Effect of [BMIM]BF4 on corrosion of carbon steel in MEA-CO2 media

The corrosion behavior of carbon steel in MEA-CO₂ media containing [BMIM]BF₄ was investigated in this work. The IL can effectively suppress the corrosion of the steel in the solution and facilitates the activation-passivation transition of the steel in the anodic polarization. Molecular dynamics simulations show that the cationic moiety of the ILs can strong adsorb on the surface of Fe in the parallel mode. However, the high content of the IL results in the slight reduction of the passive potential range of the steel, which may be related to the anions of the IL or the free F⁻ ions. It is demonstrated that the dissociation of BF₄⁻ ions gives rise to a relatively high concentration of F⁻ ions in the solution containing [BMIM]BF₄. The addition of NaF indicates the free F⁻ ions can induce the similar localized corrosion of the steel to that in the case of [BMIM]BF₄.