Assessment of reactive species concentrations in plasma-treated water: a pH and conductivity-based method validated by absorption spectroscopy

To assess the species in plasma-treated water, two methods were compared: calibrated absorption spectroscopy and a method using pH and conductivity to determine the amount of dominant reactive species in the water. A function fitting method was developed for the analysis of the absorption spectra based on solutions with known concentrations. The influence of plasma treatment time on demineralized water and the NOx- concentration was studied using the two methods; the results in both cases show an almost linear growth with time. The method, utilizing pH and conductivity, shows consistent results with those achieved using UV absorption spectroscopy in considerably less time and in a more cost-efficient manner.