Synthesis and evaluation of new isoxazolidine derivatives of aldehyde as corrosion inhibitors for mild steel corrosion in acidic and saline media

Abstract

new series of isoxazolidine derivatives of aldehyde were synthesized using a nitrone cycloaddition reaction. The corrosion inhibition efficiency of these synthesized compounds on mild steel were determined using a gravimetric method, linear polarization resistance, Tafel extrapolation method, electrochemical impedance spectroscopy, and surface tension in various solutions of the inhibitors in 1 M HCl, 0.5 M H2SO4, and CO2-saturated 0.5 M NaCl (40 °C, 1 atm; 120 °C, 9.9 atm). The p-9-[hexahydropyrrolo(1,2-b)isoxazol-2-yl]nonyloxybenzaldehyde performed the best in comparison to the other synthesized inhibitors and two commercial inhibitors. The anodic shift of the Ecorr values, and the larger reduction of icorr values in the anodic side of the Tafel plots, suggest that the inhibitor molecules acted primarily as anodic inhibitors. The ΔGoads points towards both physisorption as well as chemisorption of the inhibitors on the metal surface. The inhibitor molecules are best fitted by a Temkin adsorption isotherm in both acids, while the Langmuir adsorption isotherm performed best in a CO2-saturated saline media. The surface tension confirms that the inhibitor molecules form a film at the metal's surface. The surface coverage data and CMC values demonstrate that the inhibitor molecules undergo adsorption on the metal surface, rather than micellization.