Process development for pilot-scale spray drying of ultrasmall iron (oxyhydr)oxide nanoparticles

In manufacturing iron (oxyhydr)oxide nanoparticles, drying is often necessary to increase stability or to enable granulation and tableting. Lyophilization is a simple drying method, although it is characterized by high energy consumption and high cost. This study aims to demonstrate that spray drying is a suitable alternative for preparing iron (oxyhydr)oxide nanoparticles. A Design of Experiment approach was used varying the inlet air temperature, feed flow rate, and feed concentration. Especially a low feed flow rate was beneficial for low residual moisture (< 7%) and high yield (> 80%). The process was subsequently transferred to pilot scale at a feed flow rate of 2.3 kg/h. The nanomaterial had comparable properties and efficacy to the freeze-dried product. However, about 15% lower yield and 35% lower energy consumption were found for spray drying the nanoparticles. This study shows that spray drying is a suitable alternative to freeze drying for iron (oxyhydr)oxide nanoparticles.