I would like to ask: since water and ethanol have an azeotrope, how is separation achieved through distillation? ?
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I would like to ask: since water and ethanol have an azeotrope, how is separation achieved through distillation? ? What are the technological processes and principles involved? ?
When an azeotrope is formed, for example with an ethanol concentration of 40%, the ethanol content in the vapor phase resulting from the azeotrope is also 40% – so isn’t it possible to separate them?
It depends on your water content. If your water content is less than 5%, you can use a distillation tower for separation; at the top of the tower there is 95% alcohol, while at the bottom there is anhydrous ethanol. Of course, the anhydrous ethanol obtained by this method still contains a small amount of water (less than 0.5%). It can be reprocessed chemically, for example using anhydrous calcium chloride. If your water content is greater than 95%, you can follow the rapid current method. Azeotropic distillation can also be used. How should this sentence be understood? ? Is it correct? ?
Distilling an ethanol solution can yield 95% alcohol; at this point it is an azeotrope. By adding calcium oxide and mixing thoroughly before distillation, 99% ethanol can be obtained. To get pure ethanol, magnesium powder is added for further purification.
Because the boiling points of alcohol and water are different. Water boils at 100 degrees at standard atmospheric pressure, while alcohol boils at just over 80 degrees. So, as long as the mixture is heated, when it is observed that the temperature of the liquid no longer rises, it means that the alcohol has begun to vaporize. When the temperature of the liquid rises again, it indicates that the alcohol has completely vaporized, and what remains is only water
I’m too tired; it’s simply impossible to explain to a layperson how distillation works in such a way that they can meet the design requirements. In this regard, it is necessary to read more books to deepen one’s understanding of the theoretical concepts; no matter how much someone else explains it, it will be useless if one does not fully grasp it. The azeotropy between ethanol and water occurs under certain conditions; at concentrations below 95%, distillation can be used to separate them. To overcome this limitation and enable distillation, other substances must be added to break the azeotropy. Ordinary industrial alcohol has other substances that react with water added after 95%, such as calcium oxide
Distill first, then add calcium chloride and carry out distillation in a column exchange; the calcium chloride solution is distilled for recovery
Over 95% is dehydrated and separated by molecular sieve adsorption.