Effects of the number of imidazoline ring and the length of alkyl group chain of imidazoline derivatives on corrosion inhibition of carbon steel in HCl solution: Molecular simulation and experimental validation

Abstract

The effects of the number of imidazoline ring and the length of alkyl group chain of imidazoline derivatives were investigated using quantum chemical calculation, molecular dynamics simulation and experimental techniques. Three corrosion inhibitors including symmetrical lauric acid imidazoline (SAI), tetracyclic lauric acid imidazoline (LAI), and symmetric stearic acid imidazoline (SPI) were synthesized and their inhibition performance was evaluated using weight loss measurement, electrochemical techniques and surface characterization. The results show that SAI and LAI with the same length of alkyl group chain, LAI with more imidazoline rings could supply a better inhibition performance since the increase of active sites. The increase of active sites attached to the metal surface may also change the distribution of corrosion inhibitor, which could limit inhibition performance improvement. While, SAI and SPI with the same number of imidazoline rings, SPI with longer alkyl group chain shows a better inhibition efficiency due to the better hydrophobic performance of alkyl groups. Among the three inhibitors, SPI shows the best inhibition performance, indicating that the alkyl group chain length affects the inhibition performance more obvious than the number of the imidazoline rings.

Keywords

• Imidazoline derivatives
• Corrosion inhibition
• Imidazoline ring
• Alkyl group chain