Dissolution experiments cellulose

The developed paracrystalline layers contribute also to dissolution of cellulose samples. Dissolution experiments with samples of pure cellulose showed that increasing of p-value leads to enhance of cellulose solubility in the solvents (loelovich et al., 2010). 

Most experiments were performed with cotton or cotton linters as highly crystalline celluloses. Table I shows conditions leading to complete dissolution. A minimum amount of an acid which forms a cellulose ester (sulfuric or trifluoromethylsulfuric acid) (Entries 5 7-14) is necessary for the reaction. The dissolution is accelerated by a temperature increase (Entries 10-12 13, 14) and leads to water-soluble cellulose acetate hydrogensulfate. Whereas this primary hydrolysis can be achieved within 1-5 min, the deesterification and complete hydrolysis of the soluble cellulose derivative proved to be much more difficult. This is in contrast to the generally accepted view that the main resistance to the hydrolysis of cellulose lies in the crystalline nature or low accessibility determining the heterogeneous first step of the reaction. 

The combined action of xylanase and mannanase on sprucewood holocellulose increased the hydrolysis of hemicelluloses without any detectable attack of cellulose. At the end of the experiments—i.e., after 48 hr of xylanase incubation followed by 32 hr of combined xylanase-mannanase incubation—about half the hemicelluloses present in the starting material were selectively converted into low-molecular-weight sugars. The amount of mannan removed was two times higher than after 80 hr of incubation with mannanase only. Unexpectedly, the xylan dissolution was scarcely increased by the combined action of the two hemicellulases. 

For the determination of antimony, the digestion efficiency of particulate matter, collected on Whatman 41 cellulose filters, was evaluated by means of radiotracer experiments [6], A quantitative recovery was obtained using 8 ml sulfuric acid and 4 ml hydrogen peroxide, when applied to a quarter fraction of the filter. For the dissolution of residual silicates 0.5 to 4 ml of hydrofluoric acid were added, which were later on evaporated. After digestion the solution was filtered if needed and diluted appropriately. 

One possible explanation for these different modes of cellulose depolymerization in the same species of wood is that the cellulolytic enzyme molecules of Poria monticola are smaller than those of Polyporus versicolor and for that reason would be able to penetrate and act in regions of the fine structure of the fibers that are not accessible to those of the latter fungus. This hypothesis has led to efforts (as yet incomplete) to determine the molecular size of the cellulolytic enzyme proteins of these two organisms. Another possible explanation is that the initial dissolution of cellulose and other cell-wall polysaccharides is accomplished by catalysts that are not enzyme proteins and therefore could be substantially smaller in molecular size. Halliwell (21) has described experiments on the... 

Electrospun bacterial cellulose fibers have been produced by first achieving dissolution in l-allyl-3-methylimidazolium chloride at 5% bacterial cellulose at 70°C. This experiment also involved the production of electrospim composite fibers with M WCNT [148], as is discussed further below. 

Many experiments with production, dissolution, and regeneration of bacterial cellulose extracted from nata-de-coco were reported (Valla 2008 Pandey et al. 2014) (see Chap. 3). 

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