The study of surface activity and anti-corrosion of novel surfactants for carbon steel in 1 M HCl

Three triazine-based surfactants with different hydrophobic chain lengths were synthesized and characterized, namely, 2-(n-Hexylamino)-4,6-bis (3-N, N-dimethylaminopropyl) amino-1,3,5-triazine, 2-(n-Octylamino)-4,6-bis (3-N, N-dimethylaminopropyl) amino-1,3,5-triazine and 2-(n-n-Dodecylamino)-4,6-bis (3-N, N-dimethylaminopropyl) amino-1,3,5-triazine, labelled C 6 , C 8 and C 12 respectively. The chemical structure was confirmed by FTIR and 1 H NMR. The surface activity was evaluated by surface tension. C 12 had a lower critical micelle concentration (CMC) value (0.5 mM) than C 6 and C 8 , which suggested that a lower concentration was required to reach interfacial adsorption saturation, representing better inhibition performance. The corrosion inhibition of surfactants for 45 # carbon steel in 1.0 M HCl was studied by static weight loss measurement, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. Inhibition results showed that C 12 was better than C 6 and C 8 with the maximum inhibition efficiency of 96% at 0.1 mM. The surface analysis had given a clear view of the mechanism of surfactants in inhibiting the corrosion process. Moreover, the Freundlich adsorption isotherm was the best description for the adsorption process of surfactants on 45 # carbon steel in 1.0 M HCl.