Extraction of wood compounds by use of subcritical fluids

Abstract

A study of the extraction of oak wood compounds with subcritical water-ethanol mixtures as extractant, with an ethanol content between 0-60%, is reported. Identification and characterisation of the extracted compounds have been made by spectrophotometry and gas chromatography with either flame ionisation or mass detectors. Extraction was performed statically manner by use of a single cycle or repeated cycles. All variables affecting the extraction process were studied and optimised. Extraction time and temperature are 60 min and 200ºC, respectively. Comparison of the extract thus obtained with commercial extracts showed the former to be rich in compounds characteristic of the commercial extracts. The method enables manipulation of the extract composition by changing the temperature and water/ethanol ratio used. It is faster than the traditional procedures for obtaining wood extracts.

Superheated liquids for extraction of solid residues from winemaking processes

“…A time of 65 min and a temperature of 210º C were selected as optimum. Temperatures higher than this were not used in order to avoid cleavage and oxidation reactions of some of the extracted compounds [13,14].…”

“…It has prompted the development of an alternative to the conventional manual methods based on organic solvents. The use of superheated ethanol-water mixtures has previously been checked for the extraction of phenolic compounds from oak wood [12,13]. The extracts obtained were compared with commercial wood extracts with an excellent agreement concerning composition, and with drastic reduction of both time and costs.…”

A Method for Determination of Alcohol Content in Dielectric Liquids by a Longitudinal-Slot Waveguide

“…The accuracy of alcohol content determination ensured by these methods is about 0.1 vol.%. There also exist other methods (see, for example, [4][5][6]) that provide higher accuracy; however, these methods involve more sophisticated and expensive equipment.…”

Characteristics and antioxidative ability of defatted rice bran extracts obtained using several extractants under subcritical conditions

“…Subcritical organic solvents such as compressed hot water/ethanol and water/acetone were used for the extraction of biomass from woods 16,17 . The former was useful in extraction of nonylphenol polyethoxy carboxylates from industrial and municipal sludge 18 , and the latter was also used for organosolv pulping of wheat straw to obtain paper sheets 19 .…”