View Full Version : Chemistry people: What did I do?

Doc Nickel
01-29-2008, 01:36 AM
I have a couple of gallons of the cleaner I used a few weeks ago to clean out my parts washer. It's water with some Simple Green and some drain cleaner in it- so mainly just water, sodium hydroxide, and some potassium hydroxide.

Not very concentrated, maybe a cup, cup and a half to around 4-1/4 gallons. More drain cleaner than 'Green. There is, of course, some of the smut from the parts washer in there- some of the coagulated citrus stuff, traces of oil and grease, sand and dirt, probably some waxes, you name it.

Anyway, I've been needing to dispose of the stuff, but I don't like putting it down the drain as I have a septic tank, and the cleaner tends to kill the microbes that break stuff down in there.

Well, I got the bright idea I could try nullifying the base by adding some acid- and I have a dozen jugs of vinegar from some rust-stripping projects I did last summer. The vinegar isn't as strong as it used to be (barely "strips") and is the color of creamed coffee from all the rust residue (which doesn't seem to settle much, so it must be pretty fine "dust".)

Anyway, I took a clean glass measuring cup and dipped some of the cleaner out of the bucket, and set it in the sink. I then tipped in some of the vinegar, expecting at least a little bubbling, if not a vinegar/baking soda reaction.

Almost nothing happened, however... Until I took a closer look. The mixture was now "gelled", and dark green.

Not heavily gelled, but it was... lumpy, I guess. Like a thin milkshake. There was a spotty, almost sandy residue on the cup as I poured some out. And it was green- very dark green, almost black.

I dumped it out (about 3/4 cup) down the drain and tried the same thing again- and it gelled again. A definite reaction of some kind- not terribly energetic, but something happened all right.

Both substances were rust-brownish before mixing, and water-thin. The mixed stuff is dark green and chunky-gelled.

So what happened? What's in the "new" stuff that turns it green? Is the mix safe to flush? I was under the impression that, generally speaking, when you mixed an acid and a base you got a release of some gas, and a remainder that was mostly water. (At least for most acids I'd be dealing with in the shop.)


01-29-2008, 01:44 AM
You makin' napalm there Nickel?



01-29-2008, 01:50 AM
It sounds as if the acid base reaction, in the presence of oil and other gunk is forming an oil/water emulsion. Depending on the exact composition it may be very stable. You can try heating it to see if that breaks the emulsion down to liquid state from the current gell.

Check with EPA for disposal recommendations.

01-29-2008, 01:51 AM
A "new green" version of "Agent Orange"?

01-29-2008, 01:55 AM
I don't know what you made, but technically you should never try to neutralize a base with acid. The other way around is perfectly acceptable, but from my years working in a lab at a major chemical company, any time we had a spill of caustic material we always just dilute with H20 and rinse to the chemical sewer. Anytime we have a acid spill we just hit it with sodium bicarb, swept it up, and fiber packed it as hazardous waste. Both of your ingredients are billed as biodegradable, and one specifically meant to be put down a drain... If you consider the PH of the current waste in your septic system, I doubt you will see the cleaner as being such a problem. The microbes are tough buggers, at least the ones in our chemical sewer treatment facility are. The only thing they can't eat is ethanol, and that is just because they like it far too much! Go figure.


01-29-2008, 02:11 AM
The green is a ferrite/zinc compound. I'm going to guess that your parts washer is galvanized metal so the solution contains enough zinc to react with the rust to form ferrite green. It precipitates and coagulates in the presence of a wide variety of liquids such as various poly alcohols and and other basic aqueous mixtures. It forms a dark green gelatinous mixture just as you describe.

Doc Nickel
01-29-2008, 02:38 AM
You makin' napalm there Nickel?

-Well, I was shootin' for Thermite... you know, powdered iron oxide and all... :D

The green is a ferrite/zinc compound. I'm going to guess that your parts washer is galvanized metal so the solution contains enough zinc to react with the rust to form ferrite green.

-Nope, it's the usual red-powder-coated import. In the places the powder has either been chipped or dissolved away, the base metal appears to be bare steel. There are no chips or thin spots below the "waterline".

Now, that's not to say that somewhere in all the smut I rinsed out, there wasn't a trace of some zinc of some sort. I mean, it's a parts washer, so presumably the previous owner cleaned carburetors and the like in it.

He was, when I picked it up, in the middle of doing some snowmobile work, and any number of parts might have been die-cast...

But I have a hard time seeing even a large quantity of zinc, powdered or dissolved, in the leftover smut would be sufficient. I mean, I scraped the majority of it out of the tub, with the remainder being at best a quarter or half cup of gunk.

And that's dissolved in over four gallons of lye-water... even if the black gunk was entirely zinc, I'm not sure I can see that as being enough to make this stuff as dark green as it gets.

I don't know what you made, but technically you should never try to neutralize a base with acid.

-I know about adding acid to water and not water to acid, but that's about as far as my knowledge goes.

I did 'neutralize' some of the leftover vinegar I used, with baking soda before I dumped it out, and there was a clear bubble/froth reaction as is normal for baking soda and vinegar.

I wonder if I ought to see what happens if I take a cup of vinegar and pour in some of the lye...


01-29-2008, 06:36 AM
The green is from the iron, not the zinc. I don't know how much zinc it takes to precipitate the ferrite green reaction but I'm pretty sure that's what you have there.

Doc Nickel
01-29-2008, 07:28 AM
Ah! Yes, there was plenty of iron in the vinegar. I used it to strip quite a few parts, and it was- even after settling for a couple of days before decanting back into the jugs- still the color of thin creamed coffee.

Anything else that would cause the green? I still don't really see there being much, if any, zinc in either mixture. It's certainly possible, as I noted above, but it seems unlikely a significant quantity got dissolved into the original citrus cleaner, enough so that the minimal residues would contain enough for this kind of reaction.

Certainly nowhere near as much zinc in the cleaner as there was iron in the vinegar.

The drain cleaner had a potassium compound, would that have done it? I tend to associate green chemicals (right or wrong, I'm not a chemist) with copper compounds... Then again, I have some Caswell electroless nickel solutions, and the nickel... sulfate? is a green fluid...

But then I don't see where there could have been a lot of copper or nickel in that crud either... Unless that original citrus stuff, before it coagulated, was so acidic or basic that small parts, like the aforementioned carb parts, were entirely dissolved.

I do recall back in the days when you could get the "real" carb cleaner- the stuff that eventually ate through the bottom of the 5-gallon steel pail- that people'd dip their parts in the basket and let 'em "soak", only to come back a few days later to find them gone- or at least heavily pitted.

That's complete and total guess, though, as a source of the metal(s)... Not that this whole thing is even remotely important, I was just curious as to what happened. That and I'm hoping the new crud isn't some toxic sludge I shouldn't be pouring down the drain. :D


01-29-2008, 10:23 AM
I'm guessing the green color might be from the simple green or copper compounds. The gelled situation could be a reaction of the surfactant in the simple green with the potassium/sodium hydroxide in the drain cleaner which would change the properties of the surfactant and cause the gelling effect. Surfactant chemistry is a wierd and involved chemisry, sometimes it seems to verge on black magic. With everything you have in the "pot" so to speak, it would be tough to figure out exactly what happened.

I don't see a problem neutralizing a base with an acid or an acid with a base, same reaction.


01-29-2008, 11:30 AM
Certain Chromium compounds will also produce green.

01-29-2008, 11:42 AM
I tend to associate green chemicals (right or wrong, I'm not a chemist) with copper compounds..
Iron makes all sorts of colors. Ferric chloride for instance is violent yellow that stains almost anything. Ferrite compounds come in all colors and green is common. These are all iron oxides in this photo.


Pete H
01-29-2008, 11:51 AM
Like Chris said, with all the stuff in that soup, it's hard to figure out exactly what's happening. With the combination of grease, alkali, surfactants in the detergent, and dissolved metals, you might have gotten some kind of insoluble (or slightly soluble) soap.

BTW, I'd be more worried about the dissolved metal putting "paid" to the bugs in your septic, than the alkali. Do you have a dry-sump for the laundry washer? That might be a safer way of disposing of it.

BTW2, be careful how you phrase the question if you ask EPA or any other agency... last thing you want to hear is "I'm from the government and I'm here to help".


01-29-2008, 12:15 PM
I wouldn't put it down the septic either. I don't put anything down there that I didn't eat first, excepting paper.

01-29-2008, 02:17 PM
Well, now that its a gel it ought to sit fine in the trash bin!

01-29-2008, 03:56 PM
In Alaska do you have facilities for recycling used automotive lubricating oil? If so ... problem solved.