Distillation is a method of liquid separation and purification achieved by heating a liquid to the point of vaporisation and then capturing the vapour as a condensate.
The elevated temperature needed to distil a compound with a high boiling point at atmospheric pressure will often have a detrimental thermal effect on the compound. In such cases, the process of vacuum distillation is preferred.
Vacuum distillation separates compounds with a high boiling point through the interaction of pressure and temperature. Lowering the pressure means that the required temperature can also be lowered, making for gentler distillation.
The distillation process is typically carried out with laboratory vacuum distillation apparatus and a suitable vacuum pump. The choice of pump will be determined by numerous factors including desired vacuum depth, total system volume, and desired temperature. The interaction of the system temperature with the solvents’ boiling points will determine the desired vacuum depth. The total system volume will help establish the optimal pump flow rate, with larger volumes requiring a higher flow.
Considerations for selecting the optimal pump include:
- Oil-free operation with excellent chemical compatibility
- Ability to process wet vapours
- Ultimate depth of vacuum
- Flow rate in proportion to the system volume
- Solvent recovery options at both the inlet and the outlet
- Adjustable control of vacuum levels
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