Information AboutAzeotrope |
| CATEGORIES ABOUT AZEOTROPE | |
| thermodynamics | |
| phase changes | |
| separation processes | |
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An azeotrope is a mixture of two or more Compounds ( Molecule s) which at a specific composition has a Vapor in Equilibrium with that Liquid with the same composition as the liquid. This means that you cannot change the composition of that liquid at its azeotropic composition by simple Boiling . This constant composition will (almost always) occur at a minimum or maximum temperature over the composition space. The exception for Binary Mixture s is the rare Double Azeotrope . The exception for three or more components is the intermediate boiling azeotrope ( Saddle Azeotrope ). In order to enrich a mixture past the azeotrope (or "break" the azeotrope), one may use several techniques: # Use Azeotropic Distillation , by adding in a third component which will generate a lower boiling heterogenous azeotrope that can be broken by phase separating the two immiscible liquids and decanting. # Use Extractive Distillation where a third compound is added near the top of a distillation column that reduces the volatility of one compound over another. # Use Liquid-liquid Extraction to separate the compounds by segregating them into two different liquid phases. # Use a Membrane to separate them, as in Pervaporation . # For azeotropes that change composition when pressure is changed, you can use pressure swing distillation by operating two distillation columns at different pressures, and recycle material between these two distillation columns. One column will remove a pure component (two-component systems) in the bottom of one distillation column, the other will remove a pure component in the bottom of a second distillation column, and the azeotrope (of two different compositions) will be fed to the other column. The word azeotrope comes from the Greek "zein tropos", or "constant boiling". An azeotrope is said to be positive if the constant boiling point is at a temperature maximum, and '''negative''' when the boiling point is at a temperature minimum. The vast majority of azeotropes are minimum boiling. All liquid mixtures which are Immiscible and which form azeotropes are minimum boiling . EXAMPLES OF AZEOTROPES
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