Impact of Porous Copper Metallic Interface on Ammonium Ion ( ${\mathrm{NH}}_{4}^{+})$ Production in Water Medium Through Nitrogen Gliding Arc Plasma

This work investigated the ammonium ion (
${\mathrm{NH}}_{4}^{+})$
formation through the interaction of nitrogen (N
$_{2})$
gliding arc plasma with the water surface, supplemented with and without a porous copper (Cu) metal foam interface. For this purpose, 3-D open-cell porous Cu metal foam (40 PPI) was used as the interfacial material. The experiment was performed at fixed discharge power (44 W), N
$_{2}$
flow rate (10 slpm), and interaction time (10 min). The concentration of
${\mathrm{NH}}_{4}^{+}$
present in plasma-treated water was determined by ion chromatography. The results showed that the ammonia concentration increased by 2.46 times when the Cu metal foam interface was introduced. The wet Cu metal foam interface during N
$_{2}$
plasma exposure enhanced
${\mathrm{NH}}_{4}^{+}$
production rate and production efficiency from 1.1 to 2.9 mg/h and 0.031 to 0.065 g/kWh, respectively. The Cu metal foam surface was examined before and after the processes with X-ray diffraction (XRD) and a field emission scanning electron microscope equipped with an energy-dispersive X-ray spectrometer (FESEM-EDS) to gain a better understanding of the structural changes and predict the mechanism of N
$_{2}$
species formation under the four-phase reaction interface. The reproducibility of
${\mathrm{NH}}_{4}^{+}$
concentration was almost ideal for the first two cycles and gradually decreased as the testing cycle increased due to the formation of cuprous oxide (Cu
$_{2}$
O) on the Cu foam surface as validated by XRD and EDS results.