Binary diffusion coefficients of α-pinene and β-pinene in supercritical carbon dioxide

Silva, Carlos M.; Filho, Cláudio Antônio Pinheiro Machado; Quadri, Marintho Bastos; Macedo, Eugénia A.

doi:10.1016/j.supflu.2004.01.003

Cited by 45 publications

(20 citation statements)

References 32 publications

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“… † Indicates that the diffusion coefficient was calculated from Lenard-Jones potential parameters 35,36 . Values without superscripts are looked up and evaluated for 25 °C using the Chapman-Enskog theory 36,37 .…”

Section: Resultsmentioning

confidence: 99%

Aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures: Modeling and experimental characterization

Bainschab

Martikainen

Keskinen

et al. 2019

Sci Rep

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An aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures was developed, modeled, and further characterized with laboratory tests with respect to gas exchange efficiency and particle losses. The model describing the gas exchange was first verified with oxygen and later studied with several inert gases having molecular masses between 18 and 135 u. The exchange rate of the lightest compounds exceeds 90% efficiency at the flow rates used. In order to reach similarly high removal efficiencies for larger molecules, the residence time in the AGES has to be increased. The removal of sticky gases was studied with gaseous sulfuric acid. Results agreed with the model where the boundary condition is zero concentration on the wall. The AGES exhibits very limited particle losses (<5%) for mono-disperse 6 nm particles. Furthermore, diffusional losses for particles down to 1.2 nm were measured utilizing polydisperse aerosol. The experimental findings are in good agreement with the model derived. As both, gas exchange rate and particle losses, rely on the physical effect of diffusion, an optimization for enhanced gas exchange efficiency will come at the cost of increased diffusional particle losses. The presented model can be used as a tool to redesign and optimize the AGES for a desired application. With an application targeted design, particle dilution can be avoided, which can lead to improved results in many fields of aerosol measurement.

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Section: Resultsmentioning

confidence: 99%

Aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures: Modeling and experimental characterization

Bainschab

Martikainen

Keskinen

et al. 2019

Sci Rep

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show abstract

“…The fluid mass transfer coefficient and effective diffusion coefficient enhance with temperature due to the enlargement of binary molecular diffusivity. 42 Where the desorption kinetic rate constants. 43 The data fitted the Arrhenius correlation very well, where k d0 = 1.0479 × 10 −3 (h −1 ), E = 1.1676 × 10 7 J/mol, and AARD of 4.92%.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

Extraction of Andrographolide from Andrographis paniculata Dried Leaves Using Supercritical CO₂ and Ethanol Mixture

Kumoro

Hasan

Singh

2018

Ind. Eng. Chem. Res.

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The increase in the number of world's elderly population and changes in their lifestyle has triggered to the formation of diseases susceptible communities. Inherent with the aforementioned conditions, the need in andrographolide as one of natural remedies isolated from the leaves of Andrographis paniculata also increases. In this work, supercritical fluid extraction employing CO 2 −ethanol mixture as solvent has shown its capability in extracting andrographolide from dried leaves of A. paniculata. The andrographolide yield largely increased when the ethanol concentration in the solvent mixtures was increased from 0 to 12.5 mol %, but there was no significant increase in andrographolide yield as ethanol concentration was further increased. Although an enhancement of both temperature and pressure gave favorable effects on the yield of andrographolide, a crossover effect existed in this supercritical system causing no significant increase of andrographolide yield. The downflow mode performed the highest extraction efficiency compared to both upflow and horizontal-flow modes. Supercritical CO 2 −ethanol mixture containing 12.5 mol % ethanol flowed at 2 mL/min according to downflow mode at 323 K and 15 MPa was found to be the most effective in extracting andrographolide. The integral desorption model satisfactory described the extraction profile as shown by its low average error of about 5%.

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“…If the pipe is not straight but coiled, Eq. 16 can be applied if the following restriction is verified18–20 where Re is the Reynolds number, η the viscosity, and r coil is the coil radius (0.13 m in our case). The HP SFC automatically measures W 1/2 and t R .…”

Section: Methodsmentioning

confidence: 99%

Application of the corresponding states principle to the diffusion in CO₂

González¹,

Suárez-Iglesias²,

Bueno³

et al. 2007

AIChE Journal

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in Wiley InterScience (www.interscience.wiley.com).Binary diffusion coefficients at infinite dilution in supercritical carbon dioxide, D AB , have been measured for the four monohalogenated benzenes (fluorobenzene, chlorobenzene, bromobenzene, and iodobenzene) with the Taylor-Aris technique in a chromatographic apparatus as a function of temperature and pressure. The ranges covered for these two variables were 313-333 K and 15.0-35.0 MPa, respectively. As the four solutes are similar molecules, the corresponding states principle (CSP) has been tested, together with the results of several predictive equations.

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Binary diffusion coefficients of α-pinene and β-pinene in supercritical carbon dioxide

Cited by 45 publications

References 32 publications

Aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures: Modeling and experimental characterization

Aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures: Modeling and experimental characterization

Extraction of Andrographolide from Andrographis paniculata Dried Leaves Using Supercritical CO₂ and Ethanol Mixture

Application of the corresponding states principle to the diffusion in CO₂

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Binary diffusion coefficients of α-pinene and β-pinene in supercritical carbon dioxide

Cited by 45 publications

References 32 publications

Aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures: Modeling and experimental characterization

Aerosol gas exchange system (AGES) for nanoparticle sampling at elevated temperatures: Modeling and experimental characterization

Extraction of Andrographolide from Andrographis paniculata Dried Leaves Using Supercritical CO2 and Ethanol Mixture

Application of the corresponding states principle to the diffusion in CO2

Contact Info

Product

Resources

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Extraction of Andrographolide from Andrographis paniculata Dried Leaves Using Supercritical CO₂ and Ethanol Mixture

Application of the corresponding states principle to the diffusion in CO₂