Control of chloride ion corrosion by MgAlOx/MgAlFeOx in the process of chloride deicing
2022
Wang, Dongdong | Zhu, Qi | Xing, Zipeng | Fang, Lei
Adding a corrosion inhibitor to the chloride deicing salt can prevent the corrosion and pollution of Cl⁻, which is very important. Layered double hydroxide (LDHs), calcined at high temperature is used as adsorbents to remove various anionic contaminants, and it can reduce the freezing point of solution after adsorbing anions. Therefore, this paper reports the use of calcined LDHs as corrosion inhibitors in deicing salts, which are denoted as MgAlOₓ or MgAlFeOₓ depending on the preparation element. By analyzing the removal efficiency and the freezing point of MgAlOₓ and MgAlFeOₓ to Cl⁻, the feasibility of the study was determined. Resulted that the removal efficiency to Cl⁻ of MgAlFeOₓ at low temperature (0 ± 2 °C) and room temperature (25 ± 2 °C) was higher than that of MgAlOₓ, reaching 39.4% and 85.60%, respectively. And the freezing point of MgAlFeOₓ was lower than that of MgAlOₓ, the value was −12.0 °C. At the same time, we also found that CaCl₂-MgAlOₓ and CaCl₂-MgAlFeOₓ significantly reduced the corrosion of carbon steel and concrete compared with chloride salts, and CaCl₂-MgAlFeOₓ had the lowest corrosion degree. Hence, MgAlFeOₓ was chosen as the corrosion inhibitor in chloride deicing salt. The metal molar ratio, synthesis temperature, and calcination temperature for preparation of MgAl/MgAlFe-LDHs were determined by XRD and TG-DSC analysis that were 9/2/1, 120 °C, and 500 °C, respectively. Characterization methods such as Zeta, XRD, XPS, BET, and SEM were used to study in detail the characteristic changes of MgAlFe-LDHs and MgAlFeOₓ after Fe³⁺ was added, and the mechanism of corrosion inhibitors was further determined that was achieved by adsorption and neutralization.
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