Summary

Proceedings of the 2013 International Symposium on Nonlinear Theory and its Applications

2013

Session Number:A3L-B

Session:

Number:78

Re-Dispersion of Flocculated Nanoparticles Using Back Pressure Valve with Small Orifice Channel

Nobuaki Aoki,  Noriyoshi Manabe,  Tadafumi Adschiri,  

pp.78-81

Publication Date:

Online ISSN:2188-5079

DOI:10.15248/proc.2.78

PDF download (550.3KB)

Summary:
Nanoparticles tend to flocculate owing to their high surface energy. Flocculated nanoparticles can cause a loss of properties and problems when used in applications. This paper describes an easier and more effective method for producing a colloidal solution in which flocculated nanoparticles become re-dispersed by using a back pressure valve. First, we identify the mechanism of re-dispersion in this valve from simulations integrating the shear force and the van der Waals attractive force for a nanoparticle solution with a Couette flow. From the results, shear stress dominates the re-dispersion of flocculated particles. In experiments, a large shear stress is applied to the solution in a back pressure valve for re-dispersing the flocculated particles. The clearance of the flow path in the valve decreases with increasing primary pressure. The re-dispersibility is evaluated through the measurement of their size distribution using dynamic light scattering. The results show that the method re-dispersed the flocculated particles and reduces their modal diameter from over 6000 nm to 21.0 nm. Additionally, increasing the pressure decreases the particle diameter after the re-dispersion. Moreover, we can predict the particle diameter after the re-dispersion from the dispersion numbers Di (the ratio of the shear force to the van der Waals attractive force).

References:

[1] P. Alivisatos, “Semiconductor clusters, nanocrystals, and quantum dots,” Science, vol. 271, pp. 933-937, 1996.

[2] Derjaguin, B. and L. Landau; “Theory of the stability of strongly charged lyophobic sols and of the adhesion of strongly charged particles in solutions of electrolytes,” Acta Physico chemica URSS, vol. 14, pp. 633-662, 1941.

[3] T. Iwasaki, J. H. Kim and M. Satoh, “Characterization of media mills based on mechanical energy applied to particles,” Chem. Eng. Sci., vol. 61, pp. 1065-1073, 2006.

[4] M. Inkyo, T. Tahara, T. Iwaki, F. Iskandar, C. J. Hogan Jr. and K. Okuyama, “Experimental investigation of nanoparticle dispersion by beads milling with centrifugal bead separation,” J. Colloid Interface Sci., vol. 304, pp. 535-540, 2006.

[5] E. Katayama, S. Togashi and Y. Endo, “Production of AgCl nanoparticles using microreactors,” J. Chem. Eng. Jpn., vol. 43, pp. 1023-1028, 2010.

[6] S. Hashimoto, A. Sando and Y. Inoue, “Effect of bending direction on mixing performance of zigzag microchannels,” J. Chem. Eng. Jpn., vol. 45, pp. 67-73, 2012.

[7] N. Manabe, S. Hanada, N. Aoki, Y. Futamura, K. Yamamoto and T. Adschiri, “Flocculation and redispersion of colloidal quantum dots,” J. Chem. Eng. Jpn., Vol. 45, pp. 917-923, 2012.

[8] J. O. Wilkes, “Fluid mechanics for chemical engineers with microfluidics and CFD,” 2nd ed., pp. 70-77, Prentice Hall, Indiana, U.S.A., 2005.

[9] L. Bergström, “Hamaker constants of inorganic materials,” Adv. Colloid Interface Sci., vol. 70, pp. 125-169, 1997.

[10] R. F. Popovici, E. M. Seftel, G. D. Mihal, E. Popovici and V. A. Voicu, “Controlled drug delivery system based on ordered mesoporous silica matrices of captopril as angiotensin-converting enzyme inhibitor drug,” J. Pharm. Sci., vol. 100, pp. 704-714, 2011.

[11] J. Tsubaki K. Kato, Y. Nagahiro and G. Jimbo, “Experimental investigation of the disintegrating phenomena of aggregates of fine powders in air flow,” Kagaku Kogaku Ronbunshu, vol. 9, pp. 189-194, 1983.

[12] Y. Adachi, M. Kobayashi and Y. Fukuhara, “Breakup strength of flocs analyzed using orifice converging flow,” Nihon Reoroji Gakkaishi, vol. 35, pp. 69-72 2007.