Heptadecyl-tailed mono- and bis-imidazolines: A study of the newly synthesized compounds on the inhibition of mild steel corrosion in a carbon dioxide-saturated saline medium

The study compares, for the first time, the corrosion inhibition properties of a diethylenetetramine-derived imidazoline (I), and tetraethylenepentamine-derived imidazoline (II) and bis-imidazoline (III), all having heptadecyl pendants as hydrophobes. The newly synthesized imidazolines show excellent inhibition efficiencies against the corrosion of mild steel in 0.5 M sodium chloride solutions saturated with carbon dioxide. The inhibition efficiencies increased with the increasing temperature. At a concentration of 100 ppm at 40 °C, imidazolines I, II, and III imparted inhibition efficiencies of 84, 95 and 96%, respectively. The imidazolines cover most of the steel surface before their critical molar concentrations are reached.

Graphical abstractThe study compares the inhibition of mild steel corrosion in a carbon dioxide-saturated saline medium.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► New mono- and bis-imidazolines having heptadecyl pendants have been prepared. ► Inhibition of mild steel corrosion by the imidazolines in NaCl–CO2 is compared. ► Imidazolines cover most of the metal surface before reaching their CMCs. ► At a 100 ppm concentration at 40 °C, the bis-imizdazoline provided a 96% IE. ► Bis-imidazoline gave better protection than the mono-imidazolines.