The Southern Forest Biorefinery project, directed by Professor Art Ragauskas, has extracted hemicellulose from Loblolly pine wood chips, and duplicated the pulp’s pre-extracted strength and quality by adjusting cooking conditions. This will be of interest to those seeking to produce byproducts from hemicellulose without disrupting existing pulp mill operations using Loblolly pine furnish.

Linerboard grade kraft pulp and bleach grade pulp were made from the Loblolly pine woodchips and the hemicelluloses pre-extracted. In order to obtain pulp quality and strength similar to the pulp from the non-extracted woodchips, the cooking conditions for the hemicellulose pre-extracted Loblolly pine woodchips were alleviated either by reducing the H-Factor or by decreasing the chemical charges. 

The objective of this DOE-funded project is to facilitate the conversion of southern softwoods (principally Loblolly pine) into pulp, paper, bioenergy and biofuels. During the initial stages of our studies Loblolly pine residues, bark and woodchips were collected from a forestry site in Macon, GA. The chemical compositions in these biomasses were determined upon receiving the samples. The fundamental structure of lignin (tannins for bark) and cellulose isolated from these biomasses were further analyzed for molecular weight determinations. In addition, the sugar profiles in the hemicellulose and chemical structure of extractives were established

The Loblolly pine residues were then pretreated with dilute H2SO4 and SO2. These processes were optimized to facilitate subsequent enzymatic deconstruction to simple sugars and fermentation for bioethanol production. Meanwhile, the hemicelluloses were partially extracted from Loblolly woodchips with the use of additive (borate) under alkali conditions. This hemicellulose pre-extraction process was also optimized to remove hemicelluloses without significantly degrading subsequent pulp properties. Since the isolated hemicelluloses were rich in glucomannans, they were further deconstructed to monosaccharides with the application of mannanase and finally fermented to bioethanol with yeast.  With modification of cooking conditions by reducing the H-factor or decreasing the chemical charge, pulp strength and quality similar to unextracted pulps were achieved.

For further information, contact Art.Ragauskas@IPST.GaTech.edu.