Electrical Discharges for Environmental and Medical Applications

Non-equilibrium plasma generated by pulsed electrical discharges in gases and in liquids induces a number of processes that can be utilized in various environmental, biological or medical applications. Researchers at IPP AS CR are focusing on electrical discharges in water and their potential applications for removal of chemical and biological contamination from water. Research work involves complex study of the physical and chemical processes induced by the electrical discharges in water and their effects on model organic compounds and microorganisms as well as development of electrical discharge reactors. Pulsed electrical discharges are generated in various electrode geometries either directly in the liquid phase or in the gas phase in close proximity to the liquid surface or in both phases simultaneously. Special metallic electrodes covered by thin layer of porous ceramic sprayed by thermal plasma spraying were developed in order to generate multichannel discharge in water (see Fig.). Electrical discharges generated directly in the liquid were demonstrated to initiate a variety of physical and chemical effects in water including the high electric field, intense ultraviolet radiation, overpressure shock waves and, of particular importance, formation of various reactive chemical species such as radicals (H·, O·, OH·) and molecular species (H2O2, H2, O2, O3). Depending on the type of electrical discharge these reactive species and physical conditions are involved at effective degrading of organic compounds and in the destruction and inactivation of microorganisms in water (e.g. bacteria). In the field of focused shock wave generated by the electrical discharges in water, medical application possibilities are investigated, specifically the influence on the growth of cancerous tissues. This subject continues previous successful research on focused shock wave generators for non-invasive removal of bodily concrements, mainly kidney stones.