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Author: Subject: Recovery of Iodine from Iodine, Hydrogen Iodide and water mixture
hardik22
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[*] posted on 11-1-2018 at 22:44
Recovery of Iodine from Iodine, Hydrogen Iodide and water mixture


Someone suggest me that if Hydrogen Iodide, water and Iodine boil up to 101 C with super-heated steam in stripping column then Iodine (gas phase) can recover from top of the stripping column with water vapor and Hydrogen Iodide with water get from the bottom product as liquid state.

but, Iodine boiling point is 184.3 C while Hydrogen Iodide boiling point 127 C
then how can its possible to get Iodine in gas phase in top of the column?

Please suggest me right method to get recovery of Iodine from Water And HI and I2 mixture.
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Melgar
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[*] posted on 12-1-2018 at 01:28


HI is strongly attracted to water. I2 sublimes easily, and is nonpolar. The I2 is just evaporating, not actually boiling.

If getting Cl in your I2 isn't a huge problem, I've found that stirring a KI solution, acidified with HCl, while adding chlorine bleach dropwise works a lot better than H2O2 and H2SO4. With H2O2, KI catalyzes its decomposition, and the flakes never settle due to all the bubbles being produced.

Ironically, meth cooks that use I2 combine it with the HCl salt of pseudoephedrine. So it's safe to say that Cl being present doesn't inconvenience them in the slightest.




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PirateDocBrown
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[*] posted on 12-1-2018 at 03:06


It's a good question. I have often ended up with a saturated solution of I2 in water, and I hate wasting something as valuable as I2.

What's a good technique for recovery?




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hardik22
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[*] posted on 12-1-2018 at 03:21


Thanks for your replied,

--> Now i found recovery of I2 from HI and water mixtures using stripping column, Condenser, Scraped Condenser and decanter.
--> Maximum temperature of stripping column is 105 C and heated by super heated steam.
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hardik22
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[*] posted on 12-1-2018 at 04:02


in this unit process contain four unit operations.
1) stripping column
--> HI, Water and I2 mixture adding into column counter currently with upstream super-heated steam like scrubbing.
--> Temperature of this system is around 99 - 105 C.
--> super-heated steam never condensed into column so that temperature increase some degree by electric heater and further heating by super-heated steam.
--> H2O and I2 get from top section of the column in gas phase.(I2 is sublimies by heating) and HI-water mixture get from bottom product.

2) Condenser
--> some part of I2 converted into liqiud phase and most part convert into solid phase by spray cooling water.
-->liquid I2 separated from solid I2 and water (I2 is less soluble in water)

3) Scraped condenser
--> solid I2 and water are separated from this at room temperature.

4) Decanter
--> still some percentage of I2 contain in water it can be separated by decanter.

the most important part in this process is maintain the temperature and weight ratio
water to HI ratio is 1:1 to 25:1

Example

feed contain
I2 --> 31 gm
HI --> 15.5 gm
H2O --> 150 gm

stripping time --> 12 mins

Temp. --> 101 C

Condensed --> I2 : 11 gm
HI : NIL
H2O : 197gm ( steam condensed in condenser)
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clearly_not_atara
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[*] posted on 12-1-2018 at 11:21


If you oxidize thoroughly with bleach, you can convert the iodine to periodate. Potassium periodate is very insoluble in cold water (0.6g / 100 mL) so it will precipitate almost quantitatively.

However I'm not sure how to return this to being iodide I'm afraid :p but it does let you recover a pure substance.




[Edited on 04-20-1969 by clearly_not_atara]
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[*] posted on 12-1-2018 at 14:36


Useful info, though! Beats throwing out iodine water!



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[*] posted on 12-1-2018 at 20:57


I2 can be recovered by using strong oxidized agent like Cl2, Nitric acid, various Nitrogen oxides, Chromic acid, hydrogen Peroxide, Potassium Permangnet etc.

but you can recover only small amount of I2.
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[*] posted on 13-1-2018 at 07:20


Periodate seems more useful than iodine, you could always keep it in that form.

https://www.google.com/patents/US6620928




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[*] posted on 13-1-2018 at 10:20


To recover iodide from iodine, react your iodine in solution with iron metal to form ferrous iodide solution, and then cement out the iron with potassium carbonate or hydroxide. I have a procedure for this somewhere-- if I remember I'll attach it later.
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[*] posted on 13-1-2018 at 11:12


Quote: Originally posted by clearly_not_atara  
If you oxidize thoroughly with bleach, you can convert the iodine to periodate. Potassium periodate is very insoluble in cold water (0.6g / 100 mL) so it will precipitate almost quantitatively.

However I'm not sure how to return this to being iodide I'm afraid :p but it does let you recover a pure substance.

Precipitation by copper sulphate and bisulphite or ascorbic acid as CuI is a lot nearer to quantitative. (0.0042 g/100 ml).
Adding H2O2 and H2SO4 will free the iodine which will precipitate once all the iodide is oxidised.
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