(Short version: Aluminum oxides react with acids and facilitate alcohol oxidation reactions. Some of the byproducts of these reactions aren't so good. Unless producing max-purity etoh, why not play safe and use anodized aluminum, which is non reactive?)
Disclaimer: not a chemist, nor chemEng. These are reasoned opinions, that you may refute or extend.
Newbie here who's done a bunch of reading on this subject, and can't find a whole lot of well-argued conclusions. But there is a lot of data. The key is to examine the reactivity of Al with all the compounds found in the wash. What those reactions can produced, whether they'll make it into the distillate, and whether the by products are healthy or not.
Aluminum oxide (the surface) is pretty reactive and creates some nasty byproducts.
The aluminum oxide formed naturally on the surface of the aluminum reacts with ethanol to produce ethene (ethylene).
Ethene is pretty widely used, but isn't terribly great for humans. But, the other alcohols in the wash will form other alkenes, by the same reaction. The boiling points of the alkenes are either well below or well above the range of etoh distallates.
It seems that ethoxide and methoxide salts of alumimum can be formed, as well. These are hazardous substances. But in what proportion are they formed? And will they make it into the distallate? BPs are hundreds of degrees C.
In acids with the presence of chlorine (is your water chlorinated)? Aluminum chloride is formed --http://www.chemguide.co.uk/inorganic/period3/oxidesh2o.html -- a neurotoxin. BP 120C but soluble in both ethanol and water. http://en.wikipedia.org/wiki/Aluminum_chloride
Ketones, aldehydes, esters all participate in some reactions with aluminum salts.
---In firstname.lastname@example.org, <last2blast@...> wrote:In truth, we can't compare an aluminum engine to an aluminum pot for several reasons friction, heat, and constant exposure to ethanol under adverse conditions. There is potential for low Ph levels to cause some eventual erosion of any metal over time, but the real question is whether that extremely small amount of trace metal can be transferred from pot to distillate? FDA labels distilled water as purified for a very good reason, and if you distill properly there will be nothing but distilled water and ethanol in your jars.Robert
From: Zapata Vive <zapatavive@...>
Sent: Friday, November 22, 2013 10:11 AM
Subject: Re: Re: [new_distillers] aluminum pot
So the labs say aluminun is corroded by ethanol. But first hand use in our hobby reports minimal to nonexistant corrosion. At that, the labs modeling car parts say the corrosion is formed by a reaction between ethanol and aluminum, forming aluminum ethoxide before drying. BP for aluminum ethoxide? 320ºc, im not concerned, but we all choose for ourselves....On Nov 21, 2013 6:56 PM, "Wes" <yhetti@...> wrote: