Electrochemical studies of packed iron powder electrodes: Effects of common constituents of natural waters on corrosion potential

Using a powder disk electrode (PDE) made with micron-sized, high purity iron metal we investigated how the corrosion of this material is affected by solution conditions that are relevant to the degradation of contaminants in environmental remediation applications. Changes in corrosion potential (Ecorr) with time showed that low pH, high concentrations of chloride, and natural organic matter led to breakdown of the passive film. Bicarbonate caused Ecorr to decline rapidly into the active potential region, but then Ecorr rose back into the passive region over 10s of hours. The rate of decline in Ecorr was greatest at higher pHs, suggesting a specific effect of HCO3- rather than a general effect of pH.