Experimental and analytical study on electrolytic decomposition of HAN-water solution using graphite electrodes

This paper describes the investigation of electrolytic decomposition of hydroxylammonium nitrate (HAN)-water solution using graphite electrodes. The decomposition reaction consists of two stages. Electrical energy was consumed for 5 s before the stage 1 reaction ceased. An interesting phenomenon was observed in the stage 2 reaction where the decomposition of HAN resumed after the power supply was switched off. A series of spectroscopy and microscopy analyses confirmed that the production of nitric oxide (NO) in the stage 1 reaction causes the formation of nitrous acid (HNO2), which leads to a further autocatalytic reaction. The reaction mechanisms were proposed and compared with the case of using copper electrodes. Graphite electrodes were demonstrated as more energy efficient in initiating the electrolytic decomposition of HAN-water solution as lower energy consumption (342 J) was achieved in comparison to copper electrodes (1926 J). (C) 2019 Elsevier B.V. All rights reserved.