Effect of Lignin Carbohydrate Complexes of Hardwood Hybrids on the Kraft Pulping Process

Lignin-carbohydrates complexes influence many chemical properties in the wood, such as difficult-to-remove lignin from Kraft pulps at the end of pulping due to the occurrence of lignin carbohydrates bonds. Therefore, this study aimed to study the influence of lignin-carbohydrate complexes on eucalyptus Kraft pulping. Spectroscopic techniques (C-13 NMR and HSQC-2D) were applied for the determination and quantification of lignin-carbohydrate complex (LCC) structures, and then evaluated the effect of LCC on Kraft pulping of eucalyptus hybrids. The analytical tools allowed the identification and quantification of the benzyl ether, -ester, and phenyl glucoside linkages of the lignin-carbohydrate complexes in eucalyptus hybrid wood. The glycosidic phenyl and -ester linkages are, respectively, more and less significant from the quantitative point of view. Analysis of C-13 NMR of the samples showed that the eucalyptus hybrid GxGL contained high -O-4 linkages content and also higher pulping yield than the other samples, suggesting that the linkages between lignin are more important than LCC linkages in pulping.