Cleaning discolored H2SO4 with H2O2

[Andrew W]

All,
I've boiled down some battery acid that I bought from O'Reily's, and ended up with a dark, amber colored solution...must've gotten some trash in it somehow. My intention is to use the sulfuric to make nitric with lazersteve's method. Would this discolored/dirty sulfuric affect the amount and purity of nitric that is produced? If so, how could I go about cleaning it up? Now, I've heard that you can add just a few drops of peroxide to clear up dirty sulfuric. Does that sound accurate? I've also heard about something called piranha solution which is along the same lines, and believe I'd like to stay away from that mess.

Second question:
Since Steve's method of making nitric acid calls for "56ml of (96%+) sulfuric acid", I recon I should add more to compensate. How much more should I add? Does anyone have the factors and formulas that he used to come up with this method? I guess I'll pm lazersteve.

Thanks in advance for your help!
-Andrew

 

[lazersteve]

Andy,

I sent you a reply to your PM on this subject.

I would go to NAPA and get the clear battery acid in a 5 gallon box for $15 and boil it down instead of the dirty drain cleaners.

Steve

 

[Andrew W]

Steve, I bought the battery acid from O'Reily's; I'd assume its the same stuff...definately not drain cleaner, though :lol:

If anyone's interseted, I found this thread from sciencemadness.org that talks about cleaning dirty sulfuric acid with hydrogen peroxide.

Quote from the above thread:
Add some high strength H2O2 to your sulfuric and heat to 150C or so, should oxidize the carbon to CO2 and any dyes too. At least speculating from my arm chair it would seem so.
Added 50 ml black drain cleaner to 15 ml 12% H2O2, the solution lightened slightly and vigourous fizzing ensued. Little droplets of hot H2O2 released hurt. The solution heated of its own accord and it was placed on a hot plate and put on a low heating setting with magnetic stirring. The mixture turned slighlyt yellow and was fairly clear, I took a picture with a beaker held next to it containing some acid before treatment. Being that the acid was clear and bubbles were still coming up like mad I added some more acid, it cleared up in a few minutes so I added some more, overall 15 ml 12% H2O2 treated a little over 125 ml concentrated acid. After a while the fizzing stopped and heating was discontinued. A fairly clean and simple procedure.

 

[Harold_V]

I know little about sulfuric, having used it almost exclusively for precipitating lead from gold chloride solutions, and pickling buttons after melting. I still have the majority of the last 5 gallon container that I purchased years ago, from a chemical supply house. If it brings you any comfort, it, too, was not clear. It had a hint of yellow/orange/brown color.

Sorry, I do not recall the quality, but I know it was not reagent grade. Could be that grade is clear.

Harold