Electrochemical evaluation and DFT calculations of aromatic sulfonohydrazides as corrosion inhibitors for XC38 carbon steel in acidic media

Two newly synthesized sulfonohydrazide derivatives, namely N '- {(E) - [4- (dimethylamino) phenyl] methylidene}benzenesulfonohydrazide (MBSH), and N '- {(E) - [4- (dimethylamino) phenyl] methylidene} -4- methylbenzenesulfonohydrazide (MpTSH) have been investigated as corrosion inhibitors for XC38 carbon steel in 1 M HCl using electrochemical measurements (potentiodynamic polarization, linear polarization resistance, electrochemical impedance spectroscopy) and theoretical calculations. Results obtained show that these derivatives are good corrosion inhibitors for carbon steel in molar HCl. Their inhibition efficiency increases with their concentration, but decreases with increasing temperature. Substituting a methyl group in MpTSH for a hydrogen atom in MBSH slightly improves its effectiveness. Both inhibitors display a mixed-type. Their adsorption on the steel surface proceeds essentially via physisorption mode and obeys the Langmuir adsorption isotherm. Good correlations were obtained between the anti-corrosion performance of these donor-acceptor compounds and their molecular properties. (C) 2019 Elsevier B.V. All rights reserved.