sodium bicarbonate peroxyhydrate

I don't know that H2O2 reduces Fe(III). (It does reduce Mn(IV) and (VII) quite nicely however.)

Plain old base of any sort (sodium carbonate, oh and BTW Oxyclean isn't sodium bicarbonate peroxyhydrate, it's carbonte peroxyhydrate, mislabeled as percarbonate) will neutralize the acidity, producing -- what else -- rust.

Make a solution of base (alkali [bi]carbonate, hydroxide, etc.) and add to the ferric chloride until the solution is clear (the solution, not the precipitate!).

If you would like to reduce it first, toss in some cheap metal like iron nails and stuff. You'll get brown crud and a green solution of Fe(II) chloride. Then neutralize.

Or just flush it with a lot of water, iron ions don't last long in the environment and a little acidity (diluted, that is!) never hurt anything.

Tim

The best suggestion I ever heard about how to best dispose of ferric chloride etch solution is to use it to mix concrete and send the resulting brick off to the dump.

Screw the ferric cloride, I switched to Sodium Persulphate. Its totaly clear in solution so you can watch your boards etch without pulling them out each time, and it does not make nasty stains in you washstand when rinsing out boards either.

Luhan

Hmm, I don't see that working-- concrete needs to be basic to set up, something ferric chloride tends not to be. If you neutralized it first, then mixed concrete with the murky glop, that would get you a very servicable red-stained brick. (For that matter, cement red and brown colors are exactly that stuff.)

Tim

IIRC sodium persulphate will neutralise ferric chloride.

if it's going in the garbage, concrete would be a waste of sand and gravel, juse use cement (which is alkaline anyway), more concentrated active ingredient, and costs about the same (per 40Kg bag) last time I looked.

chlorides aren't real good for concrete anyway so concrete bricks would probably make lousy pavers....