Inhibitive effect of ester-quats surfactants in the series of (alcanoyloxy)propyl n-alkyl dimethyl ammonium bromide on the corrosion of iron in acid medium

• We synthesize new surfactants in the series of (alcanoyloxy) propyl n-alkyl dimethyl ammonium bromide.
• We study the effect of this kind of surfactant on the inhibition of iron corrosion in aggressive medium.
• We use weight loss, polarization and impedance spectroscopy methods to perform this study.
• We study the effect of the concentration of surfactant on the inhibition efficiency of iron corrosion.
• We determine thermodynamic and activation parameters related to corrosion process.

Ester-quats surfactants in the series of (alcanoyloxy) propyl n-alkyl dimethyl ammonium bromide referred as LC3Cm (where m is the hydrocarbon chain lengths 8, 12 and 14) were synthesized and characterized by the usual spectroscopic methods (RMN, IR, MS). Their critical micellar concentrations were determined by conductimetric measurements. The inhibitory effect of these ester-quats on the corrosion of iron in 1 M HCl was investigated using weight loss, resistance, electrochemical polarization and electrochemical impedance methods. Results obtained show that these compounds are good corrosion inhibitors and the high inhibition efficiencies were observed around their critical micellar concentrations (CMCs). The effect of temperature on the corrosion inhibition of iron has been also studied in the temperature range [20–60 °C] and then the activation energies in the absence and presence of different concentrations of surfactants have been evaluated. Kinetic and thermodynamic parameters of adsorption were also determined and discussed. The surface morphology of iron samples immersed in 1 M HCl in the absence and in the presence of inhibitor at various concentrations was studied by scanning electron microscopy (SEM).

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