Corrosion inhibition efficiency and adsorption behavior of N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-alkylbenzenaminium bromide surfactant at carbon steel/hydrochloric acid interface

Three cationic Schiff surfactants namely; N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-octylbenzenaminium bromide (APS-8); N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-dodecyl benzenaminium bromide (APS-12) and N,N-dimethyl-4-(((1-methyl-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)imino)methyl)-N-hexadecylbenzenaminium bromide (APS-16) were synthesized and confirmed. The corrosion of carbon steel in 1.0 M HCl solution at 20-60 °C was studied by weight loss, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS). The results show that synthesized cationic surfactants are excellent inhibitors even with very low concentration, and the adsorption on carbon steel surface obeys Langmuir adsorption isotherm. Polarization curves reveal that the synthesized inhibitors behave as a mixed-type inhibitor. Adsorption of used inhibitors led to a reduction in the double layer capacitance and an increase in the charge transfer resistance. Thermodynamic and activation parameters were discussed. Calculated ΔG°ads values indicated that the adsorption mechanism of the prepared cationic surfactants on carbon steel in 1 M HCl solution is a chemical adsorption.