A rotary evaporator (rotovap or rotavap) refers to a kind of equipment for solvent evaporation under reduced pressure, which is composed of a vacuum system, a heated water or oil bath, a condenser and a motor that rotates the evaporation flask. As its name suggests, what makes it special is that the evaporation flask can rotate.
Parts of a Rotary Evaporator and Their Functions
There are four parts in a whole rotary evaporator equipment: the condensing part, evaporation part, vacuum pump and receiving part. Each of them is in charge of different functions. The parts of a rotary evaporator, together with their functions, will be specifically discussed in the following.
- In the evaporation part, the evaporation flask rotates at a constant speed to facilitate evaporation by enlarging evaporation area. In this part, there is a heating mantle to heat materials in the evaporation flask, and get materials evaporated. What’s more, the evaporation flask will keep rotating at a constant speed to get a bigger evaporation area, in order to get materials evaporated more quickly.
- The vacuum pump removes gas from the sealed equipment to leave behind a partial vacuum, in order to create a continuous feed system and keep the purity of extracted solvents. It provides the rotary evaporator equipment a vacuum environment. This vacuum environment has two functions: firstly it maintains a reduced pressure environment required by a rotary evaporator; secondly, the pressure difference between a vacuum environment and atmosphere pressure creates a automatic feeding system.
- The condensing part cools the equipment and turns extracted solvents from gas into liquid. In this part, the gas-phase materials can get condensed by condensing tubes, and then they will be turned into liquid-phase materials. After condensing materials, it is more convenient to collect materials for users.
- Then the solvents liquid goes into the receiving flask for users to collect. This part is about the final step of the working process. In this part, the liquid-phase materials will be transferred and collected here. And then the users will take the receiving flask down very easily.
These four parts are the main parts of a rotary evaporator equipment. They cooperate with each other and all of them plays an important role in the working process of a rotary evaporator. Besides these four parts, there are still some tiny accessories, such as iron holders and valves.
How does a Rotary Evaporator Work?
A rotary evaporator is used to extract solvents from liquid mixtures by evaporation in chemical, biochemical and other fields. The working process of a rotary evaporator can be roughly described below. At first, samples are placed in the evaporation flask. With the evaporation flask rotating at a constant speed, there will be a thin film of sample inside the evaporation flask, which facilitates evaporation rate. Then extracted solvents are transferred into condenser and condensed into liquid from gas. This whole process takes place in a partial vacuum created by the vacuum pump.
Functions of a Rotary Evaporator
A rotary evaporator is an essential separation equipment, which can remove a valtile solvent from a liquid mixture through evaporation and condensation. For example, a rotary evaporator can be used to remove ethanol from the mixture of ethanol and cbd oil in order to improve the purity of cbd oil. Also, it can be used to remove water within fruit juice, in order to make the fruit juice have a higher concentration. It can be seen that a rotary evaporator has a great number of functions.
Is a Rotary Evaporator Distillation?
In essence, a rotary evaporator can be regarded as a kind of reduced pressure distillation. As it is mentioned above, the entire working process of a rotovap takes place in a partial vacuum or reduced pressure environment created by the vacuum pump. The round-bottom flask containing the solution is placed in the water bath of the equipment, and rotated when the system is partially evacuated by a vacuum pump.