Corrosion inhibition of mild steel using Novel Bis Schiff’s Bases as corrosion inhibitors: Electrochemical and Surface measurement

Abstract

Purpose: The aim of the present investigation is to evaluate the corrosion inhibiting properties of four novel synthesize compounds namely N1,N1′-(1,4-phenylene)bis(N4-(4-nitrobenzylidene)benzene-1,4-diamine) SB-I, N1,N1′-(1,4-phenylene)bis(N4-benzylidenebenzene-1,4-diamine) SB-II, N1,N1′-(1,4-phenylene)bis(N4-(4-methylbenzylidene)benzene-1,4-diamine) SB-III, N1,N1′-(1,4-phenylene)bis(N4-(4-methoxybenzylidene)benzene-1,4-diamine) SB-IV for mild steel in 1M HCl. Corrosion inhibitors find wide application in industries during pickling of steel, descaling and oil well acidization. Inhibitors have attracted great attention due to cost effectiveness and simplicity of the methods. Method: Different experimental techniques such as weight loss, open circuit potential (OCP), electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization were used to evaluate the corrosion inhibition performance of SBs for mild steel in acid solution. After the corrosion experiments, the surface morphology of metal surface in the absence and presence of SBs were studied by scanning electron microscopy (SEM) and Atomic force microscopy (AFM). Findings: The corrosion inhibition efficiency of SBs for mild steel are 71.42% (SB-I), 89.52 (SB-II), 92.85 (SB-III), 96.19 (SB-IV). Tafel polarization revealed that all the SBs behaved as mixed-type inhibitor but predominantly of cathodic type. The inhibition actions of these Schiff base molecules blocked the electrode surface by means of adsorption of the inhibitor molecule on metal surface, obeying the Langmuir adsorption isotherm. SEM/AFM studies of the metal surfaces confirm the protection of metal surface in presence of inhibitor as compared to the damaged surface in blank acid solution.