Sciencemadness Discussion Board - Why is arsenic still so regulated in the US?

Why is arsenic still so regulated in the US?

Upsilon - 26-9-2015 at 07:46

It seems pretty ridiculous to me. I can see why they would put a regulation on it back when people didn't have as good an understanding of chemistry, but it seems pointless to have it regulated now. One could easily make a poison just as or even more deadly than arsenic with OTC ingredients. I don't want to have to pay an arm and a leg for arsenic compounds just because of how much it costs to pull the necessary strings to allow its sale.

violet sin - 26-9-2015 at 13:15

So.. playing with arsenic and HF,.. sounds like you pick some dangerous substances to fool with. What's the game plan here?

aga - 26-9-2015 at 13:31

Don't panic violet sin.

He just wants a decent propellant and warhead for the 90,000 bullets in his home defense M134 minigun is all.

Nothing to worry about.

All normal and as safe as wooden houses in a hurricane.

violet sin - 26-9-2015 at 15:15

Arsenic compounds aren't too hard to find, but I'm reticent to supply info if some one just wants to mess about without concerns for safety... Or a solid game plan.

Upsilon - 27-9-2015 at 14:21

You may be misunderstanding - I am after a lot of different chemicals. You only see me ask about these more dangerous ones because they are more difficult to obtain. I need not ask where to find NaCl, do I?

And I'm not after arsenic just yet. I'm only looking ahead; I'm starting an element collection, and somewhere down the road I'll need a sample of arsenic. I suppose I could just buy a sealed sample, but I'm trying to isolate as many of the elements as I can myself. What's the enjoyment in just buying yourself an element collection?

aga - 27-9-2015 at 15:14

Building an element collection from scratch would be an amazing chemistry adventure, and learning experience.

It would certainly not focus on 1 element in their questing post LA:Upsilon (Lizard Alien of Arsenide knowledge seeking-ness)

j_sum1 - 27-9-2015 at 16:01

Let me speak for my element collection.
The goal is to have each sample tell its own story and thus far, most of my approx 45 elements are represented by more than one sample. Some samples are the element in use. Some are pure samples I have purchased. Some are elements I have isolated themselves -- either from OTC sources or natural sources in some cases. (I will do seaweed iodine one day.)
The point is that I feel no need to do anything hazardous to build the collection. Home lab arsenic chemistry seems to be inviting trouble.

violet sin - 27-9-2015 at 16:12

Search Orpiment or realgar eBay. Beautiful in their own right.

https://en.m.wikipedia.org/wiki/Realgar,
https://en.m.wikipedia.org/wiki/Orpiment

Do NOT kill your self or others on accident, mmkay. I would not try separation, they can be stunning in the *as is* state. Much more attractive than a lump of mettaloid, and a nice story to explain to others

[Edited on 28-9-2015 by violet sin]

woelen - 28-9-2015 at 13:02

Arsenic indeed is hard to find and with a good reason. It also is quite difficult to isolate from its compounds using aqueous chemistry. Aqueous arsenic chemistry can be done at home without too much risk, as long as no strong reductors are involved, which can produce hydrogen gas (e.g. zinc in acid, borohydrides, electrolysis). In the latter situations, besides the hydrogen also some AsH3 is formed if arsenic is present in solution as As(III) or As(V). AsH3 is unbelievably toxic, NEVER play with this in a home setting! Non-aqueous arsenic chemistry (e.g. subliming the element or its compounds) is totally out of the question. Even well-equipped labs frown upon that kind of chemistry.

Making element samples can be a fun activity and I did also myself, e.g. Cl2 and Br2, but if you want an arsenic element sample, then I strongly suggest you to buy one, even if it is expensive. An affordable sample (appr. 1 gram of element 33) can be obtained here:

http://www.ebay.nl/itm/1-out-of-pure-element-samples-15-17-3...

A safer and also much more beautiful sample (but unfortunately also much more expensive) can be obtained here:

http://www.smart-elements.com/?arg=detail&element=As&...

Btw, arsenic in its usual appearance is really ugly, it is one of the ugliest elements. It consists of dull dark grey globules. The dull dark grey color is due to an oxide layer. If this layer is removed and the pure non-oxidized element is exposed, then it looks much more attractive, then it looks like a silvery/grey metal with nice glittering reflections at the crystal. I myself made a nice sample of arsenic from a dull oxidized piece by dissolving the dirty-looking layer (with a hot solution of K2Cr2O7 in dilute H2SO4) and then keeping it under pre-boiled distilled water, in which a small amount of SO2 is dissolved, so that it is not quickly re-oxidized. A picture of this sample will follow soon.

[Edited on 28-9-15 by woelen]

S.C. Wack - 28-9-2015 at 14:56

> Why is arsenic still so regulated in the US?

What regulation? OSHA, FDA, DOT, and EPA regulations are to be expected as for everything else. Perhaps the regulation is that no one is in the business of selling elemental arsenic to you? Regulation by fear of liability? Sense? Import some from Asia and corner the market.

macckone - 29-9-2015 at 07:46

They are still trying to get rid of the arsenic containing treated lumber
that has contaminated soil and ground water. Most of the contamination
concern is chemophobia, but there was a significant amount used
for garden borders and now people are growing vegetables in those
gardens and getting high levels of arsenic in their diet. Most of the
regulations around arsenic date back to when it was commonly
used to get rid of household pests, like your spouse and mother-in-law.
If people hadn't used it as to poison others then it would probably still
be on the shelf in rat poison.

woelen - 29-9-2015 at 11:13

I made a nice sample of arsenic, which shows the true color and shiny nature of the element:

This is made from a dull dark grey looking sample by immersing that in a hot solution of K2Cr2O7 in dilute H2SO4, rinsing with water and then storing under distilled water with a little SO2 dissolved in it. This prevents re-oxidation of the sample. The sample is put in the SO2-water in a perfectly sealed vial with only a very small bubble of air in it.

Click on the picture to see it in full resolution.

[Edited on 29-9-15 by woelen]

macckone - 29-9-2015 at 14:35

Ok that is a beautiful sample. I am jealous.

j_sum1 - 29-9-2015 at 16:30

That's awesome woelen. I am going to have to do the same for my arsenic sample. It won't be the first time that I have copied one of your procedures. I might break off a piece first so that I can show it in its raw oxidised state as well.

What would I need to do to safely dispose of the acidified dichromate tainted with arsenic?

woelen - 29-9-2015 at 22:55

The dichromate can be easily dealt with by reducing it to non-toxic trivalent chromium, which can be done by adding some acidified alcohol, acidified sulfite or acidified hydrogen peroxide. The arsenic is harder to deal with. So, after neutralisation of the hexavalent chromium you should keep it and bring it to a proper waste processing facility. Do NOT flush it down the drain, even if it contains no hexavalent chromium anymore.

I myself have a bottle in my lab, in which I pour all of my toxic inorganic waste (arsenic, mercury, cadmium, thallium, lead, other heavy metals if quantities are larger than a few hundreds of mg). If the bottle is full, I bring it to the municipal waste processing facility, telling that it is heavy metal waste from dark room/photography processes. Up to now I never had problems with acceptance of the bottle. On the bottle I have written what kind of elements are in there.

j_sum1 - 29-9-2015 at 23:25

Hmmm.
I am not aware of my municipality accepting toxic waste in the manner you describe. I will have to check.
Thus far I have been collecting all waste from solutions, oxidising/reducing to benign states and precipitating to a non soluble form. When I get a litre, I stir it into some concrete and let it set in a bucket. I then dispose of it in the regular collection. But so far, the most toxic thing I have dealt with is Pb. A tiny bit of lead carbonate in a concrete block is hardly concerning.

unionised - 30-9-2015 at 02:24

Quote: Originally posted by woelen

I myself have a bottle in my lab, in which I pour all of my toxic inorganic waste (arsenic, mercury, cadmium, thallium, lead, other heavy metals if quantities are larger than a few hundreds of mg). If the bottle is full, I bring it to the municipal waste processing facility, telling that it is heavy metal waste from dark room/photography processes. Up to now I never had problems with acceptance of the bottle. On the bottle I have written what kind of elements are in there.

And I suspect that they throw the bottle in with the stuff that's on its way to a landfill.
If your bottle contains 20 grams of lead a few grams of arsenic and a few tenths of a gram of mercury and cadmium, then when it' s mixed with 10 tons of other junk, it's going to be a few ppm at most. Yet those elements occur naturally in the environment at levels of the order of 0.1 to 10 ppm so, in the grand scheme, you have hardly made a difference to the toxicity of the waste.

Proper waste handling is important, but there's no call to get obsessive about the kind of quantities that most home experimenters use.

Texium - 30-9-2015 at 08:31

I have a bucket with a mesh lid that I keep outside, but under the edge of the roof so it doesn't get rained on. I put toxic inorganic solutions in there, precipitate with carbonate, and allow it to evaporate to keep the volume down.
Eventually I'll need to dispose of it, but for now I have plenty of room in it and I don't produce much toxic waste at all.

Praxichys - 30-9-2015 at 09:12

On the subject of waste management, I do about the same thing as zts16. When the stuff dries out and I have a reasonable amount of it, it gets mixed with cement in a small bucket and left to harden, then tossed with the trash. The cement powder is very cheap, widely available, and passivates the already poorly-soluble oxides and carbonates. As unionized says, improper disposal of an old TV is probably worse for the landfill than that. Besides, my local landfill is isolated from the environment because of nearby water wells, and its leachate is treated in a treatment plant onsite. In the future, we will probably be mining that landfill to recover those metals anyway.

woelen - 17-10-2015 at 13:29

I made a picture of a commercial sample of arsenic (500 grams) and a cleaned sample (90 grams) in the same picture. The difference is striking:

Click on the picture for a full-resolution version.

[Edited on 17-10-15 by woelen]

aga - 17-10-2015 at 13:52

18% !

What were the impurities and how was the Commercial sample purified ?

(worried now - i just managed to summon enough courage to ask woelen a question)

j_sum1 - 17-10-2015 at 14:52

woelen explained the procedure uothread.
www.sciencemadness.org/talk/viewthread.php?tid=63777&got...
Have fun with it.

woelen - 18-10-2015 at 10:01

Quote: Originally posted by aga

18% !

What were the impurities and how was the Commercial sample purified ?

(worried now - i just managed to summon enough courage to ask woelen a question)

It is not so that I used 500 grams of impure arsenic to make 90 grams of pure arsenic. I started with 700 grams. Set 500 grams aside and cleaned the remaining 200 grams by immersion under acidified potassium dichromate solution. Repeating this two times leads to nice shiny metallic looking arsenic. The 200 grams of arsenic only lost a few grams of weight (oxide layer and maybe a small amount of arsenic at the outside of the granules). I divided this over two bottles with appr. 90 grams of arsenic and a display vial, containing 15 grams of arsenic. The picture shows only one of the 90 grams bottles.

shadowwinter - 19-10-2015 at 02:30

Excuse me if I'm wrong but isn't arsenic used to treat wood.

woelen - 19-10-2015 at 03:25

The element is not used for treating wood. Certain compounds of arsenic were used for treating wood in the past, but where I live this is quite a long time ago. IIRC the compounds, used for treating wood were metal arsenates or metal arsenites.