Siphoning doesn't occur and the solvent seemed stuck at the top part of the siphon tube but enough to make some of the solvent flow constantly. I observed that the amount flowing from the condenser is the same as the amount that flows back to the flask.
I already tried heating the neck of the flask, sealing all joints, and there's no problem with siphon tube blockage since I'm using a round-end thimble. I am using dichloromethane as solvent. What can you suggest for me to do?
Dear Riza Gabriela Bonifacio,
if your compounds are not heat sensitive, than increase the temperature of heating mental/hot plate by doing this rate of evaporation of DCM increases. similarly rate of condensation also increases which finally increases the rate in Soxhlet Extraction.
With Regards
Ajay Sharma
You can check the following to solve your problem:
1. Temperature of the heating source (must be high enough to boil the solvent)
2. Condenser water supply (suffiecient and cool enough to condense the solvent vapour)
3.Suffiecient solvent in the collecting flask
Dear Riza,
if you want to increase the rate of extraction you should increase the temperature of mantel in order to increase the cycling rate of solvent and as a result increase the rate of extraction. but if the siphone tube has been fulled with condensed solvent but the solvent doesn't discharge, you should contort the soxhlet a little bit with hand to force the condensed fluid pass from the top of capillary tube. as soon as a little fluid pass from the top of capillary tube, all the tube will be discharge from the solvent. but be careful in this work. seal all joint very well and keep firm the soxhlet with both your hands. remember you don't need to contort very much. just a little to force the fluid pass the top of cappillary tube.
Regards,
Thank you for all the answers, Mr. Sharma, Ms. Doke and Mr. Shojaati. I truly appreciate your responses.
The thing is, I did 2 set ups at the same time, but the other one was not going through the drainage cycle. I was suspecting that it has something to do with pressure? If I try to force the siphoning by moving/tilting the setup a bit (similarly suggested by Mr. Shojaati), the liquid drains until it fills up the tube and then get stuck at the top of the tube again. I would have to tilt the set up again and again. But since I have to run it for 16 hours with 4-6 cycles per hour, it would be too inconvenient for my experiment. I'm running out of ideas to circumvent this problem.
Can anyone please enlighten me about the principles (pressure, temperature, etc) of siphoning in soxhlet extraction? Thank you once again.
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