INFLUENCE OF ANODE MATERIAL ON CURRENT YIELD DURING FERRATE(VI) PRODUCTION BY ANODIC IRON DISSOLUTION .3. CURRENT EFFICIENCY DURING ANODIC-DISSOLUTION OF PURE IRON TO FERRATE(VI) IN CONCENTRATED ALKALI HYDROXIDE SOLUTIONS

The dependence of the current efficiency for the oxidation of a pure i ron (99.95%) anode to ferrate(VI) ions in 14M NaOH was measured in the region of bubble induced convection for the temperature range 20 to 5 0 degrees C. The highest current yield obtained after 180 min electrol ysis was 60% at a current density of 2.3 mA cm(-2) and a temperature o f 30 degrees C. The same current yield was found at a current density of 4.5 mA cm(-2) and a temperature of 40 degrees C. The dependence of the ferrate(VI) current yields on the NaOH concentration in the electr olyte solution was studied in the range 12 to 17M. The optimum concent ration was found to be 16M. The quasistationary anodic polarization cu rve of pure iron in the transpassive potential region was measured. Ap parent oxygen evolution starts at a potential 110 mV higher than for w hite and grey cast iron anodes.