Experimental and theoretical research on the corrosion inhibition of 1-octyl-3-methylimidazolium L-prolinate for copper in 3.5% NaCl solution

An amino acid ionic liquid, namely 1-octyl-3-methylimidazolium L-prolinate ([OMIM]L-pro), was investigated as the corrosion inhibitor of copper in 3.5% NaCl solution through electrochemical techniques, surface analysis and molecular dynamics simulation. The results showed that [OMIM]L-pro was a mixed type inhibitor with a predominantly anodic action for copper in NaCl solution, its inhibition efficiency increased with the increase of concentration, but decreased with rising temperature, the highest inhibition efficiency was up to 97.5%. The adsorption of [OMIM]L-pro on the copper surface was found to follow the Langmuir isothermal equation, and the corrosion kinetic characteristics of copper in the test solution was discussed and analyzed. Moreover, L-prolinate anion was found to play a significant role in the corrosion inhibition performance of [OMIM]L-pro, but there was a synergistic effect between L-prolinate anion and imidazolium cation, which synergistically inhibited the corrosion of copper in NaCl solution. Molecular dynamics simulation data supported the experimental results.