Abstract

The present study demonstrates the successful production of alkaline plasma-activated tap water (PATW), effectively addressing the challenge of acidity in traditional PATW for a range of applications. Through precise control of plasma-forming gases (oxygen, air, argon) and process parameters, particularly by producing PATW under sub-atmospheric pressure conditions, it becomes possible to shift the pH of acidic PATW towards the alkaline range. This transformation enhances its suitability for applications like agriculture, aquaculture, sterilization, wound healing, disinfection, and food preservation, etc. The investigation encompassed the characterization of plasma and the identification of various plasma species/radicals. The impact of different plasma-forming gases on the pH of PATW and the concentration of reactive species in PATW was thoroughly analyzed. Plasma generated using oxygen and argon resulted in the production of reducing or alkaline PATW, while the use of air and air-argon mixtures led to an acidic or oxidizing nature. The study also discussed the stability of nitrate ions, nitrite ions, and hydrogen peroxide in PATW, shedding light on their behavior over varying plasma treatment times and plasma-forming gas. Finally, the investigation explored the effects of gas flow rates, gas pressures, water volume, and plasma discharge powers on the concentration of H<inf>2</inf>O<inf>2</inf> in PATW, providing valuable insights into optimizing the production process.