How to improve the distillation efficiency of rotary evaporator in laboratory?

The evaporator is a laboratory instrument used to distill and extract materials, which is widely used in chemical, chemical, biomedical and other fields It is understood that the distillation efficiency of the rotary evaporator in the laboratory is a very important performance On the one hand, it determines the efficiency of the experiment, on the other hand, it also reflects the quality of the equipment "The distillation efficiency of the rotary evaporator in the laboratory determines the number of samples that can be distilled every day Under the same solvent, the higher the distillation efficiency, the more samples that can be distilled." According to the industry, more and more attention has been paid to the distillation efficiency of rotary evaporators in the laboratory So, what are the factors that affect the distillation efficiency of rotary evaporators in the laboratory, and how can users improve the distillation efficiency? First, the temperature of the cooling medium According to the industry, the temperature of the cooling medium will affect the distillation efficiency of the rotary evaporator In general, it is recommended to maintain a temperature difference of about 40 ° C between the cooling medium and the heating pot, so as to allow the hot steam to condense rapidly, so as to reduce the impact of steam on the system vacuum Second, the temperature of the heating pot It is reported that the higher the temperature of the heating pot of the rotary evaporator in the laboratory, the faster the distillation effect of the solvent Due to the safety of operation and the thermal sensitivity of the target components, the commonly used temperature is generally 60 ℃ or above 80 ° C However, due to the difficulty of cleaning the silicone oil medium, the rotary evaporator manufacturers generally recommend that users reduce the vacuum value to achieve faster distillation efficiency Third, the vacuum value of the system The closed space of laboratory rotary evaporation instrument is generally composed of evaporation bottle, evaporation tube, sealing ring, condensation tube, vacuum buffer bottle, vacuum pump and vacuum pipeline The key factors affecting the system vacuum are vacuum pump, sealing ring and vacuum pipe According to the industry, in distillation, it is generally necessary to set a reasonable vacuum value through the vacuum controller to ensure the distillation efficiency and avoid boiling In addition, it is suggested to add a vacuum controller or a vacuum valve to better control the vacuum value of the system required for distillation The sealing ring is the key seal for the evaporation pipe and the condensation pipe, and its wear resistance and corrosion resistance are the key PTFE and rubber are commonly used as sealing ring materials, of which PTFE has better wear resistance and corrosion resistance than rubber Silica gel tube is a better choice for vacuum tube because its aging efficiency is slower than that of ordinary rubber tube Fourth, the speed of the evaporation bottle It is reported that the faster the rotating speed of the evaporation bottle, the larger the wetted area of the inner surface of the bottle and the larger the heated area However, the thickness of the liquid film will also increase, increasing the temperature difference of heat transfer For materials with different viscosities, proper rotational speed should be designed Fifth, the size and power of the system It is understood that the distillation speed in a given system is mainly limited by the condenser's ability to condense solvent vapor, but rarely by the heater "If too much steam is allowed to rush into the condenser, it will not work effectively due to overload, resulting in valuable volatiles loss." According to the industry, in order to avoid saturation, users should monitor the pressure of the system so that 2 / 3 of the condenser is always covered by condensate In addition, if the liquid begins to form at the top 1 / 3 of the coil, there is a risk that the incoming steam will be drawn into the vacuum pump Therefore, in practice, it is recommended to make the condensate close to 3 / 4 of the condenser In addition, continuous operation mode can also improve distillation efficiency It is reported that at present, foreign manufacturers of rotary evaporators control the feed valve switch through the liquid level sensor of the evaporating bottle, realize the release switch of the collecting bottle by controlling the sensor of the liquid level collecting bottle, realize the automatic continuous distillation of the industrial rotary evaporators, and realize the unmanned operation It can be seen that the level of rotary evaporators in China needs to be further improved compared with that in foreign countries.