Corrosion inhibition of mild steel by the hydrolysate of an imidazoline-based inhibitor in CO2-saturated solution

Abstract

The synthesized imidazoline phosphate quaternary ammonium salt has low stability, which is spontaneously and rapidly hydrolyzed to the long-chain fatty acid amide (LFA). The hydrolysate (LFA) has been found to be an efficient inhibitor for Q235 steel against CO₂ corrosion, which yields a maximum value above 90% at a concentration of 1000 mg L⁻¹. The LFA inhibitor acts as an anodic type inhibitor and its inhibition mechanism is a “negative catalysis effect”. The heteroatoms in the acyl, amine and phosphate groups in the LFA molecule are the active centers to bond with Fe atoms to form a chemisorbed film on the steel surface.