Patent ID: 7341655
Filing Date: 2008-03-11
Classification: C02F,C25B

Abstract:
1. A process for increasing the active surface area of at least one electrode, acting as a cathode, having a surface comprising rhodium in an electrochemical cell, which also comprises at least one balancing electrode and an aqueous alkaline electrolyte which comprises nitrate ions and halide ions; which comprises applying a sweeping voltage across the electrodes at a rate of at least 0.2 V/s, the sweeping voltage being from a lower voltage which is between the voltage at which hydrogen evolution occurs and −0.7 V to an upper voltage which is between −0.2 V and +0.3 V, all of the above voltages being with reference to a standard calomel reference electrode (V SCE ), wherein the activated electrode converts nitrate ions in the electrolyte solution to nitrogen gas and wherein the sweeping voltage is applied either continuously or at a rate of from 1 to 10 sweep cycles even 10 seconds to 5 minutes to maintain the activity of the activated electrode.