Drying is a very ancient operation, but heating and drying of powders and biological products often results in irreversible agglomeration of particles, especially in the preparation of ultra-fine powders. The agglomeration of nanoparticles in liquid phase is difficult to disperse through drying. This is mainly due to the release of water from intergranular pore channels during the drying process of ordinary particles and the high additional pressure caused by surface tension. The particles are pressed together to form a mass. Freeze drying is a way to avoid this problem. Freeze drying is to freeze the gel or blood to be solid, and then vaporized the water in a reasonable condition to remove moisture. Because the process of ice gasification does not affect the coalescence of solid particles, it can preserve the original particles without being compressed and reunited. Freeze dryer is very suitable for biological products, such as blood, because it has no high temperature operation, can prevent the deterioration of biological products.
The drying products generally have the problems of shrinking volume and hardening texture. Most of the volatile components will be lost. Some thermosensitive substances will be denatured and deactivated, and some substances will even be oxidized. Therefore, the properties of dried products are quite different from those before drying. The principle of freeze-drying is basically below 0 C, that is, under the condition of product freezing, only when the residual moisture content of the product is reduced in the later stage, can the product be raised to above 0 C, but generally not more than 40. Under vacuum conditions, when water vapor is sublimated directly, the drug remains in the freezing ice shelf, forming a spongy porous structure, so the volume of the drug is almost unchanged after drying by freeze dryer. Before reuse, as long as water for injection is added, it will dissolve immediately.
There are many methods for drying the freeze dryer, such as drying, boiling, drying, spray drying and vacuum drying. However, the common drying methods are usually carried out at temperatures above 0 degrees Celsius or higher. The drying products generally have the problems of shrinking volume and hardening texture. Most of the volatile components will be lost. Some thermosensitive substances will be denatured and deactivated, and some substances will even be oxidized. Therefore, the properties of dried products are quite different from those before drying. The principle of freeze-drying is basically below 0 C, that is, under the condition of product freezing, only when the residual moisture content of the product is reduced in the later stage, can the product be raised to above 0 C, but generally not more than 40. Under vacuum conditions, when the water vapor is sublimated directly, the drug remains in the ice shelf when it is frozen, forming a porous structure similar to sponge, so its volume is almost unchanged after drying. Before reuse, as long as water for injection is added, it will dissolve immediately.
Mini-Small-Laboratory-Vacuum-Freeze-Dryer
Tabletop-Mini-Small-Laboratory-Vacuum-Freeze-Dryer
Vegetable-Fruit-Meat-Vacuum-Freeze-Dryer
China-Vegetable-Fruit-Meat-Vacuum-Freeze-Dryer
