Mn(IV) and Mn(III) Cycling In Microbiologically Influenced Corrosion

摘要

The formation of biofilms on metal surfaces has been reported to cause sustainable increases in the corrosion currents. This is accomplished through the alteration of the surface chemistry upon biofilm formation. Many mechanisms have been proposed for this aspect of microbiologically influenced corrosion. One of these mechanisms is the cycling of manganese at the metals surface. This study identifies two reactions that take place as a result of biofilm formation. These reactions are indicative of the reduction of Mn(IV) to Mn(III) and the reduction of Mn(III) to Mn(II). Of these two reactions, the reduction of Mn(IV) to Mn(III) may be responsible for the previously reported sustainable increases in the cathodic current because of its persistence over multiple polarizations. The results also suggest that organic ligands, capable of stabilizing Mn(III) in the environment, may be present in marine biofilms of Delaware Bay.