New developments in active freeze-drying by Hosokawa Micron have created a quicker less labour-intensive and improved process for pharmaceutical and nano-material applications.
Applications in the pharmaceutical industry in the production of antibiotics macromolecules and electrolytes are now common along with freeze drying of proteins, hormones, viruses, vaccines, bacteria, yeast, blood serum, liposomes and transplant materials such as collagen sponge.
According to Hosokawa Micron, the advantage of using the freeze-drying process in the development of nano-materials is that the suspended particles remain separated during both the freezing and drying process. During the sublimation process single particles will become separated but the continuous motion of the material will induce the formation of weak agglomerates. The final product will consist of loosely bound single particles forming a fine cohesive powder.
Active freeze dryers are said to exhibit a good heat transfer rate due to the continuous motion of the product, which shortens the drying process because the dried product does not hinder the sublimation. In addition, the active freeze-drying process steps are carried out in a single processing unit, resulting in easy-to-handle, lump-free, free-flowing product.
Once the freezing step is completed the drying chamber is closed and vacuum applied. After evacuation of the freezing agent the sublimation process starts. From this stage the vacuum level dictates the product temperature.
During sublimation the heat is supplied through the jacket and efficiently distributed throughout the product by the chamber design. The initial coarse granules gradually reduce in size due to the sublimation of the connecting ice structure in between the forced material. The released dried particles will make up a loose powder.
Towards the end of the drying process when most of the frozen solvent is sublimated the product temperature will start to rise and finally equalise the wall temperature indicating that the drying process is finished.