Comparison between the degradation effect induced by low pressure air plasma and at atmospheric pressure of diethyl (3h-1-ethoxy-3-phenoxazinylidene) ammonium chloride solution

The influence of the number of air molecules on the degradation process of a dye (diethyl (3H-1-ethoxy-3-phenoxazinylidene) ammonium chloride) in aqueous solution by plasma was determined. The concentration of the solution was 17.00 mg/L, and it was exposed to plasma treatments performed at two different pressure values (~24 Torr / ~760 Torr), with an exposure duration of 50 minutes per treatment. Four plasma generation conditions (10, 15, 20 and 30 mA) were used at a voltage of 1500 V. The degradation of the dye was determined by UV/VIS spectrophotometry (absorbance and percentage of degradation) and chemical oxygen demand (COD), pH and bioassays with lettuce (Lactuca sativa) seeds. The temperature change was analyzed for both pressures. The degradation of the dye is more significant at atmospheric pressure than at low pressure for all treatments. The higher the plasma power, the greater the degradation.