Nanofluidization as affected by vibration and electrostatic fields

Quintanilla, M. A. S.; Valverde, José Manuel; Castellanos, A.; Lepek, Daniel; Pfeffer, Robert; Davé, Rajesh N.

doi:10.1016/j.ces.2008.08.012

Cited by 36 publications

(25 citation statements)

References 31 publications

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“…The Sevilla Powder Tester (SPT) (Quintanilla et al 2008) was utilized as the fluidization setup, and two electrodes were placed on either side of the column and were connected to a DC high-voltage source. One of the electrodes was grounded and a high voltage (up to 30 kV) was applied to the opposite electrode using a high-voltage DC supply.…”

Section: Fluidization Of Nanopowders Using External Assistance Methodsmentioning

confidence: 99%

Fluidization of nanopowders: a review

2012

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Nanoparticles (NPs) are applied in a wide range of processes, and their use continues to increase. Fluidization is one of the best techniques available to disperse and process NPs. NPs cannot be fluidized individually; they fluidize as very porous agglomerates. The objective of this article is to review the developments in nanopowder fluidization. Often, it is needed to apply an assistance method, such as vibration or microjets, to obtain proper fluidization. These methods can greatly improve the fluidization characteristics, strongly increase the bed expansion, and lead to a better mixing of the bed material. Several approaches have been applied to model the behavior of fluidized nanopowders. The average size of fluidized NP agglomerates can be estimated using a force balance or by a modified Richardson and Zaki equation. Some first attempts have been made to apply computational fluid dynamics. Fluidization can also be used to provide individual NPs with a thin coating of another material and to mix two different species of nanopowder. The application of nanopowder fluidization in practice is still limited, but a wide range of potential applications is foreseen.Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-012-0737-4) contains supplementary material, which is available to authorized users.

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Section: Fluidization Of Nanopowders Using External Assistance Methodsmentioning

confidence: 99%

Fluidization of nanopowders: a review

2012

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“…Bed expansion of fluidized beds of nanoagglomerates, and consequently the efficiency of gas‐solid contact, can be further increased by means of assisted fluidization methods, including external vibration,26, 30 sound wave pulsation,31 centrifugation,32 and addition of large magnetic particles that are excited by a variable magnetic field 33. These techniques promote complex agglomerate agitation, which increases the flow shear on their surface and thus decrease their size, and have been proven to be effective in enhancing the fluidization of presieved samples of silica nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

“…The agglomerate charge absolute value Q **, obtained from manual tracking of the agglomerates subjected to an electrostatic field, was found to be of the order of 10 −14 C 34. Experimental observations have shown that fluidized nanoparticle agglomerates excited by an electrostatic field experience an electrophoretic force as a consequence of being naturally charged, which leads to agglomerate electrophoretic deposition on the vessel walls, and subsequent channeling and depletion of the bed 30, 35. In this case, the electrostatic field has a detrimental effect on fluidization.…”

Section: Introductionmentioning

confidence: 99%

Enhanced nanofluidization by alternating electric fields

et al. 2009

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We show experimental results on a proposed technique to enhance the fluidization of nanoparticle beds. This technique consists of the application of an alternating electric field to the nanofluidized bed. Three different field configurations have been tested: co-flow field, cross-flow field, and variable field configurations. Nanoparticle agglomerates are naturally charged by contact and tribo charging mechanisms and therefore are agitated by the action of the externally applied field, which enhance fluidization. According to our observations, the best results are obtained for the variable field configuration. In this configuration, the electric field strength is higher at the bottom of the bed, whereas it is almost negligible at the free surface. Thus, the larger agglomerates, which tend to sink at the bottom of the bed due to stratification, and usually impede uniform fluidization, are strongly agitated. It is thought that the strong agitation of the bigger agglomerates that usually sink to the bottom of the bed contributes to further homogenize the distribution of the gas flow within the bed by destabilizing the development of gas channels close to the gas distributor. On the other hand, the smaller agglomerates at the vicinity of the free surface are just weakly excited. Consequently, fluidization is greatly enhanced, whereas at the same time excessive elutriation is avoided. It is demonstrated that this technique is even suitable to achieve highly expanded fluidization of unsieved nanopowder samples even though the fluidization state returns to be heterogeneous upon the electric field being turned off. V V C 2009 American Institute of Chemical Engineers AIChE J, 56: 54-65, 2010

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“…[1][2][3][4][5] These nano materials represent a new class of novel materials which have many of excellent properties, including mechanical strength, thermal stability, activities of photocatalysis, and so on. Nowadays, more and more nano materials are synthesized by different ways, and it is extensively used in our daily life because of their special functions.…”

Section: Introductionmentioning

confidence: 99%

Research on the Preparation of Nano SiO2–Al2O3–TiO2 Particle

Chen¹,

Jiang²,

Liu³

2012

Jnl of Comp & Theo Nano

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The organic alkoxides including ethyl silicate, aluminium isopropoxide and butyl titanate were used as raw materials and preparing nano SiO 2 -Al 2 O 3 -TiO 2 particle by sol-gel method in the study. The influences of some determinant parameters such as the dosages of the ethanol, the water and the ammonia on the efficiency of the reaction and on the size of micro particles were investigated in details. In addition, the temperature was considered as one of the crucial factors. Moreover, the characters of nano particles were tested by X-ray diffraction (XRD) and transmission electron microscopy (TEM). The results show that the nano SiO 2 -Al 2 O 3 -TiO 2 particle can be obtained at 55 C for 2 h, and the crystal form was Amorphous State. The optimal mole ratios of the variables were confirmed by orthogonal test. Based on the optimal variables, nano particles were synthesized. The morphology of the nano SiO 2 -Al 2 O 3 -TiO 2 particle investigated by TEM was random grain with the size of 20-50 nm.

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Nanofluidization as affected by vibration and electrostatic fields

Cited by 36 publications

References 31 publications

Fluidization of nanopowders: a review

Fluidization of nanopowders: a review

Enhanced nanofluidization by alternating electric fields

Research on the Preparation of Nano SiO<SUB>2</SUB>–Al<SUB>2</SUB>O<SUB>3</SUB>–TiO<SUB>2</SUB> Particle

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