Corrosion of iron and aluminum in acidic and basic media: theoretical and experimental investigation

The purpose of this investigation is to study the corrosion behavior of iron and aluminum in HCl and NaOH media by means of theoretical and experimental approaches.

For theoretical investigations, the quantum chemical calculation was performed. In this regard, the adsorption of OH⁻ and Cl⁻ on iron and aluminum surfaces was investigated. Furthermore, the natural bond orbital for the direction and magnitude of charge transfer interactions were calculated. In addition, the electrochemical evaluations based on potentiodynamic experiments were carried out.

The quantum chemical calculation results showed that the charge transfer from OH⁻ to the iron surface is more than that from Cl⁻, and also the charge transfer from Cl⁻ is more than that from OH⁻ to aluminum cluster. Furthermore, these anions donate more electrons to the iron cluster than to the aluminum cluster. The experimental data showed that the rate of corrosion of iron in 1.0M NaOH solution was less than in 1.0M HCl solution. The corrosion of aluminum in HCl solution was less than that in NaOH solution. The rate of corrosion of iron in both solutions was less than that of aluminum.

The findings of this paper indicate that calculations based on the natural bond orbital analysis of the charge transfer rates from OH⁻ and Cl⁻ to the iron or aluminum surfaces, and their comparison with experimental results, exhibited excellent agreement.