Reduction of nitric oxide at a flow-through mercury plated nickel electrode

Abstract

The electrochemical reduction of nitric oxide at a flow-through mercury-plated nickel gauze electrode in sulphuric acid was investigated. The current efficiencies of hydroxylamine, nitrous oxide and of hydrogen formation were determined. The main experimental results are: 1. The ratio between the NH 2OH and N 2O formation depends on the cd and on the flowrate of the electrolyte through the electrode, but does not depend on the H 2SO 4 concentration in the investigated range from 0.25 to 2.0 M and likewise not on the temperature. 2. The rate of the reduction of nitric oxide to NH 2OH and N 2O increases with increasing cd up to a maximum value, thereafter this rate decreases with increasing cd. 3. The ratio between the current efficiency of the NH 2OH formation and the current efficiency of the N 2O formation increases slowly with increasing cathodic potential. It seems that at low cd (much lower than the cd where the rate of the reduction of NO reaches its maximum) the reduction of NO is affected by both the electrochemical parameters and by the transport of NO to the electrode surface. However, at high current densities the reduction is dominated by mass-transport of NO only. NOH is an intermediate for both the NH 2OH and the N 2O formation.