Sciencemadness Discussion Board

prepairation of Br2 from sea water

Dr. Beaker - 13-9-2005 at 13:43

Hi ppl.
wanted to share with you a nice way inwhich I obntaine Br2. It works nice for me, and I hope It'll be for you as well. I use water from the dead sea, which are the most rich naturally occuring marine bromide source on earth, and use it as is. I guess "normal" ocean or sea water should be concentrated 1st by evap in the sun.
I saturate home bleach with NaCl, and then add H2SO4. Chlorine is liberated according to the reaction:
2(H+) + (OCl-) + (Cl-) --> H2O + Cl2
now I have chlorine water, and I add them to the sea water. bromide is oxedize to chlorine:
2(Br-) + (Cl2) --> Br2 + 2(Cl-)
the solution becomes yellow-brown.
the crude Br2 (actually Br2X- complex of Br2 and halogen) is distilled and the vapor collected into ice cooled erlenmayer through ice water cooled condenser. the brown-red bromine is the lower layer, and can be easily separated, dryed and stored. the main contaminants are chlorine and water. chlorine is eliminated by passing the bromine in seawater (where it produces even more bromine if it's there...:) and repeating distilation.) water are removed by conc. H2SO4

good luck.:)

vulture - 14-9-2005 at 12:52

Dead Sea water is not really an OTC precursor...:D

Dr. Beaker - 14-9-2005 at 14:03

yeh, but since I can get there in an hour drive it's the best source for me.
you can use ordibary sea water (if you relatively near sea that is)
ah.. abd if it doesn't work you can buy anti dipression pills (not for your'e mental condition, but for the bromide they contain ;-) just kidding offcourse

kazaa81 - 14-9-2005 at 14:15

Nice beaker, nice.... ;)
Have you pumped the Cl2 in sea water or just let it absorb from normal water then put it in sea water?
Would commercial marine NaCl (not mined, from sea) be used to do this experiment?

Thanks at all for help

Dr. Beaker - 14-9-2005 at 14:45

regarding the 1st question: I don't use gasous chlorine but a chlorine solution (which is actually Cl3- since there is exess of Cl-) I simply mix my chlorine water and sea water.
2nd question: marine salt won't do:(, since it's quite pure NaCl that was made by fraction crystalization of sea water.

BromicAcid - 14-9-2005 at 20:01

There is a thread around here on obtaining bromine from sea salt (considering it is a concentrated source of what is avalible in natural ocean water) and I think it was concluded that the bromine content was so small that most people dismissed it. However Dead Sea water has an even greater concentration by far
Quote:
The concentration of SO4 ions is very low, and the bromine ions concentration is the highest of all waters on Earth.
From the Wikipedia article on the Dead Sea. So I think there may be an advantage to using that water, even compared to a saturated solution of sea salt. However there are wells in my area that contain a brine that is 3-5% bromide (in terms of the dissolved content), similar wells are located around the world, noteably in Arkansas. A little off topic, but I was under the impression that the trichloride anion concentration in the equilibrium between chloride and trichloride was nearly zero, bromine forming the tribromide anion to a slightly greater extent, and iodine being the most able to form this anion, salts of it being isolateable readily with cesium. I may be wrong though.

azaleaemerson - 21-9-2005 at 04:48

A tech I know from an old job works for a company that actually makes bromine from the water from the Dead Sea. Maybe they use a unique process you can research and mimick.

garage chemist - 21-9-2005 at 04:53

I have some "dead sea bathing salt" which lists the ion concentrations on its side.
The bromide concentration is 800mg/kg.

So I'd get 0,8g bromine from a kilogram of the stuff. This would be the most expensive bromine source I am aware of.

However, this salt might not be "evaporated dead sea water" but rather a crystallisate, made by boiling down dead sea water until crystals form and then filtering those off.
This would leave ions of lesser concentration in solution.
Maybe the resulting bromide- enriched water actually goes to a bromine production facility?


[Edited on 21-9-2005 by garage chemist]

chloric1 - 21-9-2005 at 20:11

Hey bromic, I have heard if the brine wells of Michigan. Is this water easily obtainable? Or is it private property not publicly available?


3 to 5% would actually be quite good since the cost of operation would be mainly hypochlorites, a little acid,and the distiller.