hodges
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Bromine from Sea Salt
While at the grocery store I saw "100% Mediteranian Sea Salt". According to the label, it is made "naturally" by evaporating sea
water in the sun. 1.5 pounds was $2.75.
I figured this salt should contain some bromide, since sea water has a fair concentration of bromides. I made a saturated solution of this salt in 3%
H2O2 and added a small amount of dilute H2SO4. Over a period of about a half hour, the solution gradually turned a pale brown. The brown color was
not impressive and barely visible but it was there. More impressive was the smell. I definitely smelled a halogen, and it didn't smell like
chlorine or iodine. It smelled closer to chlorine than iodine but it was not quite the same. I've never smelled bromine before but I'm
guessing this was bromine.
After a few hours small bubbles of oxygen began forming as the H2O2 started to decompose on its own. The bromine smell continued.
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BromicAcid
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This site lists the percent composition of bromine in sea salt as .00071%
This site also lists the bromine % as .00071%
Maybe they both got their numbers from the same place.
Regardless, the percentage is incredibly low and I would not use this personally as a reliable method for production of Br2. Sea salt is only about
98% salt, maybe some of the other impurities caused the bulk of the color change. You could set up a continuous boiling process with aqueous
solutions with sulfuric acid, the HCl azeotrope boiling over first then at the very end the HBr azeotrope and the HI azeotrope from there you could
oxidize your HBr by your choice method to get a more concentrated source of Br- anion.
Seasalts are a somewhat commonly availible resource though. Although the bromine concentration in some salt rich brine wells can reach 4% in my area.
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unionised
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If this data
http://www.seafriends.org.nz/oceano/seawater.htm
is correct then there is about 67 ppm of Br in seawater compared to about 280 times as much chlorine so the Br is about 0.2% of the sea salt.
You should be able to get about a gram of bromine from each pound of salt. Not a cheap idea
I think the best way to try to recover it would be to acidify it and oxidise it to Br2 then distill it as such or drive it into a collection vessel
containing NaOH soln using a stream of air.
Acidify the NaOH soluion and you should get the Br2 back.
Do remember that Br2 isn't very nice stuff to work with.
[Edited on 3-7-2004 by unionised]
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Chemtastic
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I have a pretty nice method for iodine from iodized salt when you're finished with that
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sanity gone
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I'd be intrested to hear your method.
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hodges
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From the smell, I'm thinking I did get some halogen. It wouldn't be chlorine since H2O2 won't oxidize Cl-. Iodine concentration in
seawater is miniscule (unless concentrated in sea weed). I think it has to be bromine. What else would have such a strong smell. Obviously not
practical for making large enough amounts to experiment with, but I do believe the reaction did work.
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The_Davster
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Chemtastic: I would be interested in your method of I2 from sea salt.
I tried once before by bubbling chlorine through a saturated solution of sea salt but I got zero yield .
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Reverend Necroticus Rex
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I don't think that sea salt is going to be a practical source for iodine,
http://nautilus.fis.uc.pt/st2.5/scenes-e/elem/e05340.html lists the iodine content as one part KI/NaI to 100, 000 of salt!
I think seaweed is worthwhile looking into, all it takes, isto burn the seaweed, treat the ashes with H2SO4 and distill to sublimise the I2, this
could be a good way to put all that dirty drain cleaner and battery acid to good use .
The sun is shining on a brand new day
Blackened corpses burn where they were slain
Self-flagellation prompts him to confess, Bless me father, for I made this mess.
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BromicAcid
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My OTC iodized salt contains 45% of the daily value of iodine per serving (1.5 g). The % daily recommended value of iodine is 150 mcg. So .000150g
of iodine recommended, 45% of that per 1.5g so taking those numbers into consideration, table salt would contain .045g per 1 kg table salt. So I
would guess Chemtastic's method for producing I2 from iodized salt is a joke, as his little smiley face suggests
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Reverend Necroticus Rex
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A single kilo of seaweed has as much iodine as 10,000 liters of sea water.
considering how much salt is in sea water, the content of I2 in these salts is just not worth considering unfortunately.
The sun is shining on a brand new day
Blackened corpses burn where they were slain
Self-flagellation prompts him to confess, Bless me father, for I made this mess.
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sanity gone
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heh, I've heard of recovering KI from iodized salt (ethanol and petroluem ether method I believe), so I was curious to see how they yeilded;
apparently not so well.
[Edited on 7/4/2004 by sanity gone]
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Magpie
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iodine source
The best iodine source I've discovered so far is the 7% tincture in water/isopropanol available at my local farm & ranch supply. I believe
it is used to treat cuts on cows & horses.
I bought a pint and did some preliminary testing on a test tube scale. I converted the dissoved I2 to I- using sodium metabisulfite. Then boiled off
the alcohol until I couldn't smell it anymore. Then converted the I- back to I2 using 3% H202. I think that if I boil this in a tube with a
coldfinger I should have sublimed I2 crystals, right? When I get my coldfinger I'll let you know the results. This is my first official mad
science experiment - it felt damned good!
The single most important condition for a successful synthesis is good mixing - Nicodem
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unionised
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If you oxidised all the iodide to iodine then most of the I2 should fall out of solution.
Is it just me or is it a long time since anyone posted anything about getting bromine from sea salt?
I checked, and in my local supermarket sea salt was about £4 per kilo. If I need any Br2 I will have to find a cheaper source than that.
[Edited on 4-7-2004 by unionised]
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Magpie
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iodine isolation & purification
unionized: I think you are saying to filter out the iodine first. Then sublimate for purification, correct?
On the bromine, it seems that this is mostly an interesting but academic discussion about the miniscule amount of bromine in sea water. Unless you
can't buy NaBr for $1/ounce as I can at my pool chemical supplier.
The single most important condition for a successful synthesis is good mixing - Nicodem
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JohnWW
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I understand that the Israelis recover a number of chemicals from the highly concentrated brine of the Dead Sea, which has the highest dissolved
solids of any natural waters, due to continual inflow of the Jordan River and loss of water through intense solar radiation. This high concentration
of solutes makes recovery of chemicals more economic than from ordinary sea-water. Electrolysis produces concentrated alkali solution, with mostly Cl2
(and of course Br2 and I2) being evolved at the anode; and the latter is reacted with more Dead Sea brine to produce more Br2 and I2, which can be
separated by evaporation.
John W.
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Nitrate
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Don't bother with sea salt
Just go to a spa supply place (or better yet Safeway) and buy some 2 part bromine mix for hot tubs. The part you put in fresh water (rather than the
actual oxidizer) is conc. sodium bromide solution.
I got 1L for <10$us.
I can post a picture of Safeway's product if you desire. (It is a white bottle with blue lettering.)
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budullewraagh
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iodine from seaweed
burn seaweed, acidify the ashes with sulfuric, filter the organic mess out, add h2o2 and you will oxidize your KI/NaI to I2...don't use
hydrochloric and be careful not to add too much peroxide lest you burn your hands off with peroxymonosulfuric
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unionised
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That's nearly related to the topic.
Just for the record, the point about burning the seaweed is to gt rid of the organic stuff; there's no reason to get rid of it twice.
Sulphuric acid is a strong enough oxidant to liberate I2 without adding H2O2.
If you are going to add H2O2 (and, I grant you it has the advantage of not giving SO2 in the product) then, povided that you don't overdo the
peroxide, you can use HCl.
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budullewraagh
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| Quote: | | Just for the record, the point about burning the seaweed is to gt rid of the organic stuff; there's no reason to get rid of it twice.
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yeah, i knew that and i only said to burn it once.
| Quote: | Sulphuric acid is a strong enough oxidant to liberate I2 without adding H2O2.
If you are going to add H2O2 (and, I grant you it has the advantage of not giving SO2 in the product) then, povided that you don't overdo the
peroxide, you can use HCl. |
sulfuric acid is not a strong enough oxidizer for oxidizing the iodide to iodine
i wouldnt recommend using HCl...at all
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S.C. Wack
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| Quote: |
sulfuric acid is not a strong enough oxidizer for oxidizing the iodide to iodine
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HI, however, is a very strong reducer. Notice how HI is never made with H2SO4 and an iodide? This is because SO2, S, and/or H2S is formed in
equilibrium.
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