Analysis of the decomposition of methylene blue dye under the action of a pulsed DBD plasma jet

A DBD plasma jet excited by a repetitively pulsed ns pulse power modulator was used to decolorize a 1.4 × 10^-4 M solution Methylene Blue (MB). Time-resolved decomposition of the MB in solution was assessed using spectrophotometry and high-pressure liquid chromatography (HPLC). Spectrophotometry results were found to be in agreement with chromatography measurements. HPLC revealed the absence of appreciable intermediates suggestions high-level mineralization. Acidification was also observed during processing. Also anecdotally explored was the affect of starting volume size on decomposition rate, which revealed that decomposition rates fairly invariant to volume over the range investigated. The discharge apparatus efficiency was also compared as a function of two distinct methods of excitation: 1) ac sinusoidal excitation and 2) excitation via ns pulsed power modulator. Finally, the stable operation of two applicators operating in parallel was demonstrated. Two-applicator operation was found to greatly improve decomposition times though overall decomposition efficiency remained approximately equal to that of a single applicator.