The secondary drying phase purpose is to remove the remaining
unfrozen water molecules. In this phase the temperature rises above 0, unlike
the primary phase, in order to break any
interactions that have formed between the water molecules and the frozen
material.
During this process the pressure is lowered and head is inserted
to the material in order to
make the water sublime. In this slow process, about 95 percent of the water is
sublimed. Furthermore the temperature during the primary drying phase is around
-50 Celsius.
The main stages of the freeze-drying process are placing the
material in the freeze-drying flask, rotate the flask in a bath which is cooled
by mechanical refrigeration in a
larger scale freezing is usually done
using a freeze-drying machine
There are four main
stages in the freeze-drying process, the pretreatment, the freezing, the primary
drying and the secondary drying phases.
141 views
Usually answered in minutes!
×