Today, I would like to explain how to choose and buy rotary evaporator. Before choosing rotary evaporator, I would like to ask yourself the following questions:
What is the quantity of a distillation?What is the approximate number of samples to be distilled per day?What are the expected solvents for distillation?What is the approximate boiling point range of the solvent?Are these solvents flammable or explosive, or toxic or harmful solvents?Once we've determined the experimental requirements and the type of solvent we need to distill, we can start shopping for a rotary evaporator.
Specification of rotary evaporator the specification of rotary evaporator is usually distinguished by the volume of evaporator bottles. The size of evaporator bottles required depends on the quantity of evaporated materials. Generally speaking, 2L, 3L and 5L rotary evaporators are suitable for small volume laboratory tests.5L, 10L and 20L are suitable for pilot test;20L and 50L are suitable for pilot test and production.Of course, in special cases, we can also use continuous feed tube to expand the volume of the evaporation bottle, so as to expand the amount of a continuous distillation.
The distillation efficiency of the rotary evaporator determines the number of samples that can be distilled every day. In the case of the same solvent, the higher the distillation efficiency, the more samples can be distilled.If the sample size is large, we need to consider the distillation efficiency
The key factor that affects distillation efficiency
NO. 1 [system vacuum value]
The enclosed space of the rotary evaporator consists of glass components such as evaporating bottle, evaporating tube, sealing ring, condensing tube, vacuum buffer bottle, vacuum pump and vacuum tube. Among them, the most critical and changeable factors affecting the vacuum of the system are: vacuum pump, sealing ring and vacuum tube.
Vacuum pump and vacuum controller: the lower the vacuum pump limit, the lower the vacuum value of the system.During distillation, a reasonable vacuum value should be set through the vacuum controller to ensure the distillation efficiency and avoid the explosion boiling.At present, the ultimate vacuum of diaphragm vacuum pump can reach as low as 2mbar, and the ultimate vacuum of circulation pump is about 50mbar (0.095kpa).If the budget allows, a vacuum controller or valve is necessary to control the system vacuum value required for distillation.
Seal ring: as the key seal to accept evaporating tube and condensing tube, its wear resistance and corrosion resistance are the key.Commonly used as sealing ring material is: PTFE and rubber, apparently PTFE wear resistance and corrosion resistance will be better.Some manufacturers in the seal ring, add the stainless steel buffer shrapnel, wear resistance is better.
Vacuum tube material: generally, the manufacturers do not have standard vacuum tube, choose and buy, silica gel tube is the natural first choice, because its aging efficiency is slower than rubber tube.
NO.2 [heat 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, the safety of the operation, the most commonly used temperature is 60℃.Moreover, over 80°C, switching to silicone oil as the medium will bring cleaning problems, and it is generally recommended to lower the vacuum value to achieve faster distillation efficiency.At present, the best diaphragm vacuum pump on the market, the ultimate vacuum can reach 2mbar, DMF can be distilled at room temperature.
No.3 [speed of evaporation bottle]
The faster the speed of evaporation bottle is, the larger the surface infiltration area is and the larger the heating area is.But at the same time, the thicker the liquid film thickness, increase the heat transfer temperature difference.For materials with different viscosity, there is an optimal speed.And the rotation power is provided by the motor, the market brushless dc motor, ac motor and step motor are uneven, brushless dc motor feedback is the best, 10 years maintenance free.
No.4 [temperature of cooling medium]
To ensure optimal distillation efficiency, it is generally recommended to maintain a temperature difference of 40°C between the cooling medium and the heating pot temperature in order to rapidly condense the hot steam and reduce the influence of steam on the vacuum of the system.Safety risk assessment the safety risk of distillation mainly comes from the solvent of distillation and the heating medium.
1) if the heating medium is silicone oil, the ignition point should be at least 25°C higher than the maximum temperature of the heating pot.
2) if the distillation solvent with flammable, explosive nature, the explosion-proof glass components can be used as the first choice, the end of distillation, if the instrument can automatically vent the best, so as to avoid artificial vent too fast, causing the explosion.
3) to optimize the laboratory environment, secondary condensing device can be selected to maximize the recovery of distilled solvent.
What is the quantity of a distillation?What is the approximate number of samples to be distilled per day?What are the expected solvents for distillation?What is the approximate boiling point range of the solvent?Are these solvents flammable or explosive, or toxic or harmful solvents?Once we've determined the experimental requirements and the type of solvent we need to distill, we can start shopping for a rotary evaporator.
Specification of rotary evaporator the specification of rotary evaporator is usually distinguished by the volume of evaporator bottles. The size of evaporator bottles required depends on the quantity of evaporated materials. Generally speaking, 2L, 3L and 5L rotary evaporators are suitable for small volume laboratory tests.5L, 10L and 20L are suitable for pilot test;20L and 50L are suitable for pilot test and production.Of course, in special cases, we can also use continuous feed tube to expand the volume of the evaporation bottle, so as to expand the amount of a continuous distillation.
The distillation efficiency of the rotary evaporator determines the number of samples that can be distilled every day. In the case of the same solvent, the higher the distillation efficiency, the more samples can be distilled.If the sample size is large, we need to consider the distillation efficiency
The key factor that affects distillation efficiency
NO. 1 [system vacuum value]
The enclosed space of the rotary evaporator consists of glass components such as evaporating bottle, evaporating tube, sealing ring, condensing tube, vacuum buffer bottle, vacuum pump and vacuum tube. Among them, the most critical and changeable factors affecting the vacuum of the system are: vacuum pump, sealing ring and vacuum tube.
Vacuum pump and vacuum controller: the lower the vacuum pump limit, the lower the vacuum value of the system.During distillation, a reasonable vacuum value should be set through the vacuum controller to ensure the distillation efficiency and avoid the explosion boiling.At present, the ultimate vacuum of diaphragm vacuum pump can reach as low as 2mbar, and the ultimate vacuum of circulation pump is about 50mbar (0.095kpa).If the budget allows, a vacuum controller or valve is necessary to control the system vacuum value required for distillation.
Seal ring: as the key seal to accept evaporating tube and condensing tube, its wear resistance and corrosion resistance are the key.Commonly used as sealing ring material is: PTFE and rubber, apparently PTFE wear resistance and corrosion resistance will be better.Some manufacturers in the seal ring, add the stainless steel buffer shrapnel, wear resistance is better.
Vacuum tube material: generally, the manufacturers do not have standard vacuum tube, choose and buy, silica gel tube is the natural first choice, because its aging efficiency is slower than rubber tube.
NO.2 [heat 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, the safety of the operation, the most commonly used temperature is 60℃.Moreover, over 80°C, switching to silicone oil as the medium will bring cleaning problems, and it is generally recommended to lower the vacuum value to achieve faster distillation efficiency.At present, the best diaphragm vacuum pump on the market, the ultimate vacuum can reach 2mbar, DMF can be distilled at room temperature.
No.3 [speed of evaporation bottle]
The faster the speed of evaporation bottle is, the larger the surface infiltration area is and the larger the heating area is.But at the same time, the thicker the liquid film thickness, increase the heat transfer temperature difference.For materials with different viscosity, there is an optimal speed.And the rotation power is provided by the motor, the market brushless dc motor, ac motor and step motor are uneven, brushless dc motor feedback is the best, 10 years maintenance free.
No.4 [temperature of cooling medium]
To ensure optimal distillation efficiency, it is generally recommended to maintain a temperature difference of 40°C between the cooling medium and the heating pot temperature in order to rapidly condense the hot steam and reduce the influence of steam on the vacuum of the system.Safety risk assessment the safety risk of distillation mainly comes from the solvent of distillation and the heating medium.
1) if the heating medium is silicone oil, the ignition point should be at least 25°C higher than the maximum temperature of the heating pot.
2) if the distillation solvent with flammable, explosive nature, the explosion-proof glass components can be used as the first choice, the end of distillation, if the instrument can automatically vent the best, so as to avoid artificial vent too fast, causing the explosion.
3) to optimize the laboratory environment, secondary condensing device can be selected to maximize the recovery of distilled solvent.
