Electrochemical Study of Iron Deposit in Acid Media for Its Recovery from Spent Pickling Baths Regeneration

Abstract

Electrochemical technologies for the regeneration of spent pickling baths are feasible since they allow simultaneous metal deposition and acid production in the same process unit. In this work, the effect of Fe2+ concentrations on the electrochemical iron deposition from model spent pickling baths is analyzed by voltammetry switching potentials, Tafel plots and spectrum-electrochemistry studies. The analysis showed that the electrodeposition rate and potential decreased as Fe2+ concentration increased. Moreover, at higher Fe2+ concentrations, a decrease on the hydrogen evolution reaction was observed. Moreover, chemical Fe dissolution is present at all concentrations studied, due to the high corrosion rate of iron at low pH of the model bath. Thermodynamic diagrams and electrochemical tests coupled to UV-Vis analysis demonstrated the presence of iron sulfate complexes suggesting that iron deposit is conducted by an inner sphere layer mechanism.