Stefan Trethan wrote:
>
>
> no, i get copper with no hydrogen too.
> I aim for a area ratio that starts to produce hydrogen and chlorine at the
> same time,
> and then use current slightly below that point.
> It is better if i get hydrogen before chlorine because that means the
> copper area
> is the absolute minimum. if i get clorine earlier then the copper could
> still be made
> smaller.
Its not good idea to have cathode CD (current density) at level where
hydrogen is almost being produced. I would operator at about half the CD of
the CD needed to produced hydrogen. The ratio of grams of recovered copper
per unit charge depends on the CD and solution agitation near cathode
surface. You trying to maximize this ratio.
Here is a copy of a document I wrote when doing experiments with alkaline
ammonia sulfate electrolytic regeneration.
http://members.optusnet.com.au/~eseychell/etching_eff.html >
> Yesterday i let it run for several hours with some 200mA and at then end i
> got visible regeneration.
> I didn't want to run it overnight without supervision so i turned it off
> and pulled ou the copper.
> now i will go and switch it on again i think.
>
> The lid for the vertical tank seems to be set now, but i have still some
> work to do before i can
> activate it.
> It will hold 1 liter of etchant, and accept boards up to 35cm x 20cm which
> is more than i need.
> It is also about the size i can make a TT (A4).
> I'm stuck right now with creating the lid, it got more complicated since i
> aimed for electrolytic
> regeneration. Right now i think i will seperate the lid in 3 sections, the
> middle conaining
> the pcb clamp and the outer 2 containing the electrolysis electrodes. This
> way i can input/output
> boards without disturbing electrolysis and i can also completely remove
> the electrodes if i should
> once need the whole 35cm length. I will most likely make the copper
> electrode holding lid twice,
> one holding a wire, the other blank, because obviously the copper needs to
> b taken out
> if there is no current present.
>
>
> I would have one other question now - do you think the etchant penetrates
> the welding rods?
the graphite rods are a somewhat porous, I guess a millimeter or two of
penetration.
> I connected them by drilling a hole and inserting a wire. then i sealed it
> with silicone.
> If the etchant seeps through this is no good of course.
Epoxy would be best choice for a wire sealant. Heat the rod red hot near
where you want to connect the wire. This will remove all traces of etchant
and copper salts absorbed in the graphite.