Synthesis, characterization and corrosion inhibition studies of N-phenyl-benzamides on the acidic corrosion of mild steel: Experimental and computational studies

摘要

AbstractPresent study aims to demonstrate the effect of electron withdrawing nitro (NO2) and electron releasing methoxy (OCH3) substituents on the inhibition behavior ofN-Phenyl-benzamide derivatives (BNAs), namelyN-(4-nitrophenyl) benzamide (BNA-1; NO2),N-phenylbenzamide (BNA-2; H) andN-(4-methoxyphenyl)benzamide (BNA-3; OCH3) for mild steel acidic (1M HCl) corrosion. Results of the computational and experimental studies showed that methoxy (OCH3) substituent enhances the inhibition efficiency whereas nitro (NO2) decreases the inhibition efficiency. Electrochemical impedance spectroscope (EIS) study showed that BNAs acted as interface corrosion inhibitors and polarization study shows they acted as cathodic type corrosion inhibitors. They showed maximum efficiencies of 89.56%, 93.91% and 96.52% for BNA-1, BNA-2 and BNA-3, respectively. The BNAs strongly (highKadsvalues)and spontaneously (negative ?G0values) adsorbed at metal/electrolyte interfaces and their mode of adsorption obeyed the Langmuir adsorption isotherm. Surface investigation of the mild steel surfaces using AFM and SEM analyses revealed that BNAs adsorb on the surface and increase the energy barrier for corrosive dissolution which is also supported by the higher values ofEa(activat