Improving the purification of aqueous solutions by controlling the production of reactive oxygen species in non-thermal plasma; a systematic review

Abstract

Abstract Treatment with non-thermal plasma is a reliable technology to oxidize chemical impurities that exist in polluted water, wastewater, and leachate, those degradation-resistant and cannot be removed by conventional treatment methods. In this study, the effective factors affecting in the formation ofreactive oxygen species in non-thermal plasma treatment process, as a new advanced oxidation process method explianed. In this manner, all associated manuscripts existed in the main databases including Google Scholar, Science Direct, PubMed, and Open Access Journal Directory from 1990 until 2022 were explored. The utilized keywords were involved non-thermal plasma, Cold plasma, Measurement, •OH, O3 and UV. Overall, 8,813 articles were gathered and based on the relevance titles and abstracts, 18 paper were selected for further reviewing. In several studies, plasma techniques have been used to treat water, wastewater and leachate, but few studies have evaluated the factors influencing the production of ROS species by non-thermal plasma. The non-thermal plasma destroys pollutants by reactive free radicals spices (hydroxyl, hydrogen atoms, etc.) a combination effect of strong electric fields, energetically charged particles, and ultrasound. Some factors such as water vapor, hydraulic retention time, inter-electrode spacing, discharge power density, and aeration of the effluent as well as use of catalyst have direct effect on the reactive oxygen species formation. If these factors controlled within the best ranges, it will promote the oxidizing radical production and system performance. Also, high-energy electrons and oxidizing species produced in the cold plasma system can well degrade most of pollution in water and wastewater.