NZniceguy
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Iodine crystals from Lugols solution
Can anyone please tell me how to extract the iodine and potassium iodide from the Lugols solution?
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Tsjerk
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Add an oxidizer and an not oxidizable acid, vacuum filter and re-sublime.
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ninhydric1
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I'm pretty sure you need to add an acid (e.g. HCl), then add an oxidizer to recover all the I2.
The philosophy of one century is the common sense of the next.
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Bert
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What concentration are you working with, it is compounded in a range of anywhere from 1 to 15% of Potassium iodide and elemental Iodine by weight
dissolved in water.
Perhaps explain what you are wanting Iodine for, there may be an easier solution to your solution, so to speak.
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NZniceguy
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I have 5 bottles of Lugols solution but the labels are in Russian so I cant tell the concentration unfortunately......I just wanted to see if I could
extract the elemental Iodine and/or the Potassium Iodide to expand my collection of chemicals and to learn at the same time......no real purpose as
such.
Maybe I could upload a picture of the label if there were any Russian fluent members here?
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CobaltChloride
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Easiest way is to add drain cleaner sulfuric acid. It doesn't have to be pure. It reacts with iodides to make iodine. This precipitates. The only
problem with this method is that it makes a lot of SO2. In order to purify the iodine, first wash it a few times with water and then put it in a
beaker. Suspend on the beaker a round bottomed flask with cold water inside. Heat the beaker. The iodine should sublime and collect on the flask. Do
this step outside as iodine has a penetrating odor which is very hard to remove from all things but glass.
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NZniceguy
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That sounds like something im quite capable of, thank you.....I'll let you guys know how I get on.
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j_sum1
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I composed a reply yesterday but it glitched.
My recommendation having done this recently
1. Make sure you have containers suited to holding iodine. It is something of a houdini element. Ampouling in glass really is the only completely
sure way of keeping it securely. Lab bottles with teflon caps apparently work ok. You can keep it under conc H2SO4 apparently and there is also some
merit in submerging it in water. There is a thread on this.
2. This sounds like a good time to conduct an experiment -- go small scale and work with whatever oxidants you have available. Work out the best /
most cost effective one to use and also how much is needed. Then scale up. The practice is good.
3. It might be worthwhile doing a titration on your solution -- that is if you have the skill and the reagents and the equipment. You can actually
get away with rudimentary equipment if you are prepared to tolerate 5% inaccuracy. You'll need some thiosulfate and some starch and some volumetric
glassware. Syringes or graduated cylinders will pass if you don't have a burette.
4. Oxidants you might try: bleach, H2O2, Calcium hypochlorite, Pool chlorinator (NaDCCA or TCCA), Cl2 gas directly, ammonium persulfate, sodium
persulfate. The last three will work without an acid. The others will require acid - H2SO4 is probably best most of the time. HCl is more readily
available in NZ. You will need to figure out how much acid you need to use with your oxidant.
5. Caution when scaling up -- it is really easy if using a chlorinated oxidant to inadvertently produce Cl2 which can be unpleasant (to say the
least.) Prepare for the worst. Add the oxidant dropwise and slowly.
6. Handling large quantities of I2 can be messy. Especially if you are trying to dry it. It makes everything it touches brown and it sublimes and
coats everything if you are not careful. The vapours are not a whole lot of fun to breathe. Work outside if possible. Use gloves (duh) and have some
spares. Carry a spray bottle with a solution of thiosulfate, bisulfite or sulfite. NaOH will also work but you will need to then neutralise. Keep a
bunch of chux cloths on hand.
7. I have only a little experience of the sublimation method for purifying. I had problems in that I got water condensation as well and so my product
was wet. I also found it slow going and there were obvious losses of vapour. I think this is a method for small batches and taking your time. Others
may share tiops and tricks that I don't know.
8. Have fun. Iodine is pretty cool stuff.
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Sulaiman
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Based on only a few small scale experiments subliming iodine from flask to beaker bottom,
. don't do the 'logical' thing - use ice or very cold water in the flask.
- a flask of very cold or iced water will condense atmospheric moisture - D'oh!
+ even boiling water is well below the m.p. or b.p. of iodine, so use hot water.
. the purified iodine crystals hang so beautifully from the flask,
- until you try to collect them, a slight shake and they drop back into the melt
+ refine in annoyingly small batches
Because iodine is solid at room temperature,
and my sample is in prill (little balls) form,
which I can handle without gloves, suffering only temporary stains,
it is easy to forget that solid iodine is a solid halogen - just below bromine and chlorine and fluorine !
With surprisingly little heat it can suddenly change from a teaspoonful of little balls
to a rather large cloud of very nasty iodine smoke - don't breathe, and keep your eyes closed 
I also discovered that liquid iodine eats stainless steel for breakfast.
So
Do not let those cute little balls or crystals fool you - they want to eat you 
P.S. Even Lugol's is HIGHLY CORROSIVE to human skin.
I made some myself and we use it as an antiseptic for abrasions, cuts, pustules etc.
A tiny drop works because iodine is so reactive.
(also, it 'diffuses' into the wound and stays there for days, judging by colour)
[Edited on 21-3-2018 by Sulaiman]
CAUTION : Hobby Chemist, not Professional or even Amateur
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NZniceguy
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Thanks guys, so much useful info......I didnt expect such kind and helpful replies.....I have a good variety of glassware, i just want to increase my
reagents etc so i can do more experiments etc and collect the elements too as they come up.
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Chemi Pharma
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Bubble into the Lugols solution Chlorine gas, generated from calcium Hypochlorite (HTH pool) and Hydrochloric acid (muriatic acid) from a vessel with
a hose. The chlorine don't need to be dry.
The iodine will precipitate immediately as a black/brown ppt. Then, when Iodine precipitates no more from the clear yellow solution, filter the iodine
onto a filter paper. Wash the ppt with cold water, let it dry, scratch the paper, and get your pure iodine. Sublimate the iodine if you want to get
it in the cristaline form.
I did it too many times in my Lab to get iodine and I think it's the easiest way to extract it from lugols solution with high yields and no side
products.
Cl2 + 2 KI3 --> 2 KCl + 3 I2
[Edited on 23-3-2018 by Chemi Pharma]
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