Control of chloride ion corrosion by MgAlOx/MgAlFeOx in the process of chloride deicing

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 MgAlO x or MgAlFeO x depending on the preparation element. By analyzing the removal efficiency and the freezing point of MgAlO x and MgAlFeO x to Cl - , the feasibility of the study was determined. Resulted that the removal efficiency to Cl - of MgAlFeO x at low temperature (0 ± 2 °C) and room temperature (25 ± 2 °C) was higher than that of MgAlO x , reaching 39.4% and 85.60%, respectively. And the freezing point of MgAlFeO x was lower than that of MgAlO x , the value was −12.0 °C. At the same time, we also found that CaCl 2 -MgAlO x and CaCl 2 -MgAlFeO x significantly reduced the corrosion of carbon steel and concrete compared with chloride salts, and CaCl 2 -MgAlFeO x had the lowest corrosion degree. Hence, MgAlFeO x 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 MgAlFeO x after Fe 3+ was added, and the mechanism of corrosion inhibitors was further determined that was achieved by adsorption and neutralization.