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.