Solubility of chlorpheniramine maleate in supercritical carbon dioxide

Solubility of chlorpheniramine maleate in supercritical carbon dioxide at different temperatures (308–338 K) and pressures (160–400 bar) is measured using static method coupled with gravimetric method. The measured solubility data demonstrated that the solubility of chlorpheniramine maleate was changed between 1.54 × 10⁻⁵ and 4.26 × 10⁻⁴ based on the mole fraction as the temperature and pressure are changed. The general trend of measured solubility data shows a direct effect of pressure and temperature on the solubility of chlorpheniramine maleate. Finally, the obtained solubilities correlated using four semi-empirical density-based correlations including Mendez Santiago–Teja (MST), Kumar and Johnston (KJ), Bartle et al., and Chrastil models. Although the results of modeling showed that the KJ model leads to the average absolute relative deviation percent (AARD %) of 8.1% which is the lowest AARD %, deviation of other utilized correlations are rather the same.     

Solubility of niflumic acid and celecoxib in supercritical carbon dioxide

The solubility data of two fluorinated and non-steroidal anti-inflammatory drugs, niflumic acid (CAS No. 4394-00-7) and celecoxib (CAS No. 169590-42-5), in supercritical carbon dioxide were measured with a semi-flow type phase equilibrium apparatus at temperatures ranging from 313.2 K to 353.2 K and pressures up to 31 MPa. At the highest extraction temperature and pressure, the solubilities are 2.09 × 10⁻⁵ and 1.52 × 10⁻⁵ in mole fraction for niflumic acid and celecoxib, respectively. The saturated solubility data were correlated with the Chrastil model, the Mendez-Santiago–Teja equation, and the Peng–Robinson equation of state. The Chrastil model fitted the experimental data to about within the experimental uncertainty. The correlated results of the Mendez-Santiago–Teja model confirmed the consistency of the solubility data over the entire experimental conditions. Incorporating with two-parameter van der Waals one-fluid mixing rules, the Peng–Robinson equation of state represents satisfactorily the gas–solid equilibrium behavior of niflumic acid and celecoxib in supercritical carbon dioxide.     

Solubility of gabapentin in supercritical carbon dioxide

The purpose of this study was to measure the solubility of gabapentin in supercritical carbon dioxide at different pressures and temperatures of 16–40 MPa and 308–338 K, respectively. The measured solubility data revealed that solubility of gabapentin was 8.97 × 10⁻⁵–7.36 × 10⁻³ based on the mole fraction in supercritical carbon dioxide at the aforementioned operational conditions. At last, the obtained results were correlated using four density based semi-empirical correlations namely Bartle et al., Mendez-Santiago and Teja (MST), Chrastil and Kumar and Johnston (K–J). The results revealed that according to the obtained average absolute relative deviations (AARD) for the used density based correlations of MST (AARD % = 9.88%), Chrastil (AARD % = 9.47%), K–J (AARD % = 11.5%) and Bartle et al. (AARD % = 9.29%), none of the correlations can be considered as the most accurate one. In other words, all the examined semi-empirical correlations are in the same level of accuracy.     

Lycopene solubility in mixtures of carbon dioxide and ethyl acetate

In order to improve the efficiency of processes using supercritical (sc) carbon dioxide (CO₂) to micronize the carotenoid “lycopene”, it is important to know the solubility of lycopene in mixtures of the organic solvent ethyl acetate (EA) and the antisolvent CO₂ at elevated pressures. The solubility of lycopene has been determined for different temperatures (313–333 K), pressures (12–16 MPa) and CO₂ molar fractions (0.58–1). The obtained data show that CO₂ acts as an antisolvent in the system lycopene/EA/CO₂ in the range of CO₂/EA ratios studied. The solubility of lycopene is rather small with lycopene molar fractions ranging from 0.1 × 10⁻⁶ to 46 × 10⁻⁶. The solubility of lycopene increases with temperature, pressure and EA concentration.     

Supercritical CO2 and highly selective aromatase inhibitors: Experimental solubility and empirical data correlation

The solubility of highly selective and potent third-generation aromatase inhibitors includes the non-steroidal agents letrozole and anastrozole and the steroid exemestane in supercritical carbon dioxide (SC-CO₂) has been investigated. The experiments were carried out using the simple and static method at pressures in the range of 12.1–35.5 MPa and temperatures ranging from 308 to 348 K. The mole fraction solubilities ranged from 0.22 × 10⁻⁵ to 1.88 × 10⁻⁴. Solubility data were correlated using six empirical models (Chrastil model, dV–A model, K–J model, Bartle model, Yu model and Gordillo model). The results showed that these models can be applied to satisfactory solubility predictions at different pressures and temperatures. A comparison among the six models revealed that the K–J, and Gordillo models gave much better correlations of the solubility data with an average absolute relative deviation (AARD%) ranging from 0.2 to 2.3 and from 1.6 to 2.5%, respectively. Using the correlation results, the heat of drug–CO₂ solvation and that of drug vaporization was separately approximated in the range of −17.3 to −17.5 and 93.0–112.1 kJ mol⁻¹.     

Decaffeination of guaraná seeds in a microextraction column using water-saturated CO2

Experimental data on the reduction of the caffeine content of guaraná seeds with water-saturated supercritical carbon dioxide were obtained in order to provide information on the ability of supercritical fluids for the decaffeination of widely consumed caffeine-rich natural products. The extraction was performed using a semi-continuous flow high-pressure micro-extraction apparatus at 40 and 70 °C and pressures of 100, 200 and 400 bar. Carbon dioxide flow rates of 5.7 and 9.4 g min⁻¹ were used. The extraction curves obtained showed the existence of thermodynamic solubility dependent, intermediate and diffusion controlled regions. Extraction at 400 bar and 70 °C using water-saturated supercritical carbon dioxide at a flow rate of 5.7 g min⁻¹ allowed the removal of almost 98% of the initial caffeine content in wet ground guaraná seeds, in a period of 240 min. When extractions were performed at lower pressures or temperatures, additional time and larger amounts of carbon dioxide were necessary to achieve the same yield. Increasing carbon dioxide flow rate did not present any economic advantage unless the extraction was limited to the thermodynamic solubility region. For total extraction of caffeine, the use of low flow rates resulted in a similar final product yield but at a much lower solvent consumption. A retrograde behavior for the extraction of caffeine from guaraná seeds was also observed at 100 bar for the 40 and 70 °C isotherms.     

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.     

Solubility of Disperse Red 82 and modified Disperse Yellow 119 in supercritical carbon dioxide or nitrous oxide with ethanol as a cosolvent

Ethanol was used as a cosolvent to enhance the solubility of disperse dyestuffs in supercritical fluids. In the presence of ethanol, from (1 to 5) mol%, the gas–solid equilibrium data of the Disperse Red 82 and modified Disperse Yellow 119 in supercritical carbon dioxide or nitrous oxide have been measured at temperatures from (353.2 to 393.2) K and pressures from (15.0 to 30.0) MPa. The experimental results show that the solubility increases substantially, up to (9 to 25)-fold, by adding 5 mol% of ethanol to the supercritical fluids. In the presence of cosolvent ethanol, the solubility enhancements in nitrous oxide system are much greater than that in carbon dioxide system for modified Disperse Yellow 119 at the same temperature and pressure. The solubility data were correlated with the Chrastil and the Méndez-Santiago and Teja models. The Méndez-Santiago and Teja model yields slightly better results than Chrastil model.     

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.     

Supercritical carbon dioxide extraction of Gac oil

Supercritical carbon dioxide extraction of Gac (Momordica cochinchinensis Spreng) aril was performed at pressures ranging from 200 to 400 bar, temperatures from 313 to 343 K and specific flow rates from 50 to 90 kg h⁻¹ CO₂ kg⁻¹ Gac aril. Total oil recovery and carotenes concentration were investigated in the course of extraction. Mathematical modelling of oil solubility data was also performed. The results showed that at specific flow rate of 70 kg h⁻¹ kg⁻¹, pressure of 400 bar and temperature of 343 K, Gac oil recovery exceeded 95% after 120 min of extraction. Gac oil loading of supercritical carbon dioxide was successfully described by Chrastil's model. Carotenes concentration of extracted Gac oil was found at level of thousands of ppm.     

Extraction of jojoba seed oil using supercritical CO2+ethanol mixture in green and high-tech separation process

In this study, the extraction of jojoba seed oil obtained from jojoba seed using both supercritical CO₂ and supercritical CO₂+ethanol mixtures was investigated. The recovery of jojoba seed oil was performed in a green and high-tech separation process. The extraction operating was carried out at operating pressures of 25, 35 and 45 MPa, operating temperatures of 343 and 363 K, supercritical fluid flow rates of 3.33 × 10⁻⁸, 6.67 × 10⁻⁸ and 13.33 × 10⁻⁸ m³ s⁻¹, entrainer concentrations of 2, 4 and 8 vol.%, and average particle diameters of 4.1 × 10⁻⁴, 6.1 × 10⁻⁴, 8.6 × 10⁻⁴ and 1.2 × 10⁻³ m. It was found that a green chemical modifier such as ethanol could enhance the solubilities, initial extraction rate and extraction yield of jojoba seed oil from the seed matrix as compared to supercritical CO₂. In addition, it was found that the solubility, the initial extraction rate and the extraction yield depended on operating pressure and operating temperature, entrainer concentration, average particle size and supercritical solvent flow rate. The solubility of jojoba seed oil and initial extraction rate increased with temperature at the operating pressures of 35 and 45 MPa and decreased with increasing temperature at the operating pressure of 25 MPa. Furthermore, supercritical fluid extraction involved short extraction time and minimal usage of small amounts entrainer to the CO₂. About 80% of the total jojoba seed oil was extracted during the constant rate period at the pressure of 35 and 45 MPa.     

Optimization of supercritical fluid extraction of phytosterol from roselle seeds with a central composite design model

Recovery of phytosterol from roselle (Hibiscus sabdariffa L.) seeds via supercritical carbon dioxide extraction modified with ethanol was investigated at pressures of 200–400 bar, temperatures from 40 to 80 °C and at supercritical fluid flow rates from 10 to 20 ml/min. It was found that an entrainer such as ethanol could enhance the solubility and extraction yield of roselle seed oil from the seed matrix, compared to values obtained using supercritical CO₂. After a typical run (holding period of 30 min, continuous flow extraction of 3 h), the results indicate that the oil recovery was optimal with a recovery of 108.74% and a phytosterol composition of 7262.80 mg kg^?1 at relatively low temperature of 40 °C, a high pressure of 400 bar and at a high supercritical fluid flow rate of 20 ml/min in the presence of 2 ml/min EtOH as entrainer. The solubility of roselle seed oil increased with temperature at the operating pressures of 200, 300 and 400 bar. Supercritical fluid extraction involved a short extraction time and the minimal usage of small amounts of entrainer in the CO₂.     

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.     

Near critical and supercritical impregnation and kinetic release of thymol in LLDPE films used for food packaging

The impregnation of organic compounds in polymeric materials using supercritical carbon dioxide (scCO₂) is a well-known technique, which is currently used in drug/polymer formulation. In this work, near critical and supercritical impregnation of thymol in linear low-density polyethylene (LLDPE) films was done in order to develop a new technique for preparation of active polymers to be used as food packages. The properties of thymol as a natural antimicrobial and antioxidant agent have motivated this study about the assessment of its migration from the polymer to different food simulant. Impregnation assays of thymol in LLDPE films were done in a high-pressure cell, where pure thymol was solubilized in supercritical carbon dioxide at 313 K and pressures varying from 7 to 12 MPa. This procedure allowed the preparation of plastic films with thymol concentrations ranged between 5100 and 13,200 ppm. Migration tests showed that the pressure applied during the impregnation procedure is a key parameter that affects the content of the active compound into the polymer, since thymol solubility in scCO₂ and absorption phenomena in the polymer increased with the pressure. The correlation between experimental data and a phenomenological transfer model allowed the estimation of the diffusion coefficient of thymol in LLDPE, which was ranged from 7.5 × 10⁻¹³ to 3.0 × 10⁻¹² m² s⁻¹.     

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.     

Simple three parameter equations for correlating liquid phase compositions in subcritical and supercritical systems

Two Chrastil type expressions have been developed to model the solubility of supercritical fluids/gases in liquids. The three parameter expressions proposed correlates the solubility as a function of temperature, pressure and density. The equation can also be used to check the self-consistency of the experimental data of liquid phase compositions for supercritical fluid–liquid equilibria. Fifty three different binary systems (carbon-dioxide + liquid) with around 2700 data points encompassing a wide range of compounds like esters, alcohols, carboxylic acids and ionic liquids were successfully modeled for a wide range of temperatures and pressures. Besides the test for self-consistency, based on the data at one temperature, the model can be used to predict the solubility of supercritical fluids in liquids at different temperatures.     

Measurement and correlation of the solubility of two steroid drugs in supercritical carbon dioxide using semi empirical models

The solubilities of desoxycorticosterone acetate (DA) and clobetasole propionate (CP) in supercritical carbon dioxide (SC-CO₂) were measured at temperature ranging from (308 to 348) K and pressures from (12.2 to 35.5) MPa using a static method. The mole fraction solubilities ranged from 10⁻⁷ to 13.93 × 10⁻⁵. The crossover region was observed for DA and CP at 24.3 and 25.3 MPa, respectively. Solubility data were correlated using four semi-empirical density-based models (Chrastil, Bartle, Kumar, Johnston (K–J) and Mendez-Santiago and Teja (M–T) models). The average absolute relative deviations (AARD%) ranged from 9.3 to 13.6; 8.9 to 11.9; 6.5 to 10.3 and from 10.4 to 13.4 for Chrastil, Bartle, K–J and M–T models, respectively. A comparison among the four models revealed that the K–J model gave much better correlation of the solubilities in comparison with other models. Using the correlation results, the heat of drug–CO₂ solvation and that of drug vaporization was separately approximated in the range of −24.2 to −24.5 and 63.8 to 64.8 kJ mol⁻¹. The correlation results showed good agreement with the experimental data.     

Supercritical CO2 extraction of omega-3 rich oil from Sacha inchi (Plukenetia volubilis L.) seeds

Supercritical carbon dioxide (SC-CO₂) was employed to extract omega-3 rich oil from Sacha inchi (Plukenetia volubilis L.) seeds and partially defatted cake. For ground seeds, the supercritical extraction was carried out at temperatures of 40, 50 and 60 °C and pressures of 300 and 400 bar, and for the cold pressed partially defatted cake, the extraction was carried out with 300 bar at 40 °C and with 400 bar at 60 °C. The global extraction yields (X₀), oil solubility, fatty acid composition of the oil and tocopherol content were determined. The seed samples used in this work contained 54.3% oil, of which 50.5% was linoleinc acid (ω-3). The maximum extraction recovery for the seeds as 92% at 400 bar and 60 °C, but on one occasion a recovery of 99.1% oil was obtained when cold pressed extraction was employed, followed by supercritical extraction at 400 bar and 60 °C. A high tocopherol content of about 2–3 g/kg of oil was obtained.     

Acid-catalysed methanolysis reaction of non-polar triazinyl reactive dyes in supercritical carbon dioxide

An extensive study of the reaction mechanism of the methanolysis reaction of triazinyl systems of non-polar reactive dyes has been done in a neutral, moderately acidic and strongly acidic medium. In a neutral reaction medium, dichlorotriazines are more reactive than the monochlorotriazines. However, in a moderately acidic medium, as supercritical carbon dioxide, an inversion in the reactivity pattern of monochlorotriazines was observed, which is related to the dye structure. Amines as substituent group attached to the triazinyl ring showed the largest conversion and k values, approaching those values of dichlorotriazine. Protonation of the ring, and stabilization of the positive charge in the triazinyl ring due to the mesomeric effect, explain the reactivity increased of monochlorotriazines. When acids were added to the reaction medium, resulting in an increase of the acid concentration, the reactivity of monochlorotriazinyl dyes was surprisingly much larger than dichlorotriazine; k values increased up to a factor of 54. The largest k was measured for the monochlorotriazinyl dye, S1Cl–NH₂, showing a value of 3.0 × 10⁻³ s⁻¹, while a value of 3.2 × 10⁻⁴ s⁻¹ was measured in supercritical carbon dioxide. In a strongly acidic medium, the reactivity of triazinyl reactive dyes is substantially influenced by the basicity of the substituted groups in the reactive group, and in the chromophore. Based on this kinetic study, the dyeing of cotton in supercritical carbon dioxide under acidic conditions seems to be very promising when triazinyl dyes are used.     

Phase behavior of 1,3,5-tri-tert-butylbenzene–carbon dioxide binary system

1,3,5-tri-tert-butylbenzene (TTBB) is solid at ambient conditions, and has substantial solubility in liquid and supercritical carbon dioxide. We present the phase behavior of TTBB–CO₂ binary system at temperatures between 298 and 328 K and at pressures up to 20 MPa. Phase diagrams showing the liquid–vapor, solid–liquid and solid–vapor equilibrium envelopes are constructed by pressure–volume–temperature measurements in a variable-volume sapphire cell. TTBB is highly soluble in CO₂ over a wide range of compositions. Single-phase states are achieved at moderate pressures, even with very high TTBB concentrations. For example, at 328 K, a binary system containing TTBB at a concentration of 95% by weight forms a single-phase above 2.04 MPa. TTBB exhibits a significant melting-point depression in the presence of CO₂, 45 K at 3.11 MPa, where the normal melting point of 343 K is reduced to 298 K. With its high solubility in carbon dioxide, TTBB has potential uses as a binder or template in materials forming processes using dense carbon dioxide.