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@ARTICLE{Viell:280498,
author = {Viell, Jörn and Inouye, Hideyo and Szekely, Noemi K. and
Frielinghaus, Henrich and Marks, Caroline and Wang, Yumei
and Anders, Nico and Spiess, Antje C. and Makowski, Lee},
title = {{M}ulti-scale processes of beech wood disintegration and
pretreatment with 1-ethyl-3-methylimidazolium acetate/water
mixtures},
journal = {Biotechnology for biofuels},
volume = {9},
number = {1},
issn = {1754-6834},
address = {London},
publisher = {BioMed Central},
reportid = {FZJ-2016-00266},
pages = {7},
year = {2016},
abstract = {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
constituents of lignin and hemicellulose, however, limit a
recrystallizationof the solvated cellulose. These
pretreatment mechanisms are beyond common pretreatment
concepts and pavethe way for a formulation of mechanistic
requirements of pretreatment with simpler pretreatment
liquors.Keywords: Ionic liquid, Lignocellulose, EMIMAc, XRD,
SANS, Pretreatment, Crystallinity, Disintegration,
Microfibrils},
cin = {JCNS (München) ; Jülich Centre for Neutron Science JCNS
(München) ; JCNS-FRM-II / Neutronenstreuung ; JCNS-1},
ddc = {570},
cid = {I:(DE-Juel1)JCNS-FRM-II-20110218 /
I:(DE-Juel1)JCNS-1-20110106},
pnm = {6G15 - FRM II / MLZ (POF3-6G15) / 6G4 - Jülich Centre for
Neutron Research (JCNS) (POF3-623)},
pid = {G:(DE-HGF)POF3-6G15 / G:(DE-HGF)POF3-6G4},
experiment = {EXP:(DE-MLZ)KWS2-20140101},
typ = {PUB:(DE-HGF)16},
UT = {WOS:000367708400001},
doi = {10.1186/s13068-015-0422-9},
url = {https://juser.fz-juelich.de/record/280498},
}