VOLTAMMETRIC MICROELECTRODES FOR BIOCORROSION STUDIES

Understanding various biocorrosion mechanisms requires direct measurem ent of chemical concentrations and profiles within thin biofilms or di screte biodeposits. A gold-based mercury microelectrode was developed for simultaneous measurement of dissolved O-2, Mn, Fe, S(-II), and low pH using square wave voltammetry. It was constructed by electroreduci ng NS(II) on a gold wire of 25-mu m diameter encased in glass. By moun ting the electrode on a computerized micromanipulator, vertical microp rofiles of the key redox species were measured with 10-mu m depth reso lution across marine biofilms formed on metal coupons. Various interfe ring factors and experimental parameters of the voltammetric measureme nts were reviewed Results revealed the heterogeneous nature of the bio film and complex microbially mediated heavy metal (Mn and Fe) cycles w ithin the film system Data interpretation provided further insight int o the mechanism of microbiologically influenced metal corrosion.