Wyniki wyszukiwania - BazTech

1

Modelling of microporous membrane cleaning using supercritical fluids

Krzysztoforski J., Henczka M.

Czasopismo Techniczne. Chemia

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2014

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R. 111, z. 2-Ch

63--72

EN

In this paper, a method for CFD modelling of microporous membrane cleaning by supercritical fluid extraction (SFE) is presented. Results of CFD simulations results are shown and compared with experimental data for the process of microporous polypropylene membrane cleaning by SFE in a continuous-flow lab-scale SFE module.

PL

W artykule przedstawiono sposób modelowania CFD oczyszczania membran mikroporowatych metodą ekstrakcji nadkrytycznej. Zaprezentowano wyniki symulacji CFD i porównano je z danymi doświadczalnymi dla procesu oczyszczania mikroporowatych membran polipropylenowych metodą ekstrakcji nadkrytycznej w module przepływowym w skali laboratoryjnej.

2

Efficient method for extraction and isolation of shionone from Aster tataricus L. f. by supercritical fluid extraction and high-speed counter-current chromatography

Wang D, Bai A, Lin X., Fang L., Shu X., Shi X., Sun Q., Wang X.

Acta Chromatographica

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2012

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Vol. 24, no. 4

615--625

EN

Supercritical fluid extraction (SFE) was used to extract shionone from Aster tataricus L. f. The effect of various parameters, i.e., temperature, pressure and sample particle size on yield was investigated with an analytical-scale SFE system to find the optimal conditions. The process was then scaled up by 50 times with a preparative SFE system under the optimized conditions of temperature 40 °C, pressure 30 MPa, and a sample particle size of 40–60 mesh. Then preparative high-speed counter-current chromatography was successfully used for isolation and purification of shionone from the SFE extract with a two-phase solvent system composed of n-hexane-methanol (2:1, volume ratio). The separation produced a total of 75 mg of shionone from 500 mg of the crude extract in one step separation with the purity of 98.7%, respectively, as determined by high-performance liquid chromatography (HPLC) and 92% recovery. The structure of shionone was identified by electrospray ionization-mass spectrometry (ESI-MS), hydrogen-1 nuclear magnetic resonance (1H-NMR), and carbon-13 nuclear magnetic resonance (13C-NMR).

3

Triterpenes in traditional and supercritical-fluid extracts of Morus alba leaf and stem bark

Böszörményi A, Szarka Sz., Héthelyi É, Gyurján I, László M, Simándi B, Szőke É, Lemberkovics É

Acta Chromatographica

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2009

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Vol. 21, no. 4

659--669

EN

Our objectives were to establish a GC method capable of quantitative analysis of terpenoids without derivatisation and to examine the amount of β -sitosterol extracted from Morus alba L. leaf and stem bark by use of traditional organic solvent extraction and supercritical-fluid extraction (SFE). To measure β -sitosterol content without derivatization, GC-FID was used with 5- α -cholestan-3-one as internal standard. To identify terpenoid constituents, GC-MS was used; β -sitosterol, phytol, lanost-7-en-3-on, α -amyrin, β -amyrin, and lupeol were identified. We established that for Morus leaf the best SFE method for β -sitosterol was pilot scale SFE; the β -sitosterol content of this extract was higher than that of the hexane solvent extract. Among analytical SFE conditions, 200 bar for 90 min and 300 bar for 60 min resulted in extraction of the most β -sitosterol. For mulberry stem bark, solvent extraction with hexane and SFE at 400 bar and 40°C for 60 min proved the best methods.

4

Study of Extraction of Cinnamon Oils from the Bark of Cinnamomum cassia presl by Supercritical Carbon Dioxide

Zhao S., Liang H.

Polish Journal of Chemistry

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2006

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Vol. 80, nr 1

99-105

EN

Cinnamon oils were isolated from the bark of Cinnamomum cassia presl by supercritical fluid extraction (SFE) and compared with steam distillation (SD). The extracts were analyzed with GC-MS. The yield from SFE was around four times as that from SD. The results from GC-MS revealed that the constituent components obtained from SFE and SD are similar while the distributions of individual compounds are different. In SFE, effects of various factors such as time (t), extraction pressure (P), extraction temperature (T), particle size (S) and flow rate of supercritical carbon dioxide (F) on the yield of target components were investigated. Favorable operation conditions were found at t = 2 h, P = 22.5 MPa, T = 50°C, S < 0.3 mm and F = 9.0 1/h.

5

Supercritical fluid extraction in anal ysis of PCBs and PAHs in beer

Horak T., Jurkova M., Čulik J., Čejka P., Kellner V., Krasek P., Varadova Ostra E.

Chemia i Inżynieria Ekologiczna

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2005

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Vol. 12, nr 7

703-708

EN

A method for the direct CO2 supercritical fluid extraction (CSFE) of aqueous samples used in previous work for measuring of distribution coefficients of substituted phenols was modified for analytical purpose. The apparatus enabling a continuous flow of sample in two ways, in co-current and counter-current mode, was used in the co-current mode with trapping of analytes to n-hexane. Although supercritical CO2 is a nonpolar solvent, good extraction efficiencies have been found for low-to-moderately polar compounds (PAHs and PCBs). The reason is that water and ethanol (in the case of beer) take effect as modifiers. In this work, the results of CSFE extraction of extraneous pollutants like PAHs and PCBs from beer samples were compared with those obtained by c1assicalliquid-liquid extraction used as a reference method. It was demonstrated that the CSFE method gives a similar efficiency as using of liquid-liquid extraction and can be suitable for the determination of PCBs and PAHs in beer.

PL

Opisana we wcześniejszej publikacji metoda bezpośredniej ekstrakcji ditlenkiem węgla w stanie nadkrytycznym (CSFE) rozpuszczonych w wodzie fenoli została wykorzystana do celów analitycznych. Metodę CSFE zastosowano do ekstrakcji PCBs i PAHs z próbek piwa. Uzyskane dane porównano z wynikami wyznaczonymi za pomocą klasycznej metody ekstrakcji ciecz-ciecz, która jest stosowana podczas standardowego oznaczania tych węglowodorów w piwie. Porównanie to wskazuje, że metoda CSFE jest odpowiednia do oznaczania tych substancji w piwie.

6

Selektywna ekstrakcja olejku lotnego z nasion czarnuszki siewnej (Nigella Sativa L.)

Wawrzyniak P., Iwanek D., Kalemba D.

Inżynieria i Aparatura Chemiczna

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2004

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Nr 3s

161-162

EN

Essential oils from black cumin seeds (Nigella Sativa L.) were obtained in the process of extraction with supercritical CCh- The effect of pressure, process temperature and moisture content of extracted raw material on the quality and percentage of components was studied. It appeared possible to affect the product composition by selecting the extraction parameters.

7

Simultaneous determination of phenols and polyaromatic hydrocarbons isolated from environmental samples by SFE-SPE-HPLC

Buszewski B., Buszewska T., Szumski M., Siepak J.

Chemia Analityczna

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2003

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Vol. 48, No. 1

13-25

EN

Modem sample preparation techniques should be characterized by low chemicals consumption. Exemplary techniques are solid phase extraction (SPE) and supercritical fluid extraction (SFE). The latter method often uses solid traps to prevent the loss of the analytes. Therefore, both SFE and SPE require adsorbent selection during the development of extraction procedure. This contribution presents sorbent selection based on adsorption isotherms analysis performed for phenols and PAHs using phenol and naphtalene as model compounds. Obtained results allowed to build SPE-SPE and SFE-SPE couplings and use them for real samples analysis (water and sediment).

PL

Współczesne techniki przygotowania próbek powinny charakteryzować się małym zużyciem odczynników. Takimi technikami są: ekstrakcja do fazy stałej (SPE) i ekstrakcja płynem w stanie nadkrytycznym (SFE). W tej ostatniej, wykorzystuje się również odbieralnik ze stałym adsorbentem w celu zapobieżenia stratom analitów. Dlatego, zarówno SFE jak i SPE wymagajądoboru adsorbentu w czasie opracowywania procedury ekstrakcji. Wybór adsorbentu, w przypadku ekstrakcji fenoli i wielopierścieniowych węglowodorów aromatycznych, polegał na wyznaczeniu izoterm adsorpcji fenolu i naftalenu jako reprezentantów tych grup związków. Otrzymane wyniki pozwoliły zbudować połączenia SPE-SPE i SFE-SPE, które zastosowano do analizy próbek środowiskowych (wody i osadu dennego).

8

Szybkie i ekonomiczne metody ekstrakcji pestycydów z produktów żywnościowych

Błaszczyk A., Jasiczek J.

Wiadomości Chemiczne

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2002

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[Z] 56, 11-12

1035-1052

EN

Food analysis is very important for the evaluation of the nutritional value and quality of fresh and processed products, and for monitoring food additives and other toxic contaminations. Sample preparation such as extraction, concentration and isolation of analytes, greatly influences the reliable and accurate analysis of food. Currently there are some techniques of sample preparation such as SPE, SPME, MSPD, SFE, which have the following characteristic features: - Speed - Reduced labor - Better recoveries - Improved sample-to-sample consistency - Significantly reduced solvent consumption and waste - Ruggedness and reliability. Solid-phase extraction (SPE) is a rapid and sensitive sample preparation technique, whose use has considerably increased within the last decade. This emerging technology has successfully replaced many tedious conventional methods of isolation and extraction of various chemicals in food. Sample preparation and concentration via SPE can be achieved in a one-step extraction, and the methodology is appropriate for isolating trace amounts of chemical compounds from complex matrices such as food. Solid-phase microextraction (SPME) is a new sample preparation technique using a fused-silica fibre that is coated on the outside with an appropriate stationary phase. This technique has been successfully applied in the analysis of pesticides in food. Supercritical fluid extraction (SFE) is sample preparation technique, which does not use organic solvents for trapping and for washing out of analytes. SFE usually with carbon dioxide and often with a modifier, is a rapid, selective and convenient method for sample clean-up in environmental analysis. In the past decade, SFE has been applied successfully to the extraction of a variety of organic compounds, e.g. pesticides from herbs, food and agricultural samples. Three inter-related factors influence analyte recovery in SFE: solubility in the fluid, diffusion through the matrix and adsorption in the matrix. Matrix solid-phase dispersion (MSPD), a patented process for the simultaneous disruption and extraction of solid and semi-solid samples, was first reported in 1989. Since that time, MSPD has found application in numerous fields, but has proved to be particularly applicable for the analysis of drugs, pesticides and other components in food. MSPD enables complete fractionation of the sample matrix components as well as selective elution of a single compound or several classes of compounds from the same sample. The method has been applied to the isolation of pesticides from animal tissues, fruit, vegetables and other matrices. --

9

Rapid extraction and clean-up of PCNs and PCDFs from soil samples using SFE-LC with solid phase carbon trap : comparison with other methods

Wiater-Protas I., Bavel B. van, Parczewski A.

Chemia Analityczna

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2002

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Vol. 47, No. 5

659-667

EN

An extraction-clean-up procedure using supercritical fluid extraction-liquid chromatogra-phy (SFE-LC) was tested for isolation of polychlorinated dibenzofurans (PCDF) and poly-chlorinated naphthalenes (PCN) from real soil samples. PCDF and PCN were successfully extracted from the sample and separated on a carbon trap. Addition of methanol as a modifier caused dramatic decrease in PCN extraction efficiency, but slightly improved recovery of higher chlorinated PCDFs. The extraction efficiency of SFE-LC has been compared with ASE (accelerated solvent extraction) and Soxhlet extraction.

PL

Testowano procedurę ekstrakcji i oczyszczania rzeczywistych próbek gleby zawierających polichlorowane dibenzofurany (PCDF) oraz polichlorowane naftaleny (PCN) za pomocą ekstrakcji cieczą w stanie nadkrytycznym połączonej z chromatografią cieczową (SFE-LC). PCDF i PCN były ekstrahowane z próbek oraz oddzielane od innych związków na odbieralniku — kolumnie z wypełnieniem węglowym. Dodatek metanolu jako modyfikatora drastycznie zmniejszał efektywność ekstrakcji PCN, ale poprawiał odzysk wyżej chlorowanych kongenerów PCDF z próbki. Porównano efektywność ekstrakcji metodą SFE-LC z metodą przyspieszonej ekstrakcji rozpuszczalnikiem (ASE) i z ekstrakcją w aparacie Soxhleta.