Electrochemical reduction of ferric corrosion products and evaluation of galvanic coupling with iron

Ferric product powders were synthesised. The purity of each compound was controlled by FTIR and XRD analysis; the BET surface area and electrical conductivity were also reported. The galvanostatic electrochemical reduction of graphite/ferric product composite electrodes was investigated at 25 °C in mildly alkaline pH-buffered solutions containing chloride, sulphate or bicarbonate anions. The efficiency of the reduction process (FeIII-to-FeII reaction) was quantified by reporting the potential value obtained at half the transition time, Eτ/2, on the E–t transient, as a function of Qτ, the coulombic charge obtained at the end of the reduction. The possibilities for a galvanic coupling to occur have been discussed based on the reduction efficiency plots and corrosion potential values of iron in the various media.