LAUSR

Abstract The inhibition of X80 steel corrosion by a 3-Methoxypropyl-amine (MOPA) as a new corrosion inhibitor in saline solution (3.5 wt% NaCl) was optimized at different temperatures, inhibitor concentrations, the rotation speed of the solution and pH. Mass loss and polarization measurements were used to evaluate the corrosion rate and other kinetics parameters. The inhibition performance of MOPA was optimized by factorial experimental designs. Optimum conditions for the minimum corrosion rate were 12.89 °C, 8.63 g/l, 1097.69 rpm, pH 4.03. It was observed that MOPA follows the Langmuir adsorption isotherm with negative values of ΔGadso, proposing a spontaneous and stable inhibition process. According to ΔGadso values, a physical adsorption was suggested. The inhibitor efficiency increased with increasing the inhibitor concentration and pH of the solution. Moreover, increasing the solution temperature and rotation velocity had an adverse influence on inhibitor efficiency. Results of mass loss technique were agreed with the polarization one. Polarization diagrams revealed that the inhibitor affects as a mixed-type inhibitor. Surface morphology and FTIR spectrum studies were confirmed the effectiveness of the inhibitor. A theoretical quantum chemical simulation was a powerful tool for the optimization of the MOPA structure.