ultrasound nanomixing- aiche\' 07
TRANSCRIPT
Environmentally Benign Nano-mixing by Sonication in Supercritical CO2p 2
Ganesh P. Sanganwar, Ram B. GuptaD t t f Ch i l i iDepartment of Chemical engineering
Auburn University, Auburn, AL
Alexandre Ermoline, James V. Scicolone, Rajesh N. Dave, , jNew Jersey Center for Engineered Particulates New Jersey Institute of Technology, Newark, NJ
Outline
IntroductionApplications of nanoparticles / nanocomposites and importance of nano-mixingA il bl th dAvailable methods
ObjectiveExperimental studyExperimental studyResultsConclusionConclusion
Introduction
Nanoparticles and Nanocomposites/Why nanomixing is important ?important ?
Nanoparticles: particle sizes whose novel properties differentiate from bulk material( normally <100 nm)
ApplicationsCarbon nanotube/carbon fiber based composites and films
Continued….
High strength material consisting of
Titania nanoparticles in asphalt and cement
nano grained Aluminium
1-5 micron drug particle
Available Methods for Nano-particle Mixing
Nano-mixing methods*
Dry mixing Rapid expansion of supercritical suspension Magnetically assisted impact mixing Sti d i iStirred mixing Fluidized bedHybridization system (Nara Machinery of Japan)Mechanofusion (Hosokawa Micron Corp )Mechanofusion (Hosokawa Micron Corp.)
Wet mixingSonication in solvent like n-hexane or tolueneMicros (Nara Machinery of Japan)Micros (Nara Machinery of Japan)
*Wei D., Dave R. and Pfeffer R., 2002. Mixing andcharacterization of nanosized powders: An assessment ofdifferent techniques. J.Nanoparticle Res. 4, 21-41.
*Yang j., Wang Y., Dave R.N., and Pfeffer R., 2003. Mixing ofnano-particles by rapid expansion of high pressuresuspensions. Adv. Powder Tech. 14, 471-93.
Objectivej
Wet mixingSonication in n-hexane or
Proposed mixingSonication in high pressure cotoluene
Material has to wet the liquid Involves additional
pressure co2Material does not have to wet the liquid Recovery by simple d i tisteps of filtration
and dryingUses harmful, flammable and
i l t
depressurizationUses environmentally friendly, non-flammable and cheap solventexpensive solvent
Residual solventssolventNo residual solvents
CO2-Sonication Apparatus
Ultrasonic Horn in Pressure Vessel
Experimental studySelection of materials for studies
(Silica/Titania, Silica/Alumina, MWCNT/Silica, MWCNT/Titania)
y
(S ca/ a a, S ca/ u a, C /S ca, C / a a)
Effect of different process variables
Pressure (21 55 and 90 bar)Pressure (21, 55, and 90 bar) Ultrasound amplitude (10, 30, and 50%)
Characterization of Nano-mixtureTEM (Transmission Electron Microscopy) for Silica/Titania
EDS (Energy dispersive X-ray spectroscopy) for Silica/Alumina and Silica/Titania
SEM (Scanning Electron Microscopy) for MWCNT/Silica and MWCNT/Titania
S f C /SDay-light illumination Spectrophotometry for MWCNT/Silica and MWCNT/ Titania
Nanomaterials
Alumina Titania
50 nm50 nm
MWCNTSilica MWCNTSilica
50 nm100 nm
Analysis of Composition
Procedure for EDSCompressed into wafersCompressed into wafers (1mm thick and 13mm diameter) with applied load of 5-8 ton for 4 min Carbon coatedmin.Carbon coated before analysis
El t b ltElectron beam voltage of 10 keV
Two representativeTwo representative areas with each including 20 randomly selected points
21 µm
Intensity of Segregation
Intensity of segregation
10002
×=I σy g g
[No mixing: I=1000, Complete mixing: I=0]
1000ba
I
2 2( ) ( )N N
a a b b− −∑ ∑2 1 1
( ) ( )
1 1
i ii i
a a b b
N Nσ = == =
− −
∑ ∑Variance
1a b+ =Mixture composition
Danckwerts P.W., 1952. The definition andmeasurement of some characteristics of mixtures.Appl. Sci. Res. A3, 279-296
Results
TEM of nanomixed silica/titania
Effect of ultrasound amplitude and pressure (Silica/Titania mixture)(Silica/Titania mixture)
Mixing of MWCNT/Silica in 90 bar CO2 andMixing of MWCNT/Silica in 90 bar CO2 and n-hexane at various ultrasound amplitude
Day-light illumination spectrophotometry of MWCNT/Silica
TEM of Nanomixed Silica/Titania in CO2
Silica Titania
10 µm 10 µm
Silica/Titania mixtureSilica/Titania mixture
50 nm
Effect of pressure and ultrasound amplitude on mixing
Silica/Titania
100
120
gatio
n
Mixing in CO2, 21 barMixing in CO2, 55 bar
60
80
f Seg
reg g ,
Mixing in CO2, 90 barMixing in n-hexane
20
40
ensi
ty o
f
0
20
0 10 20 30 40 50 60 70
Inte
Amplitude (%)
Intensity of Segregation versus Power Consumption
Silica/Titania
100
120
atio
n
Mixing in CO2, 21 barMi i i CO2 b
60
80
100
Segr
ega Mixing in CO2, 55 bar
Mixing in CO2, 90 barMixing in n-hexane
40
60
nsity
of
0
20
0 10 20 30 40 50
Inte
n
0 10 20 30 40 50Power (W)
Mixing of CNT/Silica at 10% amplitude
S iti l CO
n-hexane
Supercritical CO2
100 nm
1µm
1 µm
100 nm
100 nm100 nm
Mixing of CNT/Silica at 30% amplitude
Supercritical CO2
1 µm 100 nm
n-hexane
1µm 100 nm
Photographs of MWCNT Mixed with SilicaSupercritical
CO2MWCNT
10% amplitude 50% amplitude
n-hexaneSilica
Day-light illumination spectrophotometry
MWCNT/Silica in CO2 at 90 bar and 45 oC
5
6CNT SiO2 Hand MixedCNT-SiO2 10%
4
ce (
%) CNT-SiO2 30%
CNT-SiO2 50%CNT
2
3
Ref
lect
anc
0
1
R
0400 500 600 700
Wavelength (nm)
Comparison of Nano-mixing Methods
3
2
2.5
3
o A
l/Si
1
1.5
Ato
mic
Rat
io
0
0.5
A
1 h 3 h 2000 psi1300 psi 15 min 60 min 25% 85% 1500 psi 1000 psi
Fluidized Bed
1 hr 3 hr
Stirring
pp
MAIM
15 min 60 min
Sonicator
25% ampl ampl
RESS
p p
J Scicolone G Sanganwar D To R Dave R B Gupta R Pfeffer 2007 “ Deagglomeration and mixing ofJ. Scicolone, G. Sanganwar, D. To, R. Dave, R. B. Gupta, R. Pfeffer, 2007. Deagglomeration and mixing of nanoparticles, Partech 2007, Germany.
Conclusions
Nanomixing in CO2 for studied mixture found to be d i has good as in n-hexane
Deagglomeration and mixing of particles occur d i i i i hi h b di idduring sonication in high pressure carbon dioxide
High ultrasound amplitude (30-50%) gave good ltresults
Mixed powder is free of organic solvent and powder i f ilrecovery is facile.
Acknowledgement
The National Science Foundation
g
NIRT grant DMI-0506722
Myself in a Nanomixed world
Colleagues/Team-mates/Friends from 23 countries !
y