Preprint Article Version 1 This version is not peer-reviewed

Heat-Induced Discoloration of Chromophore Structures in Eucalyptus Lignin

Version 1 : Received: 13 July 2018 / Approved: 16 July 2018 / Online: 16 July 2018 (12:45:03 CEST)

A peer-reviewed article of this Preprint also exists.

Zhang, P.; Wei, Y.; Liu, Y.; Gao, J.; Chen, Y.; Fan, Y. Heat-Induced Discoloration of Chromophore Structures in Eucalyptus Lignin. Materials 2018, 11, 1686. Zhang, P.; Wei, Y.; Liu, Y.; Gao, J.; Chen, Y.; Fan, Y. Heat-Induced Discoloration of Chromophore Structures in Eucalyptus Lignin. Materials 2018, 11, 1686.

Journal reference: Materials 2018, 11, 1686
DOI: 10.3390/ma11091686

Abstract

The color changes corresponding to chromophore structures in lignin caused by exposure of Eucalyptus(Eucalyptus grandis and E. urophylla)to heat were investigated. Eucalyptus wood samples were heated in saturated steam atmospheres for 10 h at 110℃, 130℃, and 150℃. The lignin was isolated before and after heat treatment. The physicochemical properties of the lignin and changes in chromophore structures during heat treatment was evaluated through wet chemical analysis, FTIR, UV-Vis, GPC, XPSand 13C-NMR. The color of the wood became darker and redder with the increase in pressure and temperature. Depolymerization and dehydration reactions occurred via demethoxylation with heat treatment in saturated steam at 110℃ or 130℃. Lignin condensed to form insoluble compounds after heat treatment in saturated steam at 150℃. G units increased and S units decreased through demethylation during heat treatment, as revealed by FTIR and 13C-NMR analysis.

Subject Areas

heat-induced; wood discoloration; Eucalyptus; lignin; chromophore system.

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