Rotary evaporation instruments are mainly used for concentration, crystallization, drying, separation and solvent recovery in the pharmaceutical, chemical and biopharmaceutical industries. The principle is as follows: under vacuum condition, the constant temperature is heated, so that the rotating bottle rotates at a constant speed, and the material forms a large-area film on the bottle wall and evaporates. The solvent vapor is cooled by the glass condenser and recovered in the collection bottle, thereby greatly improving the evaporation efficiency, and is especially selected for the concentration and purification of the biological product which is easily decomposed and degenerated by high temperature.
Rotary evaporators have the following main features:
1. All rotary evaporators have a built-in lift motor that automatically raises the flask to a position above the heating pot when the power is off.
2. Due to the centripetal force and friction 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 heat receiving area is large;
3. The force generated by the rotation of the sample effectively suppresses the boiling of the sample. The above features and its convenient features make the modern rotary evaporator available for rapid and gentle distillation of most samples, even for operators with no operational experience.
The biggest drawbacks of rotary evaporator applications:
It is the boiling of certain samples, such as ethanol and water, which will cause the experimenter to collect the loss of the sample. In operation, it is usually possible to prevent boiling by carefully adjusting the working strength of the vacuum pump or the temperature of the heating pot during the mixing phase of the distillation process. Alternatively, it is also possible to add anti-boiling particles to the sample. For samples that are particularly difficult to distill, including samples that are prone to foaming, a special condenser can also be configured for the rotary evaporator.
Principle: An evaporation instrument widely used in laboratories. Suitable for reflow operations, rapid evaporation of large amounts of solvent, concentration of minor components, and reaction processes requiring agitation. The rotary evaporator system can seal the pressure to 400-600 mmHg; the solvent in the distillation flask is heated by a heating bath, the heating temperature can be close to the boiling point of the solvent; and the rotation can be performed at a speed of 50-160 rpm. The solvent is formed into a film to increase the evaporation area. In addition, under the action of a high-efficiency cooler, the hot vapor can be quickly liquefied to accelerate the evaporation rate.
Uses: Rotary evaporators are mainly used for concentration, crystallization, drying, separation and solvent recovery in the pharmaceutical, chemical and biopharmaceutical industries. The principle is that under vacuum condition, the temperature is heated at a constant temperature, so that the rotating bottle rotates at a constant speed, and the material forms a large-area film on the bottle wall, and evaporates efficiently. The solvent vapor is cooled by a high-efficiency glass condenser and recovered in a collection bottle to greatly increase the evaporation efficiency. It is especially suitable for the concentration and purification of biological products which are easily decomposed and degenerated by high temperature.
Definition: A device for concentrating a fast liquid sample. The sample is heated, depressurized, and continuously rotated in a spherical glass vessel to increase the evaporation surface area and accelerate the evaporation rate.
As the production technology of laboratory equipment in the world has become more mature, more and more university laboratories have begun to use rotary evaporators. The rotary evaporator is a device that uses a rotary evaporation bottle to increase the evaporation area while being placed in a water bath under a reduced pressure while heating, and the solution in the bottle is diffused and evaporated. Next, NewLabX will talk about the role of rotary evaporator, the factors affecting distillation efficiency and the scope of application.
1. Rotary evaporator function
Rotary evaporators are primarily used to continuously distill large amounts of volatile solvents under reduced pressure. In particular, the concentration of the extract and the distillation of the receiving liquid in the chromatographic separation can separate and purify the reaction product. The basic principle of a rotary evaporator is vacuum distillation, that is, under reduced pressure, the distillation flask is continuously rotated as the solvent is distilled.
Factors affecting distillation efficiency of rotary evaporator
2. Vacuum degree of the rotary steaming system
1 Rotary evaporation evaporator is composed of vacuum pump and its pipeline, evaporation bottle and receiving bottle, condenser tube and other components. Among them, the key factors affecting the degree of vacuum are: vacuum pump power, system tightness. Among them, the equipment includes: a vacuum pump, a sealing ring and a vacuum tube.
2 The lower the vacuum pump limit, the lower the vacuum value of the system. However, the vacuum value that the system can form is determined by the pressure resistance of the equipment of the rotary evaporator and the avoidance of bumping when the distillation efficiency is ensured. To set a reasonable vacuum value, it is necessary to combine the above two factors and adjust it by the vacuum controller.
3 sealing ring: connecting the key parts between the evaporation tube and the condensation tube, wear resistance and corrosion resistance are the most important performance requirements. Common materials are PTFE and rubber. Among them, PTFE has better wear resistance and corrosion resistance than rubber.
4 Vacuum pumps and seals are all wearable parts. The vacuum pump should be tested frequently during use to ensure the stability of its vacuum. The seal ring is a detachable accessory that can be replaced directly. Vacuum tubes often use silicone tubing instead of rubber because of their slow aging.
Rotary heating power
The higher the temperature of the oil bath, the faster the distillation rate of the solvent. In the actual distillation process, distillation efficiency is often not pursued by setting an excessively high reaction temperature. Reasons include:
1 If the distilled substance is a heat sensitive substance, the high temperature is easily decomposed and deteriorated;
2 Excessive temperature can easily lead to high temperature softening of seals and other components, reducing their service life and reducing the tightness of the system. Typically, the oil bath is heated in a water bath with a temperature setting below 60 °C. The temperature is higher than 80 ° C and heated in an oil bath.
3 motor speed
The faster the motor speed, the larger the area of the evaporation bottle, the larger the heat receiving area, the thicker the liquid film formed, the higher the heat transfer temperature difference, and the higher the distillation efficiency. In actual use, the speed is not as fast as possible. It is mainly due to:
1 The faster the rotation speed, the greater the centrifugal force formed, which easily leads to the drop of the bottle;
2 The viscosity of the material is different, there is an investigation of the rotational speed.
4 cooling system
The distillation efficiency is better, the temperature of the cooling system is kept at a temperature difference of 40 ° C from the temperature of the heating pot, so that the formed hot steam is rapidly condensed to reduce the influence of steam on the vacuum degree of the system. A commonly used cooling medium is circulating condensate. If there is a substance with a particularly low boiling point, an ice water bath and an ice ethanol bath using a circulating refrigerator as a carrier are also common choices.
Rotary evaporator application range
The rotary evaporator is a device that uses a rotary evaporation bottle to increase the evaporation area while being placed in a water bath under a reduced pressure while heating, and the solution in the bottle is diffused and evaporated. It is an ideal basic instrument for chemical industry, pharmaceutical industry, universities and research laboratories for the production and analysis of experiments, such as concentration, drying and recycling.