PHOSPHORIC ACID 25% V/V
PHOSPHORIC ACID 25% V/V
Application: RUST REMOVER
Among the various types of acids, phosphoric acid is used commonly in the removal of rust from metals like iron, steel, etc. Usually, when this acid is applied, it reacts with the rust and converts the reddish-brown iron (typically ferric oxide or iron oxide) to a black-colored compound known as ferric phosphate. This black ferric phosphate substance is easily removed.
Product Description
The reason to use phosphoric acid in particular for rust removal is that phosphoric acid, after dissolving the rust, will attack the unoxidized iron underneath (often with the help of an added oxidizer like a nitrite salt) to form iron phosphate in solution. Since phosphate salts are almost universally insoluble except in acidic conditions, and the reaction uses up acid causing a reduction in the acidity, the iron phosphate falls out of solution and deposits on the iron, forming a sort of phosphate patina.
This is helped along by the fact that most commercial phosphoric acid treatments include phosphate salts pre-dissolved in the acid, and they also fall out of solution once the acidity starts dropping when the acid is applied to metal.
This essentially uses up the available iron on the surface before it can turn into rust.
