Lignin treatment

ION RADICAL ROUTES TO LIGNIN TREATMENT 7.6.1 Paper Fabrication... 

Figure 8. Partial spectra of high MW fractions of 140 °C lignin treatments in the presence of a. control b. unlabeled guaiacyl model VII c. 7-labeled guaiacyl model VII d. 7-labeled veratryl model VIII.

Kind of Composite Lignin treatment n Tensile strength in N/mm Young s modulus in N/mm Elongation at break in % n Charpy impact strength in kJ/m ... 

Figure 7. Young s modulus of the lyocell-PLA composites with lignin treatment reinforced with 20 and 40 mass% (mean values, standard deviations are shown as error bars dots show the dimension of the fiber diameter).

Conversion of Aromatic Rings to Nonaromatic Cyclic Structures. On treatment with oxidants such as chlorine, hypochlorite anion, chlorine dioxide, oxygen, hydrogen peroxide, and peroxy acids, the aromatic nuclei in lignin typically ate converted to o- and -quinoid stmctures and oxinane derivatives of quinols. Because of thein relatively high reactivity, these stmctures often appear as transient intermediates rather than as end products. Further reactions of the intermediates lead to the formation of catechol, hydroquinone, and mono- and dicarboxyhc acids. 

Cleavage of Carbon—Carbon Bonds. Under appropriate conditions, the propanoid side chain in lignin maybe mptured to form three-, two-, or one-carbon fragments. This carbon—carbon fragmentation occurs in a variety of laboratory treatments and technical processes such as in bleaching of chemical pulps with CI2, CIO2, and O2, in microbial degradation (15), and in photooxidation (16). 

Phosphate—Polymer Control. Phosphate treatment results are improved by organic supplements. Naturally occurring organics such as lignins, tannins, and starches were the first supplements used. The organics were added to promote the formation of a fluid sludge that would settle in the mud dmm. Bottom blowdown from the mud dmm removed the sludge. 

Further Preparative Reactions. When pulps are to be used in the production of materials that do not retain the original fiber stmcture, such as rayon or ceUulose acetate film, the lignin, hemiceUulose, and other components must be reduced to the lowest possible concentrations. A surfactant (ionic or nonionic) is often added during a hot, weakly alkaline extraction step after chlorination. Another approach, sometimes used in addition to the surfactant step, is to treat the pulp with 6—10% NaOH after most of the oxidative bleaching is finished. This treatment removes most of the hemiceUulose. In most purification plants the final stage includes use of sulfuric acid chelators are optional. 

Sodium chlorite has also been used for treatment and removal of toxic and odorous gases such as hydrogen sulfide and mercaptans. Chlorine dioxide from chlorite is also useful for microbial and slime control in paper mills and alkaline paper machine systems (164,165). The use of sodium chlorite in textile bleaching and stripping is well known. Cotton is not degraded by sodium chlorite because the oxidation reactions are specific for the hemiceUulose and lignin components of the fibers. 

Group of plastics composed of resins formulated from the treatment of lignin with heat or by reaction with chemicals. 

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