School of Earth and Environment

Freeze dryer

Freeze-drying is a dehydration process that occurs under vacuum. This reduced pressure allows the frozen water in the material to sublimate directly from the solid phase to the gas phase. For this reason samples must be frozen before they are placed in the freeze dryer.

Phase diagram for water.

Instrument capabilities

The instrument is a Edwards Modulyo 4K freeze dryer.

Practical considerations

Samples should be in containers such as centrifuge tubes or petri dishes with clear sides so the rate of drying can be monitored. Samples must be pre-frozen.

If you want to know the sample moisture content then you should weigh them before freezing. If they become iced it will affect the length of time needed to dry a sample. In general, sample thickness should be less than 10mm.

Written by Andy Connelly (13/06/2014)

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