Brönsted acid ionic liquid: Electrochemical passivation behavior to mild steel

Abstract Bronsted acid ionic liquid (BAIL) 3-methyl-1-(4-sulfonic acid) butyl imidazolium bisulfate, a promising acid catalyst instead of conventional acid, was investigated with respect to the corrosion ability to Q235 steel. A wide passive range could be observed by electrochemical tests even when increasing temperature or diluting IL with water. The corrosion morphology and elemental compositions of the corroded surface were studied by SEM-EDX, XPS depth profiling and its possible electrochemical passivation mechanism was proposed.