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Extraction of wood

Aqueous alkaline extraction of wood was employed by Poumarede and Figuier48 in 1846 for the removal of a substance called wood gum. Similar very crude xylan or hemicellulose preparations were made by other workers of the early period. Extractions were made not only from wood sawdust, but from annual plant materials such as wheat straw, corn cob, etc.49-66... [Pg.288]

To compare lignins produced from supercritical fluid extraction of wood with lignins from conventional pulping processes, a kraft pine lignin... [Pg.57]

Table III. Continuous Extraction of Wood with Dioxane, Acetals, and 0.2IV HC1... Table III. Continuous Extraction of Wood with Dioxane, Acetals, and 0.2IV HC1...
K Randerath Texas A M University Measure chemical DNA alterations in exposed experimental animals, humans, and cultured cells induced by exposure to aromatic and halogenated aromatic hydrocarbons, reconstituted mixtures from these compound classes, and field extracts of wood-preserving and oily waste dump sites ... [Pg.376]

Pre-extraction of Wood. Since the major factor causing a reduction in the permeability of wood during heartwood formation is occlusion of the pit membranes with extraneous material, one would anticipate that pre-extraction of the wood with a suitable solvent would be a method of increasing the permeability of wood. This contention has been verified by a number of studies (15, 16, 17, 18, 19, 20, 3, 21). However, it appears doubtful that such treatments would be commercially feasible since the solvents are expensive and excessive time is required for the additional step in the treating process. [Pg.44]

Figure 2. Hot-water extractability of wood chips as a function of saturated steam pressure used in the preheat segment of the digesting operation... Figure 2. Hot-water extractability of wood chips as a function of saturated steam pressure used in the preheat segment of the digesting operation...
Turpentine and Rosin The major naval stores products are turpentine, primarily composed of volatile terpenes, and rosin, mainly a mixture of resin acids. Principally the same products, but in different proportions, can be recovered by tapping resin-rich trees or by steam distillation or solvent extraction of wood residues and especially stumps. Today, however, the most important source for turpentine and rosin is the tall oil recovered after pulping of pine wood (see Section 10.3.1). [Pg.191]

The pre-extraction of wood or pulp is routinely performed to remove extraneous substances which would otherwise interfere with the determination. However, as emphasized by Lai and Sarkanen (1971), any advantage gained through inclusion of a pre-extraction step may be offset as a result of extractants such as hot water and ethanol removing a portion of the lignin. According to Brauns (1952), the hot water extraction may be omitted in the case of chemical pulps and the ethanol-benzene extraction may be disregarded for pulps produced under alkaline conditions. [Pg.38]

Most of our knowledge of the chemistry of the polyoses in wood-cellulose preparations comes from studies made on fractions of the hemicelluloses obtained from alkaline extracts of wood, agricultural residues, or other plant material. In the following, some of these studies will be considered as a starting point, and then the effect of pulping procedures on the amount and nature of the associated polysaccharides will be discussed. It is not the purpose of this article to treat the chemistry of plant polysaccharides in detail, but rather to consider only those aspects which, in the opinion of the author, are pertinent to an understanding of the factors affecting the composition of wood-cellulose preparations. [Pg.288]

However, it appears that better correlation with gel times is obtained when the amounts of extractable and unextractable wood acids are considered separately (37). Although several procedures do exist in the literature for the determination of acid content in wood, many of these involve extraction of wood with various solvents, and they estimate the acid content in the extractives only. In contrast, we developed a procedure that acknowledges the presence of soluble as well as insoluble acids in wood. The method is based on the reaction of wood acids with aqueous sodium acetate to liberate an equivalent amount of acetic acid. Subsequent pH titration gives the total acid content. The soluble acids are determined by water extraction... [Pg.345]

A group of methods to obtain lignin are known as organosolv procedures. They consist of an extraction of wood sawdust with an alcohol (such as ethanol) and some acid (5% HCI) in stronger conditions (boiling under reflux) followed by the reprecipitation of lignin from the extract. [Pg.328]

Ester hydrolysis in basic solution is called saponification, after the Latin sapo, meaning soap. As we ll see in Section 27.2, the boiling of animal fat with extract of wood ash to make soap is indeed a saponification, because wood ash contains base and fats have ester linkages. [Pg.867]

Nitrogen rings and nitrogt nous compounds of unknown constitution A nes, phenols, naphthols, aminophenols, aminonaphthols Distillation of tar, extraction of wood vinegar, etc. [Pg.86]

All values in per cent of extractive-free wood. Corrected for unhydrolyzed (4-0-methyl-D-glucosylurono)xylose. On direct extraction of wood with aqueous alkali. [Pg.253]

Alkaline extraction of wood is usually carried out at or below room temperature for limited periods of time and in an atmosphere of nitrogen. Under these conditions, any changes in the xylan brought about by the alkali are kept at a minimum, excepting a complete de-O-acetylation. Whistler and Corbett found that a corncob xylan was stable in N sodium... [Pg.256]

The phenomena which have been observed on extraction of wood with aqueous sodium hydroxide - also occur, albeit to a smaller extent, with holocelluloses the restriction to dissolution is, in this case, mostly due to the fiber structure itself. In a study of the extraction of a chlorine holocellulose from European beech with sodium hydroxide solutions of various concentrations, Corbett and Ewart found that 87% of the (4-0-methyl-glucurono) xylan could be removed under mild conditions, and another 10% by extraction with hot alkali, but that 1.3% remained associated with the cellulose. The same authors have also described an apparatus suitable for the alkaline extraction of wood or holocellulose in an atmosphere of nitrogen. [Pg.262]

McDaniel, L. Ashraf-Khorassani, M. Taylor, L. T. "Supercritical Fluid Extraction of Wood Pulp with Analysis by Capillary Gas Chromatography-Mass Spectroscopy", J. Supercrit. Fluids, 2001,19,275. [Pg.50]

On extraction of wood of white spruce with water, Adams obtained two polysaccharides, one of which, a galactoglucomannan, will be discussed later (see p. 458). The other, an acidic arabinogalactan still containing some xylan, was subjected to a structural investigation. The methylation data (see Table XI) were very similar to those observed for the polysaccharide... [Pg.427]

In the search for the paper factor, extracts from several gymnosperms were assayed on P. apterus fifth instars (Table 1) [83, 84, 85]. Extracts of wood and bark of a number of these conifers were also injected into pupae of the wax moth, Galleria mellonella a localized scaleless patch was observed in the pupal cuticle at the site of injection with these extracts. However, no abnormal effects on development were observed [86]. The authors speculated that this absence of activity may be attributable to the dilute concentration of active ingredients in the extracts. [Pg.384]


See other pages where Extraction of wood is mentioned: [Pg.1064]    [Pg.4]    [Pg.4]    [Pg.109]    [Pg.266]    [Pg.276]    [Pg.4]    [Pg.4]    [Pg.91]    [Pg.139]    [Pg.163]    [Pg.1120]    [Pg.1064]    [Pg.303]    [Pg.87]    [Pg.187]    [Pg.1122]    [Pg.215]    [Pg.1142]    [Pg.1064]    [Pg.1328]    [Pg.5]    [Pg.87]    [Pg.39]    [Pg.255]    [Pg.436]   


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Contribution of Extractives to Wood Characteristics

Of woods

Solvent extraction of wood

Supercritical extraction of wood

The Future of Wood Extractives

The Utilization of Wood Extractives

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