Of cellulose from wood

Polymers are very large organic molecules that are either made synthetically or are of natural origin, and find use as plastics, rubber, fibers, and coatings. Polymers were first produced commercially in 1860 by modification of cellulose from wood or cotton, followed by a fully synthetic product made from phenol and formaldehyde in 1910. 

XExtraction from wood by org solvs) 38) A.Roudier, MSCE 34, 263(1948XExtraction of cellulose from wood by org solvs) 39)A. 

The isolation of cellulose from wood may employ any one of several process options [13,15, 16]. Chemical wood pulp may be derived by delignification using acidic solutions of sulfur... 

Ceiiuhse for nitration. In most European countries wood cellulose is now used for nitration (Vol. II. p. 364), The success of the nitration of cellulose from wood depends on a high proportion of a-cellulose in wood cellulose. According to Pctropavlovskii, Krunchak and Vasilyeva (7) the yield of nitrocellulose highly depends on the ot-cellulose content and can be proportional to this content. Some authors (8) consider that lower quality of nitrocellulose from wood-cellulosc is due to the presence of hemi-cclluloses (mainly penios-anes) in it. 

B. G. Ranby, Inst. Phys. Chem., Univ. Uppsala, Arkiv Kemi, 4, 241 (1952). Fine structure and reactions of native cellulose. Electron microscope study of morphology of celluloses from wood, cotton, bacteria, tunicates, and algae behavior of samples on swelling in sodium hydroxide and hydrolytic degradation. 

Regenerated cellulosic fibers are made out of cellulose from wood or cotton lint. The most used fibers are viscose, acetate, cupro (very small quantity), and lyocell. These fibers are produced in various titers as filament (endless fiber) or staple fiber. 

The separation of ethanol from water can also be effected by freezing. The effect of ethanol concentration on the freezing point is given in Table 5.4. Thus, a Uter of fermented brew with 12.5% ethanol by volume was completely frozen and then allowed to thaw. The first 500 mL of solution was 17% ethanol. When this 500 mL solution was frozen and allowed to thaw, again the first 250 mL was 23% ethanol. Various freeze-thaw cycles can thus concentrate ethanol. Another process which has been studied extensively for more than 70 years is the conversion of cellulose from wood and straw to glucose by enzyme or by acid hydrolysis. 

Acidified sodium chlorite (NaClO HjO ) is used as a standard reagent for delignification and extraction of cellulose from wood materials (Wise, 1946). Chlorite (CIO ) may produce chlorine radical, Cl, which reacts and fragments the lignocellulosic material into highly toxic organochlorine compounds. Several studies have reported cellulose extraction by chlorites, in combination with alkali and heating at different duration (Table 13.1). 

Horns and hooves were the raw materials for the early polymer preparations. These materials were ground up and treated in various ways so that they could be fabricated into such items as combs to use for ladies hair, and other specialty things of that sort. The next development was the use of cellulose from cotton or from wood as the raw material which was studied for making films and fibers. Work on the cellulose structure had provided information that it was a hydroxylated product, and by converting the hydroxyls to esters, the natural cellulose could be turned into a soluble material, which was spun into fibers and cast into films to make the first cellulose rayon-type material and cellulose films. 

A hydrolysis step is involved in the pulp industry in order to concentrate the cellulose from wood. This uses large-scale processes whereby a liquid fraction, the lignocellulose, is formed as a by-product in the process, and contains high levels of phenolic components and their derivatives. These compounds also constitute an environmental problem due to their possible introduction into rivers, lakes, and/or seas. Chlorophenols from the cellulose bleaching process have traditionally attracted most of the interest in the analysis of industrial waste because of their high toxicity. 

Alcohol recovery from the fermentation brews was less than complete in most cases, which may be attributable to less than ideal conditions. The best yields, 60 to 97% of theory, were obtained with sugars obtained by hydrolysis of cellulosic residues of the autohydrolysis-extraction process. Unextracted pulps, or the hemicellulose solutions, gave poor ethanol formation, which suggests inhibition. In the calculation of material and energy balances which follows, we have assumed 95% yields of ethanol from wood sugars, which is readily achieved in industrial practice and which we believe to be achievable with our wood sugars as well. 

Tokarev, B.I., Hydrolysis of Wood, Chapter XXIV in "The Chemistry of Cellulose and Wood", by N.I. Nikitin. Translated from the Russian by Israel Program for Scientific Translations Jerusalem, 1966. 

The important fiber rayon is simply regenerated cellulose from wood pulp that is in a form more easily spun into fibers. Cellophane film is regenerated cellulose made into film. One method of regeneration is formation of xanthate groups from selected hydroxy groups of cellulose, followed by hydrolysis back to hydroxy groups. 

Cellulose is sometimes used in its original or native form as fibers for textile and paper, but is often modified through dissolving and reprecipitation or through chemical reaction. The xanthate viscose process, which is used for the production of rayon and cellophane, is the most widely used regeneration process. The cellulose obtained by the removal of lignin from wood pulp is converted to alkali cellulose. The addition of carbon disulfide to the latter produces cellulose xanthate. 

The manufacture of cellulose acetate involves the acetylation of cellulose from cotton linters or wood pulp by acetic anhydride and acetic acid. Production started about 30 years ago, and early products that were developed include safety photographic films, airplane dopes, and acetate fabrics. It is now also produced in the form of sheeting, rods, and tubes and is widely used as a molding compound. 

The separation of cellulose from the wood is carried out by one of three methods the soda process, the sulphate process, and the sulphite process. Nitration cellulose is prepared chiefly by the sulphite and sulphate methods. 

An appreciable part of the lignin molecule is aromatic in character. Hence it would be expected to take part readily in the reaction of nitration. It has been found, however, that the capacity of lignin to undergo oxidation predominates especially in the presence of dilute nitric acid. This can be explained by the fact that the aromatic part of the lignin molecule derives from pyrocatechol. The reaction of lignin with nitric acid forms the basis of a method of separating cellulose from wood pulp, that consists in treating this mass with dilute nitric acid (3-10%). 

The reaction may be applied in analysis or as an industrial process. Thus Krais [57] obtained patents for producing cellulose from wood pulp by means of 3-6% nitric acid. 

Almost pure cellulose is found in pith, absorbent cotton in some filter papers. Pure cellulose is most readily obtd from cotton by treating it with dil alkalies acids and thoroughly washing, with water. Another source of cellulose is wood(mostly coniferous) which contains 50-60% cellulose and strawfmostly cereal) which contains 30-40%. A common classification of celluloses is based on their solubilities in aq alkalies If cellulose is treated with NaOH soln of ca 18% at 20°, it will swell and much of the material, which is of short chain length, will dissolve. The residue from this treatment is called alpha cellulose. 

Degradation of Cellulose. Cotton cellulose, purified by a standard method (//) was used as the starting material. The procedure was the same as for the continuous extractions of lignin from wood. 

The whole procedure normally takes about 1 hr. The acid is then evaporated, and the dry matter can be analyzed. This method can be applied to cellulose from wood, as a-cellulose or pulp, or to other celluloses (e.g., cotton) as well as to cellulosic materials with higher amounts of other polysaccharides (e.g., holocellulose). The chromatograms of the hydrolysates of a-cellulose from beechwood and of holocellulose from sprucewood (Figure 6) are examples of the application of this method. Compared with sulfuric acid hydrolysis, the total sugar yield from the spruce holocellulose is higher after the hydrolysis with concentrated TFA (Table II). Regarding the individual sugars, it can be seen that the... 

In contrast to BC, cellulose from wood is composed of fibers that are about one hundred times thicker [17] (Fig. 4a). Because of the complex and expensive cultivation of BC (sophisticated medium and long cultivation time), it is also a challenge to produce nano-fibrillated celluloses from wood. The substructures of wood are only accessible by chemical treatment [16] and mechanical disintegration procedures. 

In contrast, the energy gain of ethanol fermentation from a cellulose-based crop was estimated at only 10% [31]. A fife cycle assessment of bioethanol from wood came to a similar conclusion [32]. This unsatisfactory outcome mainly results from the energy-intensive pretreatment with steam explosion, such as is used by Iogen [16]. The replacement of the latter by COz explosion [33] may redress the energetic balance. 

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