How does a Rotary Evaporator Work?

The rotary evaporation, or rotavap, is a common and essential equipment used for  concentration, crystallization, drying, separation and solvent recovery in pharmaceutical,chemical and bio-pharmaceutical fields and other fields. Generally, it is used to remove a valtile solvent from a liquid mixture. A rotary evaporator mainly compose of following parts: a vacuum pump, a chiller, a condenser pump, a rotating flask and a receiving flask and other components. Most of people may be interested in a question how a rotary evaporator works. Hence, the working process of a rotary evaporator will be introduced specifically in the next section.

RE-501 5L Rotary Evaporator
RE-501 5L Rotary Evaporator


Working Process

1. Preparations

a. Pour the mixture of solvent and required compound in a round bottom flask, which should be fiiled less than half full of the solution.

b. Fill the rotovap cold traps with dry ice.

c. Attach a glass “bump trap” to prevent any solution from entering the main part of the rotovap. Secure with a clip.

d. Connect the flask and bump trap to the adaptation part with a clip.

e. Lower the flask into the water bath, preventing the flask from disconnection.

2. Operation

The working process of rotary evaporator is a consecutive process under a reduced environment. There are several steps for the operation:

a. Under reduced pressure, the evaporation flask was continuously rotated while the solvent was being distilled. The evaporation flask is a pear-shaped or round-bottomed flask with a standard ground mouth connection. It is connected with the pressure reduction pump through a serpentine condenser.

b. After substances get evaporated by heating, the gas-phase substances will go into condensing part to get condensed. In this step, gas substances are transferred through the glass tubes.

c. After gas-phase substances got condensed into liquid-phase, the liquid-phase substances will be transferred into receiving flask, which is the final destination of extracted substances. And then users will take the receiving flask out of rotary evaporator equipment.

During the whole working process, there is always a vacuum pump providing a vacuum environment for the rotary evaporator, which guarantees the whole system work in a reduced environment and the automatic feeding system formed by the pressure difference between atmosphere pressure and vacuum pressure.

Can a Rotary Evaporator Remove Water?

Rotary evaporator is widely used in removing water from materials, which is to concentrate substances. Removing water by rotary evaporator is commonly used in kitchen, for example, concentrate fruit juice, which is to remove water from fruit juice. Besides, there are other examples of removing water from substances.

Applications of a Rotary Evaporator

Rotary evaporators can be used to separate solvent from many organic, inorganic, and polymeric materials. It is crucial that the desired compound has a lower boiling point than the solvent and that the compound does not form an azeotrope with the solvent. If these conditions are true, rotary evaporation may be a very efficient technique to separate solvent from the compound of interest. Lower boiling solvents work best, however, rotary evaporation is commonly used to remove water. Higher boiling solvents such as DMF and DMSO are more easily removed using other techniques such as lyophilization, however, with a very good vacuum pump, they may be removed using rotary evaporation.

Related Products:

50L-100L Rotary Evaporator

50L Dual condenser rotary evaporators


10L-30L Rotary Evaporator

R-1020A Rotary Evaporator


Related Articles:

How to use a rotovap

What are rotary evaporator working principle

How does a rotary evaporator remove solvent

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