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Water pollution due to emerging organic pollutants, such as agrochemicals, has become a topic of growing interest worldwide. The increase of pollutants in aquatic systems stimulated the development of new strategies for water remediation. Plasma technology is an advanced oxidation process which has proved to be an efficient method for organic matter degradation. In this work, a novel design of a trielectrode plasma reactor based on a dielectric barrier discharge extended to a third electrode operated in ambient air is presented. The water to be treated flows through a gutter with low impedance and far from the electrodes connected to the voltage sources. The reactor operates in ambient air, and it does not rely on the use of expensive inert gases. The design of the reactor is easily scalable. The performance of the reactor, in terms of the removal efficiency and the energy yield, was tested in an aqueous solution of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D), one of the most widely used around the world. The reactor presents a good efficiency in the removal of the herbicide 2,4-D and values of energy yield of about 240 mg/kW h. [ABSTRACT FROM AUTHOR]

Interest in plasma-liquid interaction phenomena has grown in recent years due to applications in plasma medicine, water purification, and plasma-hydrocarbon reforming. The plasma in contact with liquid is generated, for example, using the plasma jets or streamer discharges. The interaction between the streamer and water can cause both physical and chemical modifications of the liquid. In this paper, the interaction between an anode-directed streamer and the de-ionized water is studied using one-dimensional particle-in-cell Monte Carlo collisions model. In this model, plasma species in both gas and liquid phase are considered as the macro-particles. We find that the penetration of the streamer head into the liquid causes ionization of water molecules by electron impact, a process which is usually ignored in the fluid models. The main charge carriers in the liquid phase are negative water ions which agree with earlier experimental and computational modeling studies. Additionally, we observe an ion-rich sheath in the vicinity of the water surface on the gas side. [ABSTRACT FROM AUTHOR]