Using Citric acid/sulphamic acid mixed with NaCl and O2 for base metals

[Chirou]

Hi, had anyone tried using citric acid or sulphamic acid mixed with NaCl and O2 from air pump or H2O2 to remove base metals and leave behind gold foils ?
I got my hands on some 20-30% citric acid detergents and one with 10% sulphamic acid mixed with few% of citric, i've been running a test for 3 days so far with aquarium pump and from some boards the tin got removed in others copper started to very very slowly dissolve but saddly i had to disconnect the pump due to excessive foaming from other components of the detergents and i've been wondering if anyone tried anything similar since i'm now battling with thoughts should i add some defoamer or something, since i cant get any SDS on it and i don't know if it wouldnt mess up something.
Also maybe someone else tried this method and got some feedback

 

[Yggdrasil]

Hi, had anyone tried using citric acid or sulphamic acid mixed with NaCl and O2 from air pump or H2O2 to remove base metals and leave behind gold foils ?
I got my hands on some 20-30% citric acid detergents and one with 10% sulphamic acid mixed with few% of citric, i've been running a test for 3 days so far with aquarium pump and from some boards the tin got removed in others copper started to very very slowly dissolve but saddly i had to disconnect the pump due to excessive foaming from other components of the detergents and i've been wondering if anyone tried anything similar since i'm now battling with thoughts should i add some defoamer or something, since i cant get any SDS on it and i don't know if it wouldnt mess up something.
Also maybe someone else tried this method and got some feedback

Immediately and from the top of my head I can't see any logic way this chemistry should do anything other than the pure chemical alone.
The bubbling will of course stir it, but unless you actually have a surplus of Cl^- there is not be much Cupric Chloride etching going on
and if you do not have the HCl there it will not be properly regenerated.

I have not tested Citric acid by itself, but remember the salts will be as toxic as the salts from HCl.

 

[Chirou]

Immediately and from the top of my head I can't see any logic way this chemistry should do anything other than the pure chemical alone.
The bubbling will of course stir it, but unless you actually have a surplus of Cl^- there is not be much Cupric Chloride etching going on
and if you do not have the HCl there it will not be properly regenerated.

I have not tested Citric acid by itself, but remember the salts will be as toxic as the salts from HCl.

Well the problem is only dissolving base metals and freeing all the gold foils since i can get those detergents with citric etc for cheap or even free sometimes, but the thing is i'm not sure if some additives in it or in defoamer if i add some won't impact the reaction (especially as i can't see SDS even on producent's site) . Toxicity of salts is of no concern, university will handle the utilisation together with way worse things we produce there.
Trial run i'm doing on some PCB's with no gold just to see if the soldermask will get removed and if copper and leftover tin will be dissolved, at first after around 9 days it showed promissing results but i also had some Phosphoric acid added to the mix and no air pump, but all tin was dissolved and copper dissolved in few places.
Now i switched to this 20-30% citric acid mix might add one with sulphamic today if i won't forget (and defoamer since it foams out of container that is filled only to 1/5th of it's volume.) and in the meanwhile this trial is running i plan to prepare some small goldplated PCB's from vapes or maybe even just metal terminals that got some goldplating to see if this might at least remove some portion of base metals as nitric is quite expencive and hard to get here lately and i'm trying to dissolve away as much as i can with stuff i can get cheaply or for free

 

[Yggdrasil]

Well the problem is only dissolving base metals and freeing all the gold foils since i can get those detergents with citric etc for cheap or even free sometimes, but the thing is i'm not sure if some additives in it or in defoamer if i add some won't impact the reaction (especially as i can't see SDS even on producent's site) . Toxicity of salts is of no concern, university will handle the utilisation together with way worse things we produce there.
Trial run i'm doing on some PCB's with no gold just to see if the soldermask will get removed and if copper and leftover tin will be dissolved, at first after around 9 days it showed promissing results but i also had some Phosphoric acid added to the mix and no air pump, but all tin was dissolved and copper dissolved in few places.
Now i switched to this 20-30% citric acid mix might add one with sulphamic today if i won't forget (and defoamer since it foams out of container that is filled only to 1/5th of it's volume.) and in the meanwhile this trial is running i plan to prepare some small goldplated PCB's from vapes or maybe even just metal terminals that got some goldplating to see if this might at least remove some portion of base metals as nitric is quite expencive and hard to get here lately and i'm trying to dissolve away as much as i can with stuff i can get cheaply or for free

The Universe will cope well with anything going on in any solar system, but the local nature and neighbors will not.
So all and and any solution has to be treated according to the waste treatment procedure or handed in to a hazardous waste treatment facility.
And as said before there is no need of constant bubbling unless you have HCl and Cl ions in the solution.

Most of us just run a Cupric Chloride etch (AP) for the foils.
Not many use Nitric.

 

[Chirou]

I thought of doing trial run on some goldplated pins but i'm not sure if the volume of base metal in them won't be a bit of overkill for what i'm testing + small surface of contact with just copper

 

[Chirou]

The Universe will cope well with anything going on in any solar system, but the local nature and neighbors will not.
So all and and any solution has to be treated according to the waste treatment procedure or handed in to a hazardous waste treatment facility.
And as said before there is no need of constant bubbling unless you have HCl and Cl ions in the solution.

Most of us just run a Cupric Chloride etch (AP) for the foils.
Not many use Nitric.

Not Universe.... University, the place where you get higher education , do research, science projects and stuff like that , please don't distort what i wrote

 

[Ultrax]

Peroxide increases reactivity (mainly for copper and iron) but quickly destroys citric acid.
Sulfuric acid (apparently, its monoamide too) also destroys citric acid to carbon dioxide, water, and acetone-dicarboxylic acid.
This mixture will have little effect and will not be beneficial.
With pure citric acid you will dissolve (slowly) Al, Ca, Cu (with peroxide), Zn, Pb and about 50% of fine iron.

 

[Yggdrasil]

Not Universe.... University, the place where you get higher education , do research, science projects and stuff like that , please don't distort what i wrote

It was not a distortion, just a misreading.
So you can hand in waste to the University?
Do you work there?

 

[Marcel]

I thought of doing trial run on some goldplated pins but i'm not sure if the volume of base metal in them won't be a bit of overkill for what i'm testing + small surface of contact with just copper

All in all, this is not a favorable concept. By the way, while citric acid appears harmless, the combination of Pb and citric acid is definitely not!
The removal of base metals is optimally achieved using either HCl or HSO4.

This approach is regarded as "best practice." If, one day, someone proposes a better solution, it should be rigorously tested and proven prior to postulating it. Decades of experiments have shown that none of the alternatives worked better or were non-toxic. So, without delving into excessive detail—since forums are replete with these questions and trials—I suggest it will lead you nowhere.
It's advisable to stick with methods that are proven to work and have minimal side effects.

 

[Ultrax]

All in all, this is not a favorable concept. By the way, while citric acid appears harmless, the combination of Pb and citric acid is definitely not!
The removal of base metals is optimally achieved using either HCl or HSO4.

PbSO4 and PbCl2 are not soluble. If you have lead in your material (especially old e-waste manufactured earlier than 2000) - it cannot be leached by hydrochloric or sulfuric acid and will remain in your material.

At subsequent stages of processing, for example with nitric acid, you will get much more toxic and carcinogenic lead nitrate.

Any heavy metals organic complexes are relatively dangerous and shouldn't be inhaled or eaten. But if you need to remove lead - citric acid is the best way (much better than acetic acid).

 

[Marcel]

You got two points there!
Still I would not favor the use of either citric acid or acetic acid for the purpose described here. Tried it both in my early days and the results were far from good. It sounds cheap and even enviromentally friendly but it is of very little use. And because these agents are so underperforming there are often long lasting discussions because it does not really work well.
I am also not aware of any industrial recycler using citric acid (or vinegear) as agent. If it was so cheap and still effective, they would surely be the first to adopt this method.
At the end of the day, people give in or use HCl. So why do we always discuss the same matter over and over again?

 

[Ultrax]

The context of my thought was lead removing. Of course, the material must be thoroughly crushed. But I repeat once again - sulfuric acid and hydrochloric acid do not work with lead. People use HCl because most of today's electronic waste contains lead-free solders.

 

[Chirou]

problem is HCl and H2SO4 are pricey here and get harder and harder to get , earlier we could get Nitric with no paperwork just claiming it's for fertilizing purposes. That's why i'm delving into possibility that those mixtures might lets say dissolve base metals like copper over long exposure time as 1-2 months etc as i got lots and lots of materials, pins, pcb's etc to process in 2 separate parts of country one in north one in south. Earlier when it was funnily cheap i used only HCl and HNO3 cause i paid something equal to 10 USD for 5l of nitric and maybe 1-2USD for 5l of HCl even cheaper when i bought two together . now it's not this pretty and for example Citric i can get in big quantities really cheap, and in 20-30% together with arund 10% sulphamic acid, for basically free from my part time job as we got tons of leftover that we don't use, not counting chlorine tablets (sodium dichloroisocyanurate, dihydrate) that saddly i found out from other posts here won't be useful either.

Rarely i can get some H3PO4 which mixed with salt actually did dissolve some tin and started to eat away at copper but i can't get big quantities saddly at least not now, and it wasn't really too effective as it's rather weak acid

 

[Chirou]

It was not a distortion, just a misreading.
So you can hand in waste to the University?
Do you work there?

Might work later, now i'm a student on Mechatronics actually in middle of my engineering paper now,
Ladies that handle all chemistry classes, projects etc are quite nice and allow us to pretty much do what we want in lab if the person askins is competent about chemistry and safety, and sometimes even they try to turn what we do into another research paper, but their main lets say goal so far is ceramics production and trying to discover new ceramic's compositions , one of them got her PHD by creating supercondensator that was supposed to be sold to city for building self energy sustained bus stops that would have heating in winter time etc but city turned this down due to costs...

 

[Yggdrasil]

problem is HCl and H2SO4 are pricey here and get harder and harder to get , earlier we could get Nitric with no paperwork just claiming it's for fertilizing purposes. That's why i'm delving into possibility that those mixtures might lets say dissolve base metals like copper over long exposure time as 1-2 months etc as i got lots and lots of materials, pins, pcb's etc to process in 2 separate parts of country one in north one in south. Earlier when it was funnily cheap i used only HCl and HNO3 cause i paid something equal to 10 USD for 5l of nitric and maybe 1-2USD for 5l of HCl even cheaper when i bought two together . now it's not this pretty and for example Citric i can get in big quantities really cheap, and in 20-30% together with arund 10% sulphamic acid, for basically free from my part time job as we got tons of leftover that we don't use, not counting chlorine tablets (sodium dichloroisocyanurate, dihydrate) that saddly i found out from other posts here won't be useful either.

Rarely i can get some H3PO4 which mixed with salt actually did dissolve some tin and started to eat away at copper but i can't get big quantities saddly at least not now, and it wasn't really too effective as it's rather weak acid

HCl is sufficient for most base metals.
With air bubbling even for Copper.

 

[Yggdrasil]

Has anyone tried using citric acid or sulphamic acid mixed with NaCl and oxidants like O2 or H2O2 to extract gold foils?It encountered excessive foaming. Any advice?

Much cheaper and predictable to use the proper Chemicals.
Use HCl and air bubbling.

 

[anarxi]

problem is HCl and H2SO4 are pricey here and get harder and harder to get , earlier we could get Nitric with no paperwork just claiming it's for fertilizing purposes. That's why i'm delving into possibility that those mixtures might lets say dissolve base metals like copper over long exposure time as 1-2 months etc as i got lots and lots of materials, pins, pcb's etc to process in 2 separate parts of country one in north one in south. Earlier when it was funnily cheap i used only HCl and HNO3 cause i paid something equal to 10 USD for 5l of nitric and maybe 1-2USD for 5l of HCl even cheaper when i bought two together . now it's not this pretty and for example Citric i can get in big quantities really cheap, and in 20-30% together with arund 10% sulphamic acid, for basically free from my part time job as we got tons of leftover that we don't use, not counting chlorine tablets (sodium dichloroisocyanurate, dihydrate) that saddly i found out from other posts here won't be useful either.

Rarely i can get some H3PO4 which mixed with salt actually did dissolve some tin and started to eat away at copper but i can't get big quantities saddly at least not now, and it wasn't really too effective as it's rather weak acid

Can you get ammonium nitrate (100% fertilizer) + battery electrolyte?

 

[Yggdrasil]

Can you get ammonium nitrate (100% fertilizer) + battery electrolyte?

Any Nitrate will do.

 

[Chirou]

So small update it took around 2 weeks to work but this mix of detergents containing citric acid mixed with salt did start to eat away the copper , only thing i changed was pouring solution out every 2 days for 1day to leave the goldplated pins to oxidate same bit. Got part of Gold foils filtered out, and added some hot water to remaining solution, which Turned yellow, makes me curious what chemical compound i got there that it turned from beautiful copper blue to this yellow , will figure out in time.

 

[Yggdrasil]

So small update it took around 2 weeks to work but this mix of detergents containing citric acid mixed with salt did start to eat away the copper , only thing i changed was pouring solution out every 2 days for 1day to leave the goldplated pins to oxidate same bit. Got part of Gold foils filtered out, and added some hot water to remaining solution, which Turned yellow, makes me curious what chemical compound i got there that it turned from beautiful copper blue to this yellow , will figure out in time.

What are you trying to accomplish with this experiment?
You certainly are creating a lot of waste.
I would go with AP, less hassle, less waste and less time needed.