Abstract
The passivation of low carbon steel was studied in aqueous solution of 0.5M 
and of 
at 
. The electrochemical methods (potentiodynamic, chronopotentiometric, and voltammetric) showed that the presence of 0.001M 
increased the thickness of the oxide film by about one order of magnitude. The spectrophotometric analysis of the solutions demonstrated that the rate of the dissolution of iron was much higher through the thick passive film, in the presence of 
ions, than through the thin passive film formed in the solution of 0.5M 
without 
ions. This is good evidence for the protective properties of the passive film being very weak if sulfite ions are present in the solution, even in a very low concentration. The conversion electron Mössbauer spectroscopy (CEMS) provides information about the compositions and thicknesses of the passive films formed in a solution containing both sulfate and sulfite ions. The major components found are 
and 
, and also 
could be identified on the surface of the low carbon steel as a minor component.