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Drying cellulose - based materials
containing copper nanoparticles
Tuhua ZHONG, PhD Student
Gloria S. OPORTO, Assistant Professor
Division of Forestry and Natural Resources,
West Virginia University, Morgantown, WV 26506, USA
58th SWST International Convention
June 7-12, 2015, Jackson Lake Lodge
Jackson, Wyoming
Overview
Long-Term Goal – Introduction
Main Goal of this work
Work performed
Results & Discussion
Conclusions
Long - term goal
To promote the utilization of
nanocellulose in areas of high economic
and social impact.
Introduction
Nanocellulose
nanofibrilated cellulose (NFC) &
Nanocrystalline cellulose (NCC)
Webinar: Cellulose Nanofibers (CNF),
VTT Technical Research Centre of Finland May 29, 2015
nanofibrilated cellulose (NFC) or CNF
Webinar: Cellulose Nanofibers (CNF),
VTT Technical Research Centre of Finland May 29, 2015
Introduction
Non-toxic, highly available, biodegradable, renewable, biocompatible, high specific surface area, and feasible to be chemically modified.
Nanocellulose
Application of nanocellulose:
High value added – Functionalization
Introduction
Copper nanoparticles as antimicrobial material
synthesized in situ on cellulose-based materials.
Application of nanocellulose:
Wet (papermaking) Dry (ex. in combination with thermoplastic resins)
optimizing drying processes, dispersability, process adaptability.
Introduction
Drying cellulose / nanocellulose
Introduction
Air Oven Spray drying
(atomization of liquid droplets-contact of the droplets with hot drying gas)
Freeze drying (removing water from a frozen sample by sublimation and desorption under vacuum)
Solvent exchange – Freeze drying(less hydrophilic liquid (typically an alcohol) reduces the capillary stresses during the drying
process)
Main goal of this work
For hybrids cellulose-based materials and copper nanoparticles…
Zhong T., Oporto G.S., Peng Y., Xie X., Gardner D.J. 2015. Drying cellulose-based materials containing
copper nanoparticles. Cellulose DOI 10.1007/s10570-015-0646-7.
Investigate the effect of spray drying, freeze drying and two
solvent exchange pretreatments previous to a freeze drying
process on their morphology, particle size, crystallinity and copper
state of oxidation.
Raw material:
• Carboxymethyl cellulose (CMC)
(average molecular weight: 90,000)
• TEMPO nanofibrillated cellulose (TNFC) (0.67 wt. %)
from the Forest Product Laboratory, Madison, WI.
Work performed
Preparation of hybrid materials:
• Carboxymethyl cellulose (CMC) - copper nanoparticles
• TEMPO nanofibrillated cellulose (TNFC) - copper
nanoparticles
Work performed
Zhong T., Oporto G.S., Jaczynski J. Tesfai A. and J. Armstrong. 2013. Antimicrobial properties of the hybrid
copper nanoparticles-carboxymethyl cellulose. Wood Fiber Sci. 45(2) 1-8.
Zhong T., Oporto G.S., Jaczynski J., Jiang Ch. 2015. Nanofibrillated cellulose and copper nanoparticles
embedded in polyvinyl alcohol films for antimicrobial applications. Biomed Research International Article ID
456834.
Drying processes:
• Spray drying (UMaine - Mini Spray Dryer)
• Freeze drying process
• Modified freeze drying process (solvent exchange
processes Ethanol-1Butanol & Ethanol-tertButanol)
Work performed
Characterization:
• SEM-EDX
• Laser diffraction
• Inductively coupled plasma-optical emission
spectroscopy (ICP-OES)
• XPS
• XRD
Work performed
SEM IMAGES OF SPRAY DRIED MATERIALS
CMC: a) spray dried, b) freeze dried
a) b)
Results & Discussion
SEM IMAGES OF SPRAY DRIED MATERIALS
CMC-copper nanoparticles: c) spray dried, d) freeze dried
c) d)
SEM IMAGES OF SPRAY DRIED MATERIALS
TNFC: e) spray dried, f) freeze dried.
e) f)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
CMC: (a) CMC freeze dried, (b) CMC after an
E/1-B-FD treatment.
a) b)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
CMC-Cu: (c) CMC-Cu freeze dried, (d) CMC-Cu after an E/1-B-
FD treatment.
c) d)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
TNFC: (e) TNFC freeze dried, (f) TNFC after an E/1-B-FD
treatment.
e) f)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
TNFC-Cu: (g) TNFC-Cu freeze dried, (h) TNFC-Cu after an E/1-
B treatment.
g) h)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
CMC: (a) CMC freeze dried, (b) CMC after an E/tert-B-FD
treatment.
a) b)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
CMC-Cu: (c) CMC-Cu freeze dried, (d) CMC-Cu after an E/tert-B-
FD treatment.
c) d)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
TNFC: (e) TNFC freeze dried, (f) TNFC after an E/tert-B-FD
treatment.
e) f)
SEM IMAGES OF FREEZE AND MODIFIED FREEZE DRIED
MATERIALS
TNFC-Cu: (g) TNFC-Cu freeze dried, (h) TNFC-Cu after an E/tert-B-
FD treatment.
g) h)
Results & Discussion
LASER DIFFRACTION
Average diameter size
histograms at 10, 50 and
90 percentile for various
spray dried particles.
CMC CMC-CU TNFC
Particle
size
(µm)
Results & Discussion
ENERGY DISPERSIVE X-RAY (EDX)
FD E/1- B - FD SDCMC-CU TEMPLATES
Copper
element
(%)
Results & Discussion
INDUCTIVELY COUPLED PLASMA-OPTICAL EMISSION
SPECTROSCOPY (ICP-OES)
CMC-CU TNFC-CU
Copper content (Weight percentage, %)
Results & Discussion
XPS ANALYSIS
1100 1000 900 800 700 600 500 400 300 200
0
2000
4000
6000
8000
10000
955 950 945 940 935 930
250
300
350
400
450
Cu2p
C1s
CP
S
Binding Energy (eV)
O1s
Cu2p1/2
Binding Energy (eV)
Cu2P3/2
fitting peak
Cu2p1/2
fitting peak
Cu2p peak
Background
Cu2p3/2
Chemical state Formula Binding energy,
Cu2p3/2
(eV)
Cu metal or (Cu0) Cu 932.5 ± 0.15
Cu(I) oxide or (Cu+1) Cu2O 932.5 ± 0.2
Cu (II) oxide or (Cu+2) CuO 933.8 ± 0.2
Cu hydroxide or (Cu+2) Cu(OH)₂ 934.4 ± 0.2
Results & Discussion
XPS ANALYSIS
XPS analysis confirms that Cu+ or Cu°is present for all
CMC-copper nanoparticle materials; Cu2+ was not detected
in these samples.
Cu2+ was found for all TNFC-copper nanoparticle materials.
Conclusions
Spray dried (SP) materials exhibit spherical shapes of small
size, whereas Freeze dried (FD) material showed plate-like
structures. The particle size of the SD materials ranged
from nanometers to microns. The length and width of plate-
like FD materials were over hundreds of microns.
Conclusions
Copper enhances the formation of porous
structures on both CMC and TNFC substrates; this
characteristic resulted improved after a solvent
exchange pre-treatment.
Conclusions
Bundle-like and porous structures were observed for
carboxymethyl cellulose (CMC) substrate when using
ethanol and “1-butanol” solvent exchange process followed
by the freeze drying step.
A film-like and porous structure was exhibited for TEMPO
nanofibrillated cellulose when using ethanol and “tert-
butanol” solvent exchange process followed by freeze
drying.
Conclusions
Copper content on CMC-copper nanoparticles material
decreased by 68.5% when using the spray-drying process.
XPS analysis confirms that Cu+ or Cu°is present for all CMC-
copper nanoparticle materials; Cu2+ was not detected in these
samples.
Cu2+ was found for all TNFC-copper nanoparticle materials.
Conclusions
The XRD data indicates that the average crystallite size of
Cu2O on SD CMC-copper nanoparticles material is 29.6
nm, while on FD CMC-copper nanoparticles material the
crystallite size is 14.2 nm.
Acknowledgments
NIFA McStennis Project WVA00098
NIFA-USDA Award Number No. 2013-34638-21481
Douglas Gardner and Yucheng Peng from UMaine for facilitating and performing the spray drying experiments, respectively.
Questions?Thank you!
Tempo mediated oxidation
