By Rachelle Dragani • Updated March 24, 2022
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Simple distillation is used to separate salt from seawater, to separate sugar from water, and to separate ethanol from water in the production of hard liquor.
Simple distillation separates liquids with markedly different boiling points by heating a mixture, allowing the more volatile component to vaporize, then condensing the vapor back into liquid in a separate receiver. For the technique to be effective, the boiling-point difference between the two components should be at least 25 °C (77 °F).
One of the most classic applications of simple distillation is the purification of seawater. As the saltwater mixture is heated, water vaporizes at 100 °C while the dissolved salts remain in the boiling pot. The vapor is directed through a condenser, where it cools and condenses into pure water, which is collected in a separate vessel. The remaining brine, rich in sodium chloride, stays behind.
Although distillation achieves complete separation, it is energy‑intensive, so many desalination plants opt for membrane‑based reverse osmosis instead. Nevertheless, distillation remains a reliable method in laboratory settings and small‑scale applications.
In the confectionery industry, simple distillation is used to isolate water from a sugar solution. Because water boils at 100 °C and sucrose at ~186 °C, the water evaporates first. The condensed water is harvested, leaving behind a more concentrated sugar syrup.
Distillation is also the cornerstone of spirit production. Fermented mash or wine contains roughly 10–15 % ethanol. By heating the mixture, ethanol—boiling at 78.4 °C—vaporizes before water (100 °C). Condensing the vapor yields a liquid richer in alcohol, typically 40 % or higher for spirits such as gin, rum, or whiskey.
Because the distilled liquid is denser than the original fermentation, multiple distillation stages or the use of a column can further raise the alcohol content.
