Experimental and quantum studies on [BMIM] BF4 ionic liquid as corrosion inhibitor for mild steel in H2SO4 solution

Ionic liquids have attracted considerable attention in recent years. They are described as having many potential applications. In particular, they have been identified as powerful solvents for green synthesis, and electrically conducting fluids. Salts that are liquid at near-ambient temperature are important for electric battery applications, and have been considered as sealants due to their very low vapor pressure [1, 2]. In this work the inhibition behavior of [BMIM]BF4 (1-butyl-3-methyl imidazolium tetrafluoroborate) on mild steel corrosion in 0.5 M H2SO4 as corrosive solution was evaluated by the weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques in the absence and presence of different concentrations of [BMIM]BF4. Surface analysis using energy dispersive X-ray (EDX) and scanning electron microscope (SEM) allowed us to clarify the mechanistic aspects and evaluate the relative inhibition efficiency. Density functional theory (DFT) calculations were performed to gain some insight into the interactions of [BMIM]BF4 with the St-37 mild steels surface. Results obtained from experimental and quantum studies are in good agreements. This work has shown that the [BMIM]BF4 has an desirable inhibition effect on St-37 mild steel corrosion in corrosive solution.