Disposing "Phosphoric Prep and Etch"

[Adam Preble]

I find Phospheric Prep and Etch--a phosphoric acid solution, does a good job ot taking rust off my grill. I have the grill in pieces and I'm very much tempted to dilute the solution and let it nibble at the grill in a large plastic tub over a few days. I suppose my big problem is how I should dispose of it. I know it etches concrete so I don't suppose it should go down the drain.

Outside of not doing this at all, the only idea I have is to let the solution evaporate down over days and then take it to a hazardous waste disposal facility; the initial, diluted quantity is going to be too much to transport elegantly. I just assume that the water will evaporate out over time. Does anybody have experience with this?

[Kuskokwim]

Phosphoric acid is commonly used in all sorts of household products. It is even used as a food additive. It's not very hazardous.

Just pour it down the drain.

[Chris Lewis]

It's probably best to make sure it gets diluted rather than having a slug of it stand in the plumbing - which if you have copper DWV, could be a problem. Phosphoric acid strong enough to eat rust will also eat copper - not very fast, but still...

I just flush it a couple of times.

[IIRC, coca cola has trace quantities of phosphoric acid sufficient to corrode a copper penny.]

[Nate Nagel]

or just throw a box of baking soda in it, let it sit, THEN flush it down the drain.

nate

[Jim Yanik]

Nate Nagel wrote in news: [e-mail]:

Yes,NEUTRALIZE the acid before putting it down the drain(diluted). (do it outdoors,it may foam up)

[Toller]

Don't know how safe or legal it is, but I would pour it along my gravel driveway. Comments?

[Stormin Mormon]

Would you suggest neutralizing with baking soda, first?

[EXT]

I have disposed of muriatic acid on my limestone driveway. The limestone neutralizes the acid by foaming up.

[Kuskokwim]

You could also use pepto bismol. It works on stomach acid which is mostly hydrochloric (muriatic) acid.

[Toller]

Lets see, pepto bismol or gravel, pepto bismol or gravel.... I guess I'll go with gravel.

[Meat Plow]

I've used Phosphoric acid to etch homemade circuit boards. Granted the copper was thousands of an inch thick it made quick work or it.

[Kuskokwim]

I wasn't being serious.

[Frank]

Unless you're talking about several pounds of concentrated acid, I'd just rinse it down the drain with plenty of water. Large quantities you could neutralize with limestone, like you spread on your lawn, or baking soda.

Frank

[Jim Yanik]

Meat Plow wrote in news: [e-mail]:

at what concentration?

[Meat Plow]

Was premixed etching solution and didn't pay attention to the mix. Just draw the circuit on a copper clad PC board with an etch resistant pen, lay it in a glass baking dish and wait 10 minutes or so.

[hallerb]

often the solution to pollution is dilution, while constantly running water add acid and finish up with lots of toilet flushes

remember always add acid to water NEVER water to acid.