Optimization of Inhibition Efficiency of a Schiff Base on Mild Steel in Acid Medium: Electrochemical and RSM Approach

This research investigates the effect of Schiff base, namely, N'-[4-(dimethylamino) benzylidene]-4-hydroxybenzohydrazide (SB) on the corrosion mitigation of mild steel (MS) in hydrochloric acid medium (HCl) using potentiodynamic polarization (PDP) technique. The study highlights the effect of SB concentration, HCl concentration, and temperature on the corrosion current density (i_corr) and inhibition efficiency (IE). The adsorption of SB onto the MS surface was justified with the support of kinetic and thermodynamic parameters. The morphological behavior of the MS surface was analyzed by scanning electron microscopy (SEM) and atomic force microscopy (AFM). A blend of statistical study and interaction plots has been applied to obtain a thorough understanding of the corrosion parameters. Experimental results obtained by PDP measurements revealed that tested compounds had a good anti-corrosion capacity. The main and interaction effects of the parameters on the response were analyzed using Box-Behnken Design. An empirical model equation from experimental results elucidates the relationship among the variables. The optimized parameters for the maximum output were recognized. The maximum IE of 81.5 was predicted by RSM with temperature (A = 30 °C), HCl concentration (B = 0.5 M), and Inhibitor concentration (C = 0.0001 M). Using RSM, further analyses regarding individual and interaction effects between the variables can be more comprehensive. Few more parameters such as pH and time can be included in the future study. Graphic Abstract: [Figure not available: see fulltext.].