Degradation of organic dyes in water by electrical discharges

Abstract

The degradation of several organic compounds in aqueous solution: methyl yellow (C 14 H 15 N 3 ), methyl red (C 15 H 15 N 3 O 2 ), methyl orange (C 14 H 14 N 3 NaO 3 S), phenol red (C 19 H 14 O 5 S) and methylene blue (C 16 H 18 ClN 3 S), was investigated in a pulsed corona discharge. High voltage pulses of 17 kV amplitude, 24 ns rise time and approximately 200 ns duration (full width at half maximum--FWHM) were applied to an array of six hollow needles. When oxygen was bubbled into the solution through the needle, current pulses of 90 A amplitude were obtained and the average power dissipated in the discharge was 19 W at 100 Hz pulse repetition rate. UV-visible spectra of the aqueous solutions show a significant reduction of the absorbance in the visible range, up to 90%, after plasma treatment, suggesting fragmentation of the compounds. Several aliphatic compounds were identified as oxidation products of methyl yellow, methyl red and methyl orange. For methylene blue and phenol red aromatic reaction products were detected as well.

Paracetamol degradation in aqueous solution by non-thermal plasma

“…H 2 O 2 was also measured since it is a well-known oxidizing species which can react non-selectively with organic pollutants [13]. In our experiments, the increase in treatment duration led to a rise in H 2 O 2 concentration; and at a given time, its concentration was in the same range whatever the inlet gas, as indicated in Table 1.…”

Improved performance of non-thermal plasma reactor during decomposition of trichloroethylene: Optimization of the reactor geometry and introduction of catalytic electrode

“…Futamura and Yamamoto [7] suggest that TCE dissociation is initiated by elimination of chlorine or hydrogen atoms from excited TCE. Secondary decomposition of TCE can be induced by radicals formed from the initial decomposition, which explains the similar or even higher decomposition efficiency obtained for higher initial concentrations of TCE [7,20].…”

“…The effect of residence time on TCE oxidation was investigated in Ref. [20] by varying the flow rate (200-510 sccm) while keeping the same electrode configuration. It was found that the residence time did not influence TCE conversion over the range of input energies used (120-2330 J/l).…”

“…In order to optimize the geometry of the discharge reactor, the effect of the discharge gap length on TCE conversion and on the selectivity to CO 2 and CO was investigated. With increasing the discharge gap, the residence time of the gas in the plasma region increases, which was found to be beneficial for pollutants removal [19,20]. On the other hand, the electrical characteristics of the discharge also change with the gap length, which may also influence TCE oxidation.…”

Characterization of DBD Multiple Bubble Jets for Methylene Blue Decolorization

“…In the present study, a multiple bubble jet system encapsulating O 3 in small bubbles, O and OH radicals generated by a DC pulsed discharge was successfully constructed for decolorizing a methylene blue solution (12)- (15) . Bubble jet dynamics with luminescence and complex streamer behavior inside an argon bubble were successfully visualized.…”