Direct and post-discharges in environmental applications of cold plasmas

Discharges in humid air are valuable tools for producing active species which react both at the liquid surface of the targets and in the solution. These species are responsible for a noticeable abatement of the pollutant concentration, even of recalcitrant compounds. The relevant kinetics are examined with special emphasis on Temporal Post Discharges Reactions which develop in the solution after the discharge is switched off and without supplying extra energy. The moieties responsible for this feature are discussed and arguments favour H₂O₂ and peroxynitrous acid. ONO₂H, which degrades lipoproteins is probably involved in the attacks at the bacterial membranes causing the death of the microorganisms. TPDR are also identified in case of bacterial inactivation. Plasma activated water induces inactivation of bacterial colonies even 24 h after the plasma treatment. Developments to improve the efficacy of the discharges and reduce the running costs are presented.