Corrosion Protection of Tin in 1M HCl by Expired Novacid Drug-Part I

Expired Novacid drug (END) in different concentrations (0-9% (v/v)) was examined as corrosion inhibitor for tin electrode in 1M HCl at different temperatures (20 ? 60 ?C) using weight loss and potentiodynamic techniques. The morphology of the surface was analyzed by scanning electron microscope (SEM) and energy dispersive X-ray (EDS) analysis. Weight loss measurements illustrated that the inhibition efficiency increased with increasing END concentration and solution temperature. Also, adsorption as well as the inhibition process followed first-order kinetics at all concentrations and temperatures. Potentiodynamic measurements showed that END is a cathodic type inhibitor and the adsorption process was chemisorption type and obey Temkin?s adsorption isotherm at all concentrations and temperatures studied. Activation energy (E_a), enthalpy (〖∆H〗_ads^?), entropy (〖∆S〗_ads^?) and free energy of adsorption (〖∆G〗_ads^?) were calculated and discussed. Results obtained from weight loss and potentiodynamic measurements were in good harmony and confirmed that END is a good corrosion inhibitor for tin in 1M HCl solution.