[jacobarmstrong]

Hi there,
I've been using activated carbon to purify vodka and it has been working very well so far, but I want to perfect the process. I was hoping the those with organic chemistry knowledge could help me.

Is there an optimal temperature the vodka should be at to increase adsorption?

Is there a specific method that I should be using to filter the vodka through the activated carbon at an optimal flow rate? (I'm currently using coffee filters and filtering 5 or 6 times)

Any other tips on increasing adsorption/purifying vodka?

Help would be much appreciated!

[Intanjir]

Most optimal parameters are going to be highly specific to your exact set up.
At best you can expect to find ballpark numbers from someone with a similar set up.
In general you cannot expect to truly optimize unless you have some method to evaluate the quality of the result.
Since you are posting in the Citizen Chemist board you probably lack expensive analytical equipment and any corresponding extensive expertise.
You might have to force some friends over to help you with some blinded trials.

I recommend trying to determine which samples are perceptually indistinguishable rather than which samples people find more agreeable. It might make it easier or it might make it harder to initially optimize by using less pure distilled alcohol, like whiskey.

Anyways, I am skeptical that what you want out of the activated carbon(AC) is really 'proper filtering'. That is I don't think you are using the AC to remove suspended solids as your vodka has already been distilled at least once. All you are doing is adsorbing any contaminants which are significantly more attracted to carbon than ethanol. Since you aren't really filtering there is no need to have it 'flow through' the AC from one end to the other. That sort of geometry is good for trapping solids but I would think that for adsorbing you would want all of your carbon to have as much access to the vodka as possible. If you have it flow through then the initial bits of AC have more access to contaminants than the later bits do. Thus the later portions of AC aren't being well utilized and will soak up ethanol without removing much contaminant. My intuition is that just stirring it with free floating pieces of AC would be a more straightforward method of giving the AC access to the vodka. Keep adding AC and stirring until the flavor doesn't noticeably change. Then filter the solids out(or let them settle and decant). Hopefully this would allow you to use less AC and thus waste less vodka.

What the optimal temperature would be is not obvious to me. The affinity for both contaminants and ethanol for the AC would vary with the temperature. What you want is that the affinity for a contaminant increases relative to that of ethanol. I would guess that low temperature would be good for some contaminants and high temperature good for others. So you might do two stages.

If you were distilling then distilling in the presence of AC would potentially be a good idea to help keep contaminants from boiling which at elevated temperatures have a high affinity for carbon relative to that of ethanol. That is, AC might be able to shorten the tail.

I don't really know if either of my suggestions here are properly grounded. I would vary my experiments to test them if I were you.