Adsorption and Corrosion Inhibition Performance by Three New Ionic Liquids on API 5L X52 Steel Surface in Acid Media

In the present work, three new ionic liquids (ILs) were tested as corrosion inhibitors (CIs): 1,2-dimethyl-3-decylimidazole iodide (DDI), N-triethyl methylammonium acetate (TMA) and N-triethyl methylammonium laurate (TML). The tests were carried out in 1.0 M solutions of sulfuric acid (H2SO4) and hydrochloric acid (HCL) in order to inhibit the corrosion of API 5L X-52 steel. The corrosion inhibitors (Cis) were evaluated by Tafel polarization and polarization resistance (R-p). The Tafel polarization results confirmed that DDI, TMA, and TML inhibited the steel corrosion and worked as mixed inhibitors in both corrosive media. In 1.0 M H2SO4, DDI featured the best inhibition efficiency (IE), which ranged from 57 to 95%, whereas TMA in 1.0 M HCl showed the best IE, which was within the 30-70% range. The IE obtained by R-p in 1.0 M H2SO4 was increased as a function of time, while in 1.0 M HCl, it was inversely proportional. The adsorption displayed by DDI, TMA, and TML on the API 5L X52 steel surface was both physical and chemical, which was obtained from different adsorption isotherms.