Just going to toss this in here, not as fact but as a possible avenue for research into the oxidation issue. I was experimenting with some dark red tails from a distillation I had just completed and came across something interesting.
I dissolved a sample of the tails in denatured ethanol, and reduced it after dissolving. I’d say it was 20-30% distillate by weight with a total volume of ~250 mL. I dumped some liquid nitrogen (~50 mL) into it while it was stirring. After the liquid nitrogen evaporated completely, nothing seemed to change until I recovered the solvent. I was left with significantly lighter distillate than I started with.
Now, I have not been able to acquire more liquid nitrogen to repeat this yet. I am not sure of any mechanism that would explain this, but I simply wanted to share my observation. If anyone could confirm this observation, that would be fantastic, otherwise, I plan to get more nitrogen as soon as possible to experiment further.
Another application I had pondered, in relation to oxidation, is pouring a small amount of liquid nitrogen on top of my distillate before storing in hopes of “stabilizing” the surface exposed to atmosphere. Thus reducing potential for oxidation. Have not been able to try this yet, but it is a test for another day.
Ive ran into this situation after releasing the bleeder valve immediately after my process. I I’m using way higher temperatures than most people and the red surface layer i believe is the change of microstates within itself and trying to achieve a mutual thermodynamic equilibrium. There is a lot of motion we cant see happening and this occurrence is leaving the distillate permabale and vulnerable to oxygen. ALso keep in mind oxygen is carrying water moisture. Its been almost 8 years since ive studied thermodynamics in college but im relearning it again so i copied a better understanding of what im saying.
Though it is not a widely named law, it is an axiom of thermodynamics that there exist states of thermodynamic equilibrium. The [second law of thermodynamics states that when a body of material starts from an equilibrium state, in which, portions of it are held at different states by more or less permeable or impermeable partitions, and a thermodynamic operation removes or makes the partitions more permeable and it is isolated, then it spontaneously reaches its own new state of internal thermodynamic equilibrium, and this is accompanied by an increase in the sum of the [entropies] of the portions.
That being said there is a couple of options i figured out. First is the easy but unsuitable for continual production. After shutting down process keep it under vacum but have your pump turned off… I dont know the exact time this can be achieved but i would guess after the system been shut down for a few hours. I never have it happen when i do this method. The rest i haven’t tried but figure it could work
Second cool off harvest vessel while under vacuum on the machine still. Im thinking cold wraps or possibly submerge the flask at room temperature water bath and apply ice slowly to increase stability but not a rapid one…
Third Transfer the distillate from your harvest vessel to your storage container. Be careful with heating the distillate out. This will make it more porous during the pour. Immediately put your storage container under vacum and start applying heat to keep the distillate porous enough to release the oxygen. I think a vac oven would work best or you can modify the top part of you storage vessel that can withstand vacuum. I think it would be safe to have temps around 110. Once vacuum is achieved turn off the heat and let it sit under vacuum until the vessel reaches ambient temperatures.
I have a question. If people are introducing Nitrogen to blanket the area not used. would that be pushing oxygen further into the distillate? causing the red area effect deeper into the distillate? Thank you!
Wow now explain the problem in simple English
Is this spd you are working on ?
What temp are you running ?
Hot condenser tech or cow ?
What temp is receiving flask that you consider it hot ?
No its a chemtech KDT-5 with 6 upgrades. My coil is running in low 80C @1.63e-3 torr. I never applied any of the sops i read on this forum. Once i reviewed the VTA sop i realized i viewed the process totally different. I cant say exact parameters due to NDA with the lab im with but im having phenomenal results. Ill post pics in a bit. My previous post was just saying the same problems yall are seeing and given the reason why i think its happening. Also providing a solution that worked for me and others im planning to do. The Flask trick wouldnt apply to me because I use a carousel and the glass mm is way to think. All its doing is just help harden the distaliate to not allow oxygen entering.
