Drying is a very old operation, but the heating and drying of powders and biological products often irreversible agglomeration of particles.In the preparation of fine powders, the particles in the liquid phase will agglomerate into dispersed agglomerates after drying, which is mainly Because the water is emitted from the pores between the particles during the drying process of the ordinary particles, the additional pressure caused by the surface tension presses the particles together to form a lump.
And freeze drying can bm the 1 problem, freeze drying is to freeze the gel or blood to be dried into a solid first, and then to remove the water by sublimation to vaporize the water in a reasonable condition, due to the vaporization of ice The process does not affect the aggregation state of the solid particles, so the original particles can be kept intact without being compacted and agglomerated.In addition, freeze-drying is often suitable for processing biological products, such as blood, because it does not operate at high temperatures and can fz biological Product deterioration.
The moisture of the product, the performance of the freeze dryer, the control time of the analytical drying and the temperature of the analytical drying are the main factors affecting the moisture. For lyophilized products, the moisture content is ≤3%. The high moisture content of freeze-dried products will cause the products to decompose and shrink.