Determination of Faradaic current through a bipolar electrode in acidic bichromate

In order to elucidate the factors determining the proportion of the Faradaic current to the applied one, the Faradaic current through a bipolar electrode was measured under various conditions in acidic bichromate solutions. A modified electrode was adopted for measurement of the Faradaic current in a compactly packed cell. The bipolar electrodes consisted of graphite disks with many drilled holes. The by-pass resistance, the electric resistance of the electrolyte filling the holes, widely varied with functions of the diameter and the number of the holes and the thickness of the electrodes. The interelectrode gaps were also varied. The proportion of the Faradaic current to the applied one was substantially determined by the by-pass resistance independent of the diameter and the number of holes, and the thickness of the electrode. As continuous electrolysis was carried out in the acidic bichromate solutions, the proportion of the Faradaic current remarkably decreased in low concentrations of Cr(VI) and this was responsible for the decrease in the gross current efficiency in the bipolar electrode cell.