Lignin kraft

Typical compositions for softwood and hardwood kraft blackhquors are shown in Table 10. Most commercial kraft lignins are sulfonated kraft lignins or lignin amines. A few nonsulfonated products are, however, available. 

The aromatic rings of kraft lignins can be sulfonated to varying degrees with sodium sulfite at high temperatures (150—200°C) or sulfomethylated with formaldehyde and sulfite at low temperatures (<100° C). Oxidative sulfonation with oxygen and sulfite is also possible. 

Many of the chemical reactions used to modify lignosulfonates are also used to modify kraft lignins. These include ozonation, alkaline—air oxidation, condensation with formaldehyde and carboxylation with chloroacetic acid (100), and epoxysuccinate (101). In addition, cationic kraft lignins can be prepared by reaction with glycidjiamine (102). 

The physical and chemical properties of kraft lignin differ greatly from those of lignosulfonates. A summary of these differences is presented in Table 11. 

Applications of Kraft Lignins. Because of the high fuel value of black Hquor, kraft lignin products are generaUy used in high value... 

Lignins are most usually employed as various types of sodium lig-nosulfonate and are products of sulfite pulping. (Kraft lignins from the Kraft pulping process are also available.) They are used as dispersants, binders, sequestrants, and emulsifiers. Sodium lignosulfonate product variables include color, MW, and the degree of carboxylation and sulfonation on the lignin backbone. 

Once lignin is separated from other plant products, it is not now widely used in resource recovery. Extensive studies on the modification of lignin have been made(24) because of the enormous mass of kraft lignin produced each year by the pulp and paper... 

Chaudhari, S.T., Ferdous, D., Dalai, A.K, Bej, S.K, Thring, R.W., and Bakhshi, N.N. (2000). Pyrolysis and Steam Gasification of Westvaco Kraft Lignin for the Production of Hydrogen and Medium Btu Gas, Abstracts Progress in Thermochemical Biomass Conversion, Tyrol, Austria, 17-22 September. 

Kraft chemical pulp process, 13 94 Kraft lignins, 15 19-20 applications of, 15 19-20 Kraft paper process... 

Sulfonated cation exchangers, 14 402 Sulfonated DNA probe, 14 153-154 Sulfonated kraft lignins, 15 20 toxicology of, 15 20... 

Two Streptomyces strains, S. badius and S. viridosporus, were found to be able to grow on kraft lignin (In-dulin ATR) as sole carbon source. The resulting APPL (Acid Precipitable Polymeric Lignin) was characterized by FTIR and elemental analysis for C, H and N, and was found to contain proteins in addition to a relatively demethoxylated lignin component. The proteins were further characterized by amino acid analysis, while the lignin component was separated by solvent extraction and its molecular weight distribution determined by HPSEC. 

In this paper, we report on the bacterial growth of S. badius and S. viridosporus with Indulin ATR, a commercial kraft lignin practically free of sugars, as sole carbon source and on the characterization of the APPL derived from this degradation. 

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