Dissolution of magnetite using an environmentally friendly chelant: an electrochemical impedance spectroscopy study

Ethylenediaminedisuccinic acid (EDDS), a biodegradable substitute for EDTA, was used as a chelant for dissolving magnetite and magnetite formed on iron metal surface. Dissolution was found to increase in presence of ferrous ions and depend on pH of solution, concentration of ferrous ion, EDDS concentration, applied cathodic potential and temperature. The impedance spectrum for the dissolution of magnetite film formed on iron exhibited two time constants. The first at high frequency range is ascribed to the reductive dissolution of magnetite. It is very crucial to carry out the dissolution process at the appropriate temperature to insure complete removal of oxide layer.