Ethanol water azeotrope is naturally a little acidic.
Getting readings around 4.0, seems a little low eh? What originally sent me down this rabbit hole was high delta 8 content in my distillate.
Did you scrub or anything like that? Are you measuring with Hydrion paper or a meter? Ethanol and meters do not mix well.
Water saturated with CO2 and carbonic acid is a little over pH 4. Distilled water left in atmosphere will actually absorb some CO2 and drop in pH. Try it.
For a while our SOP was to scrub with AC 10% by volume at 60 C for 30 mins and then filter through grade 1(11 micrometer pore size) without any filter aides. I am now realizing the errors of our ways and have started filtering through celite 545 as well. Might also switch it up to C Bleach. By now I have used both a meter and litmus paper to measure the pH of our solutions and I feel fairly confident in the readings. I used this meter and these papers from a friend. But I have ordered Hydrion paper.
Our fast filtering T5 neutral bentonite clay is a great alternative to Celite 545. DM for details.
Hmmm. This seems to be in line with my experience as well using EtOH as a solvent. What have you done, have you stopped using reclaimed solvent or attempted to neutralize it?
It would be too expensive to just dump it. We have experimented with nutralizing it, but ac just restores it. Better to pH the resin.
Cool. I just don’t want the ethanol to ruin your wet bulb. Need to thoroughly remove resin with fresh ethanol, then tap water rinse well, then immediately back into neutral buffer. Ethanol can dehydrate the glass, which can cause issues later that you may not notice are electrode issues. The paper strips you are using are likely fine.
Now, the question is: Have you measured the pH of just the (fresh, as in freshly distilled if you predistill) ethanol, and then resin-laden ethanol, before and after scrubbing/filtering?
What is your go to base for neutralizing the resin?
I have worked it out in our SOP that we pH the resin saturated ethanol after winterizing and after clarifying. We got about 20 data points and the trend seems pretty obvious. Pre-scrub pH was always higher than post scrub. I have noticed since using celite 545 as a filter aide that it has kind of switched. Now, post-scrub and celite filter, the pH seems to rise by a few decimals. That is admittedly not saying much becuase the it’s still around 4.5. I guess after talking to you and Soxhlet that it seems I need to adjust the crude pH prior to distillation.
Ok here is my plan. Since I know the pH of the solution and the volume, I know the amount of H+ ions in solution. Then I just add equal part NaOH(in mols) to neutralize the solution and theoretically I should be at a neutral pH then. Does this sound valid? I know I could just trial and error it out until I come to neutral but if I could ball park it with a calculation that would save time.
We titrate it, it’s easy to go too far.
Ah, yes! That is precisely the data I wanted and the results I expected! Thank you, @sativum ! Adjusting pH may not be a bad idea if it is more acidic after scrubbing. I would use MgO or the anhydrous hydroxide of magnesia… not milk of magnesia, iow, but the stuff in the water in that concoction. Easier to just get MgO and let it hydroxylate with the water in the ethanol, really, but as Soxhlet said, you MUST titrate with stirring and allowing for complete conversion and disassociation. It’s considered a weaker base, so it is less difficult to fuck up, but you still can if you are too hasty.
P.S. It does not mechanisticly proceed as I said with MgO, but I want to give you the concept of what is happening and why it works.
I did not see your last post, but yes, again, titrate!
My only problem with using such a powerful base is how touchy this titration will likely be, but you mentioned that, so thank you.
@sativum sodium bicarbonate solution will work if you would prefer sodium salt in your stuff. I just prefer magnesium salts because… well, I’m just weird. Let’s leave it at that.
I went on your website looking for celite and cannot find any. Link?