The reduction of nitrate at a copper cathode in aqueous acid

It is confirmed that nitrate reduces to ammonia in high yield at a copper cathode in aqueous acidic perchlorate and sulphate media. At pH below 2, well formed reduction waves are observed; the process is irreversible but in the plateau region it is mass transfer controlled. Above pH 3, no reduction occurs. It is also shown that chloride, bromide and iodide ions inhibit the reduction causing the half wave potential for nitrate to be shifted to more negative potentials.