Carbon Dioxide Supercritical Fluid Extraction with Solubility Consideration
| Autor: | Kuo-Jung Sun, 孫國榮 |
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| Rok vydání: | 1999 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 87 Employing supercritical fluid (SCF) in an extraction procedure has two goals: Number one is to substitute conventional organic solvents. Number two is to cut down extraction time. By adjusting temperature and pressure beyond the critical point, the solubility parameter (δ) of the fluid can be set to agree with the desire analyte, and therefore the solvation of the analyte in the fluid is resulted. SCF shares the same properties as a gas, such as its lower viscosity; however, the diffusion coefficient is 100-fold than organic solvents. Therefore, analyte’s mass transfer so does their extraction time inside of a supercritical extraction cell is accelerated. Soils have been recognized to have complicated matrix. Interference of matrix origin can affect the results and reproducibility of analytes. To calculate the theoretical solubility parameters of the analytes, we consider how individual atoms in analyte molecules are bonded. With the help of Fedor’s group contribution method, the energy of vaporization and molar volume are then available for the calculation. The solubility parameters we obtained for sulfur, aldrin and lindane are 16.78, 12.76, 14.17 (cal/cm3)1/2, respectively. When the supercritical fluid extraction is set to be 60℃ with 4700 psi and the density which pressure and temperature combination is 0.8858 g/mL, the solubility parameter of supercritical carbon dioxide fluid is 7.330 (cal/cm3)1/2 which is calculated by Giddings theorem. Under the proceeding hypotheses, three analytes’ recoveries in the experiment are 85.50 %、113.00 % and 121.67 % corresponding to sulfur element, aldrin and lindane. In contrast, if the experiment uses the likely solubility parameter of hexane, 7.3 (cal/cm3)1/2, to perform the tranditional Soxhlet extraction, the recoveries of sulfur element, aldrin and lindane are 33.0 %、70.0 % and 80.83 %, respectively. The solubility difference between solute and solvent,︱δ1—δ2︱, would decide solubility or recovery. By according to recovery, when the solubility parameter of solvent (δ1) is fixed, the extraction efficiency and the solubility parameter of solute (δ2) present the reverse rate. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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