Characterization of a hyperbolic vortex plasma reactor for the removal of aqueous phase micropollutants

Abstract

The present study focuses on the characterization of a hyperbolic vortex plasma reactor through the comparison of various plasma-atmospheric regimes for the production efficiency of reactive nitrogen (RNS) and reactive oxygen (ROS) species. The research also explores effectiveness in the removal of micropollutants, including pharmaceuticals and per- and polyfluoroalkyl substances (PFAS). The technology includes several degradation mechanisms, such as advanced oxidation, ultraviolet photolysis, ozonation, electrolysis, and shockwave water purification, without the need for additional chemicals. Our results indicate that the plasma of bipolar or ‘flashover’ mode is notably more effective and efficient than both positive or negative polarity. Through the testing of various energy levels, it has been demonstrated that higher energy plasma yields lower efficiency but necessitates shorter treatment times compared to lower energy treatment. When plasma is produced under ambient atmosphere, water chemical properties change significantly in comparison to treatment under argon (Ar) or nitrogen (N2) due to the presence of both oxygen and N2 molecules. In a N2 atmosphere, the predominant formation is of RNS due to the chemical reactivity of N2 exited states, whereas under Ar atmosphere, predominantly ROS are generated. Notable advantages of this technology are its scalability and its low energy requirements. The scalability of the technology involves increasing the size of the reactor, the power and electrode count.