The determination of standard Gibbs energies of transfer of cations across the nitrobenzene|water interface using a three-phase electrode

A three-phase electrode consisting of a droplet of a nitrobenzene solution of iron(III) tetraphenyl porphyrine chloride (Fe(III)-TPP-Cl) attached to a graphite electrode and immersed in an aqueous electrolyte solution was applied to determine the standard Gibbs energies of transfer of cations between water and nitrobenzene. The reduction of Fe(III)-TPP-Cl prompts the transfer of the cations from the aqueous to the organic phase. The system is chemically and electrochemically reversible.