How to dispose of a bottle of lactic acid (88%)

[SteveH aka shetc]

Hey Guys,

I have an older bottle of lactic acid that I want to dispose of. Is there a recommended way to do that?

Thanks,

Steve

 

[Gameface]

 

[Tom Foolery]

Fertilizer...

 

[Druman07]

I understand it has a very long shelf life. Don't believe it is harmful to the environment in home brew amounts.

 

[SteveH aka shetc]

I was listening to an episode of Brew Strong and I'm pretty sure JZ said it will go bad after awhile especially if not kept in the refrigerator. So I figured I'd get some new stuff. I'll need to find that episode.

 

[Silver_Is_Money]

I assume here up front that you have only perhaps about 250 mL or so of lactic acid at most to dispose of.

Pretty close to 1 gram of baking soda will neutralize 1 mL of 88% lactic acid. Do not ever attempt to mix them directly, as this is a sure-fire recipe for disaster and personal harm.

Read the disclaimer and warning below first. You might consider taking 2 x 5 gallon plastic pails and filling each with ~2-1/4 gallons of cold water. To one pail add as many grams of baking soda as you have mL of lactic acid, plus a scant few more for good measure. To the other pail add the lactic acid. Mix both well. Then slowly over time (since it will evolve heat) transfer small amounts of the diluted acid/water pail contents into the baking soda/water pail until eventually all of it is mixed together and you have ~4-1/2 gallons in a single 5 gallon pail. Wear appropriate PPE (personal protective equipment) at all times during this procedure so you do not get injured. Check the pH of the final mixture to assure neutralization. Then dispose. (In case there are fumes, do all of this outside and position yourself up-wind to avoid any potential exposure to the fumes)

Disclaimer and Warning: I have never attempted this, and I don't know the consequences. I strongly urge that you consult with a local university chemist to confirm if this method is safe, or to hear other and likely safer and better recommendations.

 

[Vale71]

I was listening to an episode of Brew Strong and I'm pretty sure JZ said it will go bad after awhile especially if not kept in the refrigerator. So I figured I'd get some new stuff. I'll need to find that episode.

I fail to see how it could spoil since at that concentration (I'm assuming at least 80%) not even lactos can survive well and they're the ones who made it in the first place.

Edit: OK, just saw in the title that it's actually 88%. If you dump it for no reason you're literally throwing away your money...

 

[ajdelange]

Lactic acid does degrade over time. It turns dark. But note that it's shelf life is, according to one paper I found, 78 years to over 90 years if stabilized.This means that it (or something in it) is decomposing into something, but very slowly. I have no idea what. Nor do I have any idea how its acidity changes as it decomposes. It's pretty innocuous stuff (though it does carry a health level 3 as it can cause eye, lung and skin burns). It is not considered hazardous (not RCRA listed) waste so the simple answer for you is to just dump it down the drain followed by plenty of water.

If you are on a septic system you might be concerned about its effect on the pH of your system. In that case dump it in a bucket with a gallon of water and add 70 grams of lye, 157 grams of sodium carbonate or 768 grams of sodium bicarbonate. In the case of the latter two, add the powder slowly at first as it will fizz as CO2 is released. Protect your eyes. You don't want particles of Na2CO3 in them! Eventually that will cease and you can dump in the rest stirring until it is all dissolved. The result will be a neutral (pH 7) solution of sodium lactate. Dump it down the drain. Note that a pound of sodium bicarbonate will get you to pH 6.8 which ought to high enough to keep your septic bugs happy. Note also that it takes more sodium bicarbonate to do the job than either of the other bases. This is because sodium bicarbonate isn't very basic at pH 7 (2.3 mEq/g) relative to how basic it is at mash pH (10.8 mEq/g @ 5.4) where we usually encounter it.

Poking about a little further reveals that lactic decomposes, when heated, to acrylic, and propionic acids and acetaldehyde. At room temperature these reactions would be very slow (the bottle I had which turned brown was probably 15 yrs old).