Kinetics of aqueous extraction of hemicelluloses from spruce in an intensified reactor system

A1 Journal article (refereed)


Internal Authors/Editors


Publication Details

List of Authors: Henrik Grénman, Kari Eränen, Jens Krogell, Stefan Willför, Tapio Salmi, Dmitry Yu. Murzin
Publisher: AMER CHEMICAL SOC
Publication year: 2011
Journal: Industrial & Engineering Chemistry Research
Journal acronym: IND ENG CHEM RES
Volume number: 50
Issue number: 7
Start page: 3818
End page: 3828
Number of pages: 11
ISSN: 0888-5885
eISSN: 1520-5045


Abstract

The aqueous extraction of hemicelluloses has gained increasing interest with new emerging applications for hemicelluloses in the modern forest-based biorefinery concept. The extraction kinetics play a key role in their industrial utilization. The traditional kinetic studies and models for the selective dissolution of softwoods, however, always incorporate high concentrations of sodium hydroxide and sodium sulfide relevant to pulping, and the kinetics in pure water is left outside the scope of these investigations. Aqueous extraction of hemicelluloses from spruce sapwood was investigated with a new cascade reactor setup, which was developed for intensified investigation of solid liquid dissolution kinetics. The experiments were performed at 150-170 degrees C with a particle size of 1.25-2 mm and solid loads of about 6.25 g of dry wood/L in the kinetic regime of intrinsic kinetics. The pH of the liquid phase was measured during the reaction. The selectivity of the dissolution and degradation of hemicelluloses was examined qualitatively. The total concentrations of arabinose (Ara), xylose (Xyl), galactose (Gal), glucose (Glc), mannose (Man), rhamnose (Rha), glucuronic acid (GlcA), 4-O-methylglucuronic acid (4-O-MeGlcA), and galacturonic acid (GalA) were analyzed from the liquid and solid phases during the reaction. The dissolution was observed to be highly temperature dependent, and degradation of the compounds was observed. A kinetic model was developed for the overall extraction of the hemicelluloses. The activation energy was determined to be 135 kJ/mol. No significant influence of the pH on the actual extraction kinetics was observed, even though it influences strongly the degradation of the compounds through hydrolysis.

Last updated on 2019-08-12 at 03:42

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