Optimization of process parameters to generate plasma activated water and study of physicochemical properties of plasma activated solutions at optimum condition

Abstract

Plasma-activated water (PAW) is gaining significant attention these days due to its potential use as a disinfectant, pesticide, food preservative, cancer cell treatment, fertilizer, etc. These applications of PAW depend on its reactivity (oxidizing-potential) and electrical conductivity (EC). In the present work, we have studied the effect of process parameters, viz., air flow rate, water stirrer speed, and the temperature of water during plasma–water interaction on the reactivity and EC of PAW using a three-way full factorial design of experiments. We have also attempted to optimize these process parameters. At optimum values of these parameters, we studied how the physicochemical properties of PAW vary by changing the volume of water and discharge power. Furthermore, we studied the physicochemical properties of the plasma-activated solution (PAS) and how the EC and pH of virgin solutions affect these properties. The obtained results of the present investigation showed that the flow rate of air, plasma treatment time with water, volume of water, and plasma discharge power play a significant role in controlling the reactivity and EC of PAW. Moreover, the pH and EC of virgin solution do not have a significant (p < 0.05) impact on the reactivity of PAS. This investigation also shows the study of aging time on reactive oxygen–nitrogen species and its effect on the physicochemical properties of PAW. Additionally, observed changes in physicochemical properties, NO3− ions, and H2O2 concentration in PAW were less than 10%. However, NO2− ions and dissolved O3 concentration in PAW decreased significantly over time.