Effect of Structural Features of Wood Biopolymers on Hardwood Pulping and Bleaching Performance

Abstract

Industrial hardwoods such as Eucalyptus species, Betula pendula, and Acacia mangium required different chemical charges during kraft pulping and presented distinct profiles of polysaccharides removal. The corresponding kraft pulps showed different chlorine dioxide consumption during bleaching. Woods and corresponding kraft pulps were characterized by chemical methods, 1 H and 13 C NMR spectroscopy, X-ray diffraction analysis, and gel permeation chromatography. The ease of lignin degradation and dissolution was essentially determined by differences in the proportion of syringyl and guaiacyl units and in the degree of condensation. The bleaching response was shown to be related also to the content of β-O-4 structures in the residual lignin. The relative stability of xylans during the pulping was suggested to be associated with differences in structure and molecular weight. The higher retention of Eucalyptus xylans was attributed essentially to their peculiar structure, including O-2-substituted uronic acid groups linked to other cell wall polysaccharides.

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

“…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).…”

Comparison of Py-GC/FID and Wet Chemistry Analysis for Lignin Determination in Wood and Pulps from Eucalyptus globulus

“…The Klason lignin of the pulps produced at 150 ºC and 170 ºC after 180 min were around 1%, whereas Pinto et al (2005) obtained 1.3% for E. globulus pulps. The residual lignin in pulps is usually determined as Kappa number in the industry and research laboratories to evaluate the performance of the kraft cook (Gellerstedt 2009).…”

Determination of Arylglycerol−β-Aryl Ether Linkages in Enzymatic Mild Acidolysis Lignins (EMAL): Comparison of DFRC/31P NMR with Thioacidolysis

“…Progressive mechanical treatments are known to lead to the formation of increasing amounts of disordered cell wall material, which is rapidly digested by cellulase enzymes, facilitating lignin extraction from wood. 9,31 Consequently, the longer the milling time is, the higher the EMAL yields are (Figure 2), although both yields and milling requirements have been shown to be wood specific. 15,16 Under the conditions applied in this study, the yields of almost all EMALs isolated from woods milled for 28 days were greater than 53%.…”

“…While gas chromatography (GC) was used to determine the monomer yields from both thioacidolysis and DFRC, 31 P NMR studies quantified the various phenolic hydroxy groups released by DFRC. The monomer yields from thioacidolysis and DFRC were substantially different, with thioacidolysis resulting in higher yields.…”