Dispersion

Dispersion of bulk powders from a dense aggregated phase to a lean phase is important in many applications including particle characterisation, delivery of therapeutic drugs to the lungs via Dry Powder Inhalers (DPIs), and preparing stable suspensions. It can be challenging to fully disperse cohesive powders due to relatively large interparticle attraction forces compared to separating forces.

Within our research group we have a number of devices for dispersing powders including and assessing the extent of dispersion by the following instruments.

• Mavern Panalytical Mastersizers 2000 and 3000
• Malvern Instruments Spraytec
• Malvern Instruments Morphologi G3

The Mastersizer and Spraytec instruments determine the particle size distributions of powders using laser diffraction technology, whereas Morphologi G3 measures particle size distributions and morphology using optical microscopy. In a recent research programme we related the aerodynamic dispersion efficiency of powders to bulk cohesion, as measured by the Schulze ring shear tester.

• Aerodynamic Dispersion of Cohesive Powders

• The Role of Surface Interactions on Aggregation and Dispersion of Particulate Solids

1. G. Calvert, M. Ghadiri, R. Tweedie, Aerodynamic dispersion of cohesive powders: A review of understanding and technology, Advanced Powder Technology, Volume 20, Issue 1, January 2009, Pages 4-16, ISSN 0921-8831, 10.1016/j.apt.2008.09.001.
2. G.Calvert, A. Hassanpour, M. Ghadiri, Mechanistic analysis and computer simulation of the aerodynamic dispersion of loose aggregates, Chemical Engineering Research and Design, Volume 89, Issue 5, May 2011, Pages 519-525, ISSN 0263-8762, 10.1016/j.cherd.2010.08.013.
3. G. Calvert, A. Hassanpour, M. Ghadiri, Analysis of aerodynamic dispersion of cohesive clusters, Chemical Engineering Science, Volume 86, 4 February 2013, Pages 146-150, ISSN 0009-2509, 10.1016/j.ces.2012.06.035.
4. G. Calvert, M. Ghadiri, M. Dyson, P. Kippax, F. McNeil-Watson, The flowability and aerodynamic dispersion of cohesive powders, Powder Technology, Volume 240, May 2013, Pages 88-94, ISSN 0032-5910, 10.1016/j.powtec.2012.07.003.