Author Topic: Iodine from KI - Working Procedure  (Read 3068 times)

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  • Guest
Iodine from KI - Working Procedure
« on: May 18, 2004, 10:19:00 AM »
Well let me start by saying thank you to all those bees that took the time to post what info they had that was related to the extraction of iodine from potassium iodide back in the thread 'Extraction of I2 from KI'.  And as I said I would do I have come up with a workable procedure for the efficient recovery of iodine from KI.  Notice I said workable, well that is because it turned out to be not as cut and dried as I had thought it would be.  This may be because I am not a chemistry major, I am self-taught mostly and therefore I am not able to figure out the precise numbers needed for the equation...maybe someone else can post those figures, however even without those exact numbers extraction was possible.

  What I can give you is a procedure that will allow you to recover as much as 35.8gms of wet I2 from 50gms of reagent grade potassium iodide.  In all I did 4 trial runs but I only recorded the results from two of them, reason being is one run was a waste of materials (wrong ratios) and the other well that was the first run and I didn't record the results in a orderly fashion and therefore when it came time to use the recorded info I was unable to read my notes clearly.  The only initial difference between runs was the amount of distilled water that was present in the starting KI solution.
The materials used were all OTC, at least in California.  The KI was from a local chemical company and no questions were asked as to the intent of use of the chemical which should be the case anywhere I would imagine.  The HCL was +/- 35% muriatic acid (same stuff that is used in swimming pools).  And lastly the H202 was 3% hydrogen peroxide solution available everywhere.

  Now before you start this procedure it would be wise to have VERY good ventilation and if you decide to do it indoors be warned that you can semi-permanently stain your walls and countertops orange if you aren't careful.  That being said here is the first procedure that was NOT useable-To a 2000ml flask 50gms of KI were added, next 1000mls of distilled water were added.  Then 25mls of HCL and then laslty the H202 was added in 25ml increments up to the point of 125mls with no I2 falling out of solution so this run was discarded.

  The second run which was successful but for which the exact results were unclear was-To a 1000ml flask 50gms of KI were added along with 300mls of DH20 and then 25mls of HCL and then the H202 was added and with the addition of only 2mls of H202 the solution turned dark brown but I2 hadn't fallen out of solution so the addition of H202 continued in increments of 25mls.  With each 25 the flask was swirled and then left to settle and there was some I2 that came out of solution as early as 75mls of H202 but I didn't want to try filtering out the I2 until there was enough to make it worthwhile.  Because the filtering of the solution can go rather slowly and during that time iodine vapors along with other noxious vapors are escaping into the room and therefore it is wise to keep the open exposure time to a minimum or as I found out later is to let the precipitated I2 fall to the bottom of the flask and then pour off the majority of the solution into another container and only filter what you can't separate easily.

  So I didn't start separating the I2 until the 125ml of H202 mark which was when a large amount quickly appeared.  But all I can say abount that run was it was successful, but how successful I am not sure of.

Now for the two runs in which the results were quite clear and repeatable-

  Procedure 1: To a 1000ml flask 50gms of KI were added along with 200mls of DH20.  Next 25mls of HCL was added slowly since there was only a small amount of liquid in the flask to mix with. And finally the H202 was added in 25ml increments, with the first 25mls the solution turned dark brown.  And the additions continued to 100mls before the  filtering off of the I2 began.  To filter off the I2 all that was done was to put one coffee filter in a funnel and pour the I2/solution through it and then rinse the I2 with only enough DH20 to make it look clear of any residual solution.  And filtering was repeated at 125,150,175 and 200mls.  At which time I added 20mls of HCL to the mixture and the reason for this was because I was doing the next procedure at the same time as this one and wanted to see if there was an effect from adding more HCL to the solution since around 175mls the precipitate seemed to drop off.  It didn't seem to have an effect of dropping more out at the time it was added, but the final results may indicate that it does have a positive effect since this procedure yeilded a final weight of 35.8gms of damp I2 and the next procedure yeilded slightly less.

  But I can't say for certain that the specific reason this procedure yeilded more was due to the HCL addition since I didn't weigh the I2 until completely finished.  And the procedure was finished by stopping the addition of H202 at the 200ml mark at which time the flask were loosely stoppered, DO NOT seal the flask.  And then the flask was allowed to sit undisturbed for a day after which time all the I2 that was going to precipitate out had done so which was determined by the very light color of the residual solution.  Now it should be noted that when filtering out the I2, the rinse water from the filtering was recombined with the KI solution and not dumped down the drain that is why only the bare minimum needed was used.

  The first two filterings are the ones that will require a little bit more water to rinse them down cause the paper seems to stain purple pretty heavily whereas the last three are easier.

  Procedure 2: To a 1000ml flask 50gms of KI were added along with 400mls of DH20, then 25mls of HCL were added.  Then 25mls of H202 was added at which time the solution turned dark brown but not quite as dark as the previous procedure(due to the fact of less concentration in the solution, no doubt). And the additions continued in 25mls increments until the 125 mark at which time the first of the I2 was removed by filtration.  And the precipitated I2 was continued to be removed at the 150,175 and 200ml mark at which time the flask was loosely stoppered and left undisturbed for a day before finally filtering the last of the I2 off.  This procedure yeilded slightly less, 28.8gms of damp I2.

  So as is indicated by the end results either of the two procedures will yeild a generous amount of I2 and is quite cost efficient since a 1lb container of KI cost only $43.00....which factors out to something along the lines of 270gms of I2 from a 1lb container of KI.  And when compared to extraction of I2 from those little one ounce bottles of iodine from the grocery store, they don't even come close.

 The I2 recovered from the KI is for some reason much easier to dry then the type found in the grocery store as well, I would guess it is probably due to less contaminents present in the KI extraction method.

  And the procedure for the final cleaning of the extracted I2 was- To a 1000ml beaker 500mls of cold DH20 was added and then the extracted I2 was added to the water and mixed throughly and then left to settle, this procedure doesn't need to be performed as quickly as the others since the I2 is submerged in the water and isn't likely to stain walls unless left for some time.  Once settled you can pour off the majority of the rinse water until you get to the I2 at which time you should filter the residual I2 through filter paper and rinse throughly.

  As for drying the I2 it has been found that a suggestion that was given elsewhere seems to work quite well and that was to wring out as much of the water as possible and then wrap the filter paper holding the I2 in more filter papers say maybe 100 and then either rubber band the papers together or tape the bundle and then put it under the tire of a car or truck and proceed to run over it slowy a few times and you'll get 95% of the water out.  And for those wanting to get the last little bit out you can put the I2 in a container with some calcium chloride and let it set for a few days.

 Another thing that should be mentioned is that when doing the procedures listed here it would be wise to use disposable latex gloves so you don't stain your hands orange plus when you are done with the procedure and you are ready to discard any of the used filter papers that have I2 on them you can hold them with your hand that has the glove on it and then turn the glove inside out while still holding the papers and what you end up with is a glove turned inside out with the dirty filter papers inside which can then be tied shut and discarded without the worry of the I2 vapors escaping the trash bag and possibly catching the attention of a nosey usually takes a number of days for the I2 to find its way out of the glove and if you enclose it in one glove and then the other your ok for probably a week or more, just a thought.

   As for discarding the leftover liquid from the procedure, dilute it before pouring it down the drain and flush with large amounts of water.  So there you have it, two procedures that will work for recovering I2 from KI.  Good Luck and Bee safe.

 Pyrex out of procedures ;-)


  • Guest
CR/LF deficiency disorder
« Reply #1 on: May 18, 2004, 02:55:00 PM »
Pyrex out of procedures ;-)

But you must for sure have a basement full of carriage returns and line feeds, as you didn't use a single such entity in the above post. I was only a micrometer from rating the above as "incomprehensible". Are you able to read your post yourself?


  • Guest
I am extremely sorry Rhodium, I am unsure what
« Reply #2 on: May 19, 2004, 04:38:00 AM »
Is that better??  I think that is what you were asking for.  Sorry for the inconvience.   Pyrex out reviewing his writing skills ;-)


  • Guest
Paragraphs are more than a nice touch
« Reply #3 on: May 19, 2004, 04:44:00 AM »
although it does go from one side to the other...maybe that is what you mean?

Yes. It is incredibly hard to read a massive block of text not structured into paragraphs of reasonable length.


  • Guest
Iodine from KI: This recently worked for me
« Reply #4 on: May 19, 2004, 07:49:00 AM »
Materials Used

100g KI
80ml 37% Hydrochloric Acid (12M)
80ml 18$ Hydrogen Peroxide
2000ml Distilled Water
2 4 Liter/1 gallon glass bottle or jug with lid
2 Large Coffee Filters
1 Large funnel


Add 1000ml of distilled water to one of the bottles add the KI and cap the bottle and shake a few times.

Add the hcl, cap and shake a few times.

Next add the Hydrogen Peroxide, cap and shake hard about 5 times and quickly unscrew the cap to releive any pressure.

At this time there should bee a very thick layer of i2 sitting on top of the solution.

Put the funnel into the other bottle and put both filters in the funnel and filter out the i2 crystals.  The solution should bee dark but not opaque.  It should not stain the filters badly or bee too thick to filter quickly.  (If so then you need to let it sit for a while or add a little more hydrogen peroxide.}

Use the remaining 1000ml of distilled water to rinse the i2 and with gloved hands take the filters and fold them up so no i2 can fall out and squeeze as much of the liquid out as you can and then wrap them in an old but clean towel and apply pressure either by standing on it or putting something very heavy on them for a few hours.

Finally, put the crystals into a airtight container along with a dessicant such as silica gel and use as needed.


  • Guest
Thanks Shorty
« Reply #5 on: May 20, 2004, 07:07:00 AM »
I need to work on my write-up skills...I like your write-up better then mine, shorty :-)    One question though...shorty is that suppose to mean 18% H202??  Just wanted to check in case it meant something different, cause I have only seen 3%(store type) and 30%(chem supplier type).  Thanks for contributing to the thread by the way. 
  Anyone else that has a method that can guarantee results should feel free to post as well, by guarantee I mean please don't put down methods that you haven't been able to verify yourself or aren't from sources such as text.  I don't mean any disrespect to anyone wanting to post, I would just like to keep this thread one that bees could find using the search engine and use for reference without having to worry about whether or not the methods they find here will really yeild what they say they will.  Bee safe and Good Luck.  Pyrex out honing his write-up skills


  • Guest
I've been able to mix just aqueous KI and HCl,
« Reply #6 on: May 23, 2004, 08:47:00 AM »
I've been able to mix just aqueous KI and HCl, then add hexane and have it turn violet while the water layer would turn yellow. I imagine that KCl is in the water and I2 in the hexane layer.


  • Guest
? ? ? i'm not a pro of chemistry, but KI + HCL
« Reply #7 on: May 23, 2004, 01:17:00 PM »
? ? ?

i'm not a pro of chemistry, but KI + HCL --> I2
 I have a little problem... Why would this happen ???

If KI reacts with HCl, why not KCl on HCl too ? (you are nearly saying that if you mix HCl with NaCl you get Cl2 gaz....)

personally, to make some I2 crystals (low scales, for grignard) I have just let to evaporate an ethanol/KI/I2 mixt (20mL, took ~24-48hours),
i got a black oily-cristallized stuff, it was in a glass, i have put another glass on it, some ice and water in the top glass, heating slowly (for 1min not more) and repeated (5times)under the lower glass  until nearly no purple vapours are seen, and nice (very small, 0.1mm) crystals obtained under the top glass !

the idea is to find some vessel that will keep the i2 vapours in the glass, not out !!!(i used 2glasses and some scotch, worked fine)
(hope my writing-skill is not too bad)


  • Guest
« Reply #8 on: May 24, 2004, 05:18:00 AM »
Yes that is correct 18% H2o2.  I get it from a store that supplies chemicals to universities.  However, one could most likely decrease the amount of dh20 and increase the amount of 3% h202.  Or use half the amount of 30% H2o2.  But i have never tried it that way.

Why don't you try one of the extraction methods for tincture.  It would bee alot faster than your method and besides with the method you posted it would take along time to accumulate enough for a decent size reaction.


  • Guest
Unproven procedure
« Reply #9 on: May 25, 2004, 01:41:00 AM »
Well I can only assume that ninesky was attempting to devise a procedure that would possibly yield I2 by way of a hexane extraction of the initial solution and then evap'ing the hexane.
  But unless someone can provide proof that ninesky's method is anything more then theory...I'd advise those wanting guaranteed results to use either of my two procedures as I will stand behind either of them as long as they are followed without any variations.  Or you could try shorty's if you want to, I'm sure shorty would stand behind his/her results.
  As for the mechanism behind why my procedure works, if you mix H20 and KI and finally'll get a solution that is clear or slightly yellow but is nearly takes the H202 to unbalance the equation and release the I2.  The only equation I can come up with is something like the following- 2(KI) + H202 + 2(HCL)------>2(H20) + 2(KCL) + I2     whether or not the formula is correct I am uncertain, but my procedures will work nonetheless.  Good Luck and Bee safe.  Pyrex out of formulas ;-)


  • Guest
I2 from KI
« Reply #10 on: May 25, 2004, 06:38:00 PM »
From what I have heard, you simply bubble Cl gas through a KI (water/aq) solution to obtain the I2 (I'm assuming that it must precipitate, being insoluble in water). There's many easy ways to generate Cl gas (UTFSE). Shouldn't be a worry.


  • Guest
I have mixed HCl solution with KI solution and
« Reply #11 on: May 27, 2004, 01:33:00 AM »
I have mixed HCl solution with KI solution and attempted to extract I2 with hexane. The hexane layer turned a dark violet and the water layer turned a bright yellow which may be KCl.. or more I2? If there's anything else that could be in the hexane, I'd like to know.
I imagine you could distill the hexane out and reuse it. You could achieve a very high purity with a very simple extraction.. and it'd be economical.


  • Guest
« Reply #12 on: May 27, 2004, 05:11:00 AM »

The hexane layer turned a dark violet and the water layer turned a bright yellow which may be KCl.. or more I2?

KCl solutions are clear always.

KI solutions are opaque, turning bright yellow with air oxidation. This is concentration dependent. Very dilute solutions of KI seem clear but may turn bright yellow with air oxidation of KI to I2 and small amounts of KIO3

Also KI helps to make I2 more soluble in water.

Look at the physical properties of KI in Merck Index.


  • Guest
geez,scottydog ,and wareami;s post's
« Reply #13 on: May 27, 2004, 08:52:00 AM »
Are a must read if ya wanna do it right and have good go go.?Read the one 'too much acid' from Geezmiester and you can't go wrong getting grey crystall spikes and wash themm outgood.