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

(1) Distillation under reduced pressure

(2) Simple distillation

(3) Fractional distillation

(4) Steam distillation

Answer ::

The distillation technique most suited for separating glycerol from spent-lye in the soap industry is distillation under reduced pressure. The boiling point of glycerol is 2900C at atmospheric pressure. At this temperature, it decomposes before it distils. Therefore, the distillation is carried out under reduced pressure by applying vacuum which decreases the boiling temperature of glycerol and thus preventing its decomposition.