Distillation of Methanol

[AMW311]

Hello everyone,

 

I'm sure everyone has heard the statement that when distilling moonshine, the first few ounces should be discarded due to the concentration of methanol. Most sources of this statement make the claim that because Methanol has a lower boiling point than ethanol, the methanol will boil off first and will be the first type of alcohol to work it's way through the still.

 

A friend of mine told me that this wasn't true, and that regardless of the difference in boiling points, a simple still would not be able to effectively separate the two. He said it mostly has to due with the low volume of Methanol that exists to begin with. He referenced Raoult's Law and the vapor pressures of both substances.

 

I am by no means an expert in chemistry, and I don't full grasp the concept of Raoult's Law, and how you would determine how much of the methanol would separate from the total solution.

 

I was wondering if anyone here could provide more insight into Raoult's Law and how it applies in this situation.

 

If I were to have 100 gallons of solution, comprised of 10% ethanol, .02% Methanol, and 88% water. Would the methanol separate from the solution during the distilling process, and would the amount of methanol be enough to cause harm if ingested?

 

I appreciate any help. Thanks!

[Iota]

If I were to have 100 gallons of solution, comprised of 10% ethanol, .02% Methanol, and 88% water. Would the methanol separate from the solution during the distilling process, and would the amount of methanol be enough to cause harm if ingested?

 

I appreciate any help. Thanks!

 

I was interested in the answer so I googled it, instantly got an answer and thought I'd share what I found: http://www.methanol.org/Health-And-Safety/Safe-Handling/Methanol-Health-Effects.aspx

 

 

 

"...However, methanol is already present within the human body in small quantities from eating fruits and vegetables. According to the FDA, as much as 500 milligrams per day of methanol is safe in an adult’s diet. In the body, methanol is metabolized in the liver, converted first to formaldehyde, and then to formate. As a building block for many biological molecules, formate is essential for survival. High levels of formate buildup after excessive methanol intake, however, can cause severe toxicity and even death."

 

 

Edited August 6, 2013 by Iota

[AMW311]

Thanks for the reply lota!

 

I'm afraid that doesn't necessarily answer my question though. I am aware of the healthy effects methanol poisoning can cause. I am specifically looking for whether or not distilling moonshine would produce a concentrated amount of methanol that could be enough to cause harm if ingested.

[John Cuthber]

Any "theory" which implies that you can't separate methanol from ethanol using a still also implies that you can't separate ethanol from water using a still.

 

Doesn't look sensible to me.

 

It's also noteworthy that a still can't add methanol to the product, but it can take it away.

 

If the material that you distil doesn't contain enough methanol to be toxic then using a still to remove the involatile material (leftover sugars, yeast, and some of the water) won't change that as long as all the ethanol is distilled out.

 

It's good practice to throw away the early running stuff from a still because it removes acetaldehyde (which doesn't taste nice) and also any methanol.

But a good fermentation will never have made much methanol in the first place.

On the other hand, don't forget that a lot more people are killed by ethanol than by methanol.

Edited August 6, 2013 by John Cuthber

[Iota]

Thanks for the reply lota!

 

I'm afraid that doesn't necessarily answer my question though. I am aware of the healthy effects methanol poisoning can cause. I am specifically looking for whether or not distilling moonshine would produce a concentrated amount of methanol that could be enough to cause harm if ingested.

 

Fair enough, but the key information there is "500 milligrams per day of methanol is safe" because you can work out the overall methanol content regardless of whether the distillation successfully removes it, to work out how much you'd need to drink for it to be over the safe limit (of your theoretical mixture) and compare that to the safe intake per day limit.

[BabcockHall]

When two liquids are relatively close in boiling point, one needs a good fractionating column in between the distillant flask and the condenser to separate them. Without knowing how good the fractionating column is, there is no way that I can see to answer your question.

http://www.chem.umass.edu/~samal/269/distill.pdf