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Influence of proteins adsorption on the electrochemical behaviour and the surface chemical composition of 70Cu-30Ni alloy in static artificial seawater

pubblicazioni - Articolo

Influence of proteins adsorption on the electrochemical behaviour and the surface chemical composition of 70Cu-30Ni alloy in static artificial seawater

Copper alloys often used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation.

Copper alloys often used in cooling circuits of industrial plants can be affected by biocorrosion induced by biofilm formation. The objective of this work was to study the influence of protein adsorption, which is the first step in biofilm formation, on the electrochemical behaviour of 70Cu-30Ni (wt. %) alloy in static artificial seawater and on the chemical composition of oxide layers. For that purpose, electrochemical measurements performed after 1 h of immersion were combined to surface analyses. A model is proposed to analyse impedance data. In the presence of bovine serum albumin (BSA, model protein), the anodic charge transfer resistance deduced from EIS data at Ecorr is higher, corresponding to lower corrosion current. Without BSA, two oxidized layers are shown by XPS and ToF-SIMS: an outer layer mainly composed of copper oxide (Cu2O redeposited layer) and an inner layer mainly composed of oxidized nickel, with a global thickness of ~ 30 nm. The presence of BSA leads to a mixed oxide layer (CuO, Cu2O, Ni(OH)2) with a lower thickness (~ 10 nm). Thus, the protein induces a decrease of the dissolution rate at Ecorr and hence a decrease of the amount of redeposited Cu2O and of the oxide layer thickness.

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