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

• Published in: Advanced powder technology : the international journal of the Society of Powder Technology, Japan Japan, 2017-09, Vol.28 (9), p.2357-2365
• Main Authors: Kamaly, Shah Waez, Tarleton, Alan C., Özcan-Taşkın, Nerime Gül
• Format: Article
• Language: English
• Subjects: Aerosil 200 V; Breakup; Deagglomeration; Fragmentation; Nanoparticle dispersion; Rotor-stator
• ISSN: 0921-8831; 1568-5527
• DOI: 10.1016/j.apt.2017.06.017

[Display omitted] •Mechanism of break up could be demonstrated to be erosion.•Dispersion fineness is shown to be limited by the aggregate size.•Breakup kinetics is faster at high power input values.•Effect of concentration assessed on the basis of [(P t)/V] and [(P t)/msolids].•Effect of rotor-stator design on breakup discussed. 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, 10wt.%), 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.