A pH and conductivity-based method for fast and accurate NO_x^- estimate in plasma-treated water

The number of plasma applications have had growth in recent years, making them an increasingly valuable and relevant technology in various fields. Plasma is applied directly or to different mediums that can later be used for different applications.

During water treatment, reactive oxygen and nitrogen species (RONS) are created and dissolved in water, resulting in a conductive solution. Their interaction mechanisms make PTW a chemically active solution for different treatments. Accurately estimating the species created during plasma treatment is critical for tailoring the treated water to different applications.

Following these species can be done in many ways, including strips, colorimetry, luminescence, absorption spectroscopy, and others. While some methods offer fast estimate of RONS, they often lack accuracy and more complex methods require expensive equipment and more time. This is why new accurate methods to follow the species are of high importance.

Conductivity and pH are parameters often followed in PTW research. The new proposed method utilizes pH and conductivity measurements by using Kohlrausch’s law of independent ion migration with the assumption that the main charged species in the water are H⁺ and NO_x^-. By using these specific PTW parameters, we can accurately and rapidly determine the concentrations of NO_x^- species up to 1mM. The new method shows consistent results with those achieved using UV absorption spectroscopy, proving the method both fast and accurate.