SUITABILITY OF IMIDAZOLIUM-BASED IONIC LIQUID FOR INHIBITION OF MILD STEEL CORROSION IN NaOH MEDIUM

This study investigated the suitability of 1-H-3-methylimidazolium p-toluenesulfonate for control of mild steel corrosion in NaOH medium. To ascertain the level of inhibitive properties, the inhibitor was characterized. Then, the efficiency of the inhibitor was examined using gravimetric measurement. It involved monitoring the attachment of inhibitor’s molecules on the mild steel and fitting the data to four physical adsorption mechanisms. Artificial neural network and response surface methodology were employed in predicting the inhibitor efficiency. Then the exact type of inhibitor was ascertained by electrochemical measurements. Analysis of the inhibitor shows that it has excellent corrosion inhibitive properties. Presence of the inhibitive ions depicts that -H-3-methylimidazolium p-toluenesulfonate is appropriate for the corrosion inhibition function. On the adsorption mechanism, Langmuir isotherm was revealed as the best fitted isotherm. It depicts physical adsorption (not chemisorption) process. The factors shared influence on the ionic liquid efficiency show parabolic curves (reflection of quadratic model). Optimum efficiency of 1-H-3-methylimidazolium p-toluenesulfonate is 92.11%. Revealed exceptional efficiency indicates that it is an appropriate inhibitive material for corrosion control of mild steel in NaOH. Electrochemical results revealed a phenomenon of ionic charge transfer in the corrosion control operation. In addition, polarization investigation showed that 1-H-3-methylimidazolium p-toluenesulfonate is a mixed-type inhibitor. Furthermore, functional density theory helped in determining attachment points of the ionic liquid’ molecules. As such, simulated mechanism of inhibitive effect of 1-H-3-methylimidazolium p-toluenesulfonate on mild steel was established.