VACUUM DISTILLATION
IMPORTANT ASPECTS OF VACUUM DISTILLATION
- Distillation under vacuum conditions is practiced to achieve one or more of the following objectives:
- Distillation of high boiling compounds like nitrobenzene, aniline, ethyl aniline, etc whose distillation at atmospheric pressure could lead to decomposition, charring, color change, etc.
- Improving relative volatility of the system. It is a known fact that with system pressure reduction, vapor-liquid equilibrium curve becomes more convex & separation becomes easier.
- It facilitates separation of azeotropic mixtures without using external compounds. Many azeotropic systems, become normal systems at reduced pressure & enables separation by distillation techniques without utilizing external compound. For illustration, water-ethanol system at atmospheric pressure forms azeotrope but becomes normal at 70 mmHg.
