Copper Chloride: neutralizing and disposal I plan on etching some PCBs with hydrochloric acid and hydrogen peroxide, which will therefore produce some kind of copper chloride (green color) which is highly toxic if released into the environnement (it may be useful as an herbicide, but I don't have any garden right now).

While cupric acid (obtained from hydrochloric acid, hydrogen peroxide and some PCBs etching) may be bubbled with air/oxygen to re-activate it to etch again other PCBs I'm not sure this may what I want and I seek suggestions in case I need to dispose of this solution.

Basically I heard (though none were actually on chemistry sites, except the 1st one):


Acid/Base neutralization: pour some baking soda to take care of the chloride
Pour some alluminium balls to get back some of the copper (didn't really understand how this works)
Copper electrolysis: basically get solid copper at the cathode, creating gaz at the anode and leaving (?) some residues that can be neutralized with baking soda (?)


Any insights on this? I think once the copper and chloride are taken care of, it shouldn't pose a huge problem to pour it down the drain or leave it outside to evaporate.

Specifically:


Which metal should I choose for the anode / cathode ? In the first source it speaks about reactivity (and since copper is less reactive than hydrogen, copper is produced at the cathode). No idea about the metal I should use though.
Would adding alluminium balls into the solution help make it more "eco-friendly" ?
Any other suggestion is welcome


Sources:


Electrolysis
How to etch PCBS - see comments
Recovery of copper using electrolysis
Regarding #2: Adding $\ce{Al}$ or $\ce{Mg}$ metal to $\ce{CuCl_2}$ solution reduces the $\ce{Cu_2^+}$ to $\ce{Cu}$, and you then have $\ce{Cu}$ metal (filter out and recover) and $\ce{AlCl_3}$ or $\ce{MgCl_2}$, respectively, in solution. Both solutions are safer in small quantities to flush down the drain.

Regarding #1: $\ce{2NaHCO3 + CuCl2 -&gt; CuCO3 + 2NaCl + CO2 + H2O}$. $\ce{CuCO3}$ is insoluble, but should still be disposed of at an appropriate facility.

In both cases, you get an insoluble copper compound (or metal) rather than a soluble one.