Cellulose-lignin mixtures

Experimenting with cellulose-lignin mixtures showed that the position of both exotherms shifted to higher temperatures with an increase in cellulose percentage (Figure 7) the heat of the reaction increased with an increase in the lignin percentage. There is a pos-... 

As was noted early, under the action of polyethylene the conversion of pine wood was increased by 1,4 times. After removing 11% wt, of lignin from pine wood by extraction with dimethyl sulfoxide this effect was less (1.2 times). In the runs with cellulose / polyethylene mixtures no positive influence of polyethylene on pine wood conversion was defected. The maximum increase of the conversion degree (1.5 times) was observed for coal / polyethylene mixture. 

Takuya Yoshida, Yukihiko Matsumura (2001), Gasification of Cellulose,Xylan, and Lignin Mixtures in Supercritical. Ind. Eng. Chem. Res. 40,5469-5474. 

Dietary fibre consists of all components of plant cell walls not digested by human alimentary enzymes. Chemically, fibre is a mixture of cellulose, lignin, heteropoly-saccharides (hemicelluloses), acidic polysaccharides and pectin. In the colon, bacteria hydrolyse up to 15% of cellulose and 70-95% of other polysaccharides giving rise to volatile gases and low molecular weight fatty acids (acetic, butyric etc.) which have weak laxative activity. In addition the cellulosic and non-cellulosic polysaccharides are hydrophilic and absorb large amounts of fluid from the gut lumen, increasing in bulk as they do so. This is exactly the... 

Aaltonen and Jauhiainen [32] prepared cellulose aerogels from microcrystalline cellulose, spruce wood, and from mixtures of cellulose, lignin, and xylan using an imiic... 

More difficult task is the determination of crystallinity degree of native cellulose located directly in the plant material. To do this, the samples of artificial mixtures containing cellulose, lignin, and hemicelluloses were prepared moreover, the crystalline D-cellobiose was used as crystalline standard and the ball-milled plant material as amorphous standard. Then, X-ray diffractograms of these samples were recorded (loelovich et al., 1989]. As a result, the following equations for calculation of crystallinity degree of native cellulose were derived ... 

It is possible to indentify the ratios of carbohydrates (110-50 ppm), the ratio of aromatics (lignin) (150-130 ppm) and aliphatic acids and sterols (175 ppm, 40-15 ppm) from the spectra. In sample I cellulose signals were dominant, in sample II, on the other hand the aliphatic fractions were the major component. Sample III represented a balanced mixture of all three material groups. It was also possible to indentify the phosphate signal at 0 ppm by means of P-31 spectroscopy. 

Brown Tree bark carbonate Mostly a mixture of cellulose and lignin... 

Wood is a composite material that is made, up basically of a mixture of three main constituents, cellulose, hemicellulose, and lignin (see Textbox 54), all of them biopolymers synthesized by the plants, which differ from one another in composition and structure (see Textbox 58). The physical properties of any type of wood are determined by the nature of the tree in which the wood grows, as well as on the environmental conditions in which the tree grows. Some of the properties, such as the density of wood from different types of trees, are extremely variable, as can be appreciated from the values listed in Table 71. No distinctions as to the nature of a wood, whether it is a hardwood or a softwood, for example, can be drawn from the value of its specific gravity. 

Various solvents are being investigated to dissolve lignocellulosic materials. Some approaches focus on the selective depolymerization and extraction of lignin and hemicellulose as pre-treatment to produce clean cellulose fibers for subsequent fermentation or for pulping. Other approaches attempt to dissolve the whole lignocellulose with or without depolymerization. The liquefaction processes that are carried out at high temperature (>300 °C), and produce a complex oil mixture, are discussed above with the pyrolysis processes. 

Lignocellulose biomass is a mixture of phenolic lignin and carbohydrates -cellulose and hemi-cellulose. It grows abundantly on earth and is largely available as agricultural and forestry residues. Lignocellulose can be converted via four major routes pyrolysis, gasification, hydrolysis and fermentation. 

Another approach to produce chemicals via degraded molecules is the fast pyrolysis of biomass at high temperatures in the absence of oxygen. This gives gas, tar and up to 80 wt.% of a so-called bio-oil liquid phase, which is a mixture of hundreds molecules. Some of compounds produced by pyrolysis have been identified as fragments of the basic components of biomass, viz. lignin, cellulose and hemicellulose. The bio-oil composition depends upon the nature of starting... 

Extraction of the cellulase system. The culture of SSF from each flask (originally 5 g of substrate) was mixed well with more water to bring the final weight of the mixture (mycelium plus unutilized lignin, cellulose, and hemicelluloses) to 100 g. Tween 80 was added at a rate of 0.1%. The mixture was shaken for 0.5 h and centrifuged. The supernatant was used for enzyme determination. We estimated that about 7% to 10% cellulases remained adsorbed on the residues (mycelium and unutilized cellulose, hemicelluloses, and lignin) when the residues were suspended in water and Tween 80 as before and the supernatant was tested for cellulase titer. 

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