A systematic review of non-thermal plasma (NTP) technologies for synthetic organic pollutants (SOPs) removal from water: Recent advances in energy yield aspects as their key limiting factor

Non-thermal plasma (NTP) is a novel oxidation method for water and wastewater treatment, which involves the interaction among free oxidative species, ultraviolet light, and synthetic organic pollutants (SOPs). So far, former review studies including the use of NTP technology for SOPs removal have only addressed the chemical inter-action, performance efficiency, and environmental applications of the NTP process. However, to the best of the authors' knowledge, one of the most crucial determinants of NTP, the energy yield, has not been systematically assessed. Herein, a comprehensive review of recent research findings provided and the systems reported in the literature have been reviewed and compared. In addition, the factors influencing the NTP oxidation systems, such as the effect of the applied voltage and frequency, pollutants' initial concentration, output power, pH and con-ductivity of the solution, time of discharge, and removal efficiency, were also reviewed, and presented in this work. We confirmed that even though NTP degradation of SOPs can be very effective, to improve the perfor-mance and energy yield of NTP, its coupling with other catalytic processes should be attempted. Furthermore, it was evidenced that the energy yield was considerably greater for the catalytic NTP technique than for the single NTP, up to x600 times more synergistic, hence future works should aim toward this direction and overcome the catalyst-related challenges.