C. Richard

Ennoblement of stainless steel in the presence of glucose oxidase: Nature and role of interfacial processes

The ennoblement of the free corrosion potential (E(corr)) of AISI 316L stainless steel which did not occur in synthetic fresh water (SFW), was observed after introduction of glucose oxidase (Gox) and glucose, or of hydrogen peroxide (H(2)O(2)). The composition of the surface was monitored using AFM and XPS, a detailed XPS analysis being based on the discrimination between oxygen of organic and inorganic nature proposed in a previous study. In H(2)O(2) medium, the main changes regarding the inorganic phase were the increase of the oxygen concentration in the passive film, the increase of the molar concentration ratio of oxidized species Fe(ox)/Cr(ox) and the growth of nanoparticles, presumably made of ferric oxide/hydroxide. In Gox medium, no significant changes were observed in both oxygen concentration and Fe(ox)/Cr(ox) ratio, but the density of colloidal particles decreased, indicating a dissolution of Fe oxide/hydroxide under the influence of gluconate. In contrast with H(2)O(2), in SFW and Gox the amount of organic compounds increased due to the accumulation of polysaccharides and proteins. The influence of glucose oxidase on the ennoblement of stainless steel is not due to indirect effects of H(2)O(2) through the change of surface composition. The E(corr) ennoblement seems to be directly due to the presence of H(2)O(2) and to the electrochemical behavior of H(2)O(2) and related oxygen species. This consideration is important for understanding and controlling microbial influenced corrosion.

Silanization with APTES for Controlling the Interactions Between Stainless Steel and Biocomponents: Reality vs Expectation

Jessem Landoulsi1, Michel J. Genet2, Karim El Kirat3, Caroline Richard4, Sylviane Pulvin5 and Paul G. Rouxhet2 1Laboratoire de Reactivite de Surface, Universite Pierre & Marie Curie -Paris VI, 2Institute of Condensed Matter and Nanosciences – Bio & Soft Matter, Universite Catholique de Louvain, 3Laboratoire de Biomecanique et Bioingenierie, 4Laboratoire Roberval, 5Genie Enzymatique et Cellulaire, Universite de Technologie de Compiegne, 1,3,4,5France 2Belgium