Acid In Supercritical Carbon Dioxide Research Articles

Fourier Transform Infrared Study on Hydrogen Bonding Species of Carboxylic Acids in Supercritical Carbon Dioxide with Ethanol

Supercritical fluid extraction has been given much attention recently as one of the new separation technologies in the chemical industry. Fourier transform infrared (FTIR) spectroscopy has been used to determine the equilibrium constants of the dimerization for carboxylic acid (acetic acid or palmitic acid) and the amount of hydrogen bonding species between carboxylic acid and ethanol in supercritical CO{sub 2}. Experiments were carried out at 308.2--313.2 K and 10.0--20.0 MPa. The noticeable band was the C{double_bond}O stretching band for carboxylic acid. In the binary system (supercritical CO{sub 2} + carboxylic acid), the equilibrium constants of the dimerization between the carboxylic acid monomer and dimer decrease with increasing pressure and temperature. The equilibrium constants of palmitic acid are larger than those of acetic acid. In a ternary system (supercritical CO{sub 2} + carboxylic acid + ethanol), the amount of hydrogen bonding species between carboxylic acid and ethanol in supercritical CO{sub 2} increases with the increasing mole fraction of added ethanol. Furthermore, the authors confirm that the solubility enhancement by ethanol used as an entrainer in supercritical CO{sub 2} related to the amount of hydrogen bonding species between carboxylic acid and ethanol.

Solubility of behenic acid in supercritical carbon dioxide with ethanol

The solubilities of behenic acid in supercritical CO 2 with and without ethanol cosolvent were determined at 308.15 K and 318.15 K in the pressure range from 8.0 to 16.0 MPa, and the concentration of cosolvent ranged from 0 to 6.5 mol%. The corresponding density of the fluid phase was also determined. The effects of the cosolvent concentration, fluid density, pressure, and temperature on the solubility are discussed. The solubility increases with ethanol concentration, pressure, and the apparent density d 1 (moles of CO 2 per liter of the fluid) of CO 2 at higher ethanol concentrations.

Methylation of carboxylic acids in supercritical carbon dioxide modified with methanol using a flow-through system

Methylation of carboxylic acids in supercritical carbon dioxide modified with methanol was studied using a flow-through system with and without catalyst. Results without catalyst revealed the reactivity of the fluid itself, although the complete conversion was difficult. Using strong cation-exchanger with H form as catalyst allowed the complete conversion under milder conditions. Parameters, such as temperature, pressure and methanol concentration, were optimized taking account of the rapidity. Applicability of this method combined with solid-phase extraction was demonstrated for the analysis of phenoxyacetic acids in water.

The interesterification of edible palm oil by stearic acid in supercritical carbon dioxide

A continuous flow apparatus is set up to study the enzymatic interesterification of palm oil by stearic acid in supercritical carbon dioxide. Domestic edible palm oil is mixed with stearic acid and loaded to a saturation tank in which the oil is extracted by supercritical carbon dioxide. The current of the extraction solution bubbled from the saturation tank is delivered to an enzyme-packed column. In this study, five triglycerides (POP, POS, POO, OOO, and SOO) and two free fatty acids (stearic acid and palmic acid) are selected as indicators to monitor the interesterification. The results show that the Mucor miehei dominantly catalyzes the interesterifications of POP+S«POS and POO+S«SOO when the stearic acid content in the extraction solution is abundant. A very limited amount of SOS is also irregularly found in the product samples. POS and SOO are rarely produced when the loaded stearic acid is completely elutriated, and the weight fraction of POO is significantly increased by the depletion of POP. It is presumed that the palmitoyl group in the 1,3 position is substituted much more readily, and that the stearic acid is a reactive acyl donor for the interesterification in supercritical carbon dioxide when catalyzed by Mucor miehei. That large amounts of palmic acid are found in the transesterified oil confirms this presumption.

Measurement and correlation of solubilities ofo- , m- andp-Coumaric Acid isomers in supercritical Carbon Dioxide

The solubility of isomerico-, m- and p-coumaric acids in supercritical carbon dioxide were measured by a flow-type experimental apparatus at 308.15-323.15 K and 8.5–25 MPa. The data were modeled by an empirical density-based correlation and a recent EOS formulated by the authors based on approximated lattice-hole theory. We found thatm-coumaric acid showed the highest solubility and o-coumaric acid showed the lowest solubility at the experimental pressures and temperatures.

Solubilities of salicylic acid in supercritical carbon dioxide with ethanol cosolvent

A circulation apparatus for simultaneously measuring the solubilities of solids in supercritical fluids and the densities of supercritical phases has been constructed. The apparatus can be used at pressures up to 20 MPa. The solubilities of salicylic acid in supercritical carbon dioxide with ethanol cosolvent and the densities of the fluid phase have been measured at 308.15 K and 318.15 K and at pressures up to 16 MPa. The concentration of ethanol in the vapor phase was in the range from 0 to 7 mol %. The effects of temperature, pressure, and cosolvent concentration on the solubility and the density have been investigated. The results show that the solubility of salicylic acid in supercritical carbon dioxide increases markedly with the concentration of the cosolvent. The solubility is a strong function of vapor-phase density when the concentration of the cosolvent is lower, and is nearly independent of the density at higher cosolvent concentrations. The interaction between the solute and the mixed solvent is very strong, especially through hydrogen bonding. The density of the fluid phase increases considerably with pressure and the concentration of the cosolvent.

Asymmetric hydrogenation of α,β-unsaturated carboxylic acids in supercritical carbon dioxide

Hydrogenation of tiglic acid in supercritical CO 2 catalyzed by a chiral H 8-BINAP-Ru(II) complex proceeds cleanly with cis stereochemistry to afford 2-methylbutanoic acid in up to 89% ee and over 99% yield.

Precipitation Polymerization of Acrylic Acid in Supercritical Carbon Dioxide

We report the successful precipitation polymerization of acrylic acid in supercritical carbon dioxide at pressures ranging from 125 to 345 bar utilizing AIBN as a free radical initiator. Analyses by GPC and SEM indicate that for the pressure range studied there is no appreciable effect on product molecular weight, molecular weight distribution, or particle size or morphology. In addition, effective molecular weight control was demonstrated for precipitation polymerizations of acrylic acid in CO 2 through the use of ethyl mercaptan as a chain transfer agent.

Solubilities of 1-Eicosanol and Eicosanoic Acid in Supercritical Carbon Dioxide from 308.2 to 328.2 K at Pressures to 21.26 MPa

The phase behavior of low-volatile components in supercritical fluid has received wide attention in recent years for potential applications in industrial fields (1,2). However, limited studies on the solubilities of heavy alcohols and their related fatty acids in carbon dioxide are presented in the literature. Kramer and Thodos (3 ,4) have measured the solubilities of 1-hexadecanol, 1-octadecanol, palmitic acid, and stearic acid in supercritical carbon dioxide. Schneider et al. (5-7) have reported the solubilities of 1-hexadecanol and 1-octadecanol in supercritical carbon dioxide a t 333 and 393 K. Giddings et al. (8, 9) have measured the solubilities of 1-octadecanol in dense supercritical carbon dioxide at 313 K. Iwai et al. (10) have measured the solubilities of 1-octadecanol, 1-eicosanol, and stearic acid in supercritical carbon dioxide at 308.2 K up to 23.7 MPa. Hamatani (11) has measured the solubilities of 1-octacosanol and 1-triacontanol in supercritical carbon dioxide. The solubilities of 1-hexadecanol and 1-octadecanol in supercritical carbon dioxide over the temperature range from 302 to 338 K at pressures from 5.0 to 20.5 MPa and the solubilities of lauric acid, palmitic acid, and arachidic acid in carbon dioxide over the temperature range from 373.2 to 473.2 K a t pressures up to 5.07 MPa have been measured previously (12, 13). Although some solubility data of heavy alcohols and their related fatty acids in carbon dioxide have been reported, none have been studied in detail from low pressure to high pressure. In this work the solubilities of 1-eicosanol and eicosanoic acid in carbon dioxide over the temperature range from 308.2 to 328.2 Ka t pressures from 33.7 to 212.6 bar have been measured, and the measured data are correlated by the proposed equations.

Influence of chemical modifiers on the solubility of o- and m-hydroxybenzoic acid in supercritical carbon dioxide

The equilibrium solubilities of o- and m-hydroxybenzoic acid in 3.5 mol% acetone-CO 2 and 3.5 mol% methanol-CO 2 binary mixtures were measured at temperatures between 318 and 328 K and pressures in the range of 90-200 bar using a continuous flow apparatus. The solubility isotherms in these ternary systems exhibit a retrograde vaporization phenomenon and a common upper crossover pressure for each ternary system. Moreover, the results demonstrate that the addition of small amounts of cosolvents to CO 2 increase significantly the solubility of o- and m-hydroxybenzoic acid. A molecular thermodynamic model was developed based on the Scatchard-Hildebrand regular solution and Flory-Huggins theory using the concept of component solubility parameters to obtain the unlike-pair molecular interactions between the solute and cosolvent. An effective volume fraction term that reflects the preferential solvation of the solute by the cosolvent molecules was included in the model development to account for differences between the bulk solvent environment and that in the immediate vicinity of the solute molecule

Solubility of fatty acids in supercritical carbon dioxide

The solubilities of lauric, linoleic, myristic, oleic, palmitic and stearic acid in supercritical carbon dioxide (SC‐CO2) at different pressures and temperatures were measured. The solubility values obtained in this work were compared with previously published data, and possible causes for observed discrepancies were discussed. The solubilities of the six fatty acids were modeled by Chrastil’s equation, and estimated model parameters were used to plot the solubility isotherms of fatty acids at 313, 323 and 333°K (40, 50 and 60°C) as a function of SC‐CO2 density. The comparison of solubility isotherms of fatty acids and vegetable oil suggests that separation of fatty acids from triglycerides might be possible by using SC‐CO2 at densities less than 700 kg/m3. From the effect of temperature on fatty‐acid and vegetable‐oil solubility, it seems that the extraction yield could be increased without sacrificing the selectivity of SC‐CO2 for fatty acids by choosing a higher operating temperature. The data also suggest that fractionation of certain fatty acids might be possible by manipulating the processing conditions. Given the values of the constants, Chrastil’s equation could serve as a guideline for choosing appropriate processing conditions and predicting the effect of pressure and temperature of SC‐CO2 on solute solubility.

Solubility of o-hydroxybenzoic acid in supercritical carbon dioxide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolubility of o-hydroxybenzoic acid in supercritical carbon dioxideGurdev S. Gurdial and Neil R. FosterCite this: Ind. Eng. Chem. Res. 1991, 30, 3, 575–580Publication Date (Print):March 1, 1991Publication History Published online1 May 2002Published inissue 1 March 1991https://doi.org/10.1021/ie00051a020RIGHTS & PERMISSIONSArticle Views416Altmetric-Citations102LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (699 KB) Get e-Alerts Get e-Alerts

Solubility of 1-hexadecanol and palmitic acid in supercritical carbon dioxide

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSolubility of 1-hexadecanol and palmitic acid in supercritical carbon dioxideAnatoly Kramer and George ThodosCite this: J. Chem. Eng. Data 1988, 33, 3, 230–234Publication Date (Print):July 1, 1988Publication History Published online1 May 2002Published inissue 1 July 1988https://doi.org/10.1021/je00053a002RIGHTS & PERMISSIONSArticle Views307Altmetric-Citations62LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (534 KB) Get e-Alerts Get e-Alerts

The use of entrainers in modifying the solubility of phenanthrene and benzoic acid in supercritical carbon dioxide and ethane

The solubilities of phenanthrene and benzoic acid were measured in supercritical carbon dioxide and ethane entrained with a small amount of benzene, acetone, methylene chloride or cyclohexane. Most of the experiments involved measuring the solubility of the solute as a function of entrainer composition, but some isocratic solubility data over a pressure range 100–300 bar was also obtained. It was found that the solubilities of both solutes increased with increasing amount of entrainer present in the supercritical gas, but that the specific entrainer used made little difference. Two elementary theoretical models of the entrained solvent were evaluated with the result that the data were better explained by considering the entrainer as a second solvent mixture rather than as a modifier of the supercritical fluid density. The solubilities of naphthalene and benzoic acid were also measured in a supercritical gas mixture containing 6.2 mol% ethane in carbon dioxide. In both cases the observed solubilities fell at an intermediate value between the known solubilities of the solutes in the pure supercritical solvents. Again, the addition of the second component to the gas appeared to behave as a chemical modifier of the solvent power of the fluid rather than only as a modifier of the solvent's P V T properties.

Solubilities of solid 1,10-decanediol and a solid mixture of 1,10-decanediol and benzoic acid in supercritical carbon dioxide

Solubilities of solid 1,10-decanediol and a solid mixture of 1,10-decanediol and benzoic acid in supercritical carbon dioxide