Adsorption and Corrosion Inhibition Behaviour of Zwitterionic Gemini Surfactant for Mild Steel in 0.5 M HCl

The adsorption and corrosion inhibition behaviour of zwitterionic gemini surfactant, 2-decyl phosphate-1-(N, N-dimethyl, N-tetradecylammonium) ethane on mild steel in 0.5 M HCl in the temperature range of 25-65 degrees C has been investigated. The zwitterionic gemini surfactant was synthesized, purified and characterized using nuclear magnetic resonance (NMR) spectroscopy. Surface tension measurements were carried out to evaluate the surface and thermodynamic properties of the surfactant in 0.5 M HCl. Weight loss measurements, potentiodynamic polarization measurements, electrochemical impedance (EIS) measurements and thermodynamic/kinetic parameters were applied to elaborate the adsorption and corrosion inhibition mechanism of the surfactant. Surface morphology of the mild steel specimen corroded in unihibited and inhibited acid was also evaluated using scanning electron microscopy (SEM). The zwitterionic gemini surfactant acts as an excellent inhibitor for mild steel corrosion in 0.5 M HCl; the inhibition efficiency (IE) of inhibitor is concentration and temperature dependent. The evaluated gemini surfactant performed as a mixed-type corrosion inhibitor. The adsorption of surfactant on mild steel surface obeyed Langmuir's adsorption isotherm. The calculated thermodynamic parameters for adsorption reveal a strong interaction between the inhibitor and the mild steel surface.