Inhibitive effect of some gemini surfactants on mild steel corrosion in acid solutions

Abstract

Four gemini surfactants namely N-trimethyl butane-diyl-1,2-ethane-bis-ammonium bromide (BEAB), N-hexane-diyl-1,2-ethane-bis-ammonium bromide (HEAB), N–dodecane-diyl-1,2-ethane-bis-ammonium bromide (DDEAB) and N-hexadecane-diyl-1,2-ethane-bis-ammonium bromide (HDEAB) were synthesized in the laboratory and their influence on the inhibition of corrosion of mild steel in 1 N hydrochloric acid (HCl) and 1 N sulphuric acid (H₂SO₄) was investigated by weight loss, potentiodynamic polarization and electrochemical impedance spectroscopy techniques. The values of activation energy and free energy of adsorption of all the compounds were calculated to investigate the mechanism of corrosion inhibition. The results of potentiodynamic polarization studies revealed that all the compounds were mixed type inhibitors and inhibit the corrosion of mild steel by blocking the active sites of the metal. The adsorption of all the compounds on mild steel surface in both the acid solutions was found to obey the Langmuir adsorption isotherm. The inhibition efficiency of the compounds was found to vary with their nature and concentration, solution temperature, immersion time and acid concentrations.