We already know a lot about rotary evaporators, including large capacity rotary evaporators and small capacity rotary evaporators. In fact, the mini rotary evaporator is also an evaporation instrument widely used in the laboratory. It is suitable for reflux operation, rapid evaporation of a large amount of solvent, concentration of trace components and reaction processes that require stirring. The rotary evaporator system can be sealed and decompressed to 400-600 mmHg; the solvent in the distillation flask is heated with a heating bath, and the heating temperature can be close to the boiling point of the solvent; at the same time, it can be rotated at a speed of 50-160 rpm, The solvent is formed into a thin film and the evaporation area is increased. In addition, under the action of the cooler, the hot vapor can be quickly liquefied and the evaporation rate can be accelerated. Overall improved Rotary Evaporator Efficiency.

1. Do not fill too much water in a Rotary Evaporator to prevent back suction

a. Before starting the rotary evaporation, adjust the angle of the eggplant bottle, water bath, and the port of the rotary evaporator, and then put the sample into the eggplant bottle to prevent the loss of the sample when the rotary evaporator is installed. and damage to the rotavapor port.
b. After the eggplant-shaped bottle containing the sample is successfully connected to the port of the rotary evaporator, the rotary button should be turned on to check whether the rotation is flexible, and more importantly, whether all or most of the rotary steamed samples are immersed in the liquid level of the water bath. In this way, the efficiency of rotary evaporation can be ensured.
c. Do not contain more than 75% of the samples in the eggplant-shaped bottle, otherwise it will suck back when decompressed.
d. Next, install the container containing the distillate, pay attention to use some alum shiline when connecting to ensure a good airtightness, pass the cooling water well, close the ventilation valve, open the decompression device, and carry out decompression distillation.
e. During the decompression process, the temperature of the water in the water bath should be adjusted so that it is compatible with the boiling point of the sample you are rotating. This can be seen from the state of the reflux liquid in the reflux tube. It is better when it is flowing.
f. When the rotary evaporator is nearing the end, first open the ventilation valve to make the air pressure inside and outside the rotary evaporator consistent, then close the rotary switch and remove the eggplant bottle.
 

2. The important role of cooling water circulation device in rotary evaporation system

What factors are related to the increase of Rotary Evaporator Efficiency? Some people may wonder whether the larger the condensation area of the rotary evaporator, the higher the concentration efficiency?
 
a. The condensing area refers to the surface area of the 10 liter rotovap condensing pipe through which the cooling water is passed. The better the cooling effect of this part, the better the condensation effect of the evaporated solvent. The cooling effect of this part depends on the size of the condensing area on the one hand. On the other hand, it also depends on the cooling capacity of the cooling water inside.
b. The cooling capacity of the cooling water is strong enough that the steam can be condensed at the lower third or fourth position of the condensing pipe. If the cooling capacity of the cooling water is not enough, the condensation position in the condensing pipe will be raised to one-half of the position, and even the steam cannot be condensed. Therefore, if the condensation area is not too small, the cooling efficiency of the cooling water first determines the The condensation efficiency of the condenser tube on the steam, so when we configure the rotary evaporator system, we must pay special attention to the configuration of the cooling water circulation device, which is one of the reasons why some of our users cannot concentrate when they use tap water for cooling. .
c. Generally speaking, the difference between the temperature of the cooling water and the boiling point temperature of the sample under reduced pressure must be at least 15~20°C for normal condensation.  

3. Development trend of rotary evaporator in chemical and pharmaceutical industry

a. The large-volume rotovap machine is an effective way and development trend to increase output, speed up production and reduce product cost. Most of the rotary evaporators used in the pharmaceutical industry are less than 50 liters in China, and some in other industries are less than 30 liters; in foreign countries, there are 100 to 500L in the chemical industry, while other industries can reach less than 200L.
b. In a Rotary Evaporator production of automatic lifting and manual lifting operations, such as button control, can not only ensure stable production, improve product quality, increase revenue, reduce manual labor, but also eliminate environmental pollution.
c. Make reasonable use of the performance of the rotary evaporator, select good process operating conditions, strengthen evaporation measures, improve heating efficiency, reduce heat loss to a minimum, and fully utilize waste heat or heat generated after heating. The application of rotary evaporator heating tube technology will be the direction of future development.
d. Explosion-proof rotary evaporators have been developed from rotary evaporators to explosion-proof motors or explosion-proof frequency converters. In foreign countries, in addition to the speed governor, the evaporator has a knob-type speed control to improve the evaporation speed.
 
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