Behavior of Eucalyptus globulus lignin during kraft pulping. I. Analysis by chemical degradation methods

authors	Pinto, PC; Evtuguin, DV; Neto, CP; Silvestre, AJD
nationality	International
journal	JOURNAL OF WOOD CHEMISTRY AND TECHNOLOGY
keywords	STRUCTURAL-CHANGES; RESIDUAL LIGNIN; COOKING; WOOD
abstract	Eucalyptus globulus wood was subjected to kraft pulping, reaching different extents of delignification. The residual and dissolved lignins were isolated by soft acidolysis and acidic precipitation, respectively, and submitted to analysis of residual sugars and methoxyl groups, as well as to analysis by nitrobenzene and permanganate oxidation and thioacidolysis. Results from both residual and dissolved lignins analyses indicated that in the initial phase of pulping there is a preferential removal of lignin enriched in guaiacylpropane (G) and p-hydroxyphenylpropane (H) units, which is highly condensed and bonded with polysaccharides, predominantly with xylan. During the bulk and residual phases of pulping, lignin enriched in syringylpropane (S) units is progressively removed, leading to the increase or S/G ratio of black liquor lignin. After a purification step of dissolved lignins, two fractions with distinct levels of carbohydrates and with different Structural features were obtained. The overall results were interpreted in terms of the topochemistry of the kraft pulping process.
publisher	TAYLOR & FRANCIS INC
issn	0277-3813
year published	2002
volume	22
issue	2-3
beginning page	93
ending page	108
digital object identifier (doi)	10.1081/WCT-120013355
web of science category	Materials Science, Paper & Wood
subject category	Materials Science
unique article identifier	WOS:000177850600002