COST ACTION FP1205 MADRID 15-16 October 2014
STUDIES COMPARING CELLULOSE NANOFIBERS FROM CURAUA FIBERS BY ENZYMATIC
AND ACID HYDROLYSIS
Ana Carolina Correa1, Adriana de Campos1, José Manoel Marconcini1, David Canella2,
1
3
2*
Luiz Henrique Capparelli Mattoso , Pierre Cassland , Anand R. Sanadi
1 National Nanotechnology
Laboratory for Agriculture (LNNA), Embrapa Instrumentation, P. O. Box 741, CEP: 13560-970, São Carlos – SP – Brazil
2Biomass Science and Technology Group, IGN, Faculty of Science, University of Copenhagen, Rolighedsvej 23, 1958 Frederiksberg, Denmark
3Novozymes A/S, 2880 Bagsvaerd, Denmark:
*Corresponding author: Anand R. Sanadi - Email: [email protected]
INTRODUCTION
The interest in biodegradable and renewable materials has increased tremendously. Cellulose nanofibers have potential for a wide range of application such as a
reinforcing agent in polymers materials which result in environmental benefits due to their biodegradability, renewability, low cost and high efficiency. This paper is a
comparative study of cellulose nanostructures obtained by acid or enzymatic hydrolyses. Whiskers are generally produced by acid hydrolysis with strong acids, to remove the
amorphous regions of the cellulose producing cellulose nanocrystals, whose shapes are like needles. Some studies have shown that cellulose nanofibers (CNF) can be
obtained by using enzymes to digest the outer amorphous part of the cellulose fibers, followed by high mechanical shear, to separate the microfibrils and subsequently the
nanofibrils are isolated, with length on the order of microns and nanometric diameter. The resultant nanofibres appear to have less defects and predicted to have less defects
than the method of producing them by mechanical means. It is possible that this route can result in higher degree of polymerization of the cellulose molecules than whiskers
obtained by strong acid hydrolysis. In our case with enzymes, both whiskers and larger nanofibers were produced, while acid treatment produced only whiskers.
EXPERIMENTAL
Curauá
Raw Fiber
Pre treatment
Mercerization
-NaOH 5%
- 80oC, 60min
Pre-treated
Fiber
FarmCare®-
mainly endoglucanase; Viscozyme
Enzymes provided by Novozymes, Denmark.
L®
Bleaching
acetic acid +
sodium chlorite
- 75oC, 4h
Acid Hydrolysis
- H2SO4 6M
- 45oC, 75min
Enzymatic Hydrolysis*
- FiberCare R® +
Viscozyme L®
- 50oC, 72h
Bleached
Fiber
-Centrifugation
-Dialysis
-Freeze drying
Cellulose
Whiskers
Sonication
-20min
Characterizations
-TEM
- XRD
Cellulose
Nanofiber
Characterizations
-SEM
- TEM
- XRD
* Biomass Load.
2%
Viscozyme FiberCare
100 FBG/g 5000 ECU/g
Enzyme Loading
g/g of biomass
10 g/g
0,033 g/g
Enzyme Activity/
1000 FBG/g 178 ECU/g
g of biomass
-multicomponent enzyme with hemicellase, pectinase activities-
RESULTS
Raw fiber
Bleached fiber
After enzymatic hydrolysis
SEM
Pretreated fiber
Table 1- X Ray Difraction results
Crystallinity Index (%)
After acid hydrolysis
TEM
After enzymatic hydrolysis + sonication
Curauá
Raw
72.9
Pre treated
77.5
Bleached
83.8
Enzymatic reacted
78.5
Acid hydrolysis (H2SO4)
85.0
X Ray Pattern of fibers and nanofibers
Cellulose whiskers (CW) were obtained from acid hydrolysis, presenting a needle like structure with a diameter of 8 ± 1 nm and length of 119 ± 36 nm, resulting in
an aspect ratio of 15, and their crystallinity was 85%.
Enzymatic reactions followed by sonication, resulted in the defibrillation of microfibrils, exposing their nanometric units, producing CNF. TEM micrographs showed
that they present length of microns and diameter of 55 ± 21 nm. XRD results presented a crystallinity of 78.5% after enzymatic reactions suggesting certain damage on
cellulose structure if compared to bleached fiber (84%) before enzymatic reactions. Both needle like whiskers and larger nanofibers were obtained.
CONCLUSION
Alkali and bleaching treatments, and enzymatic reactions were not so effective to Curaua fibers. Sonication was need to obtain nanofibers after the enzymatic reaction,
since the fibers from the enzymatic hydrolysis resulted in larger diametr fibers.
ACKNOWLEDGEMENT
We would like to acknowledge the Danish Science and Technology Foundation for funding The International Network Grant for interaction and exchange of research
staff between Denmark and Brazil. Brazilian foundations FINEP , FAPESP, CNPq and FIPAI. ARS * thanks COST FP 1205 for allowing and partly funding this Presentation.