Kinetics of fractionation by SO2–ethanol–water (SEW) treatment: understanding the deconstruction of spruce wood chips

Mikhail Iakovlev; Adriaan van Heiningen

doi:10.1039/C2RA00957A

Kinetics of fractionation by SO₂–ethanol–water (SEW) treatment: understanding the deconstruction of spruce wood chips†

Mikhail Iakovlev^a and Adriaan van Heiningen*^ab

Author affiliations

* Corresponding authors

^a Aalto University School of Chemical Technology, Department of Forest Products Technology, POB 16300, Aalto, Finland

^b University of Maine, Department of Chemical and Biological Engineering, 5737 Jenness Hall, Orono, ME, USA
E-mail: AvanHeiningen@umche.maine.edu
Fax: 1-207-5812323
Tel: 1-207-5812278

Abstract

The kinetics of SO₂–ethanol–water (SEW) fractionation of spruce were studied using wood meal and chips and compared to those of SO₂–water, acid sulfite (AS) and ethanol–acid sulfite treatment. The SEW lignin removal rate was found to be similar to that of AS at the same free SO₂ concentration, while the lignin sulfonation rate is considerably higher for the acid sulfite systems. No relation between acidity and sulfonation rate was observed putting into question the acid-catalysed nature of this reaction. The observed SEW sulfonation and delignification patterns are consistent with Hägglund's “fast sulfonation–slow hydrolysis” consecutive scheme. The data indicate that during the initial phase hemicelluloses are removed together with lignin as lignocarbohydrate complexes, while cellulose is protected from hydrolytic attack by lignin leading to a lower hydrolysis rate. The SEW hemicellulose dissolution behaviour can be understood by the low tendency of glucomannan to “crystallise” onto cellulose. The understanding of the dissolution pattern of lignin and hemicellulose may help to interpret the enzymatic hydrolysis behaviour of SEW residual solids subjected to different degree of fractionation.

$Graphical abstract: Kinetics of fractionation by SO2–ethanol–water (SEW) treatment: understanding the deconstruction of spruce wood chips$

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Article information

DOI: https://doi.org/10.1039/C2RA00957A
Article type: Paper
Submitted: 25 Oct 2011
Accepted: 08 Jan 2012
First published: 20 Feb 2012

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RSC Adv., 2012,2, 3057-3068

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Kinetics of fractionation by SO₂–ethanol–water (SEW) treatment: understanding the deconstruction of spruce wood chips

M. Iakovlev and A. V. Heiningen, RSC Adv., 2012, 2, 3057 DOI: 10.1039/C2RA00957A

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