• Korean Journal of Food Science and Technology
• /
• v.27 no.3
• /
• pp.414-419
• /
• 1995

${\beta}-carotene$ was extracted from freeze-dried carrot by supercritical carbon dioxide $(SC-CO_2)$ and mixtures of $CO_2$ doped with ethanol or methanol as a cosolvent at temperatures of 40 to $60^{\circ}C$ and pressures of 138 to 276 bar. Solubility of ${\beta}-carotene$ in $SC-CO_2$ increased with the increase of extraction pressure and the decrease of extraction temperature. The highest solubility observed was $4.90\;{\mu}g/g\;CO_2\;for\;{\alpha}-carotene\;and\;0.604\;{\mu}g/g\;CO_2$ for ${\alpha}-carotene\;at\;40^{\circ}C$ and 276 bar. Addition of ethanol increased the solubility being the largest increase of 82% using a mixture of $CO_2$ and 17.4% ethanol. $SC-CO_2$ extraction can be used to selectively obtain natural carotenoids, free of solvent residuals, which can be used as food additives.

• Clean Technology
• /
• v.18 no.2
• /
• pp.191-199
• /
• 2012

In order to reduce or remove off-flavor and volatile organic compounds (VOCs) from Laminaria japonica effectively, continuous treatment process by supercritical carbon dioxide (SC-$CO_2$) was applied. After freeze-drying, Laminaria japonica powdered with $710{\mu}m$ was used. Experiments were carried out at temperature range from 35 to $55^{\circ}C$, and pressure range from 10 to 25 MPa for evaluation of SC-$CO_2$ treatment effect. Flow rate of carbon dioxide used in this reseach was constantly fixed at 26.81 g/min. Before and after treatment of SC-$CO_2$, off-flavor and VOCs from Laminaria japonica were analyzed by gas chromatography-mass spectrometry detector (GC-MSD). Total 47 VOCs emitted from Laminaria japonica were identified before treatment of SC-$CO_2$, major components of seaweed smell (ordor) in Laminaria japonica were identified as alcohols, aldehydes, ester and acids, ketone, halogenated compounds and hydrocarbon. Off-flavor and VOCs in all experimental conditions was reduced or removed after SC-$CO_2$ treatment. Among the experimental conditions, the highest removal yield was at 25 MPa and $55^{\circ}C$.

• Journal of the Korean Ceramic Society
• /
• v.36 no.2
• /
• pp.159-166
• /
• 1999

The physical properties and microstructural changes with heat-treatment of opacified silica aerogels doped by TiO2 were investigated. Monolithic SiO2-TiO2 aerogels were prepared by supercritical drying (25$0^{\circ}C$, 1250 psig) of wet gel obtained by adding titanium isopropoxide to prehydrolyzed TEOS-isopropanol solutions. The density and the porosity of SiO2-10 mol% TiO2 aerogels were 0.23 g/㎤ and 90%, respectively. During supercritical drying, the linear shrinkage of aerogels increased with increase in the titanium content an TiO2 was transformed to the anatase phase as well as particls agglomerates led to TiO2 clusters of 100~800 nm dispersed homogeneoulsy in the silica matrix. The IR transmittance of opacified silica aerogels was very low in the region of wavelengths below 8 ${\mu}{\textrm}{m}$ compared with pure silica aerogels and SiO2-TiO2 aerogels showed the high thermal stability of microstructures up to $600^{\circ}C$.

• Clean Technology
• /
• v.17 no.3
• /
• pp.266-272
• /
• 2011

Anchovy oil was extracted using supercritical carbon dioxide ($SCO_2$) and organic solvents. Extraction was carried out at temperature range from 40 to $60^{\circ}C$, and pressure range from 15 to 25 MPa. The flow rate of $CO_2$ (22 $gmin^{-1}$) was constant entire the extraction period of 1.5 h. The fatty acid composition of anchovy oil was analyzed by gas chromatography (GC). The main fatty acids of anchovy oil were myristic acid, palmitic acid, stearic acid, palmitoleic acid, EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). In addition, the oil obtained by $SCO_2$ extraction contained a higher percentage of polyunsaturated fatty acids especially EPA and DHA comparing to the organic solvent extracted oil. The oxidative stability of oils extracted from Anchovy by $SCO_2$ extraction was compared to those extracted by organic solvents. Results showed that the storage periods of oils obtained by $SCO_2$ extraction were longer than those of organic solvents extraction.

• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.34 no.3
• /
• pp.213-217
• /
• 2001

In order to develop a new separation technology, supercritical fluid extraction process was used to produce high purity pigments and fatty acids from seaweed (Undaria pinnatifida). Supercritical carbon dioxide was used as a solvent and ethanol as an entrainer. The sample was treated by a frozen drier and experiments were conducted with a semi-batch flow system at various operating conditions (pressure range, $10.3\~17.2$ MPa; temperature range, $30\~45^{\circ}C$: particle size, $500\~1,000{\mu}m$ extraction time, 60 min). Characteristics of the recovered pigment (chlorophyll a) and fatty acids were determined by UV-spectrophotometry and gas chromatography, respectively. The highest extraction efficiency for fatty acids and pigments was achieved at 12.4 MPa, $35^{\circ}C$, $500{\mu}m$of seaweed size.

• Economic and Environmental Geology
• /
• v.45 no.6
• /
• pp.661-672
• /
• 2012

Lab scale experiments to investigate the dissolution reaction among supercritical $CO_2$-sandstone-groundwater by using sandstones from Gyeongsang basin were performed. High pressurized cell system (100 bar and $50^{\circ}C$) was designed to create supercritical $CO_2$ in the cell, simulating the sub-surface $CO_2$ storage site. The first-order dissolution coefficient ($k_d$) of the sandstone was calculated by measuring the change of the weight of thin section or the concentration of ions dissolved in groundwater at the reaction time intervals. For 30 days of the supercritical $CO_2$-sandstone-groundwater reaction, physical properties of sandstone cores in Gyeongsang basin were measured to investigate the effect of supercritical $CO_2$ on the sandstone. The weight change of sandstone cores was also measured to calculate the dissolution coefficient and the dissolution time of 1 g per unit area (1 $cm^2$) of each sandstone was quantitatively predicted. For the experiment using thin sections, mass of $Ca^{2+}$ and $Na^+$ dissolved in groundwater increased, suggesting that plagioclase and calcite of the sandstone would be significantly dissolved when it contacts with supercritical $CO_2$ and groundwater at $CO_2$ sequestration sites. 0.66% of the original thin sec-tion mass for the sandstone were dissolved after 30 days reaction. The average porosity for C sandstones was 8.183% and it increased to 8.789% after 30 days of the reaction. The average dry density, seismic velocity, and 1-D compression strength of sandstones decreased and these results were dependent on the porosity increase by the dissolution during the reaction. By using the first-order dissolution coefficient, the average time to dissolve 1 g of B and C sandstones per unit area (1 $cm^2$) was calculated as 1,532 years and 329 years, respectively. From results, it was investigated that the physical property change of sandstones at Gyeongsang basin would rapidly occur when the supercritical $CO_2$ was injected into $CO_2$ sequestration sites.

• Korean Chemical Engineering Research
• /
• v.43 no.1
• /
• pp.21-26
• /
• 2005

Experimental researches on the preparation of porous polymeric monoliths in supercritical carbon dioxide have been performed and the effects of monomer and polymerization parameters on the physical properties of the monolith prepared were examined. Polymerizations were carried out in the high pressure stainless steel reactor with sapphire window to show the phase change during the polymerization reaction, and continuous and dry porous monolithic polymer could be obtained. The specific surface area of monolithic polymer increased with monomer contents in reaction mixture and reaction pressure. The Rockwell hardness could be enhanced by the addition of co-monomer MMA in reaction mixtures.

• Applied Chemistry for Engineering
• /
• v.33 no.1
• /
• pp.44-49
• /
• 2022

Essential oil was separated from Dendropanax morbiferus (DM) by means of hot water extraction and supercritical extraction, respectively, and the separated essential oil was analyzed qualitatively and quantitatively, and the antioxidant effect of essential oil was investigated. In addition, yields of essential oil and Caryophyllene according to the drying and extraction methods for each part of DM were obtained and compared, respectively. The yield of essential oil was found to be high in the order of bark > leaves > twigs > limb. When the freeze-dried DM leaves were supercritically extracted, the yields of essential oil and Caryophyllene were 23.2 g/kg DM and 429.6 mg Caryophyllene/kg DM, respectively. The essential oil of DM showed an antioxidant effect even at a low concentration, and the concentration of the essential oil of SC₅₀, which means 50% of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity, was about 0.34%.

• Korean Journal of Food Science and Technology
• /
• v.32 no.2
• /
• pp.306-311
• /
• 2000

Lipid and cholesterol were extracted from beef and pork by the supercritical carbon dioxide $(SC-CO_2)$ for the manufacturing of low-lipid and low-cholesterol sausage. The ranges of extraction temperature and pressure were from 35 to $55^{\circ}C$ and from 103 to 375 bar, respectively. $SC-CO_2$ extraction yield of beef lipid increased as extraction pressure increased and/or extraction temperature decreased, while extraction temperature was more influential on the cholesterol extraction than pressure condition. When lipid and cholesterol of freeze-dried beef with varied moisture contents were extracted, their solubilities increased as the moisture content reduced. The extraction of lipid and cholesterol from pork was shown the same tendency as the beef. The chunk type of beef shape was more suitable for the lipid and cholesterol extraction than the powder type of beef. The color of meat after $SC-CO_2$ extraction was lighter than the raw freeze dried meat because of the extraction of color pigments. After $SC-CO_2$ extraction, beef and pork were rehydrated and mixed with raw beef and pork containing lipid and cholesterol. Their mixing ratio up to 50 : 50 did not affect physical properties of the sausage compared with the control sausage.

• Journal of the Korean Electrochemical Society
• /
• v.6 no.1
• /
• pp.13-17
• /
• 2003

Cryogel and aerogel Pt-Ru/C were synthesized by the sol-gel process for the electrooxidation of methanol. From XRD analysis, it was found that the catalysts had highly dispersed Pt-Ru alloys on carbon support although high temperature treatments have been conducted. Electrocatalytic activities of 3 type aerogel catalysts were investigated in half cell experiments by cyclic voltammetry. Among them, Phloroglucinol-Formaldehyde(PF) type catalyst shows the highest activity. From the results of deactivation test for each catalysts, the aerogel catalysts are found to have excellent durability compared with those prepared by colloidal method.