and combining rules and our proposed EOS. The AARD of our EOS is significantly lower than that obtained from the other EOS models. The proposed EOS presented more accurate correlation for solubility data in SC CO₂. It can be employed to speed up the process of SCF applications in industry.