Yang, Yi
[UCL]
Biofouling refers to the accumulation of organisms and their products onto surfaces immersed in a biological aqueous environment. It includes molecular-, micro- and macro-fouling. Molecular fouling is the initial step of biofouling, in which a conditioning film is formed by adsorption of organic biomolecules. Furthermore, surface-associated aggregates of microorganisms with their extracellular polymeric substances (EPS) are called biofilm, known to provoke the biocorrosion of metals. Chlorination is still the most common treatment to control biofouling of cooling condensers fed with fresh- or seawater in power plants, provoking harmful effects to the aquatic environment. An environmental-friendly way to replace chlorination is thus highly desired. The aim of this thesis is to design a renewable poly(ethylene oxide) (PEO)-based coating on metals (Ti, stainless steel and Al brass) used in cooling condensers, with a view to reduce biofouling. Adsorption of a PEO-poly(propylene oxide)-PEO copolymer was performed on native and hydrophobized metal surfaces. Three proteins (albumin, fibrinogen, cytochrome C) and Pseudomonas 2021, a marine bacterium, were used as model molecular- and micro-fouling agents, respectively. The results show that the adsorbed triblock copolymer prevents protein adsorption and significantly reduces bacterial adhesion on hydrophobized metal substrates, but not on native ones. The copolymer conformation plays a key role in biofouling reduction; it is believed to form a brush structure on hydrophobized substrates. In addition, proteins were highlighted as an important constituent of EPS and their conditioning films, as analyzed by X-ray photoelectron spectroscopy. This confirms the relevance of preventing protein adsorption to reduce biofouling.
Bibliographic reference |
Yang, Yi. Biofouling of metal surfaces : study of adsorbed biomolecules and prevention strategy based on renewable copolymer layer. Prom. : Dupont-Gillain, Christine |
Permanent URL |
http://hdl.handle.net/2078.1/133433 |