Coulometric titration oxygen partial pressure

Such an electrochemical arrangement can also be used to transport oxygen from one electrode to the other by the imposition of an externally applied potential. This technique, known as coulometric titration , has been used to prepare flowing gas mixtures of oxygen/argon with a controlled oxygen partial pressure, to vary the non-stoichiometry of oxides, to study the thermodynamics of dilute oxygen solutions in metals, and to measure the kinetics of metal oxidation, as examples. 

The zirconia-based pump-sensor device can be used for controlling the oxygen partial pressure in closed systems typical applications include the oxygen permeation flux measurements, oxygen monitoring in molten metals, and coulometric titration. 

By coulometric titration of oxygen at constant temperature inside or outside of chamber through the current electrodes, the new oxygen partial pressure in chamber can be established and determined by voltage U2) measured on potential electrodes (Ugi). Then the changed oxygen content of solid oxide material (A ) can be calculated for constant temperature as follows ... 

FIGURE 9.4. Experimental arrangement for the coulometric titration and emf measurements of the ternary systems Y-Fe-O and Dy-Fe-0. A double electrolyte cell is employed to avoid oxygen permeation from the outside air to the sample. The oxygen partial pressure in the intermediate gas gap is automatically controlled by a potentiostat to have the same pressure as over the sample. A current is passed to that purpose through the outer electrolyte. 

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