Influence of dyeing auxiliaries on AB74 dye degradation by UV/H2O2 process

The effect of dyeing auxiliaries on UV/H2O2 removal of an indigoid dye, Acid Blue 74 (AB74) from the solution was investigated. The inhibition effect of anions including carbonate, bicarbonate and chloride on the process efficiency was evaluated in terms of color removal and total organic carbon (TOC) abatement. The presence of carbonate, bicarbonate and chloride anions had no considerable effect on the total decolorization time. However, the degradation efficiency of the process was enhanced by bicarbonate anion during the first 80 min of the process. During this period, the formation of active oxygen species such as CO3−,HCO4−andO2− that participate in the degradation process of AB74 increases the degradation rate, in spite of the consumption of hydroxyl radicals by these anions. After this period, the overall efficiency was considerably decreased. Adding the chloride had less decreasing effect compared to the bicarbonate. The order of anions as AB74 degradation inhibitor in this study could be concluded as: Cl−

► The effect of carbonate, bicarbonate and chloride on the process efficiency was evaluated.
► The predominance of different carbonate species as a function of pH was studied.
► The effect of the simultaneous presence of bicarbonate and chloride was studied.
► The formation of CO3−,HCO4−andO2− species increases the dye removal in the first 80 min.