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Start date: 2020Subject: search.filters.subject.Pulsed corona discharge.

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    Indigo Carmine Degradation in Water Induced by a Pulsed Positive Corona Discharge in Air: Discharge and Postdischarge Effects.
    (2022) Ferreyra, Matías; Fina, Brenda; Milardovich, Natalio; Chamorro, Juan Camilo; Santamaría, Brenda; Balestrasse, Karina; Prevosto, Leandro
    In recent years, one of the fastest growing technological applications in the field of nonthermal plasmas is the degradation of organic contaminants of water. In this work, the degradation of indigo carmine (IC) in water induced by a pulsed positive corona discharge operating in ambient air is reported. Degradation levels in different volumes of IC in solution with distilled water treated with different plasma exposure times immediately after discharge (0 h), and in the postdischarge up to 24 h were examined. To explain the IC discoloration in the postdischarge phase, a chemical model was developed. The stability of the reactive species in solution nitrate (NO3 −), nitrite (NO2 −) and hydrogen peroxide (H2O2 ), as well as the properties of the solution (electrical conductivity, pH) were also measured. The results suggest that the hydroxyl radical (OH˙) as well as ozone (O3 ) are the main oxidizing species during the discharge phase, being primarily formed in the gas phase through plasma-mediated reactions and then transferred to the liquid by diffusion, while the OH˙ production in the bulk liquid through the decomposition of peroxinitrous acid (O=NOOH) plays a major role in the IC degradation during the postdischarge. These results are associated with a noticeably increase in the energy-yield values observed at 24 h post-treatment.
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    Descargas en contacto con líquidos: caracterización eléctrica de una descarga corona pulsada.
    (2021) Milardovich, Natalio; Ferreyra, Matías; Chamorro, Juan Camilo; Prevosto, Leandro
    La gran cantidad de trabajos publicados en los últimos años sobre descargas no-térmicas en (y en contacto con) líquidos,evidencia el creciente interés en este particular campo de las descargas eléctricas debido al gran número de aplicacio-nes tecnológicas. En particular, una de las aplicaciones emergentes de mayor crecimiento es el tratamiento de agua,tanto para su potabilización como para su activación, con vistas a realizar el tratamiento indirecto de alimentos y semi-llas con descargas no-térmicas; sin el agregado de sustancias químicas. En este trabajo, se presenta la caracterizaciónexperimental de una descarga corona en contacto con agua operando en régimen pulsado. Se usó una geometría tipoalambre-plano con el electrodo plano sumergido en agua. La descarga fue alimentada a través de una fuente pulsadatipo capacitiva, capaz de proveer un tren periódico de pulsos de alto voltaje (∼15 kV) y corta duración∼100 ns), conuna frecuencia de repetición de 40 pulsos/s. Se reportan y discuten resultados de las mediciones de voltaje y corrientede la descarga para diferentes condiciones de operación, y se infieren la potencia instantánea y la energía disipada en elplasma generado. Se muestran además fotografías con largos tiempos de exposición de la descarga pulsada. The large number of works published in recent years on non-thermal discharges in (and in contact with) liquids, showsthe growing interest in this particular field of electric discharges due to the large number of technological applications.In particular, one of the fastest growing emerging applications is the treatment of water, both for its purification andfor its activation, with a view to carrying out the indirect treatment of food and seeds with non-thermal discharges;without the addition of chemicals. In this work, the experimental characterization of a corona discharge in contact withwater operating in a pulsed regime is presented. A flat-wire type geometry was used with the flat electrode immersedin water. The discharge was powered through a pulsed capacitive type source, capable of providing a periodic train ofhigh voltage pulses (∼15 kV) with short duration (∼100 ns), with a repetition frequency of 40 pulses/s. The resultsof discharge voltage and current measurements are reported and discussed for different operating conditions, and theinstantaneous power and energy dissipated in the generated plasma are inferred. Photographs in the visible with longexposure times of the pulsed discharge are also shown.