Alkali-soluble cellulose from cotton

Figure 9. Effect of enzyme components from T. koningii cellulose on the formation of alkali-soluble cellulose from cotton fiber. A reaction mixture consisting of 200 mg of cotton, 2 mL of 0.2 M acetate buffer, pH 4.5, enzyme, water, and NaNs solution to give a total volume of 10 mL, was incubated at 50°C for various times. Percentage hydrolysis was calculated from the loss in weight determined on weighed crucibles. The fraction soluble in alkali (10% NaOH) was determined in a similar fashion after incubating for 3 hr at 25°C. Ct ( - 0) Cx + /3-glucosidase ( - ) ...

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. 

The amorphous or disordered component plays an enormous role in the physicochemical properties of cellulose. Its nature is still poorly defined [66-69] and like crystallites is influenced by physical and chemical treatments as reflected in solubility and reactivity characteristics [14-17]. The alkali solubility of cotton cellulose cannot be correlated entirely with its apparent amorphous content [16]. A regenerated sample prepared from a cuprammonium solution having a 94% amorphous content was totally soluble in 10% NaOH while a powdered cellulose obtained by ball milling to a similar amorphous content (92%) had an alkali solubility of only 58%. 

Cotton is frequently treated with hot alkali in the processes preparatory to dyeing, as well as in the preparation of pure cellulose for research purposes. In the now nearly obsolete process of kier boiling as much as 4% of its cellulose content might be lost as soluble products. The observations that the loss in weight of hydrocelluloses in alkali boiling is directly proportional to the copper number led to the suggestion that short-chain materials were detached from the reducing ends of the hydrocellulose chain molecules and passed into the solution [455]. This was later fully confirmed and the mechanism of the process elucidated [456 64]. 

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