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Author: Subject: Accidental dichromate?
khlor
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[*] posted on 26-6-2022 at 17:27
Accidental dichromate?


Greetings,

I have no idea how to start, so here is a short version of my story,

Well, some time ago I ran an electrolysis cell with a stainless steel cathode. It was a divided cell, but I guess during progress the division wasn't that good, just a ceramic cup... and the salt was aqueous saturated solution of table salt... i wanted chlorine gas and got it for the time I needed... upon disassembly I was hit with that strong bleach smell, and a yellowish green stuff... this was on the ceramic cup and outside... it was strong enough to react with ethanol, I thought it was just some superstrong bleach... but recently (yesterday and today) I stumbled across some videos about doing dicromates from stainless steel... and the ceramic cup from that time still leaves a strong yellow of sodium dicromate... it could be paranoia, but I think I accidentally made some amount of dicromate or "hexavalent chromium " the superstrong oxidizer solution was stored in a vial, I did not touched, but the ceramic cup, the cathode and a lot of stuff got dirty with that yellow solution, and I don't mean yellow like rust and water, I mean yellow clear solution....

My questions are... how much should I be concerned ? I mean I was expecting at worst some bleach and lye, not some terminal cancer associated compound.

What can I do? The disposal and stuff....

How to get rid of chromium ? It is everywhere!(i didn't knew it could be chromium, much less dichromate "




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Jome
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[*] posted on 26-6-2022 at 22:16


Bunch of observations:

1. Graphite (if that was your anode) often contains some iron which forms yellow iron salts upon use.

2. A stainless steel anode in an alkaline/neutral cell produces a muck/goop of iron and nickel hydroxides as well as a lime-yellow chromate solution, in particular if the cell is divided either by a semi-permeable membrane or unglazed ceramics. Otherwise the equilibrium concentration of CrO4^2- will be quite low.

3. Lye, or hypochlorite production requires a low temperature and a divided cell, and there will always be more Cl- than ClO-. ClO- and some Cl2 dissolved in the water will be produced anyway, but not that much, the stuff just stinks a lot.

If you are afraid of Cr-6, just use a reductant and some acid to lower pH, chromate turns red/orange under lower pH, and is quickly reduced to a green Cr^3+ solution if a reductant is present.
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[*] posted on 27-6-2022 at 04:16


Thank you for replying jome, so, I know my story is a hard sell, but just bear with me

1 - yes, I am often used to that lovely color however this one was... different, and able to form vapors that bioled at room temperature upon reacting with ethanol. Plus, when making chloralkali cells, the anode chamber always becomes green and the cathode chamber rarely changes(on my earlier designs ) all changed when I decided to assemble using these cheap pots made of stainless steel from china

2- the stainles steel was the cathode, I cant use stainles steel as an anode in a chloralkali cell,no matter how crude I wanna go, I will not get chlorine, plus, the stainles steel was the whole container, so I assume that the chlorine from the anode reacted with the chromium and everything else to form chlorides, however diferently from the iron that formed an orange layer of rust, the chromium got a chance to react with hypochlorites and in the basic enviroment be dissolved. The cell was last run for quite some time and the concentration was concerning, I moved away from stainless steel.
Edit 1: you said that the concentration would be quite low, which it might be since I believe that it is the result of accidental/not accounted for reactions with the lid... but the question still remains, how concerned should I be?

3. That's what I am talking about! It was strange, my earlier designs never used this can or an entire piece of metal as outer casing and cathode before, I always had beach lye hydrogen and chlorine, that stuff stinks, but this time it was different, it was smelly as usual, but it looked different, and I tried reacting with a lot of stuff and got some weird reactions.... with ethanol it instantly turns clear and raises some seet smelling vapors,boiling at room temperature, more or less, It got warm, but not hot. On citric acid it became this dark color

It is not that I am afraid, but I am concerned because it is one of those instances where there is a potential danger here,I mean, I was prepared to work with chlorine gas, but not something with so many symbols on a safety datasheet and the people who make it call it "liquid cancer"


[Edited on 27-6-2022 by khlor]




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[*] posted on 1-7-2022 at 12:46


You should not overreact. Dichromate is not instant death in a bottle. I have several hundreds of grams of dichromate and have done LOTS of experiments with it, when I was a young boy up until now I am in my fifties. I just was careful not to touch the solutions and not to inhale any dust of it. But of course, sometimes went wrong and I did get some on my skin. Just rinsing it with dilute acidified sodium sulfite solution instantly destroys it.

Working with chlorine gas is more dangerous than working with dichromates. As with any chemical, use common sense, try to work cleanly and if you get exposed, rinse away. I do not know of any chemical, which is instant death in a bottle, which you can easily make or buy as a private person. Not even cyanide is. Maybe hydrogen fluoride, and maybe some nerve agents, but the latter certainly are not something you will accidently make at home.

I consider a little exposure to stuff like dichromates as exposure to cigarettes. A single cigarette does not kill you. Of course, if you ingest multiple grams of dichromate, then you may have serious health issues, but no sane person does that.




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[*] posted on 8-7-2022 at 15:14


Quote: Originally posted by woelen  
You should not overreact. Dichromate is not instant death in a bottle. I have several hundreds of grams of dichromate and have done LOTS of experiments with it, when I was a young boy up until now I am in my fifties. I just was careful not to touch the solutions and not to inhale any dust of it. But of course, sometimes went wrong and I did get some on my skin. Just rinsing it with dilute acidified sodium sulfite solution instantly destroys it.

Working with chlorine gas is more dangerous than working with dichromates. As with any chemical, use common sense, try to work cleanly and if you get exposed, rinse away. I do not know of any chemical, which is instant death in a bottle, which you can easily make or buy as a private person. Not even cyanide is. Maybe hydrogen fluoride, and maybe some nerve agents, but the latter certainly are not something you will accidently make at home.

I consider a little exposure to stuff like dichromates as exposure to cigarettes. A single cigarette does not kill you. Of course, if you ingest multiple grams of dichromate, then you may have serious health issues, but no sane person does that.


woelen, thanks for your reply and for the information provided, I was in a more of angry state due to the fact that I had the yellow solution of sodium dicromate contaminated sodium hydroxide thinking it was just mere bleach without realizing of the possible siderreactions and concerned due to the fact that that I had that for over a year and a lot of contaminated parts with it lying around. But I am calmer now and will be more thoughtful and careful in the future of possible unexpected reactions. You were of greate help and your thoughts and experience on the matter are greatly appreciated. Truly, thank you. Sorry for the late reply, it has been really hectic for me lately




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