Clean up copper sulfate spill?

December 11, 2009 2:14 PM

ToxicWasteFilter: How do I clean up a copper sulfate spill?

I tried to clean out my backed-up sewer with copper sulfate. I poured it down the toilet, flushed...and it came right up the basement drain. The basement drain water/copper sulfate solution has now dried, leaving a whitish-blue layer on a few square feet of the basement floor. I'd like to let pets and people into the basement again, so I really want to clean the stuff up.

Is this something I can clean up with an industrial mop? Do I need to mix the solution with quicklime or soda ash to neutralize it, as is suggested in this MSDS? Is there someone I can hire to do this for me?

Please don't criticize me for using a bad-for-the-environment cleaning chemical. I went to every hardware store I can find looking for the nontoxic stuff (RootX), but no one had it in stock.

posted by miyabo to Science & Nature (5 answers total)

Copper sulphate is not particularly acidic so quicklime (I'd recommend soda ash, it's a bit less aggressive) doesn't neutralise it, but forms solid compounds (copper carbonate, copper hydroxide) that you can clean up with sawdust and a broom. If you have a dried residue, cover it with a little hot water until dissolved, then sprinkle soda ash, scrub clean and sweep away. Then wash with plenty hot water, and finally remove any copper trace with water/ammonia (ammonia captures copper ions), and rinse with water again. As you read on the data sheet, you don't want it on your skin, eyes, lungs, so the first step is wetting the floor, and using glasses and rubber gloves throughout!
posted by _dario at 2:45 PM on December 11, 2009 [1 favorite]

I had to look this up: quicklime is calcium oxide and soda ash is sodium carbonate. I agree that sodium carbonate is a better choice. It's also easier to come by; it's sold in grocery stores as "washing soda".
posted by Chocolate Pickle at 2:59 PM on December 11, 2009

oh, another very valid reason (which I took for granted above, but bears repeating here for the sake of safety) to pick sodium carbonate over quicklime: water + quicklime = quite a bit of heat and possible spattering of a very nasty chemical.
posted by _dario at 4:39 PM on December 11, 2009

The MSDS reads to me like the quicklime or soda ash is for liquid spills. You did have that, but now you don't, so you're past that point. Now you just "sweep up crystals or powder, vacuum is preferred." I'm going to guess that you don't have a dedicated hazmat vacuum, so sweeping up and putting in a plastic bag is the thing to do. Avoid making it a liquid again.

I would dampen some strong paper towels or rags (wet and then wring out all the water you can), cover the spill area with them first, to prevent dust generation. Then, wearing rubber dishwashing gloves, long sleeves, and whatever you have for a dust mask and eye protection, I would gather up the crusty residue in a ball from outside to inside, making a ball with the powder inside. Have a helper (with the same protective gear) holding a plastic bag. Pick up and place right in the open bag. Wipe down the area with more damp rags, and put them in the bag, too.

For disposal of the bag, you could call your local hazmat center, or if you don't know where that is, the fire station would probably be able to direct you where to call.
posted by ctmf at 6:05 PM on December 11, 2009

I forgot to mention, LABEL the plastic bag (preferably before the cleanup, but immediately after is ok, too.) While you're waiting to dispose of it, which, let's face it, you may put off for a while, you don't want yourself or anyone else getting curious what's in the bag and opening it to a face full of copper sulfate dust.
posted by ctmf at 12:01 PM on December 12, 2009