White water extracted lignins

Figure 6.5 Lignin structures identified in extracts from the white water from a newsprint machine.

Sometimes known as the sulfate process, since the sulfur is added as sodium sulfate. It is then reduced to S ° by burning with the evaporated black liquor (lignin and carbohydrate fragments from a previous cook) in an insufficient supply of air. Water extraction yields green liquor , a solution of (largely) sodium sulfide and sodium carbonate and which is treated with slaked lime [Ca(OH)2j. Insoluble calcium carbonate precipitates and the resulting solution of sodium hydroxide and sulfide ( white liquor ) is used for a new cook. 

Isolation and Ozonization of Lignin. The wood meal of white birch (Be-tula papyrifera Marsh.) was steamed for 15 min at 180°C, and extracted with water at 60°C, followed by extraction with methanol as shown in Figure 2. The methanol-soluble part was dried under vacuum after removal of methanol. The yield of methanol extract was 75% based on the amount of lignin present in the original wood. 

In all reactions, wood of white fir Abies concolor) has been used. For the alkaline nitrobenzene reactions, extractive-free —20+40 mesh heart-wood sawdust containing 28.0% Klason lignin was used. Sequential extraction of the original sawdust with alcohol-benzene, 95% ethanol, and hot water gave extractives amounting to 4.9, 0.5, and 1.2%, respectively. In the other oxidation reactions, nominal 5 -in. wood chips, commonly used in pulping procedures, were employed. The mixed sap wood-heart-wood chips contained 26.5% Klason lignin and sequential extractives of 3.3, 0.5, and 3.2%, respectively. 

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