Study On The Inhibition Mechanism Of Biofilm Adhesion Under Cathodic Polarization

Marine corrosion and biological fouling are two major problems encountered by human beings in the development and utilization of ocean resources. Cathodic polarization is regarded as an environmentally friendly and efficient antifouling method. Meanwhile, it can also be effective to protect metal materials from corrosion under proper cathodic polarized potentials.Although the effect of cathodic polarization on biofilm adhesion has been studied, there is no accepted mechanism of action. This work mainly studied the effect of oxygen reduction reaction (ORR) and electrostatic force.Firstly, in this study, fluorescence microscope, scanning electron microscopy (SEM), open circuit potential (OCP) and potentiostatic polarization were used to study the interactions between biofilm adhesion and the cathodic potentials in the natural seawater. Then, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were used to investigate the characteristics of ORR under cathodic polarization and its effect on biofilm adhesion. The last, this work studied the effect of electrostatic force on biofilm adhesion. Potentiostatic polarization and fluorescence microscope were used to investigate the influence of cathodic polarization on the adhesion of sulfate reducing bacteria (SRB) and the influence of stirring under cathodic polarization on aerobiotic biofilm inhibition.It can be concluded that the adhesion of microorganisms on electrode surface causes the ennoblement of open circuit potential, which provides a new method to detect the biofilm adhesion in the early stage. Cathodic polarization can effectively inhibit biofilm adhesion under proper polarized potentials, and the effective polarized potentials for stainless steel (SS) are in the potential range of cathodic protection. In addition, ORR plays a key role in inhibiting biofilm adhesion. The enrichment of OH" and H2O2near electrode surface is responsible for inhibiting biofilm adhesion, and they may make different contributions for different reaction pathways of ORR. Electrostatic force is not the main mechanism for inhibiting biofilm adhesion and cathodic polarization fails to significantly inhibit the adhesion of SRB under anaerobic conditions. Anodic reactions have no effect on biofilm adhesion. In addition, strategies which can promote the ORR and enhance the enrichment of ORR products are in favor of inhibiting aerobiotic biofilm adhesion, such as stirring, oxygen bubbling.