Organic dye decomposition by DC diaphragm discharge in water: Effect of solution properties on dye removal

The process of organic dye removal from various water solutions containing organic dyes and inorganic additives by DC diaphragm discharge has been studied in he so-called “negative part” of this discharge. The concentration of treated dye decreased almost exponentially to constant residual value. The final dye concentration reached approximately 20% of the initial value after 10 min of treating a Direct Red 79 dye solution. The dye decoloration was also affected by dye structure. The azo and diazo compounds were degraded significantly faster to be compared to thiazine compounds. The degradation process required an optimal adjustment of the initial solution conductivity. The optimum conductivity of approximately 600 µS@cm!1 was found when the solution contained either NaCl or NaBr electrolytes. The type of electrolyte used for the conductivity adjustment considerably affects the process of dye decoloration. Halogen compounds were found to be the most appropriate compounds for this purpose.