Advantages and Disadvantages of Rotary Evaporator

What does a Rotary Evaporator do?

A rotary evaporator (rotovap or rotatvap) 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 is special is that the evaporation flask can rotate. It is mainly used for concentration, crystallization, drying, separation and coal recovery in the pharmaceutical, chemical and bio-pharmaceutical industries.

Rotary Evaporator

Advantages of a Rotary Evaporator

Rotary evaporators are quite popular in the market, because it has a great variety of advantages, which can help people work efficiently. The advantages can be concluded as follows:

  1. All rotary evaporators have a built-in lifting motor, which can automatically raise the flask to a position above the heating pot when the power is turned off.
  2. Due to the centripetal force and frictional force between the liquid sample and the evaporation bottle, the liquid sample forms a liquid film on the inner surface of the evaporation bottle, and the heated area is large. In this way, rotary evaporator can guarantee a high evaporation efficiency.
  3. The feeding system of a rotary evaporator is continuous feeding, which improves the working efficiency of the evaporation system.
  4. It is suitable for reflux operation, rapid evaporation of large amounts of solvent, concentration of trace components and reaction processes that require stirring.

Disadvantages of a Rotary Evaporator

  1. Some samples will boil during the heating process, such as heated ethanol and water. Once boiling occurs, the collected sample will be lost. For samples that are particularly difficult to distill, including those that are prone to foaming, a special condenser tube can also be configured for the rotary evaporator.
  2. In the rotary evaporator equipment, the glassware needs to be cleaned very often, because rotary evaporator needs a totally clean container to guarantee the purity of materials. If there is any impurity in the glassware, the extracted materials will be not pure.

What are Functions of a Rotary Evaporator?

A rotary evaporator is an essential separation equipment, which can remove a volatile 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.

rotary evaporator
rotary evaporator

Can a Rotary Evaporator Remove Water?

A rotary evaporator can get materials evaporated, so a rotary evaporator can remove water. When there is water and ethanol in the mixture, how do we evaporate it:

  1. Change the temperature to speed up the evaporation rate. If the mixture is more complicated, it is not necessary to spend all the time to evaporate the solution. You can obtain the required substances by increasing the temperature.
  2. Vacuum with a vacuum pump to further reduce the pressure to lower the boiling point, even if the temperature is not increased, all solutions can be evaporated.
  3. The percentage of internal ethanol needs to be determined first. After several distillations, the composition of the mixture remaining in the flask will be different. You can add more than 5 degrees to the current boiling point of the mixture.

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