Some polymeric imidazolates from alkylimidazolium as corrosion inhibitors of API 5L X52 steel in production water

In this work, the synthesis route and evaluation of two poly(ionic liquids) (PolyILs) derived from alkylimidazolium imidazolate to be used as corrosion inhibitors (CIs) of API 5L X52 steel exposed to oil reservoir production water (PW) are discussed. The corrosion inhibition performance of the PolyILs was investigated by potentiodynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and X-ray photoelectron spectroscopy (XPS). According to the PDP analysis, it was concluded that the PolyILs could be classified as mixed-type CIs with anodic tendency, featuring maximal inhibition efficiency (η) of 80%. The adsorption mechanism occurred through the blocking of active sites by means of electrostatic attraction forces and formation of chemical bonds. The SEM and AFM surface analyses evidenced that the metal surface in the presence of the PolyILs was less damaged by steel corrosion. Finally, the XPS studies confirmed that the CI interaction with the steel surface reduced the amount of produced corrosion products such as FeOOH and/or FeCO₃.