Sciencemadness Discussion Board

Bleach from chlorate/chloride-brine

chief - 7-3-2009 at 00:59

Supposed I have concentrated chlorate-chloride-brine at will, from electrolysis. But I frequently want chlorine-bleach, which somehow makes the drain open, better than hot NaOH-solution can do.

How could I get me then the bleach (hypochloride) from the chlorate-brine, in a easy way ? HCl, NaOH and NaCO3 are given ..., but using H2SO4 would be considered a wasture ...

Until now I always buy the chlorine-bleach, just to give it down the drain ...

[Edited on 7-3-2009 by chief]

497 - 7-3-2009 at 01:38

Or you could just electrolyze brine directly to bleach...

Any way you do it, it's going to more expensive and much more effort than just buying some bleach... that stuff is *cheap.*

chief - 7-3-2009 at 01:58

Oh no, it's not cheap: 3 Bottles (regularly) make 5 bucks ; and only minimum quantities if the bleach-stuff inside (hypochloride) ;
whereas: The chlorate/chloride-solution I have anyhow, and 1 kg NaCl only costs 0.50 bucks, should give maybe 100 l of bleach ... ; definately cheaper to use the self-made chlorate, if possible.

If I wanted to electrolyze NaCl, would I just add some Na2CO3 to stabilize the hypochloride and prevent decomposition to NaCLO3, or what ?

hissingnoise - 7-3-2009 at 05:13

Chief, bleach is hypochlorite, not hypochloride.
Brine electrolysis at low temperature produces concentrated hypochlorite---chlorine bubbled through a saturated NaOH solution again at low temperature converts all the NaOH to NaClO.

chief - 7-3-2009 at 05:32

So once it became hot it's irreversible ?

hissingnoise - 7-3-2009 at 05:49

Yes, NaClO disproportionates to chlorate and chloride.
Bleach is ~5% NaClO in NaOH---high PH stabilises NaClO in solution.
It's the instability of NaClO that makes it an effective bleach.
But essentially you're paying for NaOH. . .

[Edited on 7-3-2009 by hissingnoise]

tryptamine - 8-3-2009 at 05:31

Electrolysis of brine produces chlorates at high temperatures, with digestion at 90C. Low temperatures produce hypo from the same setup.

hissingnoise - 8-3-2009 at 07:44

Quote:
Originally posted by hissingnoise
Chlorine bubbled through a saturated NaOH solution again at low temperature converts all the NaOH to NaClO.


I just spotted my error, sorry---half the NaOH is converted to NaClO---and half to NaCl. . .