MULTISTEP MECHANISM IN THE ELECTROCHEMICAL OXIDATION-REDUCTION OF FE-CITRATE COMPLEXES

A study was made of the electrochemical behavior of the Fe-citrate sys tem in aqueous medium using cyclic voltammetry. Potential sweeps betwe en 200 and -650 mV vs Ag/AgCl show the existence of two Fe(III)/Fe(II) redox systems. The first, with a half-wave potential close to 0 V, pr oves to be a reversible system, while the second, with a half-wave pot ential around -0.4 V, shows the characteristics of an E(r)C(i) process . Competitive reactions between hydroxy and citrate complexes of Fe(lI I) are considered. Both equilibrium measurements and kinetic evolution of the system are used in order to propose a scheme for the set of ch emical and electrode rections studied. The different behavior observed in solutions of Fe(III) or Fe(II) is suggested as a method for the ea sy electrochemical differentiation of the oxidation state of Fe in sol ution.