Anticorrosion Investigation of New Diazene-Based Schiff Base Derivatives as Safe Corrosion Inhibitors for API X65 Steel Pipelines in Acidic Oilfield Formation Water: Synthesis, Experimental, and Computational Studies

The current study examines the evaluation of diazene-basedSchiffbase derivatives, namely, 4-((E)-(3-((E)-(hexylimino)methyl)-4-hydroxyphenyl)diazenyl)benzonitrile (S1)and 4-((E)-(3-((E)-(dodecylimino)methyl)-4-hydroxyphenyl)diazenyl)benzonitrile (S2). The structureelucidation of prepared the Schiff base compounds was performed byFTIR, H-1 NMR, and C-13 NMR. In addition, thecorrosion inhibition capacity of these compounds was investigatedfor API X65 steel pipelines in 1 M HCl utilizing gravimetric and electrochemicalmethods. By conducting the experimental investigations at variousdoses, it was possible to assess the inhibition effectiveness andadsorption behavior of S1 and S2. With increasing concentration, bothinhibitors became more effective at inhibiting corrosion. S1 and S2suppressed both cathodic and anodic processes, as shown by the potentiodynamicpolarization study. The charge transfer resistance (R (ct)) increased when S1 and S2 concentrations increased,according to the electrochemical impedance analysis (EIS) data. Accordingto the Langmuir isotherm model, the adsorption of S1 and S2 inhibitorson carbon steel was discovered based on gravimetric measurements.The results were confirmed by theoretical data in addition to theexperimental tests for the presence of S1 and S2 inhibitor films overthe API X65 carbon steel surface.