Extractive Distillation

 INTRODUCTION 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.  Extractive distillation is commonly applied in industry, and has become an important separation method in petrochemical engineering. The method is used for mixtures having a low value of relative volatility, nearing unity. In extractive distillation, an additional solvent, i.e. separating agent is used to alter the relative volatility of the components to be separated. In this way, it is possible to obtain one pure component at the top of one column and the other, together with the solvent at the bottom, which may be separated easily in a secondary distillation column, due to a high boiling point of the solvent. PRINCIPLE The principle is based on the separation of a two-component mixture. By using the difference in the volatility of each component in the liqu...