Using boron doped ionic liquids as corrosion inhibitor

Corrosion inhibitors are chemical substances that, when added in small amounts, reduce or prevent reaction with an environment in which metal is present. It is desirable that inhibitors be economical to use and effective without harming the environment or human health. Consequently, the importance of research into the availability of environmentally friendly and economical inhibitors is evident. Ionic liquids remain liquid at room temperature and lower temperatures and have a cationic component usually consisting of organic-based salts. Ionic liquids exhibit high polarity and low vapor pressure and are resistant to high temperatures. Because of these properties, ionic liquids can be used repeatedly as catalysts or solvents in many reactors and can be easily removed from the reaction environment without leaving waste. This study investigated the potential of using boron-containing ionic liquids [1-ethyl-3-methylimidazolium tetrafluoroborate (EMITFB) and 1-butyl-1-methylpiperidinium tetrafluoroborate (BMPTFB)] as corrosion inhibitors on the corrosion mechanism of St37 alloy in an acidic environment using electrochemical impedance spectroscopy (EIS), dynamic electrochemical impedance spectroscopy (DEIS) and Tafel extra polarization (TP). The change in surface morphology of the metal samples used after electrochemical measurement was investigated via scanning electron microscopy (SEM) and energy diffraction X-Ray spectroscopy (EDS), and the results of all the applied methods were compared and discussed. The findings showed that both boron cationic ionic liquids can be used as inhibitors. The inhibitor activity (% IE) values for St37 steel in a medium of 0.1 M HCl, according to the use of BMPTFB or EMITFB, were 87% and 73%, respectively. It was determined that, for corrosion in the 0.1 M HCl medium, the St37 steel exhibited approximately 15% better retention of the BMPTFB than of the EMITFB.