Assessment of the effectiveness of new both pyridazine derivatives as corrosion carbon steel inhibitors in 1 M HCl: experimental, mathematical-statistical calculations and theoretical approaches

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ABSTRACT Two newly synthesised pyridazine compounds, (E)-2-(3-(4-(carboxymethoxy)-3-methoxystyryl)-5-(4-chlorobenzyl)-6-oxopyridazin-1(6H)-yl)acetic acid (CO7) and (E)-2-(3-(4-(carboxymethoxy)-3-methoxystyryl)-5-(4-methylbenzyl)-6-oxopyridazin-1(6H)-yl)acetic acid (CO8), were evaluated for corrosion inhibition on carbon steel (C–S) in 1 M HCl solution. Techniques such as potentiodynamic polarisation (PDP), electrochemical impedance spectroscopy (EIS), and the gravimetric method were employed. EIS analysis revealed an increase in resistance with increasing compound concentration, suggesting the formation of a protective film at the C–S/HCl interface. The presence of this protective coating was further confirmed through SEM-EDS analysis. PDP plots indicated a mixed-type inhibition mechanism. At 10−3 M concentrations, CO7 and CO8 demonstrated significant inhibition efficiencies of 93% and 89.6%, respectively. DFT gives insights into charge-sharing (donor–acceptor) interactions between inhibitor molecules and metallic surfaces. Dynamic molecular simulation (MDs) confirmed these results, indicating that the molecules studied adsorbed almost parallel to the Fe (1 1 0) surface.