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> safely dispose of ferric chloride, sulfuric acid, and hydrochloric acid The first step is easy: neutralize them with any base, such as baking soda. You don't
by segfaultbuserr 7y ago
> safely dispose of ferric chloride, sulfuric acid, and hydrochloric acid
The first step is easy: neutralize them with any base, such as baking soda. You don't need precision, just add a lot of it, and make sure the pH is close to 7 (or beyond, baking soda is not corrosive) at the end. After this step, the solution is no longer acidic or corrosive and much safer to handle.
Unfortunately, the next step is tricky. The solution is safe, but it still contains a lot of Cu+ ions, which is a heavy metal pollutant and poisonous.
On the other hand, if your sulfuric or hydrochloric acid is unused for etching anything (clean without those nasty ions), you are good to go, just dump them in the sink after you've neutralized them (test with pH paper) it's perfectly safe.
- m0zg 7y agoIs this what people actually do? I mean I'm aware I could neutralize them, but Cu is still going to be in there and I still can't pour this stuff down the drain. Then there's ferric chloride which is just nasty stuff that will likely stain everything it comes in contact with. I just want to get rid of it in a fully environmentally safe way.
- segfaultbuserr 7y agoDon't ask me, I don't know, as I'm asking the same question. I'm waiting for some answers to my question: https://news.ycombinator.com/item?id=20659004 https://news.ycombinator.com/item?id=20659004
- parsimo2010 7y agoI'm not sure it is economical, but I had some Sodium Persulfate etchant that was full of copper and accidentally dropped a piece of steel in it. The copper plated onto the steel almost instantly. You could probably use iron filings (or some metal that won't dissolve in your acid) to pull most of the copper out of the acid, and then neutralize. I'm not sure what you would do with the solid copper after that. It might take some effort to get a system that was reliable and economical, but the basic idea of precipitating out the copper before neutralization should work.
- marmaduke 7y agoI don't think it's hard. My high school chemistry teacher did this, reusing the same copper every year. (I dont remember the details though)