Lazko cellulose nanocrystal extraction with ionic liquids - poster - biopol 2017 vfinal

1. CELLULOSE NANOCRYSTAL EXTRACTION WITH IONIC LIQUIDS
Jevgenij Lazko, Tangi Sénéchal, Yoann Paint, Lisa Dangreau, Jean Marie Raquez, Philippe Dubois
jevgenij.lazko@materianova.be
Materia Nova, Laboratory of Polymeric and Composite Materials (SMPC), Avenue Copernic 1, 7000 Mons, Belgium
Center of Innovation and Research in Materials & Polymers (CIRMAP), University of Mons (UMons), Place du Parc 23, 7000 Mons, Belgium
Copyright : photo © Denis Lecuyer
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N N
Cl
+
N N
+
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HSO4
SO3H
REFERENCES
1. R.P. Swatloski, S.K. Spear, J.D. Holbrey, R.D. Rogers, Dissolution of Cellulose with Ionic Liquids. J Am Chem Soc.
2002, 124(18), 4974-4975. 2. J. Lazko, T. Sénéchal, N. Landercy, L. Dangreau, J.-M. Raquez, P. Dubois. Well defined
thermostable cellulose nanocrystals via two-step ionic liquid swelling-hydrolysis extraction. Cellulose. 2014, 21(6), 4195-
4207. 3. J. Lazko, T. Sénéchal, A. Bouchut, Y. Paint, L. Dangreau, A. Fradet, M. Tessier, J.M. Raquez, P. Dubois. Acid-free
extraction of cellulose type I nanocrystals using Brønsted acid-type ionic liquids. Nanocomposites. 2016, 2(2), 65-75.
INTRODUCTION
Due to their unique morphological, physical and chemical properties, cellulose
nanocrystals (CNCs) represent a great potential as fillers in renewable and sustainable
polymeric matrices. Traditional CNC extraction route, with highly concentrated sulfuric
acid, can be successfully applied to a variety of cellulosic raw materials. It requires
however supplementary water, energy and time-consuming purification steps and results,
above all, in grafting residual sulfates negatively impacting CNC thermal stability.
Therefore, alternative CNC extraction methods based on Ionic Liquids (ILs) have recently
gained an increasing interest.
Some imidazolium-based ILs such as 1-butyl-3-methylimidazolium chloride [BMIM]Cl
showed exceptional abilities to dissolve cellulose [1]. An extensive dissolution certainly
leads to major structural changes such as crystallinity loss and conversion of native
cellulose type I to regenerated cellulose type II. But a controlled swelling of cellulosic
fibres could provide both the enhancement of the substrate accessibility and the
preservation of the cellulose type I crystalline regions.
Other imidazolium-based ILs such as 1-butyl-3-
methylimidazolium hydrogen sulfate [BMIM]HSO4, and 1-(4-
sulfobutyl)-3-methylimidazolium hydrogen sulfate [SBMIM]HSO4
were successfully used for extensive hydrolysis of cellulose to
valuable chemicals and products such as reducible
monosaccharides. Following the same logic, a controlled partial
hydrolysis in mild conditions, removing preferentially amorphous
regions, could lead to extraction of nano-scale crystallites still
presenting the intrinsic cellulose morphology. This strategy,
conceptualized in figure 2, has been recently investigated in
Materia Nova Research Center, proposing innovative two-step
swelling/hydrolysis routes for the extraction of CNCs [2, 3].
RESULTS AND DISCUSSION
During the first step, a controlled swelling of pure cotton
cellulose fibres was achieved in [BMIM]Cl, adjusting parameters
such as temperature, time, substrate concentration, water
content, stirring conditions. The hydrolysis step was then
initiated by the addition of H2SO4 aqueous solution. The
controlled swelling considerably increased the accessibility of the
substrate improving acid hydrolysis kinetics, so it was possible to
extract rod-like cellulose type I nanocrystals with average
diameter and length around 20 and 300 nm even under mild acid
conditions, using up to 60 times less sulfuric acid than the
traditional extraction methods [2]. Moreover, according to XPS
and TGA results, the surface of such extracted CNCs proved to
be less contaminated with residual sulfate groups, leading to
higher thermal stability.
CNC extraction can be also successfully achieved in a single
[BMIM]Cl/[SBMIM]HSO4 reaction medium, without the use of
sulfuric acid or any other mineral acid [3]. As two ILs were
always together in the reaction medium, the water content was
the essential parameter inducing the switch between swelling
and hydrolysis stages, directly impacting nanoparticle
morphology, crystallinity evolution and cellulose type I to type II
denaturation, according to XRD and FEG-SEM observations.
Finally, the recovery of the ILs with yields reaching 95% was
achieved by centrifugation, filtration, and liquid–liquid extraction
with ethyl acetate/water biphasic system, and confirmed by FTIR
and 1H NMR analyses.
CONCLUSIONS AND PROSPECTS
Ionic liquids such as [BMIM]Cl and [SBMIM]HSO4 showed a huge potential for
extraction of well-defined, highly crystalline, pure and thermo-stable
cellulose type I nanocrystals via two-step swelling-hydrolysis route. The
recovery and reuse of ILs were demonstrated for several consecutive CNC
extractions, validating prospects of conception of multi-cycle environmentally
and economically viable processes.
5 10 15 20 25 30 35 40
2 Theta [°]
0 % [SBMIM]HSO4
1 % [SBMIM]HSO4
2 % [SBMIM]HSO4
4 % [SBMIM]HSO4
Cellulose type II
Cellulose type I
X-ray diffractograms of cellulose nanoparticles extracted in different
[BMIM]Cl/[SBMIM]HSO4 media and aspect of the final CNCs aqueous
suspension exhibiting flow birefringence phenomena
ACKNOWLEDGEMENTS
This research is supported by the
European Union and Wallonia with
the European Funds for Regional
Development FEDER 2007-2013
and 2014-2020