New apparatus for studying powder deagglomeration

Monolayer and Multilayer Particle Deposits on Hard Surfaces: Literature Review and Implications for Particle Resuspension in the Indoor Environment

“…By increasing turbulence in their wind tunnel, Gac et al (2008) noticed a decrease in the size of the resuspended particles, suggesting enhanced deaggregation of the resuspended aggregates due to higher levels of turbulence. Kurkela et al (2006) also found particle deaggregation to increase with increasing Reynolds number of the airflow. Therefore, once broken up, the smaller particles are more likely to be carried away with the airflow, rather than settle back to the surface.…”

“…As we transition from a sparse monolayer to a complex multilayer deposit, additional parameters begin to influence resuspension, most notably particle-to-particle adhesion (Lazaridis and Drossinos 1998); layer location (Lazaridis and Drossinos 1998;Friess and Yadigaroglu 2001); aggregate formation and deaggregation (Matsusaka and Masuda 1996;Kurkela et al 2006;Gac et al 2008;Gotoh et al 2011); possible saltation effects (Bagnold 1941;Shao et al 1993;Kok et al 2012); dust loading (Fromentin 1989;Nitschke and Schmidt 2010); and the deposit's structure and porosity (Friess and Yadigaroglu 2002).…”

Particle Aerosolisation and Break-up in Dry Powder Inhalers 1: Evaluation and Modelling of Venturi Effects for Agglomerated Systems

“…The lack of relationship between turbulence factors and particle size distribution is interesting, since previous studies have suggested turbulence to be a dominating factor in particle aerosolisation (8,10,12,20). Factors such as pressure drop affecting performance have also been reported by Mendes et al (28) (where the DPI devices tested had pressure drops ranging from 0.2 kPa to 1.6 kPa resulting in FPFs ranging from ∼15% up to ∼30%); however, this study again shows no direct relationship between pressure drop and aerosol performance (for example, a pressure drops of 0.9 kPa was calculated in the 10 mm venturi).…”

“…In 2008, Kurkela et al (8) developed a vertically mounted de-agglomeration apparatus utilising turbulent flow and found the Reynolds number (ranging from 7,000-46,000) to be related to the aerosol performance of a model carrier system (containing 138 μm borosilicare glass carrier particles with 2.5μm silica fines). However, this vertical design was not used to study 'real' pharmaceutical systems or agglomerate-based formulations.…”

Deagglomeration of nanoparticle aggregates via rapid expansion of supercritical or high‐pressure suspensions

“…Examples include highpressure homogenization (throttling a liquid suspension through a fine capillary nozzle) or high-speed/high-shear stirring. Using a motionless high-pressure homogenizer for individual suspensions of zirconia (12 nm), silica (7,12,20, and 30 nm), and titania (21 nm) in an ethylene glycol aqueous solution. Seekkuarchchi and Kumazawa 19 showed that nanoparticle agglomerates could be broken down below 100 nm.…”