Supercritical CO<sub>2</sub> extraction of organic contaminants from aqueous streams

Ghonasgi, D.; Gupta, Sudipta; Dooley, Kerry M.; Knopf, F. Carl

doi:10.1002/aic.690370617

Cited by 47 publications

(46 citation statements)

References 32 publications

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“…104 Table A.4. Published partition coefficient of benzene between SCC and water (Ghonasgi et al, 1991). y i and x i are the mole fraction of benzene in SCC and water, respectively.…”

Section: List Ofmentioning

confidence: 99%

“…Kim et al (1986), while those for phenol are from Pfohl et al (1997). (Ghonasgi et al, 1991) The partitioning of benzene and PAH's in SCC+water mixtures must also be evaluated. For this purpose, the partition coefficient K can be defined as the ratio of the mole fraction of an organic compound in CO 2 to the mole fraction of that compound in water (Green and Akgerman, 1996).…”

Section: Pressure (Bar) Mole Fraction Of Organics In Co2mentioning

confidence: 99%

“…For this purpose, the partition coefficient K can be defined as the ratio of the mole fraction of an organic compound in CO 2 to the mole fraction of that compound in water (Green and Akgerman, 1996). The SCC-H 2 O partition coefficient for benzene ranges from 1000 to 4000 (Ghonasgi et al, 1991) (see Appendix A, Sections A.2-A.4). The partition coefficient of phenol, as shown in Table 4.4, is much lower.…”

Section: Pressure (Bar) Mole Fraction Of Organics In Co2mentioning

confidence: 99%

“…As illustrated in Figures A13 and A14, the calculated values are slightly lower than the measured data at 40°C, whereas they agree reasonably well at 50°C. It should be noticed that Ghonasgi et al (1991) observed a large scatter in the distribution coefficients for benzene, and pointed out that even small errors in concentrations could generate significant scatter in their partition coefficient values. Given this scatter, results from TMVOC_REACT ( Figures A13 and A14) are reasonable.…”

Section: A4 Binary Benzene + Co 2 Systemmentioning

confidence: 99%

“…The differences between measured and calculated K i reflect differences in measured and calculated benzene concentrations in the aqueous phase (mole fraction, x i ) ( Figure A17), which may be the result of ignoring pressure effects in the calculation of log(K) values for the benzenewater system (Appendix A3), in addition to measurement variability. Note that Ghonasgi et al (1991) did not directly report x i values. The values listed in Table A4 were calculated using Equation (A7) and their reported measured K i and y i values.…”

Section: A4 Binary Benzene + Co 2 Systemmentioning

confidence: 99%

See 4 more Smart Citations

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

Zheng¹,

Spycher²,

Xu³

et al. 2010

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“…104 Table A.4. Published partition coefficient of benzene between SCC and water (Ghonasgi et al, 1991). y i and x i are the mole fraction of benzene in SCC and water, respectively.…”

Section: List Ofmentioning

confidence: 99%

Section: Pressure (Bar) Mole Fraction Of Organics In Co2mentioning

confidence: 99%

Section: Pressure (Bar) Mole Fraction Of Organics In Co2mentioning

confidence: 99%

Section: A4 Binary Benzene + Co 2 Systemmentioning

confidence: 99%

Section: A4 Binary Benzene + Co 2 Systemmentioning

confidence: 99%

See 3 more Smart Citations

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

Zheng¹,

Spycher²,

Xu³

et al. 2010

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Solubility of Solids and Liquids in Supercritical Fluids

Aim¹,

Fermeglia²

2003

The Experimental Determination of Solubilities

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Caffeine extraction rates from coffee beans with supercritical carbon dioxide

et al. 1992

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The extraction of caffeine from whole coffee beans with supercritical carbon dioxide was studied in a continuous-flo w extraction apparatus. Decaffeination rates were determined as a function of CO, flow rate, temperature and pressure by continuously monitoring the caffeine in the effluent with a flame ionization detector. Soaking the raw beans in water prior to decaffeination enhanced the rate of extraction, which increased markedly with water content. Using CO, saturated with water also increased the rate of extraction. The rate of decaffeination increased with pressure and temperature and was influenced by both intraparticle diffusion in the water-soaked beans and external mass transfer. A mathematical model based on a linear-driving-force approximation of mass transfer and partitioning of caffeine between the water and the supercritical CO, describes the time-dependent process.The partition coefficient for caffeine distributed between water and supercritical CO, the only parameter determined from the dynamic extraction rate data, increases with temperature and pressure. IntroductionDecaffeination of coffee beans has been carried out with a variety of conventional solvents such as dichloromethane (Stahl et al., 1988;McHugh and Krukonis, 1986), but recently supercritical C 0 2 has been the preferred solvent in large-scale commercial processes (Leyers et al., 1991). The selectivity of supercritical CO, for caffeine in green (unroasted) coffee beans is an important property that is exploited in the decaffeination process, as little else besides caffeine in the raw bean is thought to be soluble in supercritical COz (Stahl et al., 1988). Since extraction is performed on the raw beans, flavor ingredients that are developed only during roasting are not removed. Additionally, use of supercritical C 0 2 precludes any post-decaffeination treatment of the beans to remove the solvent, a necessary step if conventional organic solvents are used.This supercritical fluid process is representative of a wide range of possible extractions: (a) to remove unwanted chemicals from the desired matrix material or (b) to separate and isolate a desired chemical from the matrix. A fundamental understanding is needed of the chemical, physical and transport processes that affect such extractions. The aim of the present research is to develop general experimental and theoretical approaches to study these basic phenomena as well as the particular decaffeination process.Supercritical CO, extraction, including the patents for caffeine extraction, is discussed by McHugh and Krukonis (1986) and Paulaitis et al. (1983). Stahl et al. (1988) also provide useful information about the decaffeination of raw coffee beans, which may contain 0.6 to 3 wt Vo of caffeine. The beans are first soaked in water up to a water content of 45 wt. Yo. Essential for satisfactory extraction, this step may change the texture of the cell walls to enhance diffusion, which is considered a rate-determining step, or the water may free the bound caffeine from the coffee matr...

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Supercritical CO₂ extraction of organic contaminants from aqueous streams

Abstract: Supercritical fluid extraction (SCFE)

Cited by 47 publications

References 32 publications

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

Solubility of Solids and Liquids in Supercritical Fluids

Caffeine extraction rates from coffee beans with supercritical carbon dioxide

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Supercritical CO2 extraction of organic contaminants from aqueous streams

Abstract: Supercritical fluid extraction (SCFE)

Cited by 47 publications

References 32 publications

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

Modeling Studies on the Transport of Benzene and H2S in CO2-Water Systems

Solubility of Solids and Liquids in Supercritical Fluids

Caffeine extraction rates from coffee beans with supercritical carbon dioxide

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Product

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Supercritical CO₂ extraction of organic contaminants from aqueous streams