What to do with excess cupric chloride etchant? Perhaps this...
2013-11-15 by Philip Pemberton
Just thinking out loud here... I'd appreciate a sanity check from any chemists who might be in the audience :) Right, so let's say you've just done an acid adjustment and you're left with some cupric chloride etchant -- that is, HCl + CuCl_2 -- which you need to get rid of or convert into a more useful form. Take your waste etchant, add washing soda (sodium carbonate). This leaves you with salt water, precipitates copper (II) carbonate and releases carbon dioxide. Work slowly and with small quantities, this produces A LOT of foam. Sodium bicarbonate (baking soda) may also work but will produce more carbon dioxide (TL/DR: it'll foam up a lot more). Filter off the precipitate with a suitable filter (coffee filter?). Discard the salt water. Take the copper (II) carbonate, heat to 290C. This produces copper oxide and releases yet more carbon dioxide. But what can we do with a jar of dry copper oxide? Well, let's say your CuCl2 bath is low on copper (low specific gravity). Add the copper oxide to hydrochloric acid to form a mix of cupric chloride, hydrochloric acid and water. Cheers, -- Phil. ygroups@... http://www.philpem.me.uk/