Distillation – A Way of Life Zach Alison

What is distillation? The process of heating a liquid until it boils, capturing and cooling the resultant vapors, and then collecting the condensed vapors. Exploits the difference in volatilities of individual components within a solution. Solutions with larger differences in volatilities best to separate via distillation. Based on Raoult’s Law and Dalton’s Law of Partial Pressures.

Brief History Known to Babylonians circa 2000 BC (around same time as invention of the wheel). Later utilized by early Pakistan inhabitants and the Greeks. In all cases, early types of distillation used solely for the production of alcohols and liquors. Not refined with modern techniques until the early 19 th century.

Applications Separate crude oil for specific uses such as heating, power generation, and transportation. Purification and separation of air components for industrial use. Reduce chemical waste. Increase concentration of alcohol in beverages. Purification of water. Distill herbs for perfumes. Food processing.

Basic Terms Feed – solution or liquid mixture to be distilled. Column – pipe packed with material through which vapors travel. Vapors cool and heat up during their trip through the column; helps to further purify them. Reflux – cooled vapors that slide down the distilling column to clean ascending vapors. Trays/Packings – hold liquid and aid in more rapid distillation through the column. Condenser – coil through which cold water flows continuously during distillation.

Simple Distillation Usually preferred in general distillation. Set up: - boiling flask - thermometer - condenser - collection flask

Fractional Distillation More accurate distillation. Essentially same as simple; includes a fractionating column, usually filled with beads. Based on fact that boiling occurs when vapor pressure of solution equals environmental pressure.

Simple vs. Fractional

Vacuum Distillation The environmental pressure around the solution is lowered, allowing component with lowest boiling point to evaporate. Can be used with or without heat. Based on fact that boiling occurs when vapor pressure of solution equals the environmental pressure.

Other Types of Distillation Batch Continuous Steam “Short path” Reactive Azeotropic Pressure swing Extractive Dry* Freeze*

Factors Affecting Distillation Weather conditions Condition or number of trays or packings State and composition of feed Type of distillation and difference in volatilities of components

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