DeadHead
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Potassium Dichromate in fish treatment
I was surprised to find this as and ingredient to a medication for fungus growing on freshwater fish. I'm surprised also that there is no mention of
special disposal instructions. As a hexavalent chromium, isn't this stuff quite bad news?
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hyfalcon
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You just don't use enough to be toxic to the fish, just the fungus.
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Fantasma4500
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ive seen it sold for art (???) in my country, i believe as a colour..
got abit confused.. i mean considering how toxic that stuff is why would you want to use it for painting??
they removed it because they realised how deadly toxic it is..
but KMnO4 is also somewhat toxic, yet you purify water with it and drink the water with KMnO4 in it still, only enough to give it a slight pink colour
tho
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blogfast25
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Quote: Originally posted by Antiswat  | got abit confused.. i mean considering how toxic that stuff is why would you want to use it for painting??
they removed it because they realised how deadly toxic it is..
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Yeah, you sound it. Firstly, it's used in a variety of 'crafts/photography' ways but not in painting. Lead chromate (PbCrO4) was once used in
painting as a yellow pigment but is now largely discontinued because of toxicity concerns (both lead (II) and Cr (VI)).
Potassium dichromate is indeed toxic but can be handled very safely when minimum precautions are taken. Anyone following the guidelines set out in the
product's MSDS can handle it properly.
'they removed it'? Who are 'they'? Dichromates continue to be sold and used for a variety of applications. Avoid skin contact, ingestion or inhalation
and clean up any spills and this chemical is safe to use.
Try not to add to the general confusion/misinformation out there by this kind of generic, unqualified piffle.
Comparing toxicity of two different substances is almost nonsensical. Toxicity depends on a large number of factors, such as type of exposure,
duration, dosage and many others, making back-to-back comparisons impossible.
[Edited on 9-6-2013 by blogfast25]
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unionised
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| Quote: Originally posted by Antiswat |
but KMnO4 is also somewhat toxic, yet you purify water with it and drink the water with KMnO4 in it still, only enough to give it a slight pink colour
tho |
I wouldn't.
http://en.wikipedia.org/wiki/Manganism
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DeadHead
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I guess what my point was is should I do anything to my waste water when I do my next water change, or just down the drain with it.
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Hexavalent
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I once bought 500 g of potassium dichromate as "chrome mordant" for art supplies, no questions asked.
"Success is going from failure to failure without loss of enthusiasm." Winston Churchill
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UnintentionalChaos
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Used for affixing and modifying colors of natural dyes on fabrics. You'll find copper sulfate, stannous chloride, ferrous sulfate, and alum sold for
the same purposes.
From what I understand, Cr(III) does not exchange ligands very easily and Cr(VI) picks up ligands when reduced to Cr(III). The goal of the mordant is
to become chelated by the molecules of the fabric, and then also trap the dye as a ligand. Cotton, Wool, and Silk all have oxidizable groups present,
and I imagine that the dichromate is reduced by these, and binds to the fabric as it is reduced. Chrome alum would probably not be nearly as
effective, being a Cr(III) salt.
[Edited on 6-11-13 by UnintentionalChaos]
Department of Redundancy Department - Now with paperwork!
'In organic synthesis, we call decomposition products "crap", however this is not a IUPAC approved nomenclature.' -Nicodem
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blogfast25
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| Quote: Originally posted by DeadHead | | I guess what my point was is should I do anything to my waste water when I do my next water change, or just down the drain with it.
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I doubt if the amounts really warrant any special treatment. Sooner or later the Cr(VI) will find something to oxidise and will itself become reduced
to Cr(III).
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