Effects of Chloride Ions and Nitrate Ions on the Anodic Dissolution of Iron in Sulfuric Acid Solution

Abstract

In this paper, the flow injection (FI) technique combined with a partially-closed electrode (PCE) was used to manipulate the physicochemical microenvironment at the electrode/electrolyte interface so as to study the effects of chloride ions (Cl− ions) and nitrate ions (NO3− ions) on the anodic dissolution of the Fe/0.5 mol dm−3 H2SO4 system. The anodic dissolution is modified by injecting various composition-containing solutions into the vicinity of the PCE, and then, the electrodissolution processes are analyzed by comparing the j–t curves before and after the injections. At the initial stage of the passive region, it is found that NO3− ions promote the anodic dissolution of iron by creating more active sites on the surface of the electrode when CNO3−/CCl− = 1:1; however, they inhibit the anodic dissolution by making the film more compact for the strong oxidized characteristics of NO3− ions when CNO3−/CCl− = 10:1.