Supercritical carbon dioxide extraction with

Mendes, R.L. et al.. Supercritical carbon dioxide extraction of compounds with pharmaceutical importance from microalgae, Inorg. Chim. Acta, 356, 328, 2003. 

SFE. SFE has been established as the extraction method of choice for solid samples. The usefulness of SFE for soil samples has been demonstrated for carbamate,organophosphorus and organochlorine pesticides. However, SFE is more effective in extracting nonpolar than polar residues. In order to obtain a greater extraction efficiency for the polar residues of imidacloprid, the addition of 20% methanol as modifier is required. Extraction at 276 bar and 80 °C with a solvent consisting of supercritical carbon dioxide modified with methanol (5%) for 40 min gives a recovery of 97% (RSD = 3.6%, n = 10). It is possible to use process-scale SFE to decontaminate pesticide residues from dust waste. ... 

Gomez AM, Lopez CP and de la Ossa EM. 1996. Recovery of grape seed oil by liquid and supercritical carbon dioxide extraction a comparison with conventional solvent extraction. Chem Eng J 61(3) 227—231. 

Supercritical carbon dioxide modified with methanol has been used to extract ditallowdimethylammonium from marine sediments [8]. 

Snyder et al. [20] have compared supercritical fluid extraction with classical sonication and Soxhlet extraction for the extraction of selected pesticides from soils. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of organochlorine insecticides including Dichlorvos, Endrin, Endrin aldehyde, p,p -DDT mirex and decachlorobiphenyl (and organophosphorus insecticides). 

Snyder et al. [94] compared supercritical extraction with classical sonication and Soxhlet extraction for the extraction of selected organophosphorus insecticides from soil. Samples extracted with supercritical carbon dioxide modified with 3% methanol at 350atm and 50°C gave a =85% recovery of Diazinon (diethyl-2-isopropyl-6-methyl-4-pyrimidinyl phosphorothiodate or 0,0 diethyl-0-(2-isopropyl-6-methyl-4-pyrimidyl) phosphorothioate). Ronnel (or Fenchlorphos) 0,0-dimethyl-0-2,4,5 trichlorophenol phosphorothiodate), Parathion ethyl (diethyl-p-nitrophenyl (phosphorothioate), Tetrachlorovinphos (trans,-2-chloro-l-(2,4,5 trichlorophenyl) vinyl (chlorophenyl-O-methylphenyl phosphorothioate) and Methiadathion. Supercritical fluid extraction with methanol modified carbon dioxide has been applied to the determination of organophosphorus insecticides in soil [260]. 

Supercritical carbon dioxide extraction [98] has been applied with 85% recovery to the organophosphorus insecticides from sediments. Compounds studied include Parathron ethyl, Methiadathion and Tetrachlorovinphos. 

Grob et al. [47] compared supercritical extraction with classic sonication and including Diazinon, Ronnel, Parathion ethyl, Methiadathion and Tetrachlorovinphos. Samples extracted with supercritical carbon dioxide modified with 3% methyl alcohol at 350°Catm and 50°C gave a recovery of at least 85%. 

Supercritical carbon dioxide extraction (SCDE) is an ex situ process currently being researched for the treatment of soil and debris contaminated with polychlorinated biphenyls (PCBs) and polycyclic aromatic compounds (PAHs) as well as for the removal of solvents from low-level solid mixed wastes and land disposal restricted (LDR) wastes. 

Supercritical carbon dioxide modified with 10 vol% methanol has been employed for the removal of the amine surfactant in hexagonal mesoporous silica (HMS). The effects of temperature and pressure on the extraction efficiency have been extensively studied. It has been found that within an hour, as high as 96% of the amine surfactant can be extracted at a relatively mild condition of 85°C and 100 bar. At constant pressure, high extraction efficiencies are obtained at 50 and 85°C while at constant temperature, high efficiencies occur at 100 bar and 250 bar. This work establishes the feasibility of using supercritical fluid extraction (SFE) for the removal of the amine surfactant. In fact, it has been discovered that SFE produces EIMS of more enhanced mesoporosity as compared to that of calcination. 

Samsonov, M. D. Trofimov, T. I. Vinokurov, S. E. Lee, S. C. Myasoedov, B. F. Wai, C. M. Dissolution of actinide oxides in supercritical carbon dioxide modified with various organic ligands. In Proceedings of the International Solvent Extraction Conference 2002, ISEC 2002, eds. K. C. Sole, P. M. Cole, J. S. Preston, and D. J. Robinson, SAIMM, Johannesburg, South Africa, 2002, pp. 1187-1192. 

Lopez-Avila et al. [88] compared MAE, Soxhlet, sonication, and SFE in their ability to extract 95 compounds listed in the EPA method 8250. Freshly spiked soil samples and two SRMs were extracted by MAE and Soxhlet with hexane-acetone (1 1), by sonication with methylene chloride-acetone (1 1), and by SFE with supercritical carbon dioxide modified with 10% methanol. Table 3.16 shows the number of compounds in different recovery ranges obtained by the various techniques. Sonication yielded the highest recoveries, followed by MAE and Soxhlet, whose performances were similar. SFE gave the lowest recoveries. MAE demonstrated the best precision RSDs were less than 10% for 90 of 94 compounds. Soxhlet extraction showed the worst precision only 52 of 94 samples gave RSDs less than 10%. No technique produced acceptable recoveries for 15 polar basic compounds. The recoveries of these compounds by MAE with hexane-acetone at 115°C for 10 minutes (1000 W power) were poor. Consequently, their extraction with MAE was investigated using acetonitrile at 50 and 115°C. Ten of the 15 compounds were recovered quantitatively (>70%) at 115°C. 

The purposes of our research were to evaluate the feasibility of supercritical carbon dioxide extraction of lemon oil near ambient temperature, generate equilibrium data for carbon dioxide with multicomponent essential oil constituents, and evaluate the ability of the Peng-Robinson equation of state ( ) to model this multicomponent supercritical system. 

In or d e r to make data correlation practicable in supercritical carbon dioxide extraction, it is convenient to represent each major chemical classification by a single compound. Each select compound should have available good vapor pressure data and should be a predominant constituent in its group with regard to structure and concentration. For correlation purposes, we selected liraonene, geranial, and 3-caryophyllene. Their structures are shown in Figure 1. 

Figure 8 shows the relative volatility of geranial to 8-caryophyllene as a function of oil solubility in the vapor phase. At 313 K and 1 wt% solubility, relative volatility is 1.4. At 308 K and 1 wt% solubility, these constituents are inseparable by supercritical carbon dioxide extraction. The ratio of vapor pressures for this pair is in the vicinity of 2 (at 392 K, the lowest temperature with vapor pressure data). 

It is not surprising that fatty acids inhibit COX and LOX enzymes due to their structural similarities with arachidonic acid. A supercritical fluid extract from the fruits of Sabal serrulata (also called Serenoa repens Small. Arecaceae) has been utilized for the treatment of benign prostatic hyperplasia (BPH) and non-bacterial prostatitis. The extract was demonstrated as a dual inhibitor of COX and 5-LOX pathways with IC50 at 28.1 pg/ml and 18.0 (ig/ml, respectively. A further evaluation of the supercritical carbon dioxide extract showed the acidic lipophilic fraction, most likely fatty acids, had the same dual inhibitory activities as the parent extract [121]. 

Essential oil produced by supercritical carbon dioxide extraction is more similar to that present in the living plant, i.e. more top notes, a higher proportion of esters and some larger molecules. However, the presence of fewer terpenes may be due to their lower solubility in the carbon dioxide compared with conventional organic solvents. 

Supercritical fluid extraction (SFE) is a suitable process for many separation problems. The regeneration of the supercritical fluid is as important as the extraction step itself Therefore this paper presents a method to do this in a more isobaric way than the customary pressure reduction regeneration. For the example of soil remediation we have investigated the activated carbon regeneration of supercritical carbon dioxide loaded with the low-volatile polycyclic aromatic hydrocarbon (PAH) pyrene. Characteristics of supercritical fluid extraction for soil remediation are elevated temperatures and pressures up to 370 K and 300 bar. For this reason adsorption isotherms of pyrene on activated carbon up to these conditions are measured first. Subsequently this method is used to regenerate carbon dioxide in a closed solvent cycle plant with a 4 1 extractor. An economic analysis using these results indicate that the soil remediation costs will decrease for about 20 - 30 % by means of an activated carbon adsorber. 

Usually, the terpenes are removed from the cold-pressed oils (deterpenation) to concentrate the flavour fraction, thus resulting in a more stable product with improved solubility in the alcoholic solvents used in food and perfume processing. Supercritical carbon dioxide extraction appears as a promising and alternative technique to refine cold-pressed citrus oils [1,2, 3). Potentially, it has the advantages that it can be carried out at mild temperatures, provides better yields and leaves no solvent residues. 

Figure 1 Coexistence of the past and present techniques in F F industry classical enfleurage process (photo on the left) and a supercritical carbon dioxide extraction facility as modern factory equipment (on the right). The photo on the left shows a stock of jasmine flowers in the basket (center) that are spread upon a wooden frame (chassis) that secures a glass plate coated with fat. The chassis is then piled to allow diffusion of fragrant components (note that the fat is applied on both sides of the glass plate to gain access to the headspace volume made by the chassis underneath). Enfleurage process photo reproduced from E. Guenther, The Essential Oils with permission from Krieger Publishing Company Melbourne, FL, USA, 1948 (reprinted 2006) Vol. 1, p 192.

The fatty acid composition of the extracts was not affected by temperature, pressure, and the extraction method (Table 4). Supercritical carbon-dioxide-extracted oil samples had similar fatty acid composition to that of the Soxhlet-extracted oil (Table 4). All of the wheat germ extracts consisted of about 56% linoleic acid (18 2 n-6), which is an essential fatty acid (Table 4). The total unsaturated and polyunsaturated fatty acid (PUFA) content of the wheat germ oil was about 81 % and 64%, respectively. The SC-CO2 extraction of wheat germ resulted in extracts with similar tocopherol and tocotrienol compositions to those of the Soxhlet extracts (Table 8) (50). These results indicate that SC-CO2 technology can be used for extraction and fractionation of WGO components to obtain products with high quality. 

King, J. W. Johnson, J. H. EUer, F. J. Effect of supercritical carbon dioxide pressurized with hehum on solute solubihty during supercritical fluid extraction. Anal. Chem. 1995, 67, 2288-2291. 

Fig. 1 Chromatogram of PAHs, herbicides, and phenols obtained by supercritical carbon dioxide modified with methanol. [Reprinted from L. Toribio, M. J. del Nozal, J. L. Bernal, J. J. Jimenez, and M. L. Serna, Packed-column supercritical fluid chromatography coupled with solid-phase extraction for the determination of organic microcontaminants in water,...

Hutter and co-workers made mesoporous amorphous titania-silica aerogels by the sol-gel method, including supercritical carbon dioxide extraction in the workup.267 These were used with cumenehydroperoxide to epoxidize 1-hexene in 95% selectivity and cyclohexene in 100% selectivity. The authors state that their catalysts are superior to titanium-/ and titanium MCM 41 for the oxidation of bulky compounds such as limonene (4.55). 

Trace Level Extraction. To provide a challenging sample for evaluation of off-line SEE, activated carbon was spiked at 50 ppm with several polar and higher molecular weight polycyclic aromatic compounds. A one-gram sample was subjected to 16 h of Soxhlet extraction using carbon disulfide and then followed with a second similar extraction using methylene chloride. Another sample was extracted for 1 h with supercritical carbon dioxide at 125 and 400 bar. As shown in Table I, no detectable levels of the compounds were recovered in the combined Soxhlet extracts. However, low levels of the compounds were recovered with supercritical carbon dioxide extraction of the activated carbon. Although only low levels of the... 

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