Distillation refers to the physical separation process of components in a mixture based on their volatility. Depending on the type of distillation method used and the desired outcome, distillation can either increase the concentration of a component in a mixture or obtain a virtually pure sample from the mixture. There are many different types of distillation that are worth knowing. Below, we’ll discuss three of the most popular distillation processes used today.
Short path distillation
Short path distillation is a distillation process that requires lower boiling temperatures and that’s generally done at reduced pressure. Due to the decreased temperatures involved in the process, it’s ideal for purifying small quantities of compounds that are unstable at high temperatures. Mainly, it’s used to separate organic compounds with high molecular weight, such as consumable oils.
During the short path distillation process, the separated compounds are condensed almost immediately. As its name suggests, the distillate only has to travel a short distance of around a few centimeters before reaching the condenser. Because the distillate travels a very short distance, less product is typically wasted along the walls of the short path distillation equipment than in other distillation apparatuses.
Simple distillation is a process that involves separating multiple liquids with different boiling points. To do so, the mixture is heated to its boiling point and the vapors emitted are immediately condensed. Eventually, the concentration of the component with the lower boiling point will decrease. Once this occurs, the apparatus’s temperature will increase to match the boiling point of the compound with the next lowest boiling point. This process will repeat until all the liquids have been separated. For this distillation method to work, the boiling points of the liquids being separated must have a minimum difference of 70 degrees Celsius.
Another type of distillation worth knowing is vacuum distillation. This type of distillation is ideal for mixtures that contain liquids with extremely high boiling points. Such liquids tend to decompose when heated to their boiling points. To efficiently boil such liquids, the pressure inside the apparatus is lowered. The component is then able to boil at a lower temperature than its normal boiling point. When the vapor pressure of the component and the surrounding pressure are equal, the component is converted into a vapor and condensed. Then, it’s collected as a high-purity distillate.