Peroxymonosulfuric Acid

[Irons]

Typical sulfuric acid-hydrogen peroxide mixture (SPM) chemical reaction process:

H2SO4 (sulfuric acid) + H2O2 (hydrogen peroxide) --> H2SO5 (peroxymonosulfuric acid) + H2O (water)

When you electrolyse a dilute mixture of Sulfuric acid in water, Hydrogen Peroxide is produced:

H2SO4 (sulfuric acid) + H2O (water) --> H2O2 (hydrogen peroxide) + 2H+ (hydrogen ion) + 2e- (electron)

A Transition Metal ion such as Iron (III)+ will cause the reaction to become even more energetic by the production of Hydroxl radical, a strong Oxidizer.

This is also known as Fenton's Reagent:

http://en.wikipedia.org/wiki/Fenton%27s_reagent

It was developed in the 1890s by Henry John Horstman Fenton.

Ferrous Iron(II) is oxidized by hydrogen peroxide to ferric iron(III), a hydroxyl radical and a hydroxyl anion. Iron(III) is then reduced back to iron(II), a peroxide radical and a proton by the same hydrogen peroxide (disproportionation).

(1) Fe2+ + H2O2 → Fe3+ + OH· + OH−

(2) Fe3+ + H2O2 → Fe2+ + OOH· + H+

In the net reaction the presence of iron is truly catalytic and two molecules of hydrogen peroxide are converted into two hydroxyl radicals and water. The generated radicals then engage in secondary reactions. Iron(II) sulfate is a typical iron compound in Fenton's reagent.

This is why SPM is so reactive towards sulphides.

for some additional reading on reactions with minerals:

http://www.mindat.org/mesg-19-28644.html

 

[Lou]

Peroxysulfuric acid is wicked, wicked stuff, every bit as bad as hot chromic acid. It is used for cleaning electrodes prior to plating, and the most stubborn stains on glassware.

It's also liable to decompose if made in any concentration and allowed to overheat. It attacks wood, many metals, and most notably your skin, really quickly (as in 'eating' your flesh away before your very eyes).

Besides its technical name, it's called Caro's acid, or when used for cleaning Piranha solution. I once spilled some on a wooden bench and there was a small fire and a half inch of material eaten out of the table top.


So when you make this, make it carefully with the H2SO4 being cold as well as the peroxide.



Lou

 

[Irons]

Do not add Hydrogen peroxide to concentrated Sulfuric acid or vice versa. Very dangerous.

I use a max 15% solution and even that can be very reactive.

Iron contamination is a catalyst.

One advantage to using it is not having the fumes that HCL or HNO3 put off.

If there is arsenic present such as semiconductor chips or sulphides, it will give off AsH3 (Arsine gas)

Do not do this indoors or confined areas. Check the area for things to trip over in case you have to leave in a hurry.

 

[aflacglobal]

Check the area for things to trip over in case you have to leave in a hurry.

Now that's forward thinking and safety planning.

Good topic Irons. You helped remind me of something i forgot to.

 

[Silver]

Can 30% H2O2 be used with 98% H2SO4 to make concentrated acid or do I have to use a more concentrated peroxide? Also what is the ratio of peroxide and sulfuric acid?

 

[aflacglobal]

Can 30% H2O2 be used with 98% H2SO4

30 %, where did you find that at ?

 

[Lou]

It is easily made from distillation or by freezing out the water from 6% (see sciencemadness search engine results).

Or you could buy it.


I mentioned a while back about the pool clarifier containing 27.5% H2O2 with some phosphoric acid as a stabilizer.

You can use any concentration of peroxide and sulfuric, it's just that Caro's acid is only really useful for cleaning when made with 30% and greater hydrogen peroxide.

 

[Silver]

30 %, where did you find that at ?

I buy it at the pharmacy. 4-5 dollars per liter.

 

[Noxx]

I can't get that in Canada... Where are you from to get those prices ??

 

[aflacglobal]

You can't find anything in Canada. :shock: :shock: :shock:

 

[aflacglobal]

You can't find anything in Canada. :shock: :shock: :shock:

But i know what you mean. It is getting hard to find stuff anywhere now.
That's why i ask where he got it from. I'm not concerned about the price. :wink: What pharmacy chain :?:

 

[Never_Evil]

May I ask the advantage of this acid vs other methods?

 

[OMG]

Hair dying peroxide (at the drugstore) is higher strength peroxide that normal stuff. Not sure what % though.

 

[Irons]

Can 30% H2O2 be used with 98% H2SO4 to make concentrated acid or do I have to use a more concentrated peroxide? Also what is the ratio of peroxide and sulfuric acid?

I wouldn't even think of starting out with that formula.

I had an explosion this summer when I tried to heat and pressurize a 15% solution. Luckily, it was a small quantity and I was using a polycarbonate reaction vessel. It looked like a bullet had been fired from the inside of the vessel where it was blown out. It only took a couple of psi and 80 Deg. C. to start an uncontrollable reaction.

Don't use a glass or other material that might shatter. Metal containers will also act as a catalyst.

If you don't know what you're doing, find some other way to entertain yourself.

Heed the warnings or pay the price.

 

[Irons]

May I ask the advantage of this acid vs other methods?

It's just a quicker way to meet your maker.

 

[Silver]

What pharmacy chain :?:

It is not from a pharmacy chain. It is a small private pharmacy and they are not allowed to sell that concentrated peroxide to anyone whit out an ID check and you must sign a document that you bought it and why. But they know I like chemistry so they sell it to me whit out those checks. But in the state owned pharmacy you cant buy almost anything whit out signing and showing ID.

 

[aflacglobal]

Thanks Grasshopper.