title: Reactivity of syringyl and guaiacyl lignin units and delignification kinetics in the kraft pulping of Eucalyptus globulus wood using Py-GC-MS/FID.
abstract: Eucalyptus globulus sapwood and heartwood showed no differences in lignin content (23.0% vs. 23.7%) and composition: syringyl-lignin (17.9% vs. 18.0%) and guaiacyl-lignin (4.8% vs. 5.2%). Delignification kinetics of S- and G-units in heartwood and sapwood was investigated by Py-GC-MS/FID at 130, 150 and 170°C and modeled as double first-order reactions. Reactivity differences between S and G-units were small during the main pulping phase and the higher reactivity of S over G units was better expressed in the later pulping stage. The residual lignin composition in pulps was different from wood or from samples in the initial delignification stages, with more G and H-units. S/G ratio ranged from 3 to 4.5 when pulp residual lignin was higher than 10%, decreasing rapidly to less than 1. The S/H was initially around 20 (until 15% residual lignin), decreasing to 4 when residual lignin was about 3%.
authors.affiliation: Forest Research Center, School of Agriculture, Technical University of Lisbon, Tapada da Ajuda, 1349-017 Lisbon, Portugal. analourenco@isa.utl.pt
authors.forename: Ana
authors.initials: A
authors.lastname: Lourenço
authors.forename: Jorge
authors.initials: J
authors.lastname: Gominho
authors.forename: António Velez
authors.initials: AV
authors.lastname: Marques
authors.forename: Helena
authors.initials: H
authors.lastname: Pereira
mesh_terms: D005052:Eucalyptus / Q000737:chemistry*; D005410:Flame Ionization; D008401:Gas Chromatography-Mass Spectrometry / Q000295:instrumentation / Q000379:methods*; D007700:Kinetics; D008031:Lignin / Q000737:chemistry*; D008956:Models, Chemical; D010209:Paper; D013696:Temperature; D014934:Wood / Q000737:chemistry*
chemical_list: D008031:Lignin