Inhibition of carbon steel corrosion in HCl solution using N-oleyl-1,3-propanediamine based formulation

The relatively environmentally benign ingredient diethyl-aminoethanol (DEAE) was introduced into the film forming amine (FFA) formulation based on the unsaturated diamine N-oleyl-1,3-propanediamine (NOPDA). The optimal FFA formulation was determined by orthogonal experiment. The high corrosion inhibition efficiency of 92.1% and the images of scanning electron microscopy (SEM) and atomic force microscopy (AFM) confirmed the excellent corrosion inhibition effect of the improved FFA formulation in 1.0 M HCl acidic environment. The results proved that DEAE could promote the emulsification and dissolution of NOPDA in aqueous solution and therefore facilitate its adsorption onto carbon steel surface. The weight loss experimental results showed that the adsorption of the FFA inhibitor onto metal surface was endothermic and conformed to Langmuir isotherm model. Electrochemical impedance spectroscopy (EIS) analysis proved that a protective film was formed on the surface of carbon steel to prevent the transfer of charge. Contact angle measurements indicated that the film formed on the surface of the carbon steel was hydrophobic. According to X-ray photoelectron spectroscopy (XPS) analyses and thermodynamic calculation, it is inferred that the adsorption mechanisms mainly involved chemisorption, electrostatic attraction and hydrogen bonding. The results of this study provide a good reference for the application of unsaturated fatty diamine.

Automated summary

This study introduced the environmentally benign ingredient DEAE into the FFA formulation based on unsaturated diamine, showing excellent corrosion inhibition effect in acidic environment. The results indicated that DEAE facilitated the adsorption of NOPDA onto carbon steel surface, with adsorption mechanisms involving chemisorption, electrostatic attraction, and hydrogen bonding. The protective film formed on the surface of carbon steel was found to prevent the transfer of charge, providing a good reference for the application of unsaturated fatty diamine.