Adsorption and performance of ammonium-based ionic liquids as corrosion inhibitors of steel

Methyltrioctylammonium methyl sulfate (TMA) and trimethyltetradecylammonium methyl sulfate (TTA) were synthetized as novel quaternary-ammonium-derived ionic liquids (ILs) in order to be evaluated as corrosion inhibitors (CIs) of API-X52 steel in 1 M HCl. Electrochemical techniques were used to evaluate the anticorrosive effect, finding that TMA and TTA worked as mixed-type CIs and inhibited the corrosion process depending on the temperature, immersion time and IL concentration, being remarkably effective at 40 degrees C, which was attributed to the high thermal stability of the methyl sulfate anions. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to elicit the chemical composition and surface morphology of steel in the presence of CIs whose adsorption processes involved strong electrostatic interactions between the metal, chloride ions, methyl sulfate anions and quaternary ammonium cations in the ILs. The results allowed the development of a corrosion inhibition mechanism. (C) 2018 Elsevier B.V. All rights reserved.