Multi-scale processes of beech wood disintegration and pretreatment with 1-ethyl-3-methylimidazolium acetate/water mixtures

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Titel: Multi-scale processes of beech wood disintegration and pretreatment with 1-ethyl-3-methylimidazolium acetate/water mixtures

Beteiligte: Viell, Jörn [Verfasser:in]; Inouye, Hideyo [Verfasser:in]; Szekely, Noemi K. [Verfasser:in]; Frielinghaus, Henrich [Verfasser:in]; Marks, Caroline [Verfasser:in]; Wang, Yumei [Verfasser:in]; Anders, Nico [Verfasser:in]; Spiess, Antje C. [Verfasser:in]; Makowski, Lee [Verfasser:in]

Erschienen: BioMed Central, 2016

Sprache: Englisch

DOI: https://doi.org/10.1186/s13068-015-0422-9

ISSN: 1754-6834

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Beschreibung: Background: The valorization of biomass for chemicals and fuels requires efficient pretreatment. One effectivestrategy involves the pretreatment with ionic liquids which enables enzymatic saccharification of wood within a fewhours under mild conditions. This pretreatment strategy is, however, limited by water and the ionic liquids are ratherexpensive. The scarce understanding of the involved effects, however, challenges the design of alternative pretreatmentconcepts. This work investigates the multi length-scale effects of pretreatment of wood in 1-ethyl-3-methylimidazoliumacetate (EMIMAc) in mixtures with water using spectroscopy, X-ray and neutron scattering.Results: The structure of beech wood is disintegrated in EMIMAc/water mixtures with a water content up to 8.6 wt%.Above 10.7 wt%, the pretreated wood is not disintegrated, but still much better digested enzymatically compared tonative wood. In both regimes, component analysis of the solid after pretreatment shows an extraction of few percentof lignin and hemicellulose. In concentrated EMIMAc, xylan is extracted more efficiently and lignin is defunctionalized.Corresponding to the disintegration at macroscopic scale, SANS and XRD show isotropy and a loss of crystallinity inthe pretreated wood, but without distinct reflections of type II cellulose. Hence, the microfibril assembly is decrystallizedinto rather amorphous cellulose within the cell wall.Conclusions: The molecular and structural changes elucidate the processes of wood pretreatment in EMIMAc/watermixtures. In the aqueous regime with >10.7 wt% water in EMIMAc, xyloglucan and lignin moieties are extracted,which leads to coalescence of fibrillary cellulose structures. Dilute EMIMAc/water mixtures thus resemble establishedaqueous pretreatment concepts. In concentrated EMIMAc, the swelling due to decrystallinization of cellulose, dissolutionof cross-linking xylan, and defunctionalization of lignin releases the mechanical stress to result in macroscopicdisintegration of cells. The remaining cell wall ...

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