2 research outputs found
Spray Conditioning for the Preparation of Spray Dried Submicron Particles
[EN] Particle size reduction down to the submicron range (0.1-1 µm) is an effective option to increase the bioavailability
of low water soluble active pharmaceutical ingredients. According to the Nernst-Brunner equation, the preparation
of submicron sized particles increases the specific surface area, thus increases the dissolution rate. Conventional
spray drying devices for submicron particles show certain limitations. The main challenge is the preparation of
small and uniform droplets during the atomisation step. In this work, fine droplets were generated combining a
nozzle with a droplet separator. Therefore, the aerosol is generated with a pneumatic nozzle and is sprayed into a
cyclone droplet separator. Depending on the characteristics of the cyclone, droplets larger than the cut-off-size
were separated and returned into the liquid feed. The conditioned aerosol at the top of the cyclone separator can
then be introduced into the drying chamber. With this concept the usable part is separated, thus no classification
process after drying is necessary. The investigations show that the dependencies during atomisation of the
droplets size on the liquid-to-gas mass flow ratio µm and the liquid properties (e.g. viscosity) do not apply to the
separation step. The conditioned aerosol only depends on the separation characteristics of the cyclone droplet
separator. However, the amount of droplets separated is determined by the atomisation step. Hence, the amount
of droplets smaller than the cut-off-size can be increased by decreasing the droplet size of the primary aerosol.
This is realised by secondary droplet fragmentation. An impact surface causes breakup of the droplets of the
primary aerosol before separation. The investigations show an increased amount of droplets <2µm.Gorny, R.; Schaldach, G.; Walzel, P.; Thommes, M. (2017). Spray Conditioning for the Preparation of Spray Dried Submicron Particles. En Ilass Europe. 28th european conference on Liquid Atomization and Spray Systems. Editorial Universitat Politècnica de València. 162-166. https://doi.org/10.4995/ILASS2017.2017.4701OCS16216