Influence of bovine serum albumin in sulphuric acid aqueous solution on the corrosion and the passivation of an iron-chromium alloy

The adsorption of bovine serum albumin (BSA), and its influence on the electrochemical behaviour in deacrated 0.05 M H2SO4 solution of a ferritic stainless steel, Fe-17Cr, was studied by electrochemical methods (time dependence of the corrosion potential E-cor, polarization curves, EIS) and surface analysis techniques (PM-IRRAS, XPS). The electrochemical measurements show a corrosion inhibition by the BSA at E-cor. The charge transfer resistance decreases and hence the corrosion current of the alloy increases with immersion time at E-cor, but this phenomenon is much less marked in the presence of BSA. Impedance measurements performed after passivation of the alloy at 0 V versus SSE show that the presence of protein has no effect on the electrochemical behaviour of the passivated alloy surface. Surface analysis of the stainless steel samples by PM-IRRAS and XPS shows that chemically intact BSA molecules are adsorbed on the surface at E-cor and 0 V. The amount of adsorbed BSA is quite similar at both potentials. All these results demonstrate that the adsorption of BSA takes place on the Fe-17Cr surface both at the corrosion potential and in the passive region, and the BSA has a corrosion inhibition effect when the surface is not fully passivated. (c) 2005 Elsevier Ltd. All rights reserved.