especially for the extraction of materials that need to avoid metal ion pollution. 5. Rotary evaporator and other types of evaporators The rotary evaporator has the advantages of compact structure, high efficiency, rotary vacuum evaporator ,winterization filtration, intuitive operation and no metal ion pollution. It is suitable for laboratory, pilot production and extraction of precious materials, and its sealing performance is comparable to that of foreign machines. 6. Selection of vacuum pump We recommend the circulating water vacuum pump resistant to corrosion of various solvents, which can be vacuumized to -0.098 MPa to meet various use requirements. Advantages of Rotary Evaporator 1. All rotary evaporators have a built-in lifting motor, which can automatically lift the flask to the 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 layer of liquid film on the inner surface of the evaporation bottle, and the heating area is large; 3. The force generated by the rotation of the sample effectively inhibits the boiling of the sample. These features, together with their convenience, allow modern rotary evaporators to be used to distill most samples quickly and gently, even by inexperienced operators. Disadvantages of Rotary Evaporator Boiling of certain samples, such as ethanol and water, will result in the loss of the sample collected by the experimenter. This is often related to the nature of the solvent used. Water, ethanol, acetic acid, petroleum ether, chloroform and other solvents are commonly used in biochemical and pharmaceutical industries. However, general vacuum pumps can not resist strong organic solvents. Special vacuum pumps with strong corrosion resistance can be used. Water circulation vacuum pumps are recommended. Structurally, the enclosed space of the rotary evaporator is composed of glass components such as an evaporation bottle, an evaporation tube, a seal ring, a condenser tube, a vacuum buffer bottle, a vacuum pump and a vacuum pipeline, among which the vacuum pump, the seal ring and the vacuum tube are the most critical and variable factors affecting the vacuum of the system. Vacuum pump and vacuum controller: The lower the vacuum pump limit, the lower the vacuum value of the system. When distilling, it is necessary to set a reasonable vacuum value through the vacuum controller to ensure the distillation efficiency and avoid bumping. At present, the ultimate vacuum of the diaphragm vacuum pump can be as low as 2mbar, and the ultimate vacuum of the circulating water pump is about 50mbar (0.095 kPa). If the budget allows, a vacuum controller or vacuum valve is necessary to control the system vacuum level required for distillation. Sealing ring: As the key sealing element to receive the evaporation tube and condenser tube, its wear resistance and corrosion resistance are the key. Materials commonly used for sealing rings are PTFE and rubber. Obviously, PTFE has better wear resistance and corrosion resistance. Some manufacturers add stainless steel buffer shrapnel in the seal ring, which has better wear resistance. Vacuum tube material: general manufacturers do not have standard vacuum tube, when they choose and buy, silicone tube is naturally the first choice, because its aging efficiency is slower than rubber tube. 2. Heating pot temperature The higher the temperature of the heating pot, the faster the distillation effect of the solvent, but considering the thermal sensitivity of the target component and the safety of operation, the most commonly used temperature is 60 C. Moreover, above 80 ° C, the use of silicone oil as a medium will cause cleaning problems, and it is generally recommended to reduce the vacuum value to achieve faster distillation efficiency. At present, the best diaphragm vacuum pump on the market has a limit vacuum of 2mbar, and DMF can be distilled at room temperature. 3. Rotating speed of evaporation bottle The faster the rotating speed of the evaporation bottle is, the larger the wetting area of the inner surface of the bottle is, and the larger the heated area is; but at the same time, the thicker the liquid film is, and the greater the heat transfer temperature difference is. There is an optimum rotational speed for materials with different viscosities. And that rotation pow is provided by the motor, the DC brushless motor, the AC motor and the step motor are all available on the market, and the feedback of the DC brushless motor is the best, and the motor is maintenance-free for 10 years. 4. Temperature of cooling medium In order to ensure the best distillation efficiency, it is generally recommended to maintain a temperature difference of 40 ° C between the cooling medium and the heating pot temperature, so as to condense the hot steam quickly and reduce the influence of the steam on the vacuum of the system. The biggest disadvantage in the application of rotary evaporator It is the boiling of certain samples, such as ethanol and water, that will result in the loss of the sample collected by the experimenter. During operation, boiling can usually be prevented by carefully adjusting the working intensity of the vacuum pump or the temperature of the heating pot during the mixing stage of the distillation process. Alternatively, anti-boil particles may be adde to that sample. For samples that are particularly difficult to distill, including those that are prone to foaming, the rotary evaporator can also be equipped with a special condenser tube. (Source: Experiment and Analysis) Mumuxili Instrument said that all liquid phase veterans know this. Daily maintenance of pipette: teach you how to disassemble and assemble correctly How to obtain the ideal standard curve? Special statement: The publication of this article is only for the purpose of disseminating information, and does not represent the views of this public account; if other media,wiped film evaporator, websites or individuals reprint and use from this public account, please apply to the original author, and bear the copyright and other legal responsibilities. Return to Sohu to see more Responsible Editor:. toptiontech.com
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