Effect of Particle Properties on the Break Up of Nanoparticle Clusters Using an In‐Line Rotor‐Stator

Padron, Gustavo A.; Eagles, W.; Özcan-Taşkın, N. Gül; McLeod, G.; Xie, Liansong

doi:10.1080/01932690701729237

Cited by 25 publications

(16 citation statements)

References 8 publications

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“…This resulted in a bi-modal PSD and an increase in the volume of fines (below 1 µm) during processing accompanied by a decrease in both the volume and size of coarse material. This is in agreement with our previous findings using the GPDH-SQSH design operated in a different mode (ramping up the speed, Padron et al, 2008) and findings of previous researchers who used fumed silica particles in other devices (Xie et al, 2007, Pacek et al, 2007.…”

Section: Discussionsupporting

confidence: 83%

“…These support that aggregates, which are the smallest fragments, are eroded off the surface of agglomerates during processing. These results relating to both the mechanism of breakup and the smallest attainable size are in line with our previous findings (Bałdyga et al, 2008a;Özcan-Taşkin et al, 2009;Padron et al, 2008) and it may therefore be anticipated that for this test system, breakup will occur through erosion with other rotor-stator designs as well. …”

Section: Mechanism Of Break Up and The Finest Attainable Sizesupporting

confidence: 79%

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Comparative performance of in-line rotor-stators for deagglomeration processes

Özcan-Taşkın

Padron

Kubicki

2016

Chemical Engineering Science

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In-line rotor-stators are used for a wide range of power intensive dispersion applications, including the breakup of immiscible liquid droplets or agglomerates. This study, performed within the DOMINO project at BHR Group, aimed at studying the performance of three different rotor-stator head designs for deagglomeration processes. A given test system, nanoscale silica particles-in-water, was used to identify the mechanism and kinetics of break-up and determine the smallest attainable size. Three rotorstator head designs used were the GPDH-SQHS and EMSC screens from Silverson and Ytron Z-Lab from Ytron. These in-line rotor-stators were used in the recirculation loop of a stirred tank with a total dispersion volume of 100 litres. Power input and residence time were varied by changing the rotor speed and dispersion flow rate. Breakup was found to occur through erosion regardless of the operating conditions or rotor-stator design. The smallest fragments obtained were aggregates, rather than primary particles, and these were of a mean diameter of 150-200 nm; also independent of the operating conditions or rotor-stator head design. With a given rotor-stator operated at a given flow rate, increasing the rotor speed and hence the power input increased the break up kinetics. For a given design at a given specific power input, whilst the break up rate per tank turnover decreased when the flow rate was increased, the total processing time could be reduced. There were differences in the volume of the mixer head and chamber volumes; in addition, a smaller flow rate range could be covered with the Ytron design. Comparison of the different designs was therefore not straightforward. It could however be shown that the rotor-stator designs with a high number and small size of holes and/or gaps have a faster break up rate.

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Section: Discussionsupporting

confidence: 83%

Section: Mechanism Of Break Up and The Finest Attainable Sizesupporting

confidence: 79%

Comparative performance of in-line rotor-stators for deagglomeration processes

Özcan-Taşkın

Padron

Kubicki

2016

Chemical Engineering Science

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“…Batch rotor-stator 0.2-400 (0.8-2.5)× 10 -3 0.1-200 as was reported for Aerosil® 200-in-water by Chen et al (2005) and Aerosil® R816-in-water by Padron et al (2008). The evolution of the rheology for 15% wt.…”

Section: Process Device P (W) Volume (M 3 ) P/m (Kw/m 3 )mentioning

confidence: 72%

“…Commonly used impellers, such as turbines and hydrofoils, do not provide sufficiently high levels of power input to achieve deagglomeration into the sub-micron range (Xie, et al, 2007). Therefore, power intensive process devices such as sawtooth impellers (Xie et al, 2007), batch (Xie et al, 2007;Kamaly et al, 2017) or in-line rotor-stators (Baldyga et al, 2008;Padron et al, 2008;Özcan-Taşkın et al, 2016), high pressure jets (Wengeler et al, 2006;Sauter and Schuchmann, 2007) are employed. The hydrodynamic stresses in the flow field generated in such devices are sufficiently high to overcome the tensile strength of the agglomerates in order for breakup to occur.…”

Section: Introductionmentioning

confidence: 99%

Breakup of nanoparticle clusters using Microfluidizer M110-P

Gavi

Kubicki²,

Padron

et al. 2018

Chemical Engineering Research and Design

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A commercial design, bench scale microfluidic processor, Microfluidics M110-P, was used to study the deagglomeration of clusters of nanosized silica particles. Breakup kinetics, mechanisms and the smallest attainable size were determined over a range of particle concentrations of up to 17% wt. in water and liquid viscosities of up to 0.09 Pa s at 1% wt. particle concentration. The device was found to be effective in achieving complete breakup of agglomerates into submicron size aggregates of around 150 nm over the range covered. A single pass was sufficient to achieve this at a low particle concentration and liquid viscosity. As the particle concentration or continuous phase viscosity was increased, either a higher number of passes or a higher power input (for the same number of passes) was required to obtain a dispersion with a size distribution in the submicron range. Breakup took place through erosion resulting in a dispersion of a given mean diameter range regardless of the operating condition. This is in line with results obtained using rotor-stators. Breakup kinetics compared on the basis of energy density indicated that whilst Microfluidizer M110-P and an in-line rotor-stator equipped with the emulsor screen are of similar performance at a viscosity of 0.01 Pa s, fines volume fraction achieved with the Microfluidizer was much higher at a viscosity of 0.09 Pa s.

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“…Different process devices used for the purpose include the stirred bead mill (Stenger et al, 2005;Kowalski et al, 2008;Schilde et al, 2010), ultrasonic dispersers (Baldyga et al, 2008b(Baldyga et al, , 2009Quarch et al, 2010) in-line rotor-stators (Baldyga et al, 2008a;Padron et al, 2008;Özcan-Taşkın et al, 2016), a batch rotor-stator or high pressure devices (Sauter and Schuchmann, 2007;Seekkuarachchi et al, 2008 andXie et al, 2008). Local energy dissipation rate in these devices, responsible for the breakup of agglomerates, can be orders of magnitude higher than the average energy dissipation rate.…”

Section: Introductionmentioning

confidence: 99%

Dispersion of clusters of nanoscale silica particles using batch rotor-stators

Kamaly

Tarleton

Özcan-Taşkın

2017

Advanced Powder Technology

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Nanoparticle powders added into a liquid medium form structures which are much larger than the primary particle size (aggregates and agglomerates)-typically of the order of 10's of microns. An important process step is therefore the deagglomeration of these clusters to achieve as fine a dispersion as possible. This paper reports the findings of a study on the dispersion of hydrophilic fumed silica nanoparticle clusters, Aerosil 200V, in water using two batch rotor-stators: MICCRA D-9 and VMI. The MICCRA D-9 head consists of a set of teeth for the stator and another for the rotor, whereas the VMI has a stator with slots and a rotor which consists of a 4-bladed impeller attached to an outer set of teeth. The dispersion process, studied at different power input values and over a range of concentrations (1, 5, 10 wt.%), was monitored through the evolution of PSD. Erosion was found to be the dominant breakage mechanism irrespective of operating conditions or rotor-stator type. The smallest attainable size was also found to be independent of the power input or the design of the rotor-stator. Break up kinetics increased upon the increase of power input, and this also depended on the rotor-stator design. With MICCRA D-9 which has smaller openings on both the stator and rotor, the break up rate was faster. Increasing the particle concentration decreased break up kinetics. It could also be shown that operating at high concentrations can still be beneficial as the break up rate is higher when assessed on the basis of specific power input per mass of solids.

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Effect of Particle Properties on the Break Up of Nanoparticle Clusters Using an In‐Line Rotor‐Stator

Cited by 25 publications

References 8 publications

Comparative performance of in-line rotor-stators for deagglomeration processes

Comparative performance of in-line rotor-stators for deagglomeration processes

Breakup of nanoparticle clusters using Microfluidizer M110-P

Dispersion of clusters of nanoscale silica particles using batch rotor-stators

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