[pcm81]

Long story short, I am trying to make some Iron Nitrate to be used as an iron donor in hot caustic blackaning bath.

I started with ~30% HCL (muriatic acid from home depot). I am reacting it win an excess amount of sodium nitrate to form a mixture of sodium chloride, nitric acid and water. My goal is to isolate nitric acid and then react it with Iron Oxide to produce Iron nitrate. I will then be adding this Iron nitrate to hot caustic bath as an Iron donor.

The hot caustic bath consists of Sodium Hydroxide and Sodium Nitrate. At 290 degrees F the sodium nitrate reacts with iron on the submerged part, producing Iron nitrate, which is then reduced by sodium hydroxide to Iron hydroxide, which then looses a hydrogen to form magnetite deposit on the part being blackened. In this reaction the thickness of the magnetite layer formed is limited by supply of iron from the part being treated. My goal is to add an additional source of iron to allow for thicker layer of magnetite to form on the part being treated.

Any suggestions or Ideas are appreciated.