Treatment of an Aqueous Solution of Methylene Blue in the Droplet-Film State by Pulsed Barrier Discharge

Abstract

The influence of various factors that can affect the efficiency of pulsed barrier discharge treatment in the air of atmospheric pressure of a model sample of contaminated water in the droplet-film state was investigated. The impurity in the water was an organic dye (methylene blue) with an initial concentration of 50 mg / l. Water consumption was 2–4 l / min, the characteristic diameter of the droplets was 1.7 mm, and the film thickness at the electrodes was about 0.15 mm. The water was treated in a flat discharge chamber with gas gaps of 3.36 mm and glass dielectric barriers, and in addition in an ozonation chamber, which used ozone that had not previously been useful. The discharge was excited by short ~ 100 ns pulses from voltage up to 21 kV, which provided the current density amplitude up to 1.7 A / cm2 and their energy up to 140 mJ. The decomposition time of the impurity and the energy efficiency of the discharge depending on the pulse repetition frequency of 25–300 Hz were studied. The discharge had the highest energy efficiency at frequencies of 25-50 Hz, at which the energy yield, which corresponds to 50% decomposition of the impurity, reaches ≈270 g / kWh, and for 90% decomposition − 60 g / kWh. As the pulse energy increases, the transparency of the solution for ultraviolet light increases, which is associated with the splitting of stable benzene rings that is part of the impurity molecule. No noticeable effect of water and gas consumption (0.36-1.5 l / min) on the research results was found. References 16, figures 8.