Electrochemical impedance spectroscopy of marmatite-carbon paste electrode in the presence and absence of Acidithiobacillus ferrooxidans

The electrochemical behavior of marmatite-carbon paste electrode in the presence and absence of Acidithiobacillus ferrooxidans was investigated by electrochemical impedance spectroscopy (EIS) measurement. The effects of the concentration of Fe3+ ions, bacterial strain and temperature on the EIS spectra of the marmatite electrode were examined. The experimental data indicated that the impedance diagrams of the marmatite electrode in the different electrolytes had the similar features with two semicircles in the higher frequency range and a line in the lower frequency range. An equivalent circuit has been considered for the analysis of the EIS spectra of the marmatite electrode in the solution of 10 g/L Fe2+ ions without and with microorganisms. The fitting of experimental data along with a preliminary estimation for the characteristic parameters of the impedance model could validate the proposed mechanism, which suggested that the dissolution of marmatite proceeded by the similar kinetic processes occurring in the marmatite-solution interface in the different systems during the leaching process.