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Author: Subject: Zinc chloride from zinc used for construction - toxicity issues
Bezaleel
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[*] posted on 3-12-2018 at 16:42
Zinc chloride from zinc used for construction - toxicity issues


Last weekend, I tried to make zinc chloride. The product is intended to be used as a flux and does not need to be ultra pure. Its mere function is to dissolve oxides on the target metal (corroded lead powder) so that the latter will melt together.

I had some muriatic acid standing around which looked reasonably pure, but obviously contained some iron. Here's its colour (I just put in a piece of zinc).
IMG_1364_small.JPG - 49kB

I dissolved the strips of zinc in the hardware store HCl solution, which had a strength of "<10%". The reaction was very slow. Hoping to speed it up a bit, I added a small amount of H2O2 (approx. 20 ml, 10%). This changed the colour of the solution from light greenish-yellow to regular yellow, but it did not seem to speed up the reaction.

The amounts used were 150ml of assumed <10% HCl solution, and 13.15g of zinc (two strips). Initially 1 strip op Zn was added. After about an hour, it had completely dissolved. I added the other strip, which took about half a day to dissolve. Also some dark foamy chunks formed in the solution, which I assume to be an iron compound from iron dissolved in the acid. The final solution was completely clear and its pH is 1 or lower (pH test strip).
IMG_1369_small.JPG - 50kB

The zinc I used was cut from zinc plates used for the construction of gutters and the like. I've often heard claims that such zinc is not pure and care should be taken when dissolving it in acid, since it may contain impurities like Se, As, and Sb. Since these are unlikely to be present as solid solution, but rather as ZnSe, Zn3As2, and Zn3Sb2, the formation of H2Se and other extremely toxic substances cannot be excluded. This is why I have the questions below.

The next step I to take, is concentrating the solution and obtaining ZnCl2/ZnClOH, which I want to test as a flux for the lead powder. If there is indeed Se or As in the solution, then what can I do to get rid of that? I'm thinking about distilling of the water and acid, until dryness. I'm afraid of two things:
1. Not all of the toxic compounds which distill over may condense, leaving some of the toxins in the air;
2. Some of the toxic compounds will remain in the ZnCl2/ZnClOH, and will evaporate when using the zinc chloride as a flux.

Any suggestions on how to do this safely are welcome. I do not have a fume hood, which is why I normally concentrate solutions with excess acid in a distillation setup, so that (almost) all fumes are condensed and collected.

Obviously, I'm not sure about the presence of the named toxins, but better safe than sorry.


[Edited on 4-12-2018 by Bezaleel]
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[*] posted on 3-12-2018 at 18:21


A little internet suggests that it's likely to be alloyed with small amounts of copper and titanium probably for hardening and maybe corrosion resistance. Pure zinc reacts quite excitedly with even dilute HCl. Accumulation of the alloying elements on the surface probably slowed down your reaction a lot.

If you live in the US, post-1983 pennies are zinc with a very thin layer of copper. They can be cut up with tin snips to expose the zinc and treated with HCl to get relatively pure zinc chloride solution.

[Edited on 4-12-2018 by UC235]
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[*] posted on 3-12-2018 at 18:26


First I would like to say, I am impressed for your anticipation of possible toxic gases from known impurities that may reside in your zinc source. Definitely, perform this reaction in a well vented setting.
-------------------------------------------
There is a known electrochemical reaction in the presence of acid (H+) and oxygen (O2) with a metal in a lower valence state producing a basic salt. Some examples:

4 Cu(l)/Fe(ll)/Co(ll)...+ O2 + 2 H+ --> 4 Cu(ll)/Fe(lll)/Co(lll) + 2 OH- (see, for example, http://www.sciencemadness.org/talk/viewthread.php?tid=81800#... )

Add NaCl (good electrolyte as this is an electrochemical reaction) and also H2O2 (or pump in O2 or boil in air) to create the basic salt.
---------------------------------------

Alternatively, with respect to your preparation, you can actually make hypochlorous acid , HOCl, and then directly react it with zinc oxide (see Mellor reference, https://books.google.com/books?id=8w1GAQAAMAAJ&pg=PA274&... ). To quote:

“As with magnesium hypochlorite, A. J. Balard likewise form a soln. of zinc hypochlorite by the action of hypochlorous acid on zinc oxide. T soln. behaved in an analogous manner when the attempt was made to concentri it invacuo. A. J. Balard also prepared a similar soln. by double decomposition zinc sulphate and an excess of calcium hypochlorite. G. Lunge and L. Land obtained a soln. of zinc hypochlorite by a process similar to that employed P. Grouvelle. They found that some chlorate was formed when working at 1 and still more at higher temp. The zinc hypochlorite was found to decompo into zinc chloride or oxychloride and oxygen. “

The preparation of ZnO (or it could be the oxychloride employing HOCl and not NaOCl) in good supply can be achieved by a galvanic corrosion reaction (see my related thread at http://www.sciencemadness.org/talk/viewthread.php?tid=84047#... ). This is a simple electrosynthesis using a microwave to jump start the reaction. Just place Zn metal in a jar with aqueous chlorine bleach, NaOCl (or perhaps here try HOCl, note, I can’t remember if dilute H2O2 works to a limited degree in place of NaOCl or HOCl), some NaCl (better perhaps is sea salt) and a carbon source (a graphite rod from a pencil of say 1 ½ inches should work and is a very noble) or use noble metals like a silver plated coin, or a US quarter (Nickel-Copper alloy), but I don’t like the idea of any possible toxic nickel ions getting into the brew.

I'll give you a link to my recommended path for making hypochlorous acid using aqueous NaOCl, plus dry NaHCO3 and dry CaCl2 (see http://www.sciencemadness.org/talk/viewthread.php?tid=76591#... ). However, you may wish to try the simple impure route of mixing chlorine bleach (NaOCl) with 5% vinegar in the appropriate proportions (or excess of NaOCl) to produce HOCl and sodium acetate (no excess vinegar). Normally the acetate may be an issue, but in the presence of zinc oxychloride, I'm not sure if you would even get a reaction in cold solutions, so perhaps you can just separate out the unreacted zinc oxychloride salt that is formed with the decomposition of unstable Zn(OCl)2.

The additional benefit of this path with HOCl acting on any unreacted impure Zn, is that I'm pretty sure, for example, that if you react a sulfide with Hypochlorous acid or Chlorine Bleach (NaOCl), you would not get Hydrogen sulfide (a toxic gas also), but instead just a suspension of fine sulfur.

HOCl --> HCl + O (partial decomposition reaction)

2 HCl + ZnS --> ZnCl2 + H2S

HOCl (or NaOCl) + H2S --> H2O + S + HCl (or NaCl)

[Edited on 4-12-2018 by AJKOER]
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[*] posted on 3-12-2018 at 20:34


Quote: Originally posted by AJKOER  
First I would like to say, I am impressed for your anticipation of possible toxic gases from known impurities that may reside in your zinc source. Definitely, perform this reaction in a well vented setting.
-------------------------------------------
There is a known electrochemical reaction in the presence of acid (H+) and oxygen (O2) with a metal in a lower valence state producing a basic salt. Some examples:

4 Cu(l)/Fe(ll)/Co(ll)...+ O2 + 2 H+ --> 4 Cu(ll)/Fe(lll)/Co(lll) + 2 OH- (see, for example, http://www.sciencemadness.org/talk/viewthread.php?tid=81800#... )

Add NaCl (good electrolyte as this is an electrochemical reaction) and also H2O2 (or pump in O2 or boil in air) to create the basic salt.
---------------------------------------

Alternatively, with respect to your preparation, you can actually make hypochlorous acid , HOCl, and then directly react it with zinc oxide (see Mellor reference, https://books.google.com/books?id=8w1GAQAAMAAJ&pg=PA274&... ). To quote:

“As with magnesium hypochlorite, A. J. Balard likewise form a soln. of zinc hypochlorite by the action of hypochlorous acid on zinc oxide. T soln. behaved in an analogous manner when the attempt was made to concentri it invacuo. A. J. Balard also prepared a similar soln. by double decomposition zinc sulphate and an excess of calcium hypochlorite. G. Lunge and L. Land obtained a soln. of zinc hypochlorite by a process similar to that employed P. Grouvelle. They found that some chlorate was formed when working at 1 and still more at higher temp. The zinc hypochlorite was found to decompo into zinc chloride or oxychloride and oxygen. “

The preparation of ZnO (or it could be the oxychloride employing HOCl and not NaOCl) in good supply can be achieved by a galvanic corrosion reaction (see my related thread at http://www.sciencemadness.org/talk/viewthread.php?tid=84047#... ). This is a simple electrosynthesis using a microwave to jump start the reaction. Just place Zn metal in a jar with aqueous chlorine bleach, NaOCl (or perhaps here try HOCl, note, I can’t remember if dilute H2O2 works to a limited degree in place of NaOCl or HOCl), some NaCl (better perhaps is sea salt) and a carbon source (a graphite rod from a pencil of say 1 ½ inches should work and is a very noble) or use noble metals like a silver plated coin, or a US quarter (Nickel-Copper alloy), but I don’t like the idea of any possible toxic nickel ions getting into the brew.

I'll give you a link to my recommended path for making hypochlorous acid using aqueous NaOCl, plus dry NaHCO3 and dry CaCl2 (see http://www.sciencemadness.org/talk/viewthread.php?tid=76591#... ). However, you may wish to try the simple impure route of mixing chlorine bleach (NaOCl) with 5% vinegar in the appropriate proportions (or excess of NaOCl) to produce HOCl and sodium acetate (no excess vinegar). Normally the acetate may be an issue, but in the presence of zinc oxychloride, I'm not sure if you would even get a reaction in cold solutions, so perhaps you can just separate out the unreacted zinc oxychloride salt that is formed with the decomposition of unstable Zn(OCl)2.

The additional benefit of this path with HOCl acting on any unreacted impure Zn, is that I'm pretty sure, for example, that if you react a sulfide with Hypochlorous acid or Chlorine Bleach (NaOCl), you would not get Hydrogen sulfide (a toxic gas also), but instead just a suspension of fine sulfur.

HOCl --> HCl + O (partial decomposition reaction)

2 HCl + ZnS --> ZnCl2 + H2S

HOCl (or NaOCl) + H2S --> H2O + S + HCl (or NaCl)

[Edited on 4-12-2018 by AJKOER]


You can safely ignore all of this. It might even make you dumber if you read it.
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[*] posted on 4-12-2018 at 00:06


Can AJOEKER get a obligated disclaimer mentioning the fractal wrongness of his posts so to avoid newbies to get confused?

I tried to argue his post, but I got confused at electrochemical and got lost a couple of sentences down.
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[*] posted on 4-12-2018 at 02:18


Quote: Originally posted by UC235  
A little internet suggests that it's likely to be alloyed with small amounts of copper and titanium probably for hardening and maybe corrosion resistance. Pure zinc reacts quite excitedly with even dilute HCl. Accumulation of the alloying elements on the surface probably slowed down your reaction a lot.

If you live in the US, post-1983 pennies are zinc with a very thin layer of copper. They can be cut up with tin snips to expose the zinc and treated with HCl to get relatively pure zinc chloride solution.

[Edited on 4-12-2018 by UC235]

The reaction speed surprised me as well, but from experience I could only compare to putting purified and thin zinc shavings into 30% HCl. Your argument that this is an alloy which reacts much slower completely makes sense - thanks!

I live in the Netherlands (Europe), so have no access to pennies. My questions are about the usage of the zinc I have lying around (or of cheap stuff I have access to). Usage of pennies with a copper coating seems a bit of a hassle, but thanks for the thought.

AJOEKER suggests to pursue an entirely different pathway:
Quote: Originally posted by AJKOER  
First I would like to say, I am impressed for your anticipation of possible toxic gases from known impurities that may reside in your zinc source. Definitely, perform this reaction in a well vented setting.
-------------------------------------------
There is a known electrochemical reaction in the presence of acid (H+) and oxygen (O2) with a metal in a lower valence state producing a basic salt. Some examples:

4 Cu(l)/Fe(ll)/Co(ll)...+ O2 + 2 H+ --> 4 Cu(ll)/Fe(lll)/Co(lll) + 2 OH- (see, for example, http://www.sciencemadness.org/talk/viewthread.php?tid=81800#... )

Add NaCl (good electrolyte as this is an electrochemical reaction) and also H2O2 (or pump in O2 or boil in air) to create the basic salt.
---------------------------------------

Alternatively, with respect to your preparation, you can actually make hypochlorous acid , HOCl, and then directly react it with zinc oxide (see Mellor reference, https://books.google.com/books?id=8w1GAQAAMAAJ&pg=PA274&... ). To quote:

(...)
[Edited on 4-12-2018 by AJKOER]

Here I'd first need to oxidise the zinc, but if that would be accomplished by burning it, aerosoles of toxins would also need to be taken care of.

Thanks for taking the time to come up with alternatives, but let's please stick to my question about how to proceed from the solution I now have in a safe way.

I'll do some literature checks to find out more about the mining process and potential impurities in zinc.
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[*] posted on 4-12-2018 at 07:26


Zinc indeed can contain tiny amounts of As and Sb. I do not know of Se-impurities. I would not worry too much about the Sb, but the As indeed is a serious issue. Some of the As may escape as AsH3 and that gas is insanely toxic. Also some SbH3 can be formed, which also is very toxic. The main difference, however, is that AsH3 also has very very bad long term effects, while SbH3 only has direct effect (it is very quickly destroyed and converted to much less toxic Sb2O3 at neutral pH or SbOCl at somewhat lower pH).

I would dissolve the Zn outside. Any AsH3 formed then quickly disappears and poses no risk at all (for that it becomes too dilute, no risk for you, nor your neighbours).
If you do not use any oxidizer in the HCl, then virtually all of the arsenic will disappear as AsH3. This is true, because the percentage of As is very low. If you add H2O2, then it probably remains in solution as an arsenic(III) species (arsenious acid) or as an arsenic (V) species (arsenic acid). So, try to dissolve the zinc in HCl only. Use 30% HCl if the reaction is too slow, or apply some heat to speed up things. Just waiting and letting it stand outside for a few days also is an option (be sure that no kids or animals can reach the beaker with the solution).




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[*] posted on 4-12-2018 at 09:32


Thanks, woelen. I did the experiment outdoors, of course.

So if I understand you correctly, you suggest to bring the solution to a chemical depot and start anew without H2O2? Just to be sure that no arsenates or arsenites are present in the solution, right?
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[*] posted on 5-12-2018 at 00:00


The compounds, used in the solution are very cheap and the (financial) losses will be minimal. If you really intend to use the boiled down solution as flux then indeed consider making it again as described above. The fuzz of removing the arsenic compounds or isolating the ZnCl2 is not worth it.



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[*] posted on 5-12-2018 at 13:07


For a long time people soldering used "killed spirits" as a flux.
The "spirit" was "spirits of salt" i.e. hydrochloric acid and the process of "killing" it was to react it with excess zinc.

I imagine the stuff you made will work nearly as well as the old fashioned version- albeit that you have more water in the mix.

If you want to speed up the reaction of the acid with zinc then heating it and/ or adding a trace of copper will do the job nicely.
If you use an excess of zinc then any As or Sb will either remain undissolved or will be vented off with the hydrogen.
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[*] posted on 6-12-2018 at 09:49


Be aware that driving the water off of a zinc chloride solution is difficult, if it's the solid you're after. My zinc chloride solution is in a desiccator with calcium chloride and it won't crystallize, remaining a thick syrup. Heating to drive off the water might decompose it to zinc hydroxy-chloride, although I imagine that's what it does when applied as a flux anyway so that might not matter to you.

Something else to always consider is the amounts you're dealing with. With only 13g of zinc and arsenic impurities likely down in tiny fractions of a percent, the actual amount of toxic substances you're dealing with here is probably very small. I wasn't able to find a CoA for commercial zinc, but I did come across this paper (attached) that states on page 75:
Quote:
The conclusions at which we have arrived, after a long course of experiments with many different zincs, and various acids, are these : - first, that much of the zinc of commerce is free from arsenic, or at least contains no arsenic that can be detected by the most delicate tests known for that metal ; secondly, that the sulphuric and chlorhydric acids found in commerce do very often contain arsenic, and are always so liable to contain it as to be utterly unfit for use in Marsh's process without special purification for that purpose.


Granted, that was 150 years ago so things may have changed in the interim :)

Attachment: On the Impurities of Commercial Zinc.pdf (5.6MB)
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[*] posted on 7-12-2018 at 18:59


Here is a process to remove possible heavy metal impurity (proposed for use in commercial leaching of ores), in the current case, get a sample of pure zinc (like from inside a US penny). Turn it into powder and treat with HCl in an attempt to chemisorb hydrogen atom radicals onto the the surface of the zinc. Do not dissolve all the Zn powder, remove what is not dissolved after a period of treatment with HCl, and add to your solution containing impurities. Place in a vented area. Any observed added precipitates could be heavy metals and assume fumes to be very toxic.

Background based on chemisorb hydrogen on Aluminum metal below:

Quote: Originally posted by AJKOER  

.......
Next, imbue the surface of Mg or Al with the hydrogen atom radical (from the traditional nascent hydrogen generation methods based on say Al/NaOH).

One may assume that the •H radical functional behaves (per its seemingly reversible formation reaction: e- + H+ = •H ) as apparently a (e-,H+) pair acting on ions. For an example from 'Hydrometallurgy 2008: Proceedings of the Sixth International Symposium', p. 818, a commercial reductive leaching equation, to quote:

" PbS + 2 •H = Pb + H2S (5) " (see https://books.google.com/books?id=1etfSdk55SYC&pg=PA818&... )

which I view functionally as follows:

Pb(+2)S(2-) + 2 (e-, H+) = Pb + H2S (g)
......
[Edited on 4-10-2018 by AJKOER]


[Edited on 8-12-2018 by AJKOER]
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[*] posted on 10-12-2018 at 06:53


How do you plan on powdering a solid piece of metal at home?
And how do you propose to add HCl to Zn and NOT have it dissolve? Magic, perhaps? Or sea salt and vinegar?
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[*] posted on 10-12-2018 at 11:33


If you live in the united states, the color of your acid is not due to iron; the big name hardware stores sell HCl that does not leave a residue on evaporation and does not give a positive test for iron with salicylic acid or prussian blue tests.

That aside, your zinc looks like it might contain some copper, from the way it is becoming coated with a dark unreactive material as it dissolves.

Can we please remove AJKOER from the forum, jesus christ
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[*] posted on 10-12-2018 at 13:06


I think the "idea" behind AJKOER's post is valid.
If you added pure zinc to a solution of (a little) antimony chloride in zinc chloride the antimony would precipitate out and the zinc would dissolve- it's the same principle as the "nail in copper sulphate solution" experiment done by school-kids.

What you would end up with is a lump of zinc/ antimony in the solution.

That sounds vaguely familiar.
Quote: Originally posted by unionised  

If you use an excess of zinc then any As or Sb will either remain undissolved or will be vented off with the hydrogen.
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[*] posted on 10-12-2018 at 13:19


Quote: Originally posted by Amos  

That aside, your zinc looks like it might contain some copper, from the way it is becoming coated with a dark unreactive material as it dissolves


Dissolving lumps of pure zinc (or pure tin) in hydrochloric acid has always produced a layer of fine black powder,
which dissolves very easily in the acid when swirled.
I assume that it is metal powder suspended in the fluid near the bulk metal, where the HCl concentration is low/depleted.




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[*] posted on 10-12-2018 at 13:21


I wouldn't ask that AJKOER be banned, but he should have a custom title warning people about his flights of fancy.



Please remember: "Filtrate" is not a verb.
Write up your lab reports the way your instructor wants them, not the way your ex-instructor wants them.
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[*] posted on 10-12-2018 at 14:23


Quote: Originally posted by DraconicAcid  
I wouldn't ask that AJKOER be banned, but he should have a custom title warning people about his flights of fancy.


I second the motion.




As below, so above.
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[*] posted on 10-12-2018 at 14:35


Quote: Originally posted by Metacelsus  
Quote: Originally posted by DraconicAcid  
I wouldn't ask that AJKOER be banned, but he should have a custom title warning people about his flights of fancy.


I second the motion.


Third.
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[*] posted on 10-12-2018 at 18:15


I actually have little experience with employing chemisorbed hydrogen (like when to quench the reaction leaving some solid metal containing chemisorbed hydrogen and how long it is functional), and as organic chemists have been using hot and cold temperature path (see sources and comments at http://www.sciencemadness.org/talk/viewthread.php?tid=110096 ) employing activated hydrogen (also known imprecisely as 'nascent' hydrogen) for over a 100 years, perhaps some wisdom on implementation can be found in the literature on successfully tested procedures.

However, unlike most comments in this thread, the alluded to novel and recent methodological suggestion, with an actual source, namely the 'Hydrometallurgy 2008: Proceedings of the Sixth International Symposium', is being examined by a very real world applied branch of chemistry, so investigating and experimenting with the concept may prove to be of value.

By the way, one does not get to present 'flights of fancy' in any symposium in any field per my real world experience, and have it then cited in a book in the area of specialty in a positive frame. Claiming it occurs is much closer to a true flight of fancy.
----------------------------------------------------------------

Now I can understand how some of my more references to diverse scientific literature can be upsetting to some. For example, again from the field of hydrometallurgy, I once may a reference to the fact that one can employ a dilute acid (and save $) to dissolve minerals, with for example dilute HCl, and upon adding a significant amount of say, calcium chloride, one could have functionally a much more powerful acid (there were even detailed examples of the extreme acceleration in acid possible strength). If I had invested significant funds in my high strength of acids for a particular purpose, I would also be upset, however, the science of activity coefficients is nevertheless real. Even worse, sticking with the acid example, I once presented a thread that made use of the revelation of recent science noting that select radicals can be extremely acidic, and could be used to assist in a normally totally strong acid based prep. Even more examples extending to the unconventional use of microwave assisted heating, photolysis, electrolysis, magnetic field assisted preps,..., all based on relatively recent science as well.

So true, I am not much of a source of classic preps, and given my unfavorable jurisdiction making unlicensed labs a crime, together with neighbors seeing a flask and thinking drug cook, I prefer a different low key look, like a microwave, sunlamps,...

[Edited on 11-12-2018 by AJKOER]
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[*] posted on 10-12-2018 at 23:31


Quote: Originally posted by AJKOER  
I actually have little experience with employing chemisorbed hydrogen

[Edited on 11-12-2018 by AJKOER]

Then shut up about it.
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[*] posted on 11-12-2018 at 04:03


Quote: Originally posted by unionised  
Quote: Originally posted by AJKOER  
I actually have little experience with employing chemisorbed hydrogen

[Edited on 11-12-2018 by AJKOER]

Then shut up about it.


In the future I will unless there are safety issues, obvious given the threads topic “Zinc chloride from zinc used for construction - toxicity issues” .

An extract:

Quote: Originally posted by Bezaleel  

......................
The zinc I used was cut from zinc plates used for the construction of gutters and the like. I've often heard claims that such zinc is not pure and care should be taken when dissolving it in acid, since it may contain impurities like Se, As, and Sb. Since these are unlikely to be present as solid solution, but rather as ZnSe, Zn3As2, and Zn3Sb2, the formation of H2Se and other extremely toxic substances cannot be excluded. This is why I have the questions below.

The next step I to take, is concentrating the solution and obtaining ZnCl2/ZnClOH, which I want to test as a flux for the lead powder. If there is indeed Se or As in the solution, then what can I do to get rid of that? I'm thinking about distilling of the water and acid, until dryness. I'm afraid of two things:
1. Not all of the toxic compounds which distill over may condense, leaving some of the toxins in the air;
2. Some of the toxic compounds will remain in the ZnCl2/ZnClOH, and will evaporate when using the zinc chloride as a flux.

Any suggestions on how to do this safely are welcome. I do not have a fume hood, which is why I normally concentrate solutions with excess acid in a distillation setup, so that (almost) all fumes are condensed and collected.

Obviously, I'm not sure about the presence of the named toxins, but better safe than sorry.
[Edited on 4-12-2018 by Bezaleel]


The above concern over toxicity issues and the invitation “Any suggestions on how to do this safely are welcome” is the only reason I interjected based on my research and some personal experimenting.

I apologize if anyone finds any of the recent science unsettling, but I try, at least, to provide sources and references (which is apparently more, by the way, than I usually see in many comments espousing little or nothing in the way of science, but unfortunately replete, at times, in ad hominem attacks. And when is the last time that anyone favoring personal attacks post a new topic, or even espouse a new idea in a thread? Perhaps that's a new topic worthy of research and dissemination?).


[Edited on 11-12-2018 by AJKOER]
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Tsjerk
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[*] posted on 11-12-2018 at 11:08


Quote: Originally posted by DavidJR  


Third.


Fourth, it could be respectful though, like "Speculator of wildly radical but harmless theories"

Edit:

"Speculator of wildly radical theories"

[Edited on 11-12-2018 by Tsjerk]
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[*] posted on 13-12-2018 at 17:49


My acidic radical thread does present some interesting theories, so don't believe any of the pictures or recent sources if it makes you feel better.

Now that everyone is feeling good, I need a volunteer to place a piece of gold, perhaps a coin, jewelry (remember nothing should happen per above pronouncements, but please don't borrow anything) in a solution consisting of just dilute HOCl whose prep is detailed below, some KNO3 (sold as stump remover) together with sea salt as electrolyte, and some activated carbon. Wearing safety gear, jump start a the microwave and quickly place outdoors (a further safety precaution) to avoid any possible toxic/corrosive fumes with breathing mask and eye goggles a must. Repeat the microwave treatment as needed.
---------------------------------

My suggestion prepare HOCl by adding NaHCO3 (Baking soda) and CaCl2 (DampRid) to NaOCl (found in 6% or higher in Chlorine Bleach). Reactions:

NaOCl + NaHCO3 = Na2CO3 + HOCl
CaCl2 + Na2CO3 --> CaCO3(s) + 2 NaCl

In the presence of CaCl2, the reaction forms a suspension of CaCO3 which settles on cooling of the mix. Decant to collect the hypochlorous acid which should be kept cool, in the dark, and used within a few hours of preparation (unstable, toxic chlorine fumes on breakdown).

Note, a vinegar plus chlorine bleach path can be used to create HOCl, but the presence of the hydrocarbon could potentially latter introduce some very toxic compounds on further reacting with chlorine.
------------------------------------

What could possibly go wrong? Remember all speculative per some, but not at all, based on my experience and pictures, but I have not attempted on any metal as noble as gold.

Is today the day that you dissolve that gold ring in such an innocent mix of household chemicals?

Do not forget the before and after pictures!

All still asserting that this is just another harmless speculative reaction can still have a change of mind, but hurry!
-------------------------------------------

Disclaimer: I am not responsible if one ignores safety recommendations and suffer serious or fatal injuries, nor am I at fault for any corrosive damage due to an anodic radical assisted attack (by the chlorine radical, see, for example, https://www.redorbit.com/news/science/211943/a_method_for_le... ) of your gold or other valuables, which I suspect is a possibility (as carbon is also more noble than gold and will generate hydroxyl radicals, a precursor to other radicals, on microwave assisted heating in the presence of activated carbon, see https://www.researchgate.net/publication/239705822_Generatio... ).
================================================================================

Apparently, it is been observed that HCl/NaOCl (which creates HOCl) dissolves gold (see https://www.911metallurgist.com/pyrometallurgy/dissolving-go... ) likely as the result of eventual chlorine formation (and/or the chlorine radical from HOCl in the presence of e-, chloride and pH <5, please see all my comments and references provided at http://www.sciencemadness.org/talk/viewthread.php?tid=98989#... ).

My added use of activated carbon (a source of e-(aq) and hydroxyl radical with MW assisted heating in the presence of chloride) likely can further promote the chlorine radical attack on gold. But if anyone still has some doubts, by all means, dissolve, dissolve, dissolve,..., away.

[Edited on 14-12-2018 by AJKOER]

[Edited on 14-12-2018 by AJKOER]
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