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Supercritical fluid extraction for remediation of contaminated soil
1997
Ekhtera, M.R. | Mansoori, G.A. | Mensinger, M.C. | Rehmat, A. | Deville, B.
The supercritical fluid extraction liquid phase oxidation (SELPhOx) process is being developed as a highly flexible means of remediating and destroying both high and low concentrations of light aliphatic to heavy aromatic contaminants from solid matrices. The process employs two distinct technologies: extraction of organic contaminants with supercritical carbon dioxide and wet air oxidation (WAO) destruction of the extracted contaminants. A separation step links the two process stages. Supercritical fluid extraction tests are conducted over wide ranges of temperature, pressure, and CO2/contaminant ratios with soils from a wood treatment plant and two manufacturing gas plant sites. Extraction of polynuclear aromatic hydrocarbons (PAHs) from these soil samples are studied experimentally. The addition of methanol as an extraction modifier was also explored. At comparable CO2-to-contaminant ratios and extraction conditions of 48 degrees C and 137 atm, the total PAHs removed from the three soils ranged from 76.9 to 97.9 percent with CO2 alone and from 88.4 to 98.6 percent with methanol added. Results of these tests are presented and analysed. A skid-mounted Field Test Unit (FTU) based on the laboratory bench-scale test results is being constructed which allows on-site testing of the integrated SELPhOx process with contaminated soils.
Afficher plus [+] Moins [-]Supercritical fluid extraction with reflux for citrus oil processing
1997
Sato, M. | Goto, M. | Kodama, A. | Hirose, T.
Terpenes in citrus oil must be removed to stabilize the products and to dissolve it in aqueous solution. Supercritical fluid extraction has been investigated for the terpeneless citrus oil processing as a lower temperature process. In order to achieve higher yield and higher separation selectivity, a continuous countercurrent extraction with reflux was studied at a temperature of 333 K and a pressure of 8.8 MPa. Cold-pressed orange oil from Brazil and a model mixture of 80% limonene and 20% linalool, where limonene and linalool are principal constituent of terpenes and oxygenated compounds in orange oil, were used as feed and carbon dioxide was used as solvent. Operation at total reflux was carried out to calculate the minimum number of plates required to achieve a separation between limonene and linalool. Effects of the solvent-to-feed ratio, reflux ratio, and feed inlet position on the yield and selectivity were investigated for continuous operation. The selectivity increased with the increase in the solvent-to-feed ratio. Terpeneless citrus oil was obtained on the operation at the higher solvent-to-feed ratio and longer stripping section.
Afficher plus [+] Moins [-]Supercritical fluid extraction of recycled fibers: removal of dioxins, stickies, and inactivation of microbes
1997
Blaney, C.A. | Hossain, S.U.
Supercritical carbon dioxide and supercritical propane were found to be effective solvents in extracting stickies and trace chlorinated organics, including dioxins, from recycled fibers. These undesirable components are not effectively removed with current recycled fiber processing techniques. It was also found that endogenous yeast and mold spores on the fibers were inactivated with supercritical carbon dioxide. An economic analysis was performed for a recycled paper pretreatment process which utilizes semi-batch supercritical fluid extraction. Matrix effects were ignored owing to lack of data. Results are encouraging, estimating cost ranges of 7-17 cents per pound of fibers treated -- costs well within reasonable price targets to pretreat premium paper and tissue products.
Afficher plus [+] Moins [-]Estimation of physicochemical properties using supercritical fluid chromatography
1997
Sunol, S.G. | Mierau, B. | Serifoglu, I. | Sunol, A.K.
The selection of chromatographic techniques in determination of physicochemical properties over conventional static methods is due to quick data turnaround with such systems and readily available commercial equipment. Supercritical fluid chromatography is and can be applied to physicochemical property estimation and its use for this purpose has received considerable attention especially more recently. Moreover, some techniques that are used for determining properties of gas-solid systems using gas chromatography can easily be applied to supercritical fluid chromatography.
Afficher plus [+] Moins [-]Accumulation of sulphur in and on Scots pine needles in the subarctic
1997
Manninen, S. (Oulu Univ. (Finland). Dept. of Biology and Botany) | Huttunen, S. | Kontio, M.
Effects of diazinon on some population parameters of Moina macrocopa (Cladocera)
1997
Wong, C.K. (Chinese Univ. of Hong Kong, Shatin (Hong Kong). Dept. of Biology)
Pigment changes in Norway spruce induced by dust pollution
1997
Mandre, M. (Estonian Academy of Sciences, Tallinn (Estonia). Dept. of Ecophysiology) | Tuulmets, L.
Effects of watershed liming on Picea rubens seedling biomass and nutrient element concentration
1997
Smallidge, P.J. (Frostburg State Univ., Frostburg, MD (USA). Dept. of Biology) | Leopold, D.J.
Effect of metal ions on the entomopathogenic nematode Heterorhabditis bacteriophora poinar (Nematoda: Heterorhabditidae) under laboratory conditions
1997
Jaworska, M. (Hugon Kollataj Academy of Agriculture, Cracow (Poland). Dept. of Entomology) | Gorczyca, A. | Sepiol, J. | Tomasik, P.
Effect of copper smelting air pollution on the mites (Acari) associated with young Scots pine forests polluted by a copper smelting works at Giogow, Poland. 1. Arboreal mites
1997
Seniczak, S. (University of Technology and Agriculture, Bydgoszcz (Poland). Dept. of Ecology) | Dabrowski, J. | Dlugosz, J.