Lignin extraction from kraft black liquor by ultrafiltration
Extn. of lignin from kraft black liquor is one method of lowering the large energy surplus in pulp mills. The lignin can be used as a bio-fuel to replace fossil fuels in heat or power generation, and the lignin-depleted black liquor can be reused in the cooking operation. As kraft black liquor lignin has a fairly high mol. wt., ultrafiltration can be used to selectively fractionate lignin from coo