Sciencemadness Discussion Board

Has anyone tried the basic piranha solution?

John paul III - 19-8-2019 at 07:42

Basic piranha solution is a mixture of 3:1 parts 25% ammonia solution and 30% hydrogen peroxide. Supposedly it's just as capable as the standard piranha solution (with H2SO4 instead of ammonia). Is it really similiar in potency or should I not waste time on it and go for the sulfuric acid version?

Sulaiman - 19-8-2019 at 09:11

I do not know anything about ammoniacal piranha solution, but
sodium carbonate with hydrogen peroxide a.k.a. sodium percarbonate is a very common cleaning agent.
https://en.wikipedia.org/wiki/Sodium_percarbonate

AJKOER - 25-8-2019 at 10:23

A recent comment:
Quote: Originally posted by AJKOER  

...............
Another point, working with NH3/O2 or H2O2 is, in my assessment, not a basic piranha reaction, actually electrochemical (and a bit more) in nature. See related chemistry with copper, ammonia and O2 (or H2O2) at https://www.sciencemadness.org/whisper/viewthread.php?tid=15... and elsewhere on this forum.

Implication of this point is adding NH4Cl (or the sulfate) likely improves the reaction rate as in the case of copper.
....
[Edited on 25-8-2019 by AJKOER]


Also more possibly related comments:

Anodic corrosion apparently works more efficiently when the relative surface area of the metal anode, here Tungsten, in my proposed ammonia/H2O2 or O2 electrochemical cell scheme is small. To repeat, when the relative electrode surface area ratio is SMALL (hence low surface area metal Tungsten), say, to the solution's surface area contact with air, the anodic corrosion accelerates.

The cell may create an electric current and associated solvated electrons, e-(aq), so with preferentially added NH4Cl or the sulfate via:

NH4+ = H+ + NH3

And, the removal of H+:

e-(aq) + H+ = .H

the latter two reactions occurring in solution could supply added NH3 (and I would further guess that starting with the highest ammonia concentration is likely not optimal and having the right NH4+ concentration is a factor, see https://www.sciencedirect.com/science/article/abs/pii/S03043... which discusses optimal leaching factors).

[Edited on 25-8-2019 by AJKOER]