Abstract

ABDEL HAMEED, R.S.. Port. Electrochim. Acta [online]. 2011, vol.29, n.4, pp.273-285. ISSN 0872-1904.

Expired ranitidine was tested as a corrosion inhibitor for mild steel in 1 M HCl using different techniques: weight loss, potentiodynamic polarization, open circuit potential and electrochemical impedance spectroscopy. The polarization resistance (R_p) value increased with increase in the concentration of the inhibitor. Results obtained revealed that ranitidine performed excellently as a corrosion inhibitor for mild steel in this medium at 303 K. The protection efficiency increased with increasing inhibitor concentration. The maximum protection efficiency of 90% has been obtained at 400 ppm. On the other hand, the efficiency decreases with increasing temperature. The adsorption of the inhibitor on the mild steel surface followed Langmuir adsorption isotherm model. The activation and thermodynamic parameters of dissolution and adsorption were calculated and discussed. The negative value of ΔG_ads (-40 kJ mol-1) indicates spontaneous chemical adsorption. Results obtained from polarization, EIS and weight loss measurements are in good agreement with each other.

Keywords : mild steel; acid corrosion; weight loss; drugs; polarization.

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