نتایج جستجو برای: supercritical carbon dioxide
تعداد نتایج: 321349 فیلتر نتایج به سال:
Ionic Liquids are low melting salts (up to 100° C) and represent a new class of solvents with unusual physico-chemical properties. In the present work ionic liquids have been used as reaction media for the synthesis of phenylacetylphenylglycine and of phenylacetylphenylalanine. 3 ionic liquids: 1-Octyl-3-methylimidazolium tetrafluoroborate, 1-Butyl-3-methylimidazolium hexa fluorophosphate and 1...
We have demonstrated an improved synthesis of a cyclic carbonate of soybean oil (CSO) utilizing supercritical carbon dioxide (CO2) as the solvent. Because the mutual solubility of supercritical CO2 and soybean oil is significantly higher than that of gaseous CO2 and soybean oil, our method synthesizes the material in y1/3 of the reaction time reported in the literature. We have also demonstrate...
Supercritical carbon dioxide extraction (scCO2) is chosen to a treatment to remove lignin and to peel off outer cell wall layers to expose S2 layer of aspen wood fibres. The aim is to find an effective and environmentally friendly method to advance the fibrillation of the BCTMP pulp. The effects of the treatment are analysed by using scanning electron microscopy (SEM). The chemicals used togeth...
This research aimed at producing microcellular foams (with cell size of 1-10 μm and cell density above 10 9 cell/cm3) from PC/EPDM in order to use in medical devices. Due to the weak nucleation behavior of microcellular polycarbonate foams, it is difficult to prepare them. This research provides valuable information regarding the possibility of making microcellular foams from this polymer by u...
We describe procedures based on the polydisperse independent ideal slit-pore model, Monte Carlo simulation and density functional theory (a 'slab-DFT') for predicting gas adsorption and adsorption heats in active carbons. A novel feature of this work is the calibration of gas-surface interactions to a high surface area carbon, rather than to a low surface area carbon as in all previous work. Ou...
Supercritical carbon dioxide with ethanol as modifier was employed in the extraction of functional food ingredients from Cystoseira abies-marine algae. Three different types of pre-treatment were employed to prepare the vegetal raw material producing an important effect on extraction yield. The experimental assays were carried out in a semi-continuous extraction cell at 290 bar, 40 °C and using...
A high-performance liquid chromatographic method is developed for use in the electrospray mass spectrometric (MS)-MS analysis of alkaloids contained in Cephalotaxus harringtonia leaves. Nine alkaloids having ester groups can be separated and detected with good sensitivity. The MS and MS-MS spectra obtained provides information on their chemical structures. Supercritical fluid extraction is also...
Conversion of wet biomass via gasification in supercritical water is a promising technology for the production of hydrogen and methane from renewable resources. The properties of water above the critical point enable reactions for the fast degradation of biomass and generation of a product gas consisting of hydrogen, methane, higher hydrocarbons and carbon dioxide without disturbing sulphurand ...
A supercritical fluid chromatograph has been designed and constructed to make physicochemical measurements, while retaining the capability to perform chemical analysis. The physicochemical measurements include diffusion coefficients, capacity ratios, partition coefficients, partial molar volumes, virial coefficients, solubilities, and molecular weight distributions of polymers. In this paper, t...
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 ...
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