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Environmentally Benign Nano-mixing by
    Sonication in Supercritical CO2
                    p

         Ganesh P. Sangan...
Outline

  Introduction
     Applications of nanoparticles / nanocomposites
     and importance of nano-mixing
     Availa...
Introduction

     Nanoparticles and Nanocomposites/Why nanomixing is
    important ?
Nanoparticles: particle sizes whose ...
Continued….
Titania nanoparticles in asphalt and cement

                                          High strength material ...
Available Methods for Nano-particle Mixing

         Nano-mixing methods*
                Dry mixing
                     ...
Objective
  j
Wet mixing                      Proposed mixing
  Sonication in n-hexane or       Sonication in high
  tolue...
CO2-Sonication Apparatus
Ultrasonic Horn in Pressure Vessel
Experimental study
                 y
    Selection of materials for studies

   (S ca/ a a, Silica/Alumina, MWCNT/Silica,...
Nanomaterials

            Alumina           Titania




  50 nm               50 nm




 Silica               MWCNT

    ...
Analysis of Composition

    Procedure for EDS
       Compressed into wafers
       (1mm thick and 13mm
       diameter) w...
Intensity of Segregation

                                                                    σ2
            Intensity of ...
Results

   TEM of nanomixed silica/titania

   Effect of ultrasound amplitude and pressure
   (Silica/Titania mixture)

 ...
TEM of Nanomixed Silica/Titania in CO2

 Silica                           Titania




10 µm                               ...
Effect of pressure and ultrasound amplitude on mixing


                                           Silica/Titania
        ...
Intensity of Segregation versus Power Consumption


                                           Silica/Titania
            ...
Mixing of CNT/Silica at 10% amplitude

                                         n-hexane

Supercritical CO2
S      iti l

...
Mixing of CNT/Silica at 30% amplitude



Supercritical
   CO2

                1 µm                    100 nm




 n-hexan...
Photographs of MWCNT Mixed with Silica
                          Supercritical
MWCNT
                             CO2




...
Day-light illumination spectrophotometry

                      MWCNT/Silica in CO2 at 90 bar and 45 oC
                  ...
Comparison of Nano-mixing Methods


                          3

                         2.5
    Atomic Ratio Al/Si




 ...
Conclusions

    Nanomixing in CO2 for studied mixture found to be
    as good as i n-hexane
          d    in h

       D...
Acknowledgement
         g

   The National Science Foundation
      NIRT grant DMI-0506722
Myself in a Nanomixed world
      y
Colleagues/Team-mates/Friends from 23 countries !
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Ultrasound Nanomixing- AIChE\' 07

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Ultrasound Nanomixing- AIChE\' 07

  1. 1. Environmentally Benign Nano-mixing by Sonication in Supercritical CO2 p Ganesh P. Sanganwar, Ram B. Gupta Department of Chemical engineering D t t f Ch i l i i Auburn University, Auburn, AL Alexandre Ermoline, James V. Scicolone, Rajesh N. Dave , , j New Jersey Center for Engineered Particulates New Jersey Institute of Technology, Newark, NJ
  2. 2. Outline Introduction Applications of nanoparticles / nanocomposites and importance of nano-mixing Available A il bl methods th d Objective Experimental study Results Conclusion
  3. 3. Introduction Nanoparticles and Nanocomposites/Why nanomixing is important ? Nanoparticles: particle sizes whose novel properties differentiate from bulk material( normally <100 nm) Applications Carbon nanotube/carbon fiber based composites and films
  4. 4. Continued…. Titania nanoparticles in asphalt and cement High strength material consisting of nano grained Aluminium 1-5 micron drug particle
  5. 5. Available Methods for Nano-particle Mixing Nano-mixing methods* Dry mixing Rapid expansion of supercritical suspension Magnetically assisted impact mixing Stirred i i Sti d mixing Fluidized bed Hybridization system (Nara Machinery of Japan) Mechanofusion (Hosokawa Micron Corp ) Corp.) Wet mixing Sonication in solvent like n-hexane or toluene Micros (Nara Machinery of Japan) *Wei D., Dave R. and Pfeffer R., 2002. Mixing and *Yang j., Wang Y., Dave R.N., and Pfeffer R., 2003. Mixing of characterization of nanosized powders: An assessment of nano-particles by rapid expansion of high pressure different techniques. J.Nanoparticle Res. 4, 21-41. suspensions. Adv. Powder Tech. 14, 471-93.
  6. 6. Objective j Wet mixing Proposed mixing Sonication in n-hexane or Sonication in high toluene pressure co2 Material has to wet Material does not have the liquid to wet the liquid Involves additional Recovery by simple steps of filtration depressurization d i ti and drying Uses environmentally Uses harmful, friendly, non- flammable and flammable and cheap expensive solvent i l t solvent Residual solvents No residual solvents
  7. 7. CO2-Sonication Apparatus
  8. 8. Ultrasonic Horn in Pressure Vessel
  9. 9. Experimental study y Selection of materials for studies (S ca/ a a, Silica/Alumina, MWCNT/Silica, MWCNT/Titania) (Silica/Titania, S ca/ u a, C /S ca, C / a a) Effect of different process variables Pressure (21 55 and 90 bar) (21, 55, Ultrasound amplitude (10, 30, and 50%) Characterization of Nano-mixture TEM (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 Day-light illumination S Spectrophotometry for MWCNT/Silica and f C /S MWCNT/ Titania
  10. 10. Nanomaterials Alumina Titania 50 nm 50 nm Silica MWCNT 50 nm 100 nm
  11. 11. Analysis of Composition Procedure for EDS Compressed into wafers (1mm thick and 13mm diameter) with applied load of 5-8 ton for 4 min.Carbon min Carbon coated before analysis Electron beam voltage El t b lt of 10 keV Two representative areas with each including 20 randomly selected points 21 µm
  12. 12. Intensity of Segregation σ2 Intensity of segregation y g g I= × 1000 ab [No mixing: I=1000, Complete mixing: I=0] N N ∑ ( ai − a ) 2 ∑ (bi − b ) 2 Variance σ2 = i =1 = i =1 N −1 N −1 Mixture composition a + b = 1 Danckwerts P.W., 1952. The definition and measurement of some characteristics of mixtures. Appl. Sci. Res. A3, 279-296
  13. 13. Results TEM of nanomixed silica/titania Effect of ultrasound amplitude and pressure (Silica/Titania mixture) Mixing of MWCNT/Silica in 90 bar CO2 and n-hexane at various ultrasound amplitude Day-light illumination spectrophotometry of MWCNT/Silica
  14. 14. TEM of Nanomixed Silica/Titania in CO2 Silica Titania 10 µm 10 µm Silica/Titania mixture 50 nm
  15. 15. Effect of pressure and ultrasound amplitude on mixing Silica/Titania 120 gation Mixing in CO2, 21 bar 100 Mixing in CO2, 55 bar g , ensity of Segreg Mixing in CO2, 90 bar 80 Mixing in n-hexane 60 f 40 20 Inte 0 0 10 20 30 40 50 60 70 Amplitude (%)
  16. 16. Intensity of Segregation versus Power Consumption Silica/Titania ation 120 Mixing in CO2, 21 bar nsity of Segrega 100 Mixing i CO2 Mi i in CO2, 55 b bar Mixing in CO2, 90 bar 80 Mixing in n-hexane 60 40 Inten 20 0 0 10 20 30 40 50 Power (W)
  17. 17. Mixing of CNT/Silica at 10% amplitude n-hexane Supercritical CO2 S iti l 100 nm 1µm 1 µm 100 nm 100 nm
  18. 18. Mixing of CNT/Silica at 30% amplitude Supercritical CO2 1 µm 100 nm n-hexane 1µm 100 nm
  19. 19. Photographs of MWCNT Mixed with Silica Supercritical MWCNT CO2 10% amplitude 50% amplitude n-hexane Silica
  20. 20. Day-light illumination spectrophotometry MWCNT/Silica in CO2 at 90 bar and 45 oC 6 CNT SiO2 Hand Mixed 5 CNT-SiO2 10% CNT-SiO2 30% Reflectanc (%) 4 CNT-SiO2 50% CNT ce 3 2 R 1 0 400 500 600 700 Wavelength (nm)
  21. 21. Comparison of Nano-mixing Methods 3 2.5 Atomic Ratio Al/Si 2 o 1.5 1 A 0.5 0 1300 psi p 2000 psi p 15 min 25% 85% 1500 psi p 1000 psi p 1h hr 3h hr 60 min ampl ampl Fluidized Bed Stirring MAIM Sonicator RESS J. Scicolone, G. Sanganwar D. To, R Dave R B Gupta R Pfeffer 2007. J Scicolone G Sanganwar, D To R. Dave, R. B. Gupta, R. Pfeffer, 2007 “ Deagglomeration and mixing of nanoparticles, Partech 2007, Germany.
  22. 22. Conclusions Nanomixing in CO2 for studied mixture found to be as good as i n-hexane d in h Deagglomeration and mixing of particles occur during d i sonication i hi h pressure carbon di id i i in high b dioxide High ultrasound amplitude (30-50%) gave good results lt Mixed powder is free of organic solvent and powder recovery i f il is facile.
  23. 23. Acknowledgement g The National Science Foundation NIRT grant DMI-0506722
  24. 24. Myself in a Nanomixed world y Colleagues/Team-mates/Friends from 23 countries !

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