I did copper etching (to make a PCB) using a solution of vinegar + H202 + NaCl and now I need to dispose the solution. There is no waste collection for this kind of stuff where I live, so after some research I saw that the cleanest dispose process seams to be to make electrolysis.
I used a copper electrode at the negative pole (cathode), a nail on the positive (anode) and plugged a 9V power supply. I was expecting some bubbling on the nail (Cl2 gas) and the Cu2+ to accumulate on the copper electrode, but the bubbling happened only around the copper wire and after 15 min the solution started to get really dark brown.
My goal is to get the copper out of the solution, so that I can throw the solution away in the drain and the copper in trash.
Is this what is supposed to happen, or did I do something wrong? How do I know when it's done taking the copper from the solution? when done, can I just filtrate and then pour the solution in the drain?
Why the bubbling happened at the cathode and not the anode and why the solution turned brown?