Comparative study of electroreduction of iron oxide using acidic and alkaline electrolytes for sustainable iron production

Sustainable iron production is largely driven by the urgency to reduce the extensive energy consumption and emissions in the iron/steel sectors. Low temperature electroreduction of iron oxide technology is thus revived since it directly utilizes (green) electrical energy with a competitive energy consumption compared to the thermochemical reduction approach. In the present work, we perform theoretical and experimental studies for comparison of electroreduction of iron oxide in aqueous alkaline and acidic electrolytes. Electrochemical reduction and deposition behavior are experimentally investigated using a lab scale cell containing an electrolyte suspended with micron-sized Fe2O3 (hematite) powders. The effects of current density and hematite mass fraction on current efficiency are evaluated, as well as the total energy consumption. Results of chronopotentiometry and cyclic voltammograms (CV) reveal the electrochemical properties of each system. The CV’s cathodic peaks, corresponding to the reduction of iron oxides to iron, are observed only in the alkaline system where the iron oxide can be reduced at about − 1.4 V (vs. Ag/AgCl). It is also found that the alkaline system has higher current efficiency (25–30% higher) and lower energy consumption (~30% lower) than the acidic system. The cleaning of the deposit is also easier for the alkaline system, resulting in an iron product of high purity. Concerning the electrochemical performances and practicality, the alkaline electroreduction system shows promising potential for sustainable iron production

Experimental Study of Iron Oxide Electroreduction with Different Cathode Material

Electrowinning is the electrodeposition of metals from their oxides which are either solvent or suspended in an electrolyte solution. It receives increasing attention in the last decade as the promotion of CO2-free metal production. The design of the electrochemical cell is essential for the process performance, e.g., Faradaic efficiency. In this experimental study, we focus on the effect of different cathode materials on the electrodeposition performance of iron. Experiments are conducted in a lab-scale parallel-plates cell with the electrolyte composed of the aqueous sodium hydroxide (NaOH) 50%wt, 18 M (pH = 14.5) and micron-sized iron oxide powder with a mass fraction of around 20%. Different electrode materials are tested as the cathode for iron electrodeposition, including copper, stainless steel, graphite, and nickel mesh plates, whilst a nickel gauze is used as the anode. Characterizations of the deposition are conducted to obtain microstructural analysis and element identification. As a result, different deposit types and morphology are observed from the experiments. Stainless steel shows the highest current efficiency. The electrolyzed iron in all electrodes shows high purity (above 98%). The results from this study provide some guidance in designing key industrial processes of iron electrowinnin

Experimental Study of Iron Oxide Electroreduction with Different Cathode Material

Electrowinning is the electrodeposition of metals from their oxides which are either solvent or suspended in an electrolyte solution. It receives increasing attention in the last decade as the promotion of CO2-free metal production. The design of the electrochemical cell is essential for the process performance, e.g., Faradaic efficiency. In this experimental study, we focus on the effect of different cathode materials on the electrodeposition performance of iron. Experiments are conducted in a lab-scale parallel-plates cell with the electrolyte composed of the aqueous sodium hydroxide (NaOH) 50%wt, 18 M (pH = 14.5) and micron-sized iron oxide powder with a mass fraction of around 20%. Different electrode materials are tested as the cathode for iron electrodeposition, including copper, stainless steel, graphite, and nickel mesh plates, whilst a nickel gauze is used as the anode. Characterizations of the deposition are conducted to obtain microstructural analysis and element identification. As a result, different deposit types and morphology are observed from the experiments. Stainless steel shows the highest current efficiency. The electrolyzed iron in all electrodes shows high purity (above 98%). The results from this study provide some guidance in designing key industrial processes of iron electrowinnin