Question

The distillation technique most suited for separating glycerol from spent-lye in the soap industry is :

• A. Simple distillation
• B. Fractional distillation
• C. Steam distillation
• D. Distillation under reduced pressure

Answer 1

The Correct Option is D

The question asks about the most suitable distillation technique for separating glycerol from spent-lye in the soap industry. Let's examine each option:

1. Simple Distillation: This technique is generally used for separating liquids with significantly different boiling points. However, glycerol has a relatively high boiling point of 290^\circ C, which makes simple distillation inefficient due to the risk of decomposition at high temperatures.
2. Fractional Distillation: Suitable for liquids with closer boiling points, it involves the use of a fractionating column. However, like simple distillation, fractional distillation is not ideal at high temperatures as it can lead to decomposition.
3. Steam Distillation: This technique is useful for separating temperature-sensitive substances. However, glycerol is not volatile with steam, and this method is not suitable for its separation.
4. Distillation under Reduced Pressure (Vacuum Distillation): This technique reduces the boiling point of the substance by decreasing the pressure, making it ideal for high-boiling liquids like glycerol. It prevents decomposition and allows for efficient separation.

Conclusion: The most suitable technique for separating glycerol from spent lye in the soap industry is Distillation under Reduced Pressure because it allows glycerol to be distilled at a lower temperature, preventing decomposition.