Inhibition Behavior of Imidazoline Corrosion Inhibitor Synthesized from Oleic Acid

An imidazoline corrosion inhibitor was synthesized from oleic acid and diethylenetriamine. The infrared spectrum of the inhibitor was measured to analyze the functional groups and infer the molecular structure using a fourier transform infrared spectrometer. Weight loss method, Tafel curve extrapolation and EIS technology were used to investigate the inhibition performance and inhibition mechanism of the synthetic inhibitor in the simulated gas field water environment. The results showed that the strong imidazoline characteristic absorption peak was observed in the infrared spectra of the synthetic inhibitor. Lone-pair electrons, which can combine with the metal atom to form a strong chemical adsorption layer, were presented in the nitrogen atom of the synthetic inhibitor. The inhibitor had strong inhibition efficiency on the Q235 sample in the simulated gas field water environment. The inhibition efficiency was up to 85% when the concentration of the inhibitor was only 100 mg·L-1, and increased with the inhibitor concentration. The inhibitor molecules were adsorbed on the metal surface and formed a film, then prevented the adsorption of the aggressive ions and diffusion of oxygen atoms on the metal surface, which played the main role for protecting the metal. The synthetic imidazoline corrosion inhibitor is an anodic inhibitor for Q235 in the simulated gas field water environment.