Non-chromated De-oxidizer

[QualitymanPMF]

Non-chromated De-oxidizer

Our company uses an in-house mixed Non-chromated De-oxidizer. The percentages are fairly simple but duplicating the formula for the initial charge is posing a problem. The person who created the mix in the first place has retired and left for places unknown.
It is:
H2SO4 5-10%
HNO3 5-10%
FeSO4 15-25%
The trick is to match the total acid to the total ferrous at around 10%-20% any one have an idea on the quantities required to make up a 2000 gallon bath?

 

[swall]

What is this product used for?

 

[QualitymanPMF]

De-oxidizing and De-smuting aluminum before conversion coating with Alumibond 1200 (alodine 1200).

 

[swall]

If I were you, I would contact your Alodine supplier and purchase a commercial deoxidizing agent that is compatible with the Alodine you are using. You are much better off from an EPA and OSHA standpoint using a commercial product with an MSDS and CAS number than mixing up some witch's brew from commercial chemicals.

 

[QualitymanPMF]

I would love to use Oakite deox LNC, 100 CNC or any of the other products available for purchase but the owners of the company want to use the original mix. Also the disposal of this mix is pH balance and run down the sewer it has no controlled metals or compounds. It is only acid (that is why it is pH balanced) and ferric iron (uncontrolled or every resting car would be a health hazard) so EPA requirements are of little concern in this case. Thank you for the advice anyway any help is appreciated.

 

[SMF1964]

A chemist will have to proof this, but off the cuff: it seems that you'll need half again as much of the iron (II) sulfate as the acid solutions so that the iron charge and the hydrogen charge matches. Sulfuric acid produces 2 hydrogen ions per molecule while nitric produces one. So for a 100ml solution, if you have 5 ml sulfuric and 5 ml nitric, you'll need 7.5 g Fe(II) Sulfate to match?

Grading/corrections will be appreciated.

 

[kenvlach]

QualitymanPMF's aluminum deoxidizer/desmut is similar to some of the cheaper brand name deox's. Search out some MSDSs.
The more expensive deoxidizer (Oakite LNC) differs in not using (cheap) sulfuric acid but rather an acid salt (POTASSIUM PEROXYMONOSULFATE), and it also includes some HF (helps with Si-containing alloys).

The ferric sulfate's role is to prevent etching of the aluminum after the acids have removed any oxide or smut (hydroxides formed from caustic etching). It forms a very thin immersion plating of Fe via an exchange reaction with the exposed Al (since Fe is more noble). This trace of Fe contaminates the subsequent chemfilm layer, so for best corrosion resistance (& passing the salt spray test requirements) it is better to use a non-Fe-containing deox.
For some Al alloys, one can simply use 20 vol% nitric acid to desmut.