Influence of Lignin Structural Features on Eucalyptus globulus Kraft Pulping

Abstract

Clones of Eucalyptus globulus Labill. (5- to 7-year-old), from a common geographic area, were evaluated for chemical pulping easiness. Significant variations were observed in the pulp yield and specific wood consumption to produce pulps with similar kappa numbers, as well as in the strength properties of the resulting kraft pulps. Comprehensive lignin analyses were undertaken in an attempt to rationalize the observed differences in these clones’ pulping performance. While lignin content did not correlate with pulp yield, the data reported here provides evidence of the influence of lignin features on the pulping response of different eucalyptus clones. Significant correlations were observed between pulp yield and specific wood consumption and the content of syringyl-type arylglycerol-β-aryl structures (β-O-4 linkages). Furthermore, eucalyptus woods with a greater content of uncondensed β-O-4 linkages were found to require more PFI revolutions to obtain pulps with a given drainability. In contrast, no relationship between pulping efficiency and the other lignin structural features evaluated was apparent, including syringyl/guaiacyl ratio (S/G), total aliphatic and phenolic hydroxyl groups, syringyl and guaiacyl units bearing free phenolic hydroxyls, and the erythro-to-threo ratio of β-O-4 structures. These findings support the use of the content of syringyl-type arylglycerol-β-aryl structures as a selection parameter in clonal breeding programs for pulpwood production.

Determination of Differences in Anatomical and Chemical Characteristics of Tension and Opposite Wood of 8-Year Old Eucalyptus Globulus

“…No statistical difference was found for the amount of guaiacyl units, with similar values found in both tension and opposite wood (350-400 µmoles/g lignin). Similar trends were previously reported for tension wood of other species where low lignin content correlated with high syringyl units (Joseleau et al 2004, Pilate et al 2004, Guerra et al 2008. Ralph et al (2004) and Guerra et al (2008) previously reported a large amount of S units favours the generation of uncondensed aril-ether linkages (high amount of S units and low lignin content also correlated well with high frequency of β-O-4 linkages) which was also observed for the tension wood (46% β-O-4) in comparison with the opposite wood (39% β-O-4).…”

Wood Based Lignin Reactions Important to the Biorefinery and Pulp and Paper Industries

“…Similar results were also reported for various clones of E. grandis and the hybrid of E. grandis × E. urophylla (Gomide et al 2005;Guerra et al 2009). The correlation was not as strong, leading to the suggestion that other lignin structural features, in addition to the S/G ratio, may also play a role (Guerra et al 2009). …”

“…Even within the same species of E. globulus wood, evidence of the influence of S/G ratio on pulp yield and ease of pulping has been reported, leading to the inclusion of lignin S/G ratio as a selection parameter in clonal breeding programs for pulpwood production (González-Vila et al 1999;del Río et al 2005). Similar results were also reported for various clones of E. grandis and the hybrid of E. grandis × E. urophylla (Gomide et al 2005;Guerra et al 2009). The correlation was not as strong, leading to the suggestion that other lignin structural features, in addition to the S/G ratio, may also play a role (Guerra et al 2009).…”

“…While guaiacyl lignin (G) was found in vessels and cell corners, syringyl-guaiacyl lignin (S) was found in the secondary wall of fibers and rays, in which the S/G ratio varied from species to species among hardwoods. More recent studies demonstrated that the S/G ratio varies not only among different species (Akiyama et al 2005;Pinto et al 2005), but also among species of the same genus (Gonzalez-Vila et al 1999;Bose et al 2009), and among clones of the same species (Guerra et al 2009). A correlation has been established between the structural form of the β-O-4 structures found in lignin and the S/G ratio, indicating that the syringyl/guaiacyl composition is the key factor governing the proportion of erythro and threo forms of β-O-4 structure in hardwood lignin (Santos et al 2012c).…”

An exploratory evaluation of the pulpability of Brachystegia spiciformis and Pericopsis angolensis from the angolan miombo woodlands

“…Therefore, B. spiciformis should show a better performance during alkaline pulping procedures due to its lowest lignin content and highest S-type units amount than P. angolensis, in addition to its higher cellulose and alpha-cellulose content. In hardwoods with high pulpability, as E. globulus genotypes, the S/G ratio reported is higher (between 2,0-5,5) while lignin and cellulose contents are in agreement with these values (Guerra et al 2008, Aguayo et al 2015.…”