Inhibition Efficiency of 1-Butyl-3-methylimidazolium Bis(trifluoromethylsulfonyl)imide on AISI 316L in Strong Acid

The corrosion inhibition performance of the ionic liquid 1-butyl-3-methylimidazolium fluoromethanesulfonate (BMIFMS) on AISI 316L stainless steel was examined in the hydrochloric acid environments (1.0 M and 0.5 M HCl). The effects of BMIFMS concentration and immersion time on electrochemical behaviour were evaluated using potentiodynamic polarisation techniques over a 5-day period. Results show that BMIFMS does not significantly reduce corrosion current in 1.0 M HCl, except at the highest tested concentration (0.5 wt%), where a marked decrease in anodic current density and corrosion rate was observed. In contrast, in 0.5 M HCl, BMIFMS demonstrated a substantial inhibitory effect, with corrosion current densities reduced by up to three orders of magnitude and inhibition efficiency exceeding 99% at 0.5 wt%. The inhibition is attributed to the formation of a stable adsorbed BMIFMS layer, which is particularly effective in less aggressive corrosive media. The study highlights the influence of medium aggressiveness and ionic liquid concentration on the efficiency of corrosion inhibition.