Climate change, environmental pollution control, and resource utilization efficiency, as well as food security, sustainable agriculture, and water supply are among the main challenges facing society today. Expertise across different academic fields, technologies, and disciplines is needed to generate new ideas to meet these challenges. This “white paper” aims to provide a written summary by describing the main aspects and possibilities of the technology. It shows that plasma science and technology can make significant contributions to address the mentioned issues. The paper also addresses to people in the scientific community (inside and outside plasma science) to give inspiration for further work in these fields.

Different types of corona discharges, produced by DC of either polarity (+/-DC) and positive pulsed (+pulsed) high voltages, were applied to the removal of toluene via oxidation in air at room temperature and atmospheric pressure. Mechanistic insight was obtained through comparison of the three different corona regimes with regard to process efficiency, products, response to the presence of humidity and, for DC coronas, current/voltage characteristics coupled with ion analysis. Process efficiency increases in the order +DC < -DC < +pulsed, with pulsed processing being remarkably efficient compared to recently reported data for related systems. With -DC, high toluene conversion and product selectivity were achieved, CO(2) and CO accounting for about 90% of all reacted carbon. Ion analysis, performed by APCI-MS (Atmospheric Pressure Chemical Ionization-Mass Spectrometry), provides a powerful rationale for interpreting current/voltage characteristics of DC coronas. All experimental findings are consistent with the proposal that in the case of +DC corona toluene oxidation is initiated by reactions with ions (O(2)(+*), H(3)O(+) and their hydrates, NO(+)) both in dry as well as in humid air. In contrast, with -DC no evidence is found for any significant reaction of toluene with negative ions. It is also concluded that in humid air OH radicals are involved in the initial stage of toluene oxidation induced both by -DC and +pulsed corona.

A novel dielectric barrier discharge reactor was developed for the oxidative degradation of organic pollutants in water. Phenol, chosen as a model compound, is efficiently removed from the aqueous solution according to an exponential decay as a function of treatment time at constant voltage. The effect of different experimental variables was investigated, including the active electrodes material and size and the flow rate of air above the solution. A few intermediates and CO 2 , the final product of phenol decomposition, were detected and identified by LC/ESI-MS and FT/IR analysis. The major reactive species formed upon application of the discharge in air, the OH radical and ozone, were determined by means of specific chemical probes.

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Atmospheric plasma-based technologies are developing as a powerful means for air purification, specifically for the oxidation of organic pollutants. To achieve a better control on the emissions produced by such treatments mechanistic insight is needed in the complex reactions of volatile organic compounds (VOCs) within the plasma. An account is given here of our comparative studies of the behaviour of model VOCs in response to different corona regimes (+dc, −dc and +pulsed) implemented within the same flow reactor. Model VOCs considered include two alkanes (n-hexane and i-octane), one aromatic hydrocarbon (toluene) and two halogenated methanes, dibromomethane (CH2Br2) and dibromodifluoromethane (CF2Br2, halon 1202). Efficiency and product data are reported and discussed as well as various possible initiation reactions. A powerful diagnostic tool is ion analysis, performed by atmospheric pressure chemical ionization-mass spectrometry: it provides a map of major ions and ion–molecule reactions and a rationale for interpreting current/voltage characteristics of dc coronas. It is shown that, depending on the specific VOC and corona regime adopted, different initiation steps prevail in the VOC-oxidation process and that the presence of a VOC, albeit in small amounts (500 ppm), can greatly affect some important plasma properties (ion population, current/voltage profile, post-discharge products).