Abstract

This study introduces a green and sustainable method for synthesising ammonium nitrate (NH<inf>4</inf>NO<inf>3</inf>) using plasma activated water (PAW). Nitrate ions ((Formula presented.)) were generated via air plasma treatment, and ammonium ions ((Formula presented.)) were introduced using low pressure ammonia (NH₃) plasma exposure to nitrate-rich PAW in frozen form to produce NH<inf>4</inf>NO<inf>3</inf>. Results demonstrated that process parameters, including NH₃ gas pressure, applied voltage, and treatment time, significantly influenced PAW properties, with NH₃ plasma treatment time showing the most substantial impact. Extending the treatment time from 0.5–1.5 hours increased (Formula presented.) ion concentration by 134.2%, achieving a maximum of 168.2 mg L⁻¹ with an energy consumption of 74.8 mg (Formula presented.) ions kWh⁻¹. The (Formula presented.) ion concentration reached 63.5 mg L⁻¹ with an energy yield of 222 mg (Formula presented.) ions kWh⁻¹. This method achieved a total yield of 27.6 mg NH<inf>4</inf>NO<inf>3</inf> kWh⁻¹ and produced a neutral to slightly basic PAW suitable for agricultural applications, offering a promising alternative to traditional NH<inf>4</inf>NO<inf>3</inf> production processes.