Production of liquid nitrogen fertilizer by air activated plasma discharge in water

Abstract. In this study, a novel, continuous flow liquid-phase plasma discharge (CFLPPD) reactor was investigated to produce nitrate and nitrite in liquid as nitrogen fertilizer. Three operating parameters of the plasma reactor were examined including air flow rate, power applied, and treatment time, all at three levels (0.5, 1.25, 2.0 L/min for air flow rate; 100, 200, and 300W for power applied; and 20, 40, and 60 min for treatment time) using a 3x3x3 factorial design. The results showed that the production of NO3 and NO2 (NOx) increased linearly with increasing power usage under all tested air flow rates. The highest yields of NOx under three treatment times, i.e., 20, 40, and 60 min, were associated with air flow rate of 2.0 L/min and power usage of 300 W, which were 73.0, 110.8, and 136.2 mg/L, respectively. The best energy efficiency of 1.108 g-NOx/kWh was obtained corresponding to the operating condition of 2.0 L/min in air flow rate, 300 W in power usage, and 40 min in treatment time. The reported work clearly paves a way for continuous research to further improve the production efficiency of this green technique to manufacture nitrogen fertilizer for sustainable growth in crop agriculture.