P. Jaeger

Extraction/fractionation and deacidification of wheat germ oil using supercritical carbon dioxide

Wheat germ oil was obtained by mechanical pressing using a small-scale screw press and by supercritical extraction in a pilot plant. With this last method, different pressures and temperatures were tested and the tocopherol concentration in the extract was monitored during extraction. Then supercritical extracted oil as well as commercial pressed oil were deacidified in a countercurrent column using supercritical carbon dioxide as solvent under different operating conditions. Samples of extract, refined oil and feed oil were analyzed for free fatty acids (FFA) and tocopherol contents. The results show that oil with a higher tocopherol content can be obtained by supercritical extraction-fractionation and that FFA can be effectively removed by countercurrent rectification while the tocopherol content is only slightly reduced.

Functionalization of polycaprolactone/hydroxyapatite scaffolds with Usnea lethariiformis extract by using supercritical CO2.

Investigation of an integrated supercritical fluid extraction and supercritical solvent impregnation process for fabrication of microporous polycaprolactone-hydroxyapatite (PCL-HA) scaffolds with antibacterial activity is presented. The HA content and particle size as well as the operating conditions of the integrated process is optimized regarding the amount of impregnated antibacterial agent (Usnea lethariiformis extract) in the PCL-HA matrix, scaffold morphology and antibacterial activity against methicillin resistant Staphylococcus aureus (MRSA) strains. High pressure differential scanning calorimetry (HP-DSC) assay reveals that an increasing amount of HA results in decreasing melting temperature as well as crystallinity at an operating pressure of 17 MPa. The PCL-HA composites with micrometric sizes of the HA particles are convenient for being processed by the integrated process due to the simple preparation, a good interaction between the PCL matrix and filler and the advantageous impact on sorption. The scaffold obtained from PCL-HA with 20% of the HA shows the highest impregnation yield at 17 MPa and 35 °C (5.9%) and subsequently also the best bactericidal effect on the tested MRSA strains at an initial bacterial inoculum of 2 × 10(-4)CFU/mL.

Interfacial tension of solid materials against dense carbon dioxide

In the Young equation, only two of the four unknowns are measurable. They are the liquid interfacial tension sigma lv and the contact angle theta. To solve this equation, another correlation is required. In solving this equation, a better understanding of the magnitude of the solid interfacial tension sigma sv and the solid-liquid interfacial tension sigma sl is expected. The possibility of a theoretical estimation of the contact angle theta is sought as an alternative to the experimental method. In this paper, an attempt to calculate the solid interfacial tension sigma sv is reported. It is based on the intermolecular interaction which is mathematically described in the parameter Phi sl according to Good. The calculated sigma sv values for PTFE, steel, and glass surrounded by dense carbon dioxide are verified by comparing those values obtained from aqueous and ethanolic systems. Furthermore, the solid interfacial tension sigma sv is also used to forecast the water drop contact angle theta. The calculated values are compared with the experimental measured ones.

Interfacial tension of edible oils in supercritical carbon dioxide

Interfacial properties essentially influence fluid-liquid separation processes. Thereby, interfacial tension is an important parameter that is associated with mass transfer and mutual solubility of participating compounds. For this reason, interfacial tension of a virgin olive oil with a known amount of free fatty acids was measured in supercritical carbon dioxide atmosphere at 313 K and 353 K and pressures up to 40 MPa. The obtained values were compared to different oils some of which contain appreciable amounts of volatile components. In general, interfacial tension behaviour is dominated by the effect of pressure, whereas differences between oil compositions are secondary. Besides mutual solubility interfacial tension is supposed to be associated with the compressibility of the dense fluid phase. For predicting mass transfer area some general comments on the colloidal behaviour of systems containing supercritical CO2 are made

Significant solubility of carbon dioxide in Soluplus® facilitates impregnation of ibuprofen using supercritical fluid technology

Abstract Treatment of Soluplus® with supercritical carbon dioxide allows promising applications in preparing dispersions of amorphous solids. Several characterization techniques were employed to reveal this effect, including CO2 gas sorption under high pressure and physicochemical characterizations techniques. A gravimetric method was used to determine the solubility of carbon dioxide in the polymer at elevated pressure. The following physicochemical characterizations were used: thermal analysis, X-ray diffraction, Fourier transform, infrared spectroscopy and scanning electron microscopy. Drug loading of the polymer with ibuprofen as a model drug was also investigated. The proposed treatment with supercritical carbon dioxide allows to prepare solid solutions of Soluplus® in less than two hours at temperatures that do not exceed 45 °C, which is a great advantage to be used for thermolabile drugs. The advantages of using this technology for Soluplus® formulations lies behind the high sorption capability of carbon dioxide inside the polymer. This will ensure rapid diffusion of the dissolved/dispersed drug inside the polymer under process conditions and rapid precipitation of the drug in the amorphous form during depressurization accompanied by foaming of the polymer.

Sorption Kinetics of High Pressure Gases in Polymeric Tubing Materials

A gravimetric method was applied to determine the sorption kinetics of gases into polymers. Diffusivity as well as sorption capacity are determined directly. Data of gas permeability that are required for calculating leakage rates in polymeric flexile gas and oil ducts may be retrieved by multiplying the obtained diffusion coefficients and the gas solubility. In general carbon dioxide enters polymers to the highest extent. In industrial practice, the high solubility of CO2 e.g. may lead to explosive decompression of sealings once the operating pressure is reduced to atmospheric conditions. Diffusion coefficients are presented in the range of 75 to 130°C at 2 to 30 MPa.© 2006 ASME