Effect of aging time on corrosion inhibition of cationic surfactant on mild steel in sulfamic acid cleaning solution

The stability of the 1 M sulfamic acid solutions containing a gemini cationic surfactant (12-4-12) or its monomeric counterpart (DTAB) during 23 days of storage were studied by electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD) and surface tension measurements. The EIS studies indicated that in comparison to DTAB solution, 12-4-12 solution considerably retained the corrosion inhibition during the storage period. The surface tension of DTAB solution was increased around 10 mN/m during storage while the surface tension of 12-4-12 solution was almost unchanged. The higher stability of 12-4-12 acidic solution than that of DTAB was also depicted by XRD results.

► Stability of surfactants in sulfamic acid solution regarding corrosion inhibition.
► Stability of surfactants in sulfamic acid solution regarding surface tension.
► Evaluation of surface energy of mild steel in aged and fresh acid solutions.
► Evaluation of surface morphology of mild steel in aged and fresh acid solutions.
► Characterization of the aged solutions by XRD.