Production of medically useful nitric monoxide using AC arc discharge

Inhaled nitric monoxide (iNO) is increasingly used as a medical treatment for acute respiratory distress syndrome. A course of the existing nitric monoxide (NO) therapy with gas cylinders could cost up to approximately $15,000 for an average of 30.2 h. Moreover, a gas cylinder containing a mixture of N₂ and NO may potentially leak NO. The objective of this study is to develop an efficient and cost-effective on-site iNO generation system. In the present setup, NO was generated by using dry air or mixed oxygen/nitrogen (O₂/N₂) and an AC power source with an output power level of 5-30 W at atmospheric pressure. The simultaneously produced NO₂ was eliminated with an ammonium sulfite ((NH₄)₂SO₃) solution. The effects of the O₂/N₂ ratio, gas flow rate, discharge gap distance, output energy density and electrode structure on NO_x concentration and the NO/NO₂ ratio are reported. The concentrations of NO and NO₂ reached 62 ppm and 3 ppm, respectively, after absorption and dilution at a gas flow rate of 6 L/min. With the present setup, the AC arc discharge produced NO_x at a stable concentration for at least 6 h using dry air.