Water treatment by cold plasma of diffuse nanosecond discharge in air at atmospheric pressure

The treatment of wastewater with atmospheric cold plasma is a promising way to purify it by neutralizing various toxic components. The degradation of an aqueous solution of methylene blue, used as a model dye, was studied. The surface treatment of the solution was carried out by a cold plasma of a diffuse nanosecond discharge in air at atmospheric pressure. It was found that the efficiency of removing pollutants increased with increasing processing time from 5 to 20 minutes. Optical UV-IR spectroscopy was used to determine the transmission of aqueous solutions before and after treatment. Experimental results showed that the transmittance of an aqueous solution of methylene blue after 20 minutes of plasma treatment with a diffuse discharge increased several times. The formation of a discharge under these conditions was also studied by analyzing the waveforms of current and voltage. It was established that regardless of the presence of a cuvette on a flat grounded electrode, a large-diameter streamer is formed in the discharge gap. If there is a cuvette with a solution on the grounded electrode, breakdown on the surface of the dielectric occurs after the streamer reaches the dielectric. In this case, the plasma channel is closed on the grounded flat electrode.

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