Assembly of succinic acid and isoxazolidine motifs in a single entity to mitigate CO2 corrosion of mild steel in saline media

Inhibition of CO2 corrosion of mild steel in 0.5 M NaCl under atmospheric pressure at 40 degrees C as well as high pressure (10 bar) at 120 degrees C by 2-[2-methyl-4(or 5)-alkylisoxazolidin-5(or 4)-yl) methyl]succinic acids, a new class of molecules having inhibitive motifs of succinic acid, isoxazolidine and hydrophobic alkyl chain assembled in a single entity, has been examined by gravimetric and electrochemical methods. Inhibitor molecule containing CH3(CH2)(8) outperformed its counterpart with a shorter hydrophobe CH3(CH2)(4) and two other commercial imidazoline-based inhibitors. The effectiveness of these new inhibitors was also evaluated by electrochemical impedance spectroscopy. The inhibition efficiency by EIS was found to be 75%, 91% and 98% in the presence of 1, 5 and 20 ppm, respectively, at 40 degrees C. The potentiodynamic polarization studies indicated that the new inhibitors act as anodic inhibitors. The adsorption of the synthesized inhibitors follows Temkin adsorption isotherm model with favorable high values of -Delta G(ads)degrees and -Delta H-ads degrees pointing the inhibitors adsorbed on the metal surface by chemisorption process. The XPS study confirmed the adsorption of the inhibitors on the metal surface. (C) 2017 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University.