Research project of Yang Yi
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Chemical and bio-industry engineer
Ph.D student since April 2010
(C. Dupont-Gillain)
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Mechanisms of competitive adsorption of biomacromolecules on metallic surfaces used in cooling circuits – influence on biocorrosion
Field problem addressed :
Cooling circuits in energy production plants inland and off-shore are subject to biofouling and biocorrosion. Copper alloy, titanium and stainless steel substrates, notably in condensers of marine power plants circulating sea water rich with mud, are exposed to severe corrosion after a few months operation. Current treatments are based on ferrous iron circulation combined with ball mechanical friction and on chlorination. This latter is limited to a concentration of 0.2 mg/l for environmental reasons and shows efficiency if regularly applied. The mode of action of chlorine is not yet fully elucidated. On the one hand, it prevents biofilm formation (biocide effect) thereby allowing the formation of a protective oxide layer. On the other hand, it directly passivates the surface of metallic materials (oxidizing effect). Biofilm formation is actually known to be initiated by accumulation of biomacromolecules at the water-material interface. Chlorination could also affect the adsorbed biomacromolecule layer, which would in turn influence biofilm formation. The properties of this adsorbed layer (nature, amount and orientation/conformation of involved biomacromolecules) are expected to depend both on the physico-chemical characteristics of the material surface and on the composition of the sea water. In particular, biomacromolecules will compete for access to the interfacial area, and biofilm formation should depend on the outcome of this competitive process.
Objectives :
Adsorbed biomacromolecules are known to play an important role in early steps of biofilm formation. Sea water is a complex medium in which many biomacromolecules may be found. The composition and properties of the adsorbed layer that will form in contact with a metallic surface will depend on the outcome of the competition occurring between these different biomacromolecules for access to the interfacial area.
The aim of the project is to better understand the mechanisms leading to the formation of adsorbed biomacromolecule layers at metallic surfaces exposed to sea water. Competitive adsorption processes will especially be taken into account. The acquired knowledge is expected to allow identifying new strategies to fight against biocorrosion.
Since chlorination is widely used to prevent biocorrosion, the effect of such treatment on adsorbed biomacromolecules will also be addressed.
