Sciencemadness Discussion Board

Unusual approach to making bromine

Pyro - 9-8-2012 at 14:05

hi,
i have been watching some chemstudy vids,
and I came across this one
and here he uses this approach:
1)acidify concentrated seawater->2)pass chlorine through it to free elemental bromine -> 3)force bromine out of solution with compressed air ->
4) reduce bromine to HBr with SO2 -> 5)bring HBr into solution ->6) pass chlorine through the HBr to free Br2->7)force Br2 out of solution with steam->
8)condense Br2 to liquid
this seems like a wasteful way of producing Br2, why don't they condense the Br2 at step 3?

IDEA:how about either performing the same procedure or just passing Cl2 through a saturated solution of sea salt. (can be obtained from most supermarkets as ''sel de guerande'' or the likes) since the solution is saturated only passing Cl2 through it should be enough to force the Br2 out of solution

thoughts? suggestions? opinions?

[Edited on 10-8-2012 by ScienceSquirrel]

bbartlog - 9-8-2012 at 14:31

I expect that the multiple steps are required in order to purify the bromine, which at step 3) would surely still be heavily contaminated with water and chlorine. Remember, even if the seawater is concentrated to the point of being satured brine, it still contains only about one part in 1600 of bromine. I think step 4) may serve to separate bromine from chlorine, though I am not certain.

Endimion17 - 9-8-2012 at 14:33

Yes, those are good, old Chem Study films. You can download all of them as original "scans" from archive.org. Very nice videos that reminds us of better times, as long as we're concerned with education...

Have you seen the whole video? The yields are pathetic for laboratory setups. It's the main procedure for making bromine on industrial scale because of the energy involved.

Sea salt is artificially iodized, so you'd get plenty of iodine contamination.

On laboratory scale, it's an extremely difficult way of producing few drops (if your setup is small to avoid everything going to vapor) of impure bromine. Waste of time unless it's a demonstration experiment.

mr.crow - 9-8-2012 at 14:42

Wow, thanks for the beautiful video. So well explained

Pyro - 9-8-2012 at 18:03

lol,
I didn't make it :)
I am talking about sea salt from salt pans, they don't remove anything from that.
I have a 6l RBF, would the yields not be considerable with that much saturated brine? as the amount of water they used probably only contained about a teaspoon of solid matter and made a few grams, 6L of actually saturated brine should have a considerable amount of Br2, shouldn't it?

I personally do not agree with the many steps for pure Br because: Cl2 will hardly condense at the temperatures used, they use Cl2 to extract the Br2 from HBr, so there is Cl2 involved anyway.

yes E17, I did watch the entire vid. when I get time I'll see if chlorinating a saturated solution of raw sea salt will yield anything. anybody got a flask bigger than 6l? how about a 22l?

Dr.Bob - 9-8-2012 at 18:21

They didn't normally actually use sea water for this, instead they used mineral rich waters like the Dead Sea and salt water from other very bromine rich sources. The Dead Sea Chemical company made Bromine this way for many years. Read Max Gergel's book for more details. I am sure that there must be some other OTC source for bromine salts as well, in most areas, which would work much better.

Pyro - 10-8-2012 at 04:42

yes, but it would be fun to try as an experiment.
but it would only be useful if you do it on a large scale

MrHomeScientist - 10-8-2012 at 06:04

That would definitely be fun to try as an experiment! That was a great old video. I love the comically huge round bottom flask, especially in comparison to the few drops of bromine it yielded.

It is interesting they go through so many steps. I don't see how the steps past 3 serve to purify it further - can anyone clarify? Surely the final product is still contaminated with chlorine and water?

Pyro - 10-8-2012 at 07:26

I totally agree! I think that one could get a few mL from a 6-22l flask of saturated solution. because he got a drop from 100mL of saturated solution. so 6L will give 60drops 7L gives 70 drops... thats close to 10 ml from 6l of saturated solution of salt. 10ml of Br2 is something.

mr.crow - 10-8-2012 at 07:55

It seems very effective on a huge scale, all you need is a little chlorine and air to extract the bromine from seawater

Of course you won't be making useable bromine, just for the fun of it! A drop sealed in a glass tube would be a great element sample

There is also iodine from seaweed. There was a BBC show about the history of Britain where they recreate the discovery of iodine

Pyro - 10-8-2012 at 08:35

well Mr crow, 10ml from 6l isn't nothing! but not enough to use in syntheses. would be cool to say:''I got this dangerous element from sea salt'' :D
how would one go about extracting I2 from seaweed?

ScienceSquirrel - 10-8-2012 at 08:44

The first step is to collect and dry the seaweed, it is important not to let rain or other fresh water to fall on it as this will leach out the iodine.
When it is thoroughly dry it can be burnt to form ash.
The ash can then be leached with water to form a solution of the contained salts. This is then treated with acid and a suitable oxidising agent and the iodine is extracted.

Pyro - 10-8-2012 at 09:54

interesting, any idea about the yields?
I will definitely try this as well!

DJF90 - 10-8-2012 at 10:03

Peach has done this (I2 from seaweed). I think he posted the procedure up on here

[Edited on 10-8-2012 by DJF90]

mr.crow - 10-8-2012 at 10:23

Yeah its on the forum somewhere. I also found where I posted the BBC video and proxy so non-British people can see it. Someone scolded me for posting their proxy, I found it on google gimme a break. That was 2 years ago.

kristofvagyok - 10-8-2012 at 15:32

In a few comments chlorine was mentioned as an oxidiser to get the bromine out of the solution. It will work, there will be no problem except one: if excess chlorine is used BrCl will form (a nice reddish gas what is soluble in water)...

To separate the BrCl from the solution and get out the bromine from that, will be a hard task (and really-really smelly), I would suggest to forget the chlorine.

Pyro - 10-8-2012 at 16:56

I hope fish shops don't wash their seaweed! I eat oysters more than I go to the sea, bearing in mind that I havn't been to the sea in 4 years. :D
lol,
might have to fit in a trip to the beach for some seaweed, hurrah!

Endimion17 - 11-8-2012 at 03:08

Not all seaweed is rich in iodine. I have some experience with this. It's a pain in the ass.
You can pretty much forget any member of Chlorophyta. Rhodophyta is not far away. Members of Phaeophyta are the ones you want, and even in that group, iodine content varies greatly.

Only the richest algae are useful, like kelp. The yields are small and the process is difficult. Iodine used to be very expensive before the iodine rich brines were used.

Going to the beach is fun, but collecting one particular species of algae can be exhausting if it isn't abundant. If you live close to a ocean beach that washes up kelp to its shores, consider yourself lucky.

Drying can be smelly if not fast enough. Burning is ... omg. It's not like corpses but it induces vomiting, too. Also, it doesn't burn easily because of the salt. All in all, prepare for an episode of anger, cursing and disgusting smell.

Pyro - 11-8-2012 at 04:19

I live in belgium, that's pretty clost to the atlantic. I will do some research on it.
thanks E17

ScienceSquirrel - 12-8-2012 at 15:25

This used to be a major industry on the coast of Brittany.
Every year hundreds of tons of kelp were collected, dried and then burnt in special hearths where off shore breezes blew the fumes out to sea.
The ash was then lixiated and the extracts were concentrated, crystallised and treated to produce a range of useful products.
The quantities involved are huge and they are against you.
An eighty litre bin could hold about 100 kilos of wet kelp. After drying this might produce 10 - 20 kilos of kelp ready for burning. From this you might get a kilo or so of ash.
Extraction will produce maybe a few hundred grams of soluble salts of which a few grams will be iodide.
At this point it becomes easier and less noxious.
So 100 kilos of wet kelp plus hours of work with vile materials will result in a few grams of iodine if you are lucky.

cal - 12-8-2012 at 17:36

http://www.youtube.com/watch?v=OB4MmPTOBxg
easy way to Bromine:cool:
Quote: Originally posted by Pyro  
hi,
i have been watching some chemstudy vids,
and I came across this one
and here he uses this approach:
1)acidify concentrated seawater->2)pass chlorine through it to free elemental bromine -> 3)force bromine out of solution with compressed air ->
4) reduce bromine to HBr with SO2 -> 5)bring HBr into solution ->6) pass chlorine through the HBr to free Br2->7)force Br2 out of solution with steam->
8)condense Br2 to liquid
this seems like a wasteful way of producing Br2, why don't they condense the Br2 at step 3?

IDEA:how about either performing the same procedure or just passing Cl2 through a saturated solution of sea salt. (can be obtained from most supermarkets as ''sel de guerande'' or the likes) since the solution is saturated only passing Cl2 through it should be enough to force the Br2 out of solution

thoughts? suggestions? opinions?

[Edited on 10-8-2012 by ScienceSquirrel]

Pyro - 14-8-2012 at 04:04

i know, lol
but i was interested in the process of the chemstudy vids

Hexavalent - 5-2-2013 at 12:51

Where I live (the isle of Anglesey, north Wales) the waters surrounding have rather high concentrations of bromide. Therefore, until about 10 years ago IIRC, bromine was made there by the Octel company, however I can't be certain what method they used.

violet sin - 5-2-2013 at 22:28

The study I read on the extractin of iodine from seaweed was performed just 2 or so hours south of me by car, on the California coast. They decided the bull kelp was best. I know it's not 100% on topic, but I just brought it up because of a side note I read. They stated that while drying the long stalks(roots and leaves were a waste) of the bull kelp, the salt that dried to the exterior was almost pure KCl. I found it interesting, potassium sequestered as well as iodine in one place though both were minority compositions of all the water around them. Dillute and energy inefficient yes but still practically free if you have a bunch of time and fuel to burn.