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Influence de l'adhésion et de l'activité enzymatique du biofilm sur le comportement électrochimique des aciers inoxydables immergés en eaux de rivière

Abstract : While it is true that the Open Circuit Potential (OCP) of stainless steels increases in natural seawater, the systematic aspect of this phenomenon has not yet been demonstrated in natural freshwater. This evolution of the electrochemical behaviour is due to the colonization of the surface by microorganisms leading to modifications of the cathodic processes.
Two different enzymatic mechanisms are offered in literature : one developed in seawater and based on the enzymatic production of hydrogen peroxide and acidity within the biofilm, and the other one developed in river water and based on the deposition of manganese oxides at the surface of the material. The aim of this work was to confirm the systematic character of the increase of the OCP and to highlight the mechanism(s) responsible for this evolution, as well as to determine the influence of the adhesion of the biofilm. To achieve this, electrochemical measurements and analysis/observations of the surface were realized, both in situ, during experiments in the Seine river using an original technique of immersion, and in laboratory during adhesion experiments of wild microbial strains, coming from samples of sessile of the natural freshwater, on stainless steels.
The results of the experiments show that the two mechanisms mentioned in the literature can happen in the same water and can lead to parallel evolutions of the electrochemical behaviour. The model of production of hydrogene peroxide by glucose oxidase, creating an oxidizing and acid environment, has been adapted to the case of artificial freshwater. It enables to recreate the variations of the OCP and of the cathodic reactions but can differ from natural freshwater as to the chemical composition and electronic structure of the passive film. Finally,the study of the bioadhesive phenomenons has shown how difficult it is to obtain an electrochemically- active biofilm in laboratory.
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Contributor : Cyril Marconnet <>
Submitted on : Wednesday, April 11, 2007 - 4:21:45 PM
Last modification on : Wednesday, July 1, 2020 - 4:30:04 PM
Long-term archiving on: : Tuesday, June 15, 2010 - 4:43:52 PM

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Cyril Marconnet. Influence de l'adhésion et de l'activité enzymatique du biofilm sur le comportement électrochimique des aciers inoxydables immergés en eaux de rivière. Matériaux. Ecole Centrale Paris, 2007. Français. ⟨tel-00141130⟩

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