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Please use this identifier to cite or link to this item: http://hdl.handle.net/10261/35167
Title: Lignin modification during Eucalyptus globulus kraft pulping followed by totally chlorine free bleaching: a two dimensional nuclear magnetic resonance, Fourier transform infrared, and pyrolysis-gas chromatography/mass spectrometry study
Authors: Ibarra, David; Chávez Uribe, María Isabel; Rencoret, Jorge ; Río Andrade, José Carlos del ; Río Andrade, José Carlos del ; Gutiérrez Suárez, Ana ; Romero Sánchez, Javier; Camarero, Susana; Martínez Hernández, María Jesús; Jiménez-Barbero, Jesús; Martínez, Ángel T.
Keywords: Lignin structure
Analytical pyrolysis
Infrared spectroscopy
Eucalyptus globulus
Kraft pulping
Totalli chlorine free bleaching
Paper pulp residual lignin
Issue Date: 2007
Publisher: American Chemical Society
Citation: Journal of Agriculture and Food Chemistry 55:3477-3490 (2007)
Abstract: Chemical modification of eucalypt lignin was investigated during kraft pulping and chlorine-free bleaching by comparing milled-wood lignin, kraft lignin, and enzymatic residual lignins. The syringyl-to-guaiacyl ratio (S/G) from analytical pyrolysis slightly changed during pulping and bleaching (S/G 3-4) but was much higher in the kraft lignin. Semiquantitative HSQC NMR showed that the relative amount of β-O-4' (around 80% side-chains) and resinol-type substructures (around 15%) was only slightly modified during pulping and oxygen delignification. Other minor inter-unit linkages and terminal units were also detected. However, a decrease of resinol substructures (to only 6%) was found after alkaline-peroxide bleaching. The relative amount of surviving linkages in the highly-phenolic kraft lignin was dramatically modified, resinols being predominant. Oxygen delignification did not change inter-unit linkages, but an increase of oxidized units was found in the HSQC aromatic region, in agreement with the higher amount of pyrolysis markers with oxidized side-chains. HMBC NMR correlations showed that the oxidized units after oxygen delignification bore conjugated ketone groups, and conjugated carboxyls after peroxide bleaching. Presence of xylan and lignin-carbohydrate linkage signals was shown by the HSQC spectra of pulp lignins
Description: Centro de Investigaciones Biológicas, CSIC, Ramiro de Maeztu 9, E-28040 Madrid, Spain, Instituto de Química, UNAM, Ciudad Universitaria, Coyoacán, CP 04510, México, DF, Instituto de Recursos Naturales y Agrobiología, CSIC, PO Box 1052, E-41080 Seville, Spain, CIT, ENCE, Ctra. Campañó, Ribeiro Vao, E-36157 Pontevedra, Spain; E-mail address: ATMartinez@cib.csic.es (A.T.Martínez
URI: http://hdl.handle.net/10261/35167
DOI: http://dx.doi.org/10.1021/jf063728t
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