Have you ever had gum stuck in your hair? It’s not fun, but there are a few techniques on how to get it out without cutting your hair.
Extractive distillation is closely related to this every day situation. It is defined as: “distillation in the presence of a miscible, high-boiling, relatively non-volatile component, the solvent that forms no azeotrope with the other components in the mixture. The method is used for mixtures having a low value of relative volatility, nearing unity.”
In simple terms, extractive distillation is a means of separating two substances with similar boiling points by adding a third substance to change the boiling point of one of compounds, thus making them easier to separate.
When you get gum stuck in your hair it is difficult to separate the gum from the individual hair strands. BUT, if you introduce a third substance like vegetable oil or peanut butter it changes the properties and consistency of the gum, making it easier to extract from you beautiful head of hair.
In the chemical world there are times when two substances become very difficult to separate using standard distillation, because their boiling points are so similar. The below flow diagram explains how extractive distillation works on a large scale.
(A + B) are introduced into the first distillation column. Separately introduced in the first distillation column is a solvent (S). The solvent and B interact in such a way as to change the boiling point of B. The distillate from the first column (A) can then be effectively be separated from (B).
Now that you’ve separated (A) from (B) you are left with the mixture of solvent and (B). These two chemicals are now pumped to a solvent recovery column to be separated. Once (S) and (B) are separated (S) is recirculated back into the first column and the process starts again.
Your hair and the gum are similar to (A+B) and the peanut butter is similar to the solvent. Adding the peanut butter (S) to your hair (A) and the gum (B) change the gum’s properties and it can be easily removed from you hair.
This is a complicated concept being applied to an uncomplicated everyday life, making the complicated concept, well, less complicated.