Influence Of Marine Aerobic Biofilm On Electrochemical Behavior Of316L Stainless Steel

With the expanding scale of marine development, facilities in marine petroleumexploitation (such as oil production platform, oil and gas pipeline in seabed,steamships, et al.) are invested increasingly and continually. Metal materials becomemore and more widely applied in marine environment, but the adhesion of marinemicroorganism makes the media environment worse. So far, the study of microbialinfluence on the metal material are nearly100years, but its mechanism consists ofmany uncertainty with the combination of multiple factors because of the complexityof marine environment. Seawater dissolving oxygen is proved to be oxygen enrichedenvironment, which is conducive to the growth of aerobic microbe, therefore, thestudy of aerobic microbial effects on metal materials is brought to the forefront. Theirinfluence on stainless steel includes the ennoblement of open circuit potential and thecatalysis of cathodic oxygen reduction. Most of literatures don’t establish relationshipbetween the two phenomena and corrosion mechanism of metal materials.In this paper, the influence of aerobic biofilm on the electrochemical behaviour of316L stainless steel were studied, including open circuit potential ennoblement andcatalysis of the cathodic oxygen reduction, taking filtering natural seawater from thesecond bathing beach in Qingdao and P. aeruginosa PAO1respectively cultivated inlaboratory as experimental medium, and316L stainless steel as experimental material.Using electrochemical techniques including open circuit potential(OCP),electrochemical impedance spectroscopy(EIS), polarization curves, cyclicvoltammetry(CV). And combining with surface observation techniques consisting ofscanning electron microscopy(SEM), energy dispersive X-ray spectroscopy(EDS),and fluorescent observation. It was confirmed that the adhesion of natrual marineaerobic biofilm on316L stainlss steel in two months induced its open circuit potentialennoblement firstly, and negtive/positive reaction process were changed. The EISindicated that the marine biofilm could restrain the crossive tendency of316L SS.Further, by adding NaN3respiratory inhibitors in natural seawater system,theinfluence of microbial respiration process on stainless steel cathodic oxygen reductionand the stainless steel corrosion was studied. And selected a typical aerobic bacteria innatural seawater Pseudomonas aeruginosa PAO1as model bacteria to make researchof its influence on316Lstainless steel, which indicated that the aerobic biofilmformed by PAO1could catalyze oxygen reduction,simultaneously restrain the316LSS to corrupt in its life cycle.