Papers by Keyword: Supercritical CO₂

Abstract: A new degreasing pretreatment technology for quick-drying towels has been developed to solve the environmental pollution caused by a large amount of waste gas during the degreasing process. The optimal deoiling rate of oil extracted from the microfiber surface in supercritical CO₂ fluid is 95.45% when the temperature is 100°C, the pressure is 14 MPa, the time is 60 min, and the CO₂ flow rate is 30 g/min. The implications of various treatment temperatures and times on the effectiveness of oil agent removal are addressed.

Abstract: A pressure-induced autoclave foaming assisted by supercritical CO₂ of degradable polylactide (PLA) has been developed. A central composite design (CCD) of response surface methodology (RSM) is used to optimize three distinct process conditions: foaming temperature, pressure, and time. The mathematical model built for examining the effect of process conditions on the foam density and volume expansion ratio was verified and determined to be acceptable with an R-square value derived from the regression model of 0.930 and 0.934, respectively. The experimental and statistical results showed that of the three factors examined, the foaming pressure had the greatest impact on the density and volume expansion ratio of the PLA foams. The foaming temperature and time also had significant interaction impacts on both responses. It was observed that the following conditions are optimal for foaming of PLA, with a maximum VER of 10.107 and a minimum foam density of 0.123 g/cc: foaming temperature of 165.86 °C and foaming pressure of 152.4 bar for 2.38 h of foaming time.

Abstract: Printed circuit boards are currently coated with Br-containing epoxy resins. With respect to recycling of the material removal of the halogen is important. Moreover, it appears important to test whether recycling of the coating is feasible. The resin from circuit board reference material was extracted with extraction media containing supercritical carbon dioxide. It is shown that ternary mixtures containing 2-propanol and water allow for the complete removal of the coating. In contrast to the original material the degraded coating is soluble in organic solvents and size-exclusion chromatograpy indicates the formation of very regular fragments.

Abstract: During the process of Carbon Capture and Storage, some impurity may be found in the supercritical CO₂ fluid. The changes in corrosion of X70 Steel in water-saturated supercritical CO₂ system caused by impurity has been studied by the simulation experiment. The average corrosion rate was got from weight loss measurement. The morphologies and compositions of corrosion products were analyzed by SEM, EDS and XRD. It was observed that the existence of separate impurity would aggravate the corrosion of X70 steel in the water-saturated supercritical CO₂ system. The average corrosion rate was the highest when NO₂ or SO₂ was included, followed by H₂S, and the average corrosion rate was the smallest when O₂ was contained. Among them, X70 steel suffered local corrosion when NO₂ was contained. The corrosion scale was monolayer structure of FeCO₃ under the supercritical CO₂-H₂O system. After the addition of O₂, Fe₂O₃ appeared in the corrosion scale, indicating that the oxygen corrosion process occurred. While with the addition of H₂S, corrosion scales were double layers. FeS was mainly present in the outer layer. The corrosion process was controlled by CO₂ and H₂S. The corrosion products were mostly FeSO₃·xH₂O and a spot of FeCO₃ when SO₂ was contained. SO₂ mainly governed the corrosion process. Besides, corrosion product was Fe₂O₃ without FeCO₃ in the supercritical CO₂-H₂O-NO₂ system, NO₂ completely controlled the corrosion process.

Abstract: The present study explores CFD analysis of a supercritical carbon dioxide (SCO₂) radial-inflow turbine generating 100kW from a concentrated solar resource of 560oC with a pressure ratio of 2.2. Two methods of real gas property estimations including real gas equation of estate and real gas property (RGP) file - generating a required table from NIST REFPROP - were used. Comparing the numerical results and time consumption of both methods, it was shown that equation of states could insert a significant error in thermodynamic property prediction. Implementing the RGP table method indicated a very good agreement with NIST REFPROP while it had slightly more computational cost compared to the RGP table method.

Abstract: Particles formations of ginger rhizome were successfully produced by using Rapid expansion supercritical solution (RESS). In this study, effect of extraction temperature (40,45,55 and 65 °C) and constant extraction pressure 4000 Psi were investigated on the particle size of the produced particles. Based on the different experimental conditions, the smallest particle size of ginger after processing via the RESS process was obtained at extraction temperature of 40 °C and extraction pressure, 4000 Psi. Temperature is the one factor that can affect the average particle size of the solid oil particle. The size of the ginger particles were monitored by scanning electron microscopy (SEM).

Abstract: Epipremnum pinnatum is a vegetative, type of vines and climbing plant that can be found in a semitropical and tropical country in South East Asia and Asian region. It has been used as folk remedies due to its medicinal properties and capability in enhancing the immune system. However, limited scientific data are present to support this claim. Thus, the present study was focused on the determination of phytochemical properties of the extract E. pinnatum and the effect on the pancreatic lipase inhibitory activities. Phytochemical of E. pinnatum was extracted using supercritical carbon dioxide (CO₂) at 6000 psi and 40°C. The extracted oil was analyzed using Follin- Ciocalteu method to determine the phenolic components and followed by gas chromatography analysis. Chicken pancreas was used to investigate pancreatic lipase inhibitory activities of the extracted E.pinnatum. The results indicated that extract E.pinnatum could inhibit the chicken pancreatic lipase activity and based on the analysis obtained, the amount of lipase activity inhibited was 74 % by using 48 μg/ml of extract E.pinnatum.

Abstract: The rapid expansion of supercritical solution (RESS) is a promising method for particle formation. In this paper, general review of fundamental and available results from studies of particle formation by RESS process using carbon dioxide as a solvent for pharmaceutical compounds.

Abstract: Arthrospira (Spirulina) platensis contains large quantities of γ-linolenic acid (GLA). GLA is an essential omega-6 unsaturated fatty acid made in the human body from linoleic acid. It can be metabolized to various important eicosanoids such as prostaglandins, thromboxanes, leukotrienes, prostacyclins, and lipoxins. The aim of this study was to investigate the optimal extraction parameters of GLA from A. platensis using supercritical CO₂ technology. Results showed that operating temperatures and pressures were important factors in the extraction of GLA. A maximum GLA yield of 161.98 μg/g could be obtained at a pressure of 30 MPa, a temperature of 60°C, and a CO₂ flow rate of 6 mL/min. Conversely, only a yield of 104.16 μg/g could be obtained at a pressure of 10 MPa, a temperature of 40°C, and a CO₂ flow rate of 6 mL/min. The correlation between pressure and yield could be explained by an increase in collision rates between CO₂ molecules and carrier affinity under a high pressure. Therefore, an operating temperature between 50 and 60°C and a pressure of 30 MPa should be used to maximize the yield of GLA from A. platensis using supercritical CO₂ technology.

Abstract: This paper mainly introduces a new method of preparation of microcellular material, this method can be divided into three stages: kettle with saturation pressure, heating foaming, flattening and calendaring. During the process of supercritical CO₂ saturated, different materials need reasonable control parameters such as saturation pressure, saturation temperature and saturated time, and the values of saturation temperature and saturation pressure will directly affect the permeability of supercritical CO₂. During the process of heating foaming, it needs to strictly control the parameters such as foaming temperature and foaming time, because the bubble density and bubble size are closely related to the two parameters. During flattening and calendaring process, it is important to control temperature and speed of roller reasonably to avoid the phenomena of collapse in bubbles. There are no harmful substances emissions using this method to produce ultrathin microcellular material, which can also protect the environment.