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The Inhibitive Action Of Mono And Bis-Quats Ammonium Surfactants On The Corrosion Of Iron In Hydrochloric Acid Medium

S.Alehyen, F.Benssejjay, M.EL Achouri, M.R.Infante, L.Perez

In this work, the (mono-quat) ammonium surfactant: N, N-dimethyl dodecyl ammonio-2-ethanol and the bis-quat ammonium surfactant:1,2- ethanediyl bis-(dimethyl dodecyl ammonium bromide), were synthesised. These compounds have been purified and characterised by the usual methods. Their associative properties have been investigated by conductimetric and surface tension measurements. The critical micelle concentration (cmc) of the bis-quat is lower than that of the mono-quat by one order of magnitude. The inhibitive effect of these surfactants on the corrosion of iron in hydrochloric acid was studied by weight-loss, electrochemical polarisation methods and electrochemical impedance spectroscopy. The inhibition mefficiency increase with the increase of concentration and reach a maximum value near their critical micellar concentrations. These surfactants act on the cathodic hydrogen reaction without modifying its mechanism. Nyquist plots of iron/1M HCl systems obtained by electrochemical impedance spectroscopy(EIS) indicate that the corrosion of iron is mainly controlled by charge transfer process. This study has shown that the gemini surfactant is better than its corresponding mono- quat counterpart in the inhibition due its lower critical micelle concentration. So, the application of this gemini surfactant in corrosion industrial process could lead to a dramatic reduction in the concentration of surface active compound for the same level of performance.