Iodobenzene - 6-1-2018 at 15:58
Hi guys.
Recently I crystallized some Iodine to purify it, but I noticed that analytical grade iodine isn't crystallized, but it is in beads.
So i was wondering, how do they give I2 this form?
I thought about elastic molds filled with Iodine vapours which brinates and crystallize as beads.
happyfooddance - 6-1-2018 at 16:13
Just a guess, but I imagine they would start with iodine in the liquid phase, maybe spraying it out of a nozzle with rapid cooling. NaOH and KOH
prills are made this way.
Reboot - 6-1-2018 at 16:14
The larger grained stuff I've seen is fairly erratic in size. It might have been created by heating the iodine up to liquid form then dripping it
into cold water or something. (Some big industrial systems actually drip chemicals from the top of a very tall column, letting it dry or harden or
condense on the way down.)
DraconicAcid - 6-1-2018 at 17:30
That's weird, because it only melts under pressure. Maybe they melt it under a liquid that it's not soluble in?
happyfooddance - 6-1-2018 at 17:44
http://www.godoshigen.co.jp/english/service/iodine/
Here is a cool animated diagram of one company's process
ninhydric1 - 6-1-2018 at 19:53
@DraconicAcid in fact, iodine does melt at 1 atm. You just have to heat it high enough (113.7 degrees Celsius); solid iodine does liquefy at that
temperature.
I believe NileRed mentioned it before, let me see if I can find the video.
EDIT 1: Huh, he has a whole video on it. I should really catch up with all the chemistry videos out there.
link: https://youtu.be/dPIaEWd8zf4
[Edited on 1-7-2018 by ninhydric1]
Iodobenzene - 7-1-2018 at 03:03
Thanks to all of you.
I found particularly interesting the gif posted by HappyFoodDance.
As we can see Iodine manufacturing is pretty complex.
Anyway, why do they make iodine in beads?
Is it like this because it sublimates less?
My precipitated wet iodine sublimates a lot...
[Edited on 7-1-2018 by Iodobenzene]
18thTimeLucky - 7-1-2018 at 03:29
Subliming less is probably part of it. The main reason I think is just down to being easier to handle.
The link happyfooddance gave has the company saying at one point "In addition, we realized supply of easy-to-handle products by shaping them to be
prilled."
I think we can all agree small crystals or a fine powder of most things gets stuck to everything, the sides of any containers, your spatula etc,
whereas prills have enough weigh to be poured easily and not stick to everything but not any bigger as transporting and trying to dissolve a
bowling-ball-sized iodine prill would not be too efficent to say the least. (I have not worked with iodine but sodium hydroxide pills are nice to work
with apart from precise weighing)
Basically it is a nice strike between convenience and inconvenience.
[Edited on 7-1-2018 by 18thTimeLucky?]
Iodobenzene - 7-1-2018 at 03:52
Thanks for the answer.
Anyway, soon I 'm buying some I2 for organic synthesis.